New Break-in & Conditioning Rules for Ur New LiPo Packs

Batteries, Chargers, and Battery Management Systems.

New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby deVries » Tue Nov 16, 2010 3:55 am

Ok, this thread is waiting for the experts to post here about Break-in & Conditioning of New LiPo Packs to get optimum capacity and lifespan. I was shocked :shock: to not find much but a few sentences, much less a thread, on this subject at ES, though this has to be a timeless subject with RC groups and newbie LiPo users that just spent $$$x? :mrgreen:

The a, b, c, d, below, will be edited by me as new information is provided on this thread. These are some initial ideas subject to change and editing by the experts. Just post your ideas or PM me to change anything in the a, b, c, or d. Everything else is what I got off the net outside of ES except for a tiny bit I found on ES. Most of what I've posted below "d" is from websites that use radio controlled (RC) hobbies with planes & cars, etc. LiPo is "new" for eBike users, but many on ES were using LiPo for years in their RC hobbies before using it on their eBikes. (This includes Goodrum, Recumpence, Liveforphysics, and many other "famous posters" on ES. :)) In other words, the "RC World" has many more years experience using LiPo, so, imo, ES can learn the most as a starting point from these RC people...

Upon receipt of your new LiPo do the following for break-in...

a. Check sub-packs for voltages on all cells. If within the specified tolerance, [I will edit this in from an expert], then it's "good to go" for conditioning and break-in. Double-check all leads, connections, connectors both before and after each use connecting & disconnecting. Balance lead connections are especially prone to some level of defects in the connectors.

b. To condition and break-in your LiPo it's best to cycle a few times on an RC charger that can monitor the charging and discharging cycles on all the cells with the balancing connectors attached too. Checking for capacity and internal resistance readings (details below) using the charge-balance connections can provide you with a good gauge to find any damaged cells and make certain your cells are healthy in voltage and capacity to begin with. Details about cycling & breakin will be found in the RC snippets I posted below. Generally, cycling the sub-packs 5-10 times (some will cycle 20 times at most) is recommended before real-world use of the final battery configuration. Each cycle is counted as one charge and one discharge using the RC charger in charge, balance, discharge cycle-mode. This will be enough breakin before building the battery to use on your eBike. It is suggested to use a low-charge .5c to 1c rate and discharge between 2c to 5c for the inital breakin. Also, it is recommended to *not* deep-cycle the battery down to 3.0v, but, instead, shallow cycle the battery to 3.5v or higher to begin with. I would suggest doing this higher 3.5 voltage for the initial breakin and, also, for the first 5-10 charge/discharge cycles on the eBike too. Continuing to charge and discharge between 4.1 or 4.15v (for charge) and 3.5v for discharge will extend battery life tremendously according to scientific studies AND real-world use by at least one ES & RC LiPo "famous ES expert" (Recumpence). :mrgreen:

Another very good reason to check your sub-packs for several break-in charge-discharge cycles before building the final battery for installation is that these sub-packs are not (yet) in parallel configuration. Later, you will (probably) be paralleling these sub-packs to get a higher capacity battery, for example, combining three 5ah sub-packs to make one 15ah sub-pack in parallel. This will be your only chance to check each sub-pack before paralleling or connecting & final assembly. So do it now while it's still easy to do, rather than having to take apart the sub-packs later from their paralleled configuration if a problem is detected. Also, if you don't check now, then once the sub-packs are in parallel your voltage meters can't read the individual cells anymore. If a cell goes bad in parallel, then you can't isolate it individually. Better to be safe now than sorry later. :twisted:

c. After break-in cycles, before assembling your sub-packs in series, verify that all your sub-packs are balanced and charged identically in capacity using the RC read-outs with balance connectors or the just stored data that day after cycling & breakin on your charger's program & memory function. (I mention double-checking this just in case you take many days or weeks to complete the battery.) Next, to equalize and "match" all the sub-packs together, as one unit, connect everything in parallel (no series connections) for 1-2 days. This will balance and distribute the voltage and capacities of all the sub-packs together making a giant battery as "a unit of one" perfectly matched as can be. Think of this as a pre-paid "insurance policy" that will payback for certain, as you use the completed battery each day into the future. It is an optional step, this parallel technique, but I've noted many of "the experts" recommend doing this.

d. Finally, disconnect the giant parallel battery and assemble your sub-packs in parallel as needed for your capacity, and then connect these paralleled sub-packs in series to get your target voltage and final battery configuration. If possible, complete this task on the same day, so the sub-packs become "the final battery" on the same day while everything is perfectly matched.

The above suggestions are conservative or perhaps overly cautious, but I'd rather be on that side of the care and feeding equation for "Bad Boy" LiPo. :twisted:

What follows are more conditioning & breakin ideas from "the net" & ES, AND related info you might need to know to understand terms or how to do this, AND how to protect your batteries long-term...

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Breaking in packs – Yes, your lipo’s need a bit of a break-in. You will notice
performance improve over the first 5 flights or so. Ideally the first 5 flights would be a
gentle 5C average discharge. If you have a prop plane that will fly on a 5S or 10S pack
use that for the first 5 discharges before using them in your jet. If not, don’t worry about
it too much, by all means use full throttle on takeoff! But, once you are in the air and
have flown a circuit or two to get up to speed and trimmed out, fly around at ½ throttle
for the rest of the flight. Repeat for the next 3 or 4 flights and your packs will perform
better long term. For the first 5 charge cycles use a charge rate of no more than 1C.

====

LIPO CARE [About newer LiPo released in 2010.]

Break-In Procedure - Hyperion G3 LiPo are robust and do not need a complicated break-in procedure. We recommend that the first 5 uses are limited to 3C charge rates, and that pilots use throttle management to avoid long periods of max-rate discharge for those first 5 flights. Note also the other care suggestions below. Those apply pretty generally to any LiPo pack, not just Hyperion G3...

Discharge - Analysis of damaged packs returned to us by users shows that nearly 70% have suffered from "capacity over-discharge" conditions. This simply means that the pack has been run too long, allowing resting voltage to fall too low. Such damage is visible upon cell inspection at the factory. Every type of battery has a minimum recommended discharge level. For example, even deep-cycle lead-acid batteries should not be regularly discharged down to less than 30%~40% of capacity. In the case of lithium polymer, it is best practice to always leave 20% of rated capacity in the pack at the end of a flight, with 10% as an absolute minimum.

To avoid capacity over-discharge, we recommend the setting of an appropriate cut-off voltage (LVC) AND the use of a transmitter flight timer. For LVC, the appropriate voltage cut-off depends in large on how high the max and average discharge rates are. For very high discharge applications, like F5B competition, something around 3.2V (or even lower) may be desirable. For standard aerobatic flight, start at 3.4V to 3.5V/cell, and set your timer to 4 minutes initially. Then note the capacity charged back IN to the pack on next charge. If the pack is 1000mAh, for example, there should be no more than 800mAh charged back in, meaning that 200mAh remained at the end of the flight (20% of capacity). If the charged IN capacity is less than 800mAh, set the timer a little longer, and check again the next flight. Of course, having the Hyperion Emeter II Remote Data Logger (RDU) makes this even easier, as you can more accurately log the exact mAh Out used each flight and make quick adjustments...

Charge - All Hyperion G3 packs can be charged at 6C rates, with no reduction in cycle life or performance. However, given the negligible difference in charge time for 6C rate vs. 5C, we believe 5C to be the ideal max charge rate for any high-performance Lipo pack. We strongly recommend the use of quality-brand charger, such as the Hyperion EOS lineup, as some generic brand chargers have been shown to use poor components, and may therefore not control charge voltage properly. Hyperion holds that 4.20V/cell (+/- 0.05V) is the proper terminal voltage for Hyperion G3 packs (and all other Lipo). Use of terminal voltages higher than this (for racing, etc) is not covered under warranty, and may be dangerous. (note: some G3 packaging may still state 5C max on front or rear. However, all G3 are rated for 6C max no-loss.)

PLEASE be sure that charging is always done such that in case of fire, no damage nor injury can occur. Keep LiPo well separated (minimum 2M or 7') from flammables, and always use a brick enclosure or "LiPo sack" to insure that any possible fire can be contained. We strongly discourage charging within or near living spaces, or inside automobiles. LiPo charging should be monitored closely at all times.

Temperature - For best performance and cycle life, your Hyperion G3 battery packs should have a resting temperature no lower than 10 °C (50 °F) at the beginning of a Flight, or beginning of Charging. Keep the batteries inside your vehicle or a warmer of some kind on very cold days, to insure best performance and life (this is true for any LiPo, not just G3). If you have any concerns about the temperature on cold days and you have Hyperion NET or DUO charger, you can use the TCS function set to 90% to help insure that the batteries do not suffer over-voltage condition due to the temperature.

Physical - Never cause indentations to the covering of the pack, or cells underneath. Do not use a ball-point pen to write on the pack, for example. Use a felt-tip pen with light pressure instead. When installing packs in the model, insure that they have the best protection possible from impact and pressure damage. Use foam casing if possible. Do not over-tighten hold down straps. Straps should be cloth (velcro) as opposed to hard plastic, such as zip ties. External damage to any Lipo pack can cause salts formations which reduce performance, and in more severe cases can cause fires during charging. Impact Damaged packs should be fully discharged, and disposed of immediately. See below for Hyperion Warranty, and Crash Replacement Program details.

Storage - Lipo should never be stored fully charged, or with less than 50% of capacity remaining. We strongly recommend Hyperion EOS chargers, as they have automatic STORE functions to insure that the packs are in the range of about 60%~70% capacity (3.78V~3.92V resting voltage per cell). After returning home for the day, simply use STORE MODE to achieve this automatically. Batteries are best stored in a cool, dry environment (2~20 °C or 37~68 °F).

======================== next...

BATTERY CONDITIONING:

Contrary to popular beliefs, lithium polymer battery packs have a conditioning period. Before you run new Apogee packs at their maximum continuous discharge rate, we recommend you cycle the battery packs 12-15 times as follows:

1000 mAh – Discharge between 4A and 7A to 3.0 volts per cell.
1500 mAh – Discharge between 6A and 10.5A to 3.0 volts per cell.
2200 mAh – Discharge between 8.8A and 15.4A to 3.0 volts per cell.
3800 mAh – Discharge between 15.2 and 26.6A to 3.0 volts per cell.
5800 mAh – Discharge between 23.2A and 40.6A to 3.0 volts per cell.

If your pack is not listed above, discharge between 4C and 7C (Amp Rate = Capacity / 1000 * C-Rate) to 3.0 Volts per cell. The following conditioning routine is acceptable if you are unable to complete the conditioning process listed above.

Cars/Trucks:
1/18th Scale: Set start up power and motor timing to the lowest settings. On high KV motors, keep the power settings low even after break in. 1/10th Scale: Set start up power and motor timing to the lowest settings. Drop pinion gearing 2-3 teeth below normal. Avoid using full throttle or driving on rough terrain during the conditioning period.

Helicopters:
Gear the motor to where hovering is achieved around 75% throttle. Keep the heli low and slow during conditioning.

Aircraft:
Reduce prop diameter by 2 inches from normal, anchor the aircraft in place and run at 80% throttle until the speed controller’s low voltage cut-off engages.

STORAGE:
If you plan to store your batteries for periods of greater than 4 weeks at a time, it is necessary to store your batteries in a 50% discharge state. 50% capacity is an unloaded 3.7 volts per cell (7.4V, 11.1V, etc). Monitor the pack once a month to make sure voltage has not crept up or down.

Yikes, - "we recommend you cycle the battery packs 12-15 times" - maybe they exxagerated hoping that parkflyers will at least cycle 3 times at low rates.

Also, despite what others say LiPos actually like trickle charging if you have the time/patience. LiPos don't mind a .1C charge, but most flyers would go crazy so a .5C charge is recommended during the entire life of your battery.

So, with your 450mAh Lipo it won't hurt to baby it with a 0.1C for the first few charges. A 1.0C charge normally takes 1 hour. A .1C charge would take 4.5 hours with your 450mAh Lipo(don't know of any Lipo Charger you can accurately set to 0.045 amps) and a .5C charge would take 2 hours set at 0.23 amps. Let's see, would a .1C charge on a 2000mAh 20C battery take 20 hours (I quess that would be one way to see if it really is a 20C. In other words if I understand this--if you were to charge a used 1000mAh 15C Lipo at .1C and it is fully charged in 11 hours your Lipo now has a 11C rating or your Lipo charger isn't accurate, or at .5C and 7.5 hours fully charged would be a 11C rating (all Lipos gradually loose capacity over their life). This gets confusing, but I hope you get the idea.

Having a good Lipo charger with voltage, amperage, and charging time readout as well as a full charge cut-off is a good investment. I use a Vision Peak Ultra with a Blinky balancer. It is good practice to attach the Blinky before charging in case the 3 cells aren't balanced after any discharge.

With all this said you may not have the patience for TLC with a $40 Lipo, but what about a $100 Lipo or a $300 Lipo.

========================= next...

In any event, there have only been two things that caused me premature loss of a lipo. Number one is over discharging (both C rating and minimum voltage) and number 2 is a bad charger.

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In the past i did have 3 identical 3S packs which i broke in 2 as stated above and didn't break in the other at all, just went right into full service. the broke in packs lasted much longer than the non broken in pack. could just be coincidence, but i doubt it. bottom line is it seems true that break in helps and if you don't mind spending the time its worth it especially on a 150+ dollar pack. just my opinion

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I heard storing them 50% charge and at 40F extends their life indefinitely. southern flyer on rcgroups could tell you more.

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Ok guys hear are the facts on break in.

When LiPo batteries are manufactured they use a chemical reaction inhibitor to increase shelf life. It takes a few cycles to chemically use up the inhibitor. This varies a but between manufacturers and they keep making improvements. This is the reason that some batteries have better performance after a few cycles.

Just take it easy for the first few cycles and don’t use more than 80% of the capacity and you will get maximum performance and life out to your LiPo batteries.

The only exception that I have found is A123 batteries. It takes at least 10 cycles before they come up to full power.

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My numbers show that the packs have gradually been increasing in voltage capacity the more I break them in.

I have 3 flights on each battery at 3 minute hovers each.
battery one voltage after each charge looks like this:
12.27v initial charge
12.28v
12.30v

As you can see, the capacity is increasing exponentially with each break in cycle.

Battery #2 is progressing just a bit faster in it's break in..
12.28v initial charge
12.29V
12.32v

My numbers show there is definitely a break in period on lipos.
The pack cannot reach maximum capacity within the first few charges.
They are accepting more and more charge as I go. To what extent this ends I will know soon for these two lipos.

If anything, break them in to watch the pack voltage expand!

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INTERNAL RESISTANCE

Another rating??? Yep, the first 3 are industry standards and as was mentioned with that last one (C discharge ratings), is used by the manufacturers to market their product or justify a higher price and realistically can't be verified, but they are still a good general guide line when choosing a pack.

Internal resistance to the rescue! This one is verifiable and one of the best ways to monitor your RC LiPo batteries condition. Most decent higher discharge rated LiPo cells will have roughly 2 to 6 milliohms (0.002 to 0.006 ohms) of internal resistance when brand new. To calculate the total internal resistance of a series wired pack, you would then add these numbers together so a 4S pack with each cell having 4 milliohms of resistance will show a total internal resistance of about 16 milliohms (0.016 ohms).

As I mentioned, as packs age, the internal resistance goes up and the warmer they run. Lower discharge rated packs will generally have higher internal resistance readings. It is not unusual to measure internal resistance numbers in the region of 200 milliohms on tiny 10C park flyer LiPo packs when they are brand new for example.

Some of my older higher discharge rated packs are now showing 20 to 30 milliohms per cell but they are still working fine - they do heat up a little more however during a flight, so that increasing internal resistance is certainly showing up. As I said, it is great way to monitor the condition of your LiPo packs over the months and years of service.

Checking Internal Resistance of a RC LiPo Battery How do you measure internal resistance? This is where good computerized chargers come into play. The good ones that support this feature with built in balance boards will check the "IR" of each cell as well as the entire pack. Pictured above I am taking the IR reading of each cell in this new 6S Turnigy LiPo. It is hard to make out in the photo, but the IR of cells 1-6 are 2,2,1,1,1,2 milliohms each giving a total IR for the entire pack of 9 milliohms - pretty respectable!

Internal resistance really opens up a huge and complex topic of how to accurately calculate voltage drop in the pack and the total amount of watts being expended in the form of heat within the pack.

I am not going to get into those calculations here for the simple reason I am not qualified enough to explain them. If you are a number cruncher or just really want to dive head first into LiPo calculation and ratings, have a look at FMA's Lipo Evaluation ... Great stuff in there!

Charging RC LiPo Batteries

Charging RC LiPo Batteries is a topic in itself. LiPo, and Li-Ion batteries obviously have some very different characteristics from conventional RC rechargeable battery types. Therefore, charging them correctly with a charger specifically designed for LiPo batteries is critical to both the life span of the RC LiPo battery pack, and your safety.

Maximum Charge Voltage and Current

A 3.7 volt RC LiPo battery cell is 100% charged when it reaches 4.2 volts. Charging it past that will destroy the battery cell and possibly cause it to catch fire. This is important to understand once I start talking about Balancing RC LiPo batteries, so keep that in the back of your head for right now.

It is critical that you use a charger specified for Li-Po batteries and select the correct voltage or cell count when charging your RC LiPo batteries if you are using a computerized charger. If you have a 2 cell (2S) pack you must select 7.4 volts or 2 cells on your charger. If you selected 11.1V (a 3S pack) by mistake and tried to charge your 2S pack, the pack will be destroyed and most likely catch fire.

Most good RC LiPo battery chargers will use the constant current / constant voltage charging method (cc/cv). All this means is that a constant current is applied to the battery during the first part of the charge cycle. As the battery voltage closes in on the 100% charge voltage, the charger will automatically start reducing the charge current and then apply a constant voltage. The charger will stop charging when the 100% charge voltage of the battery pack equalizes with chargers constant voltage setting (4.2 volts per cell) at this time, the charge cycle is completed. Going past that, even to 4.21 volts will shorten battery life.

RC LiPo Battery Charging Current

Selecting the correct charge current is also critical when charging RC LiPo battery packs. The golden rule here use to be "never charge a LiPo or Li-Ion pack greater than 1 times its capacity (1C)."

For example a 2000 mAh pack, would be charged at a maximum charge current of 2000 mA or 2.0 amps. Never higher or the life of the pack would be greatly reduced. If you choose a charge rate significantly higher than the 1C value, the battery will heat up and could swell, vent, or catch fire.

Times are a changing...

Most LiPo experts now feel however you can safely charge at a 2C or even 3C rate on quality packs that have a discharge rating of at least 20C or more safely, with little effect on the overall life expectancy of the pack as long as you have a good charger with a good balancing system. There are more and more LiPo packs showing up stating 2C and 3C charge rates, with even a couple manufactures indicating 5C rates. The day of the 10 minute charge is not far off (assuming you have a high power charger and power source capable of delivering that many watts and amps).

Once again, the three main things that shorten LiPo battery life are HEAT, OVER-DISCHARGING, & INADEQUATE BALANCING.

RC LiPo Battery Balancing

Finally onto RC LiPo battery balancing – what is balancing and why is it important?

Remember me telling you to keep the 100% charged voltage value of 4.2 volts per cell in the back of your head? Well, here is where that number comes into play. For a single cell (3.7 volt LiPo battery) you don’t have to worry about balancing since the battery charger will automatically stop charging when the 100% charge voltage of 4.2 volts is reached.

Balancing is required however on any RC LiPo battery pack that has more than one cell since the charger can’t identify from different cells and know if one might be overcharged even though the total voltage of the pack indicates otherwise. For example let’s look at a 3 cell LiPo battery pack (three LiPo cells hooked in series or 3S).

This would be an 11.1 volt battery pack (3.7 volts per cell x 3 = 11.1 volts). The 100% charge voltage of this LiPo pack = 12.6 volts (4.2 volts x 3 = 12.6 volts). Our trusty charger set up for a 11.1 volt RC LiPo battery pack will then stop charging at 12.6 volts – simple right.

Well what would happen if one of those three cells is charging a bit faster than the other two? There could be two cells at only 4.1 volts and the one that is charging at bit faster could be getting overcharged up to 4.4 volts before the charger stops charging at 12.6 volts. That would certainly cause damage to that one cell, perhaps even a fire.

This is an extreme example and that kind of voltage difference between cells is unlikely with a healthy pack, but even a 0.1 (100 mV) voltage difference between cells can cause issues and damage over time.

On the other end of the spectrum is if there is one cell in the pack that is not reaching full charge when the pack is charged and then gets discharged below 3.0 volts even though the 3 cell battery pack is indicating a voltage of 9 volts or higher.

Balancing ensures all cells are always within about 0.01-0.03 volts per cell so over charging or discharging of one or more cells won’t ruin your battery pack, or worse become a safety issue from overcharging a cell.

You don’t have to balance your RC LiPo battery pack each time you charge it. Most will agree every 10th to 20th time is fine with a healthy battery pack. The problem is knowing if your pack is healthy, cells in older packs may become unstable? As far as I am concerned, if you have a good balancer or balancing charger, use it at every charge, or at least at every 2nd charge. That might be overkill, but if it prevents a damaged battery or fire just once, well, you decide.

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[I'll edit any of the above information for accuracy, etc., once we get posts from the LiPo experts on this thread.]

===========

A good basic LiPo info link LiPo Detailed Info I got some snippets from noted above...

===========

All I found on ES here...

Nominal voltage is the optimal storage voltage for all lithium based cells. For LiCo, 3.7v. For LiMnCo, 3.6v. For LiFePO4, 3.2v. This is the voltage at which the cell has the slowest rate of deterioration over time.

If you plan to keep them stored for an extended period, drop to about 3.8-3.9v, then throw them in the freezer. The temp change will drop the resting voltage to nominal, and the chart I saw for some LiCo polymer cells at 28degF showed something like 12 years shelf-life to 80% capacity. It was 3 years at 70degF.

===

Yes, 50% to 55% is perfect state of charge for long term storage.

===

Cold Weather Mode > Did you realize that charging lithium batteries in cold weather (below 50 deg F [10 C]) can cause permanent damage to the battery? Yes, it is true. In fact, at temperatures approaching freezing, a single charge to 4.2v can actually cause complete loss of battery capacity. The damage is permanent and irreversible. For this reason, the Cellpro 4s charger monitors ambient temperature and reduces the full charge voltage to 4.1v per cell below 50 deg F (10 C), preventing damage to the batteries.

===

In 5 years of running over 150 lithium polymer packs and many thousands of charges, I have never, EVER had one pack go out of ballance! Not even one! Lipo packs just tend to hold ballance. I also disagree that problems occur when smaller capacity RC packs are used. RC packs are typically the highest quality cells out there (nrmally by a very large margin).

Every single Lipo problem I have ever seen has been related to charging, not the type of cells used and/or ballancing or BMS.

I also disagree that the number of cycles is less than other cell types. For very long Lipo life, I recommend charging only to 98% capacity, keeping 40% capacity in the pack before recharge, keeping the cells over 3.3 volts under load, and keep them in a constant temperature (somewhere between 50 and 100 degrees. Very high and very low temp can shorten Lipo life as well). If they are run very hard repeatdly, yes their life will shorten. However, if you take care of them, you should see 1000 cycles or more out of your Lipo packs.

===

Absolutely NEVER Exceed 4.3v/cell, never Discharge below 2.7v/cell, never puncture the cells.

With other cells, they often give warnings similar to that, and you can break the rules as much as you want, and suffer nothing, or maybe a little drop in cell capacity. LiPo is NOT like other batteries in this regard, when you break the golden rule, often even just one time, you are effectively telling the battery to fail into a ball of fire.

If you wish to use LiPo, you MUST follow that rule. No exceptions here. No room for error. No Oops, my charger reset, no excuses.

The most simple way to follow that rule is to use the wide range of awesome microprocessor controlled chargers made for LiPo batteries. They will never let the first part of the rule be broken.

For the second part of the rule, you need to watch your pack voltage while riding, or setup a LVC if you are the forgetful type. If you do ever deep discharge a cell, you are in no immediate danger. As long as the cell doesn't reverse polarity it wont explode just from excessive discharge. However, when you go to re-charge that cell, this is when you will see the fireworks. If you want to attempt to re-charge a deep discharged cell, do it in an area that you wouldn't mind making a bonfire. Maybe invite buddies over to watch. You can always stab it to make it go off if it doesn't go by itself. A deep discharged cell should never be trusted again in a string with good cells.

===

When running a LiPo pack, the first rule is NEVER discharge the pack beyond 80% of its capacity (20% remaining). So, on my 10ah pack, I always keep at least 2ah of power left in the pack. This is extremely important. If you do not keep at least 20% capacity in the pack, the cells will have a VERY short life!

Second, never pull more C out of the pack than it is rated for. If you have a 15C pack, do NOT exceed 15C! That rule, combined with the 20% rule stated above, are critical to a long life for your pack. Also, those rules are interrelated and relative. What I mean by that is, the less C you pull from the pack and the more capacity you leave in the pack before each recharge, the longer the pack will last. I have one pack in an RC transmiter that is always recharged with 40% of the capacity left and I never pull more than 1C out of that 10C pack. That particular pack is over 5 years old and runs like new! However, if I pull the rated C out of a pack and discharge it down to 20% capacity, it will need replacement in roughly 500 to 1000 recharge cycles depending on the pack and how careful I am with it.

===

Having a fair amount of experience with high-power LiPo packs in RC Helicopters, I can attest to the fact that the higher C LiPo cells do require a bit of break-in before they really reach maximum potential and capacity.

===

On the bright side, many of the "5Ah" hobby city cells end up around 6Ah after break-in. They are also the most commonly produced cell size, so I would assume this enables the $/Wh ratio to be kept so nice.

:cool:
Last edited by deVries on Tue Nov 16, 2010 9:32 pm, edited 7 times in total.
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Re: New Break-in & Conditioning Rules for ur New LiPo Packs

Postby dogman dan » Tue Nov 16, 2010 7:18 am

Just my opinion, but at the top, I don't think step c is really needed. A good charger is going to get em close. But do take a peek at voltages before hooking up balance leads paralell. Make sure they are pretty dang close before paralelling by the balance leads. No 1v cells hooking up to 4 v cells. :roll:

I have seen the effect of break in cycles a few times now, but I don't think it usually takes a complicated procedure. I usually just put new cells on a bike, and take a mellow ride around the block, then back on the charger. Just quicker than cycling it on the charger. Pulling 10 amps on a 5 ah pack of 30c lipo is not going to faze it. If it does, I want that pack gone anyway. Same procedure for a ping or equivilant. Just put 5-6 shallow low amp cycles on it at first, then go easy on it for another 5 or so. So the second 5 cycles might be full amps, but still fairly shallow depth of discharge. About cycle 10, then let er rip and start cycling to as much as 80% dod.

All through this process, keep looking at things with the voltmeter, or if you have it, monitoring on the readout as they charge. Once in a great while, you might have a pack with one lazy cell that doesn't start perking up in 2-3 cycles. If so, you may want to cycle that individual cell a couple times with a light bulb and 5 v power supply. Once it does perk up, then continue like normal.

If a bms pack, like a ping, you don't want to trust the bms till it's proven itself. Check for excessive heat, and if hot, find out why. Don't test the lvc till the pack is well broken in, and you know it's not having one cell get very low early. Checking with voltmeter after a ride will reveal this problem if you have it.

Just a few sentences is all that was needed to explain break in. Even for me writing it.
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby GCinDC » Tue Nov 16, 2010 3:49 pm

holy long post, batman. thanks for putting it together though. saves me time hunting elsewhere!

but i wonder if any is obsolete..? if this is true, i need a spanking!
deVries wrote:Cold Weather Mode > Did you realize that charging lithium batteries in cold weather (below 50 deg F [10 C]) can cause permanent damage to the battery? Yes, it is true. In fact, at temperatures approaching freezing, a single charge to 4.2v can actually cause complete loss of battery capacity. The damage is permanent and irreversible.

well, actually it can't be true, since i charged outdoors all last freezing winter. won't do so this year though...
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Re: New Break-in & Conditioning Rules for ur New LiPo Packs

Postby deVries » Tue Nov 16, 2010 3:51 pm

dogman wrote:Just a few sentences is all that was needed to explain break in. Even for me writing it.

Hi dogman, thanks for noting a "quick and dirty" approach to "break-in", but, for me, I would not follow this approach. I am new to eBikes AND LiPo. You are new to LiPo without years of experience using LiPo from the "RC World".

I would rather set-up LiPo so it could be properly conditioned and tracked accurately from the beginning before even using it on an eBike. Especially, since I have no eBike experience and don't want "to focus" on my LiPo that intensely while riding, when I can do the break-in in a safe environment off the bike & focus intensely "there" instead. (Note this method would be ideal too for techies or "battery research", since one can log charge & discharge data on the charger's memory for tracking, on the computer with sophisticated software for tracking & charging & data plotting, or on tiny portable take-along data tracking devices, such as, Cell-Logs, etc.)

The a, b, c, d, in the initial post above is very short. It's about the same length as your post above, but I do want to provide many details below that too. Why?

Because it can take many hours, even days, to collect that information for a newbie. I put it all in one post, so one doesn't have to read 50-100 posts or even that many pages on ES or elsewhere.

I'm hoping the experienced LiPo RC users, such as, Goodrum, Recumpence, Liveforphysics, etc... will contribute to this thread too. There are very few eBike users that go back a few years that have that eBike-LiPo experience too. Of course, I welcome your post & ideas too, so thanks sincerely!

:)
Last edited by deVries on Tue Nov 16, 2010 4:25 pm, edited 1 time in total.
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby deVries » Tue Nov 16, 2010 4:09 pm

GCinDC wrote:holy long post, batman. thanks for putting it together though. saves me time hunting elsewhere!

but i wonder if any is obsolete..? if this is true, i need a spanking!
deVries wrote:Cold Weather Mode > Did you realize that charging lithium batteries in cold weather (below 50 deg F [10 C]) can cause permanent damage to the battery? Yes, it is true. In fact, at temperatures approaching freezing, a single charge to 4.2v can actually cause complete loss of battery capacity. The damage is permanent and irreversible.

well, actually it can't be true, since i charged outdoors all last freezing winter. won't do so this year though...

Thanks! "Robin" :mrgreen:

This "sock, pow, holy cow" quote came from a respected charger manufacturer, FMA's website. Check it here under "Cold Weather Mode"...

Click Here & Look for Cold Weather Mode

"...The damage is permanent and irreversible. For this reason, the Cellpro 4s charger monitors ambient temperature and reduces the full charge voltage to 4.1v per cell below 50 deg F, preventing damage to the batteries." :wink:
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby Jeremy Harris » Tue Nov 16, 2010 5:10 pm

Some of the stuff from the RC folk is OK, some is just bit anally retentive bullshit. There is a whole folklore that has built up in the RC world about LiPo, some based on fact but a lot is just near total myth. The bottom line is that these things are really, really simple devices, with very straightforward characteristics. There's no magic locked up inside a LiPo cell, just some basic ion exchange chemistry.

The "break-in" is nothing more than cycling the chemistry to get it up to a good ion exchange rate, but why waste charge/discharge cycles (which are fairly limited with LiPo anyway) doing this on the bench? It's far better to use this energy usefully, propelling your bike than just heating up a load.

Like all chemical reactions, the charge and discharge of LiPo cells is affected by temperature, but at the normal range of temperatures we work in this isn't a massive effect. Anyway, there's not much we can do about it (without expending more energy than we're likely to lose in keeping things at a constant temperature).

We can sit and worry ourselves into a frenzy about getting the last 1% from a battery pack or we can just ride and ignore most of this stuff - the performance differences that all the RC world hype will make will be less than the variation we'll see from day to day riding different routes.

They do have different objectives to us, which may colour the way they worry about cells. We are unlikely to discharge at more than 2C to 3C average (who wants a bike that runs for less than 20 mins?). The RC crowd run at massive discharge rates and frequently discharge a pack in 5 to 10 mins.

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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby dogman dan » Tue Nov 16, 2010 5:27 pm

I agree Jeremy. I think the good stuff I got started with, turnigy, zippy's, is not nearly as fussy as some people are. So being pretty new to lipo, it seems like great stuff to me, provided you don't break LFP's golden rules. I don't see the need for so much fuss.

I don't think a short ride on a bike with a 20 amp controller can do much damage to a 30c lipo pack, nor is it a usefull ride for me. Nothing is close to my house. It's simply my way of getting breaking in 8 new packs over with a bit faster. But hey, if watching the pack cycle in a charger rocks your boat, enjoy! I just want to get er done, and on to the zooming around.

If you have a sucky cell in there in your new packs, paralelling it with the rest of the pile (step c) is not going to do it any good. If the previous break in cycling didn't wake it up, it's not going to. But of course, you do want em close before you hook up paralells.
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby deVries » Tue Nov 16, 2010 7:01 pm

dogman wrote:I agree Jeremy. ...
If you have a sucky cell in there in your new packs, paralelling it with the rest of the pile (step c) is not going to do it any good. If the previous break in cycling didn't wake it up, it's not going to. But of course, you do want em close before you hook up paralells.

I think Jeremy makes a good point about "LiPo hype" in the RC World, and, also, the fact that LiPo is stressed to near its limits with 3D flying, etc. Dogman's counter point of using LiPo on an eBike at lowered C rates with a typical 20amp controller compared to RC 'is' much lower stress on the LiPo battery to begin with. (Please note there are super-charged high-amp eBikes running on LiPo though.)

Going back to the "quick & dirty" method... IF someone does not have the money to invest in a good LiPo balance-charger and "bulk charges" instead w/o balancing -OR- one just wants to hurry-up and get going w/o fancy-charger, THEN STEP C is the "quick and dirty" way to go by paralleling all the batteries together w/o a balancer available. In effect, that is perhaps the only balance method without the LiPo balancer. Of course, sub-packs would need to be near matched voltage & capacity to connect together in parallel this way. Checking the sub-packs with a LiPo voltage meter after the "bulk charge" is cheap & quick-n-easy to do.

Lastly, I will "trump a point" by suggesting for many new to LiPo AND without having their eBike finished (can not install the LiPo-battery on the bike yet)... then, definately, don't wait to test and break-in your LiPo on the eBike. Go ahead and familarize yourself with your LiPo batteries and equipment off the eBike. Condition it and break it in with 5-10 cycles off the bike while you learn what you're doing and gaining experience too. Then, when your eBike is ready for the LiPo mounting and EV grins, you can ride with confidence the LiPo is up to the challenge too.

Another very good reason to check your sub-packs for several break-in charge-discharge cycles before building the final battery for installation is that these sub-packs are not (yet) in parallel configuration. Later, you will (probably) be paralleling these sub-packs to get a higher capacity battery, for example, combining three 5ah sub-packs to make one 15ah sub-pack in parallel. This will be your only chance to check each sub-pack before paralleling or connecting & final assembly. So do it now while it's still easy to do, rather than having to take apart the sub-packs later from their paralleled configuration if a problem is detected. Also, if you don't check now, then once the sub-packs are in parallel your voltage meters can't read the individual cells anymore. If a cell goes bad in parallel, then you can't isolate it individually. Better to be safe now than sorry later.

IF you want your LiPo to last for over a 1,000 cycles, then you're not wasting time or your LiPo's lifetime capacity by carefully charging & discharging during these inital learning & breakin cycles, imo. After all, it's U that is the smart charger anyways... :wink:

:mrgreen:
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby dogman dan » Wed Nov 17, 2010 7:18 am

And now I agree with you. I never said bulk charge with a dumb charger for lipo, nor do I advocate ignoring the state of charge of each and every individual cell during break in. You definitely want to know what is going on during the break in.

Youbetcha you want to have at least one good lipo charger around if you own lipo. How else do you balance charge them occasionally when needed? One cell at a time with a phone charger? Nothing wrong with cycling the new batts on a good charger. But nothing mandatory about how you do the first few discharges, other than keep it mild.

I was just advocating a quicker way to do the discharging for the first few cycles for a guy who does have the bike up and running. And Yeah, you wouldn't want to pull full throttle if you have a 50 amp or larger controller. You want to pull about 1c max for those first break in cycles of lipo. On a 2c ping pack, you'd want to pull about .5c max.

Now I understand about step c. Makes sense if you did skip step one, getting a good charger.

I also think permanently rigging stuff on the bike is dumb. You want to be able to easliy swap out bad packs, or at the minimum, be able to hook up and balance an individual pack. Say you have three packs soldered permanently in paralell. How do you know which one has a funky cell in it later, if you can't unplug and check the cells individually. At least, you want to be able to unhook the balance wires and put a meter on the individual pack. Any time you lose the capability of monitoring your battery manualy it's bad.
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby jateureka » Sun Feb 20, 2011 10:56 pm

Thanks for condensing that info and putting here for quick access.

I would question a couple of comments though:
-------------------------------------------------------
"STORAGE:
If you plan to store your batteries for periods of greater than 4 weeks at a time, it is necessary to store your batteries in a 50% discharge state. 50% capacity is an unloaded 3.7 volts per cell (7.4V, 11.1V, etc). Monitor the pack once a month to make sure voltage has not crept up or down.".


and

"Nominal voltage is the optimal storage voltage for all lithium based cells. For LiCo, 3.7v. For LiMnCo, 3.6v. For LiFePO4, 3.2v. This is the voltage at which the cell has the slowest rate of deterioration over time.

If you plan to keep them stored for an extended period, drop to about 3.8-3.9v, then throw them in the freezer. The temp change will drop the resting voltage to nominal, and the chart I saw for some LiCo polymer cells at 28degF showed something like 12 years shelf-life to 80% capacity. It was 3 years at 70degF.

===

Yes, 50% to 55% is perfect state of charge for long term storage."

-----------------------------------------------------------------------

Tests on LiPo have shown that 3.7V is about 55% capacity under load.
If you are measuring the voltage unloaded / at rest then it is more like 3.85V.
Last edited by jateureka on Tue Jun 07, 2011 2:55 am, edited 2 times in total.
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby Bazaki » Tue Feb 22, 2011 7:09 pm

4.20v = 100% 12.6v
4.03v = 76% 12.09v
3.86v = 52% 11.58v
3.83v = 42% 11.49v
3.79v = 30% 11.37v
3.70v = 11% 11.1v
3.6?v = 0% 10.8v

Found this somewhere, it is with unloaded lipo.
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Re: New Break-in & Conditioning Rules for Ur New LiPo Packs

Postby stoney » Mon Jun 06, 2011 12:42 am

Thankyou for posting this...
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