Breaking in a new 48V 20ah Li-ion batt?

[Kerrith]

I'm about to receive my new 1000w rear gearless motor e-bike. It will have a 48V 20ah Li-ion batt. I'm assuming it will arrive at least partially charged. I'm wanting to know the best way to break in such a batt.

Is there some test I can conduct to determine if the batt is working as designed?

And, how and when to charge it? i.e. after each use even if it's not too low.

How much damage is done if I run it in the red?

Any other tips?

Thanks,

Kerry

 

[dogman dan]

Charge when you can. No benefit to discharging all the way, like riding for several days waiting to charge. Benefit from keeping it balanced, which typically happens when the bms works as the charge cycle finishes. Most bms equipped batteries need time plugged in after the green light goes on. The red light may come back on briefly several times. Don't make a habit of unplugging as soon as you get the green light every charge. But you can ride even if not fully charged when you have a need to. Just give it the overnight, or all evening on the green still plugged in regularly, to get fully balanced.

If by riding in the red, you mean discharging it completely, a bms equipped battery should shut off before it gets damaged. But 100% discharges do tend too unbalance a battery more, so I got in the habit of doing an overnight charge, or a balancing charge with RC batteries after rides that discharge deep.

Out of the box, the "break in" is really just giving the bms more time to work. This gets done fastest, by fully charging, then taking a short ride around the block, then putting back on charge for several hours. Give it time after the light turns green, so overnight is good when night comes.

Checking is made hard to do on many batteries. Generally, there is no access to individual cell terminals to check the voltage of each cell group. Later on, after the warrantee period is over, you might want to add plugs to give such access. Meanwhile, your battery should reach the same voltage as the charger puts out eventually. If you unplug, and the voltage drops immediately, it needs more time on the charger. Voltage may drop after an hour or so, in a healty battery. This can be the bms finishing up draining cells that normally receive a slight overcharge as the pack balances.

 

[mlt34]

Just make sure you are charging regularly. I always advise people like this "Did you ride the bike today? Then charge it tonight". Don't treat your battery like a cell phone and let it run all the way down. 100 half discharge cycles are better for it than 50 full discharge cycles, even though they are both technically still '50 cycles'. The nice thing is that at 1000 whrs, it will be hard to drain that sucker without a really long drive

 

[Kerrith]

Thanks dogman & mlt34,

Excellent advice(s), exactly what I was wanting to know.

I'll post a review of the Leaf once I've played with it for a week or so—it's due to be shipped 6/27.

With aloha,

Kerry

 

[chas58]

Read this:
http://electricbikereport.com/top-5-tips-for-lithium-ion-electric-bike-battery-care/

for your first 4-5 trips use the battery gently and don't draw a lot of current. This will help keep the batteries ballanced.

With a good BMS and controller, you are not going to hurt your battery by draining it, but charge it every day you use it (and regularly if you don't use it). Short charges are better than long charges.

 

[dnmun]

Read this:
http://electricbikereport.com/top-5-tips-for-lithium-ion-electric-bike-battery-care/

for your first 4-5 trips use the battery gently and don't draw a lot of current. This will help keep the batteries ballanced.

With a good BMS and controller, you are not going to hurt your battery by draining it, but charge it every day you use it (and regularly if you don't use it). Short charges are better than long charges.

that guy just talks useless blather.

only use the charger provided by the manufacturer?

charge it full to leave it stored?

where is there any evidence the guy knows anything about batteries? so many newbies with so much opinion.

never did he say a thing about the different types of batteries, why they are treated differently or even tried to explain why it is bad to leave the battery unused for lengthy periods. nothing about the balancing current when the charger led goes green. just blather.

 

[chas58]

Another article:



LifePO4 Battery Break-in Process
http://www.gocarlite.com/E-BikeTechnology.php
Battery Break-in Process
Lithium battery packs, especially LiFePO4, have to go through a break-in period. The pack is made up of several cells connected in series, for example a 36V LiFePO4 pack has 12 cells. When new, the cells do not charge and discharge at the same rate. One reason may be a chemical inhibitor that is added to slow down self-discharge. At any rate, there is a chemical process going on with-in new cells that cause them to perform differently when new.

Often the first thing a customer will do when buying a pack is to go out and really ride it hard to check the power and range. Unfortunately, that is not the best thing to do. It is recommended to perform 5 to 10 cycles of low discharges followed by full charges. A low discharge would be drawing 1-3 AH or riding 2-5 miles without heavy loads. Since the cells will discharge at different rates, the first cell to reach the minimum voltage will trigger the detection circuit in the BMS, which shuts off power. The range will be low and the customer thinks they have a bad pack. By doing short cycles the cells have a chance to equalize and not get far out of balance. The BMS has a balancing circuit, but it does not have the ability to bring up a cell that is much lower than the others. They have to be kept within a certain range of each other. In addition, leaving the pack on the charger over night gives the BMS time to equalize the cells. You may see the charge LED (green light) on the charger blink between red and green during this process. The pack is charged in "serial mode" where the charge current is passed through each cell to get to the next one. So each cell has to share part of the voltage going in, typically 44V for a 36v LiFePO4. During the critical break-in period some cells will accept current more than others. Thus, it is critical to follow the break-in process to optimize the performance of the pack.

Once properly broken in the pack will stay in balance if charged after each use and not left for long periods without charging. While rare, it is possible that a pack can become unbalanced even after being broken in. The solution is to charge up each cell separately until they are equal. This is not something the customer can do as working on the cells is dangerous. Not all suppliers have the technical ability to do this. At Electric Bike Solutions, however, we offer this service to our customers and can even replace individual cells in the unlikely event one goes bad.

So the bottom line is when you receive a new pack, for the first 5-10 times you use it, ride the bike only a few miles followed by charging.
___________

 

[chas58]

True, it is kinda lame...

The second article from gocarlite is much more useful.

Read this:
http://electricbikereport.com/top-5-tips-for-lithium-ion-electric-bike-battery-care/

that guy just talks useless blather.

only use the charger provided by the manufacturer?

charge it full to leave it stored?

where is there any evidence the guy knows anything about batteries? so many newbies with so much opinion.

never did he say a thing about the different types of batteries, why they are treated differently or even tried to explain why it is bad to leave the battery unused for lengthy periods. nothing about the balancing current when the charger led goes green. just blather.

 

[Kerrith]

Thanks all,

I'm so glad I asked the question. I sure appreciate the valuable information. I probably would have discharged the 48V 20ah batt too severely the first few rides.

I'm concerned about the Leaf's BMS because the web page doesn't mention a BMS or Controller. (see http://www.leafbike.com/products/electric-bicycle/20-inch-folding-electric-bike/new-20-inch-1000w-folding-electric-bike-957.html ) Perhaps I'm misunderstanding something?

Kerry

Thanks chas58. That's invaluable information:

LifePO4 Battery Break-in Process
http://www.gocarlite.com/E-BikeTechnology.php

 

[mlt34]

Many ebike manufacturers don't list tech specs or even mention the BMS because it is seen as a fairly technical part, and sometimes the same goes for the controller to a lesser extent. But fear not, the bike wont drive without a controller and the battery won't charge right without a BMS so they should definitely be there.

 

[dnmun]

Thanks all,

I'm so glad I asked the question. I sure appreciate the valuable information. I probably would have discharged the 48V 20ah batt too severely the first few rides.

[/quote]

no, i doubt it. if the battery has a BMS, which it does since it was made by a battery manufacturer and not a hobbiest like these people, then it would be protected from over discharge. that is the only real risk.

when the battery is manufactured the last stage is to send the battery cells through what is called the forming charge where the battery is charged up and drained to exercise the ions into storage and then out and to form what is called the SEI surface electrolyte interface as i recall the term, and you wanna do that a few times yourself as you use the battery initially. so using it at very low discharge and charge rates does the best at imitating the low current forming charge state.

the biggest problem people have is when they don't use a BMS on their home built battery and then they charge it up and some of the cells go to 5V since there is not a BMS to cut off the charging. then the battery is discharged and some cells go below the lowest voltage the cell can deliver charge and that damages it too. so after a few cycles a battery with no BMS can be totally ruined. kinda sad to watch these kids so desperate to save money they try to skimp on protection for the battery and end up losing these really nice A123 packs they built. kinda like driving a car without insurance to save money and then getting in a wreck.

 

[Kerrith]

The leaf is coming with a 2 amp charger. Would it be smart to ask them to upgrade it to a 5 amp charger or buy a quality after market one later?

 

[dogman dan]

I would recommend a 5 amp charger later. Many good vendors out there, so you aren't stuck with leaf. Upgrade now if the upgrade will be really cheap.

The 2 amp may be all you need though. Depends on what your use pattern will be.

 

[dnmun]

tell them you want both chargers. the 2A and the 5A charger and that you will only pay them an extra $25 for the extra 5A charger. they only pay about $15 so that should work for them too.

 

[Kerrith]

I agree, I'll try their included 3amp charger and then upgrade to a 3rd party 5amp one if necessary.

Thanks,

Kerry