HobbyKing Lipo Battery Pack

*I changed the title*

Couple quick questions

Got my 15 packs of batteries in, I used my Cell Log 8 to measure all my batteries.



Right so within the 0.01V to 0.03V is what I want right?
So on that basis the 40mV and 60mV batteries (1, 3, 11) are no good.

Do I do the initial charges/discharges and see what happens, do that a few times and if they are still out of spec (0.01V - 0.03V) I put them aside for "surgery" or use as spares for testing and whatever else?
 
is this the voltage they came at? did you charge or discharge them? afair those are rc lico chemistry.
celllogs sometimes give varying readings. it's always good to double check them.
batteries normally come charged TO THE VERY SAME storage voltage level of 3.85v. these seem to been have charged to 3.90v. then they are kept at this level until they are sold. so every cell that is significantly LOWER than they rest needs to be taken care off.
i personally would ditch those three cells from pack 1,3,11. and make on good pack from the remaining ones.
self discharge bench testing is something that takes a long time so normally you don't do it, and that's why checking batteries on receive is very important.
i would not call those cells bad, but i'm sure they will have a higher internal resistance and will be the weakest link in you chain.
what i would do: balance charge them to 4.20v while being next to the charger (something that should not need to be mentioned anyway) and then let them sit for 1-2 days on the shelf. then do the voltage check again and compare to your first reading.

btw: you can make screenshots from every OS i know of quite easily. posting photos adds this moire effect to the picture and make readability worse :)
 
Yes thats the voltages they were shipped at, and literally I just recieved the last 10 today, the first 5 have been sitting around for a few weeks.
I havent done nothing yet as I am waiting on a few other shipments. Just plugged in the Cell Log and wrote down the #'s cuz thats what I see/read others do. Reading the battery pages, getting more info as I go.

The batteries are Hobby King Tunrigy 4S1P 5000mAh

Picture sux I know. I just take pictures, open in paint, reduce to 50% and 50%, save to desktop and upload.
I will look into screenshots. Thanks for the headsup. Anyways I changed it, screenshot to file, doesnt pop up like before.
 
ok. so what charger do you have to charge the batteries?
i'm not sure as i didn't follow the whole thread.

you can charge the batteries as i said and let them sit for a while. this gives a good idea about their quality. common agreement is that you should not storage them fully charged. so discharge to 3.85v after testing if you won't use them.

the picture attached is 809px wide. this exceed the maximum allowed to show inline by 9px.
better tool than paint to do it is: paint.net of just use https://imageresizer.codeplex.com/ to do it with right mouse-click.
 
dnmun said:
don't be absurd. there is no reason to throw away the pouches you just bot. how loonie. reached new levels of insane assumptions about what a cell voltage means.
Click to expand...
no need to be rude. he asked for advise. and this was MY advise, and how i would do it. he can follow it or not.
DON'T CALL ME INSANE.
 
The charger I got is an IMAX 8Bplus that does 8S batteries. So was thinking connecting two 4S1P to individually balance for break-in period.
Then parallel charge them.

http://www.hobbyking.com/hobbyking/...IMAX_B8plus_Charger_Discharger_1_8_Cells.html

View attachment 2

My plan was to just balance charge them, and discharge(through IMAX) them all individually multiple times, like 5 to 10 times.
Each time I would record the voltages, noting the difference in cells, keeping in mind I need around 0.01V - 0.03V difference.
What should I do then if the cell voltages are off by more then 0.03V?

A few things to take note, my motor and wheel are not laced yet. Waiting on a bigger 24" rim, I bought a 20" rim which I think will be too small on my mountain bike. I am also waiting on the 3 prong power cord for the power supply.
http://www.hobbyking.com/hobbyking/..._105w_7A_Compact_Power_Supply_100v_240v_.html

View attachment 1

I go to get going, wrenching on my truck today. Will see what the issues are with my photo uploads.

Heres another go at voltages, see if it pops up like a picture in the thread, or just a click on it to view.

 
lico imho is not like nihm or nicd. they don't need this dicharge/charge cylcles to show their full capacity. and with this charger you will not be able to determine a weak cell. discharge rate is sooo low. so a higher internal resistance can not be noticed as easily.
i would fully charge them to 4.2v and discharge to 3.5v. so you know the capacity. weaker cells will go down faster below ~3.6-3.7v and a pack with weak cells will come out of balance faster.
then charge again to 4.2v and let them sit for 1 day or two. i no cell is way off then you're fine i guess.
 
Well, I would not recommend that eBikers go the lipo route. But now that you have, yes, you'll need to exercise the kind of caution you are anticipating, to protect your investment, home & life.

What happens (and this is true of all lithium-ion cells, but more so with lipo), is various kinds of internal degradation, on the cathode & anode plates and the electrolyte. Internal resistance builds. That IR means more heat on both charge & discharge. The heat degrades the electrolyte to the point its out-gassing. That leads to puffing of the cells. Puffing can cause failure of the wrap & seams. Which in turn can allow gases to escape, including oxygen, which is highly flammable. So now you've got an explosive situation of electrical shorting, sparking and flammable gases. Once set the intense heat causes further rapid breakdown of the electrolyte and eventually an uncontrollable fire. Lipo fires are difficult to put out once started. So the precaution of charging them in a fire proof enclosure. And having a bag of sand on hand to put a fire out before it gets out of control.

One of the important precautions is to put your battery pack in compression bound by metal plates. This actively discourages the above process and has the added benefit of containing it in a way that makes it more difficult for a fire to get under-way.
 
again, this is not true. thermal runaway is initiated when the cell reaches a critical temperature when the pack cannot continue to shed the excess heat created from overcharging. i have posted links to the lectures which explain the critical temperature for initiation of thermal runaway and the damage to lipo from charging on other threads so there is no reason for the misinformation about lipo to continue.
 
Thanks for the headsup, I was aware of the safety issues before buying, but its always a good reminder.

OK so then if the discharging is gunna be too slow.
Here are the specs for the charger
Discharge current range: 0.1~5.0A
Current drain for balancing Li-Po: 300mAh/cell

Then I do the 100W light bulb route for discharge? How fast will that deplete/discharge the battery?

As for IR, I did buy a $20 Multimeter from Crappy Tire today. Do I measure each cells resistance?
I did notice the Cell Log was off by 0.01V on total voltage of one battery I measured.
 
5A discharge is NOT for the whole pack. if you discharge a 4S lipo it will go down to 1.14A. which will mean that a 5Ah battery will take 4h to discharge. so if you want to do several (!!!) dis/charge cycles you will need A LOT of time :)
14.4V is a nice voltage for halogen bulbs (from home lightning or car head lamps).
the equation is POWER = CURRENT x VOLTAGE
100W = CURRENT x 12V -> current = ~ 8A (+/- as voltage goes down from 14.4v to 12v - so current varies between 7-8A)
and 7A discharge will discharge your battery within 5/7th of an hour (5Ah/7A)= ~45min
you can put 2 or 3 (or more) bulbs IN SERIES which will result in double or triple current = 15-20min discharge time.
measuring IR is a special science :) normally you would need multi k$ equipment to get the "real" value. yes. these tools are really expensive (ask use DOC about it). for a good estimate you will do the following:
you connect you celllog or your charger in monitor more to the balance plug. that way you can monitor the cell's voltages. write those values down. now connect your multi-bulb discharger to the power wires. this will lead to a voltage drop. the voltage drops very fast within the first seconds and then decrease line is quite flat (normal discharge process). so after let's say 5-10s you note down the voltage of every single cell. it's easy to do if you use a spreadsheat app like excel for that.
so let's make an example: all 4 cells are 3,85V when you start with the test. after connecting load and waiting some seconds you read 3,70-3,60-3,75-3,70V. that means that cell #1 has a delta V of 150mV, #2 250mv, #3 100mV, #4 150mV.
your current was eg 20A. so following the formula VOLTAGE = CURRENT x RESISTANCE you get: 150mv / 20A = 7mOhm for cell #1, 12,5mOhm for cell#2, 5mOhm for cell#3 and 7mOhm for cell#4.
you need to notice that this method just helps you determine the weakest cell in ONE pack, as this measurement depends on starting voltage, time till voltage measurement after power connection and some other things.
i hope you get the idea, and i got the calculation right :)
feel free to ask ...
 
Those 4mm bullet connectors are tough to solder with 10AWG wire.
I am on the hunt now for some local 12AWG wire. I messed up the last order with 8AWG and 10AWG.
Gunna drill some holes in some wood to hole em in place and go from there.
The 3rd hand from Hobbyking is a joke.

Series is 12AWG, parallel is 8AWG
So if AhxC-rate=continous amperage
Then 15Ahx10Crate=150A
 
Mr grippy soldering jig is a great product http://www.hobbyking.com/mobile/viewproduct.asp?idproduct=25167
Soldering 10awg wire is easy with the right equipment. Takes seconds if done right. You need a massive soldering tip that can store a lot of heat so it won't cool down when touching the wire.
4mm bullets is good for battery connection only. I would suggest 5.5mm minimum for phase wires.
 
With this iMax B8plus charger, I go and balance charge my worst battery, in terms of difference between cells, and the unit says "LiPo Balance 2.0A 14.8V (4S)", it charges cells up to 3.85V (checked with my cell log 8). So it doesnt balance then fully charge. Whats the difference then between balance charging and another program called "LiPo Storage, 2.0A 14.8V (4S)" because my notes state Stored voltage = 3.8 – 3.85V.

I currently do not have a way to discharge my batteries. I am very tempted to work on my worst battery, in terms of what the delta V was when I received the shipment. It probably doesn't mean much and I am just over worried or whatever. So I have to squash the urge to charge it up right now so that it doesnt sit at fully charged for any amount of time. Should I just go ahead and balance charge each of my 15 batteries, making notes of voltages when its done the balance charge. Its a lot of batteries. I am going to go to Princess Auto and buy some lights to discharge my batteries. Should I keep in mind the amperage of the lights, so as to not go over the stated 20C-30C discharge rating of my battery, most likely keep it within 10C discharge range.

What about if I fully charge the batteries for anticipating a ride, how long can they safely sit at fully charged. Ideally I would want to ride it right away, but its not an ideal world.
 
markz said:
Those 4mm bullet connectors are tough to solder with 10AWG wire.
I am on the hunt now for some local 12AWG wire. I messed up the last order with 8AWG and 10AWG.
Gunna drill some holes in some wood to hole em in place and go from there.
The 3rd hand from Hobbyking is a joke.

Series is 12AWG, parallel is 8AWG
So if AhxC-rate=continous amperage
Then 15Ahx10Crate=150A
Click to expand...
Here's how I connect 4 mm bullets to 10 AWG.
Drill out the little ridge inside the red protector so you can slip over the 10 AWG.
Using flame type soldering tool(or even propane torch), fill reciever cup with molten solder.
Insert stripped wire in molten solder. Hold till solder sets.
Put extra 4 mm fitting one just soldered(Male into female or female into male).
Heat protector slightly and place fitting against hard surface and push protector in place.
Heat protector slightly and crimp in place.
 
Did you add hammerhead soldering tip in your HK order? Using only 60W iron that usually remedies any heavy gauge wire or battery tab soldering issues.

You really need to scrounge up an electrical load from some old electrical gear. Junk space heaters, toaster ovens, range elements, lighting, etc. For room tests I like to be able to draw around 1C or between 5-10A.
 
Hammerhead tip nope, I will buy one though.
I have a 60W iron, maybe its a 80W, adjustable though.
12V for Junk space heaters, toaster ovens, range elements, lighting, etc.?
Yeah I could do that I suppose, I tried a 40W household lightbulb, didnt work too well on soldering wires onto bulb, I do now have an old 3 way lamp switch for a 40W/60W/100W type adjustable lamp.
 
40-100W 120VAC bulbs would be a waste of time. You need heater elements 1000-1500W 120VAC to produce any significant low voltage DC load. I generally use it on my entire 60V pack but I've used the toaster oven element for 4S bricks. If you're set on just doing 12-16VDC then you might look into a carbon load pile sold for automotive electrical testing. Harbor Freight had a cheap-ass one while back...

As far as using old space heaters and ovens you'll probably need to bypass whatever control circuitry between the AC plug and heater element. Wire your connector directly to the heater element(s). You can parallel several heater elements for a larger Amp load.

60-80W iron doesn't make a bit of difference - the main thing is the MASS a hammerhead tip provides. Otherwise, whatever heat is in a small tip is sucked right out once you touch it to a large workpiece like 10ga wire or large battery tabs.
 
Jeez, there's a lot of 'opinions' in this thread.

I have a pack assembled from these batteries, 20s 10ah. I cut and then joined pairs of batteries in parallel, both discharge leads and balance connectors and then heatshrunk together with some high density foam spacers between, effectively making 5x 10ah 4s batteries. Using the original 4mm bullet connectors I then connected them in series by simply cutting the plastic bridge between both bullets and connecting them to their neighbours. I run 8ga HK wire with appropriate 4mm bullets back to the controller from the pack. You do not need to make up a harness or add any significant numbers of connectors. K.I.S.S.

I monitor the pack via the Adaptto BMS, these batteries plug straight in, nothing else required. I charge via the adaptto controller too at 20a or just over 2c. I have done 500+ near full discharge cycles on this pack or around 7500km over a one year period with zero issues up until the last week or so where one cell has developed a fault and no longer charges > 4v and the cell voltage delta is getting worse with each cycle. I'm going to retire this pack from daily use and the faulty battery will go in the trash this weekend, however I think I have more than got my monies worth.

Before I bought the Adaptto (which I would HIGHLY recommend) I charged with a powerlab8. This is one of the higher end "RC" chargers. I used reconfigured server PSU's as the power source run in series to provide 24v @ up to 60a. I would reconfigure the pack for each charge by disconnecting from series and re-connecting in parallel before charging as effectively a 4s 50ah battery. I would strongly recommend against this . You don't want to be unplugging or reconfiguring your pack on a daily basis because inevitably you will frock it up one day when you can least afford it. It's a simple statistical certainty. Buy a bulk charger set to a suitable end voltage (83v is a good point for 20s) and then balance charge periodically. Or better yet buy the Adaptto controller and throw the lyen stuff in the bin.

Regarding terminating wiring with bullet connectors, this is dead easy. Strip back just enough insulation to reach the full depth of the bullet connector, ~4mm. Tin this exposed wire thoroughly. Heat up your bullet with a decent soldering iron and half fill the 'cup' with solder. Insert your pre-tinned wire into the molten solder and wait until it all melts together. This is key - you can easy insert cold wire in molten solder, release and have it 'hold' in place but it will not be a great electrical connection.
 
i am trying to get people to think of how to minimize the heat from soldering of large conductors to the tabs of the lipoly packs.

i use 12AWG solid copper as the termination current collector and for the connection of each of the 6S packs that are combined to make up the total 21S pack.

i feel like the 12AWG will carry up to 80A surge and 40A continuous so i think it would help to use that for the connection to the tab and then if you use a large conductor then solder the 6AWG to the 12AWG instead of the tabs on the pack. especially the negative pack terminal. solder the 6 to the 12 first and then solder the 12AWG to the tab is how i would do it.

from my experience with the nanotech packs i think the cathode is more sensitive to the heating from the soldering of the connection than the anode.

this may be the case for the 18650 cans too.
 
That sounds like a great idea, get a solid wire to fit snug in connector, solder, cut.... then what? wrap stranded wire around solid, or do a butt joint solder. Or yeah better to solder smaller stranded awg to larger solid awg, then solder solid awg onto connector. Just depends how you terminate those two wires, I think wrap it around and solder is best, but I dont know what a professional would do. I would do whatever a professional would do.

BTW - I aint touching my battery connectors.

Regarding terminating wiring with bullet connectors, this is dead easy. Strip back just enough insulation to reach the full depth of the bullet connector, ~4mm. Tin this exposed wire thoroughly. Heat up your bullet with a decent soldering iron and half fill the 'cup' with solder. Insert your pre-tinned wire into the molten solder and wait until it all melts together. This is key - you can easy insert cold wire in molten solder, release and have it 'hold' in place but it will not be a great electrical connection.
Click to expand...

Yup tried it like that many times, my technique might be wrong, or soldering iron aint cutting it. Wrong tip maybe, I use the chisel flat head one. Pretty beefy. Might try a pointier solder tip. Tried soldering tip of wire, with insulation still on. Tried soldering a heavy amount and shaping solder to fit connector. Its hit and miss with me for the traditional way of doing it, as mentioned in the quote.

Might be my solder, might be something simple I just having figured out yet.
 
Ohbse said:
Jeez, there's a lot of 'opinions' in this thread.

I have a pack assembled from these batteries, 20s 10ah. I cut and then joined pairs of batteries in parallel, both discharge leads and balance connectors and then heatshrunk together with some high density foam spacers between, effectively making 5x 10ah 4s batteries. Using the original 4mm bullet connectors I then connected them in series by simply cutting the plastic bridge between both bullets and connecting them to their neighbours. I run 8ga HK wire with appropriate 4mm bullets back to the controller from the pack. You do not need to make up a harness or add any significant numbers of connectors. K.I.S.S.

I monitor the pack via the Adaptto BMS, these batteries plug straight in, nothing else required. I charge via the adaptto controller too at 20a or just over 2c. I have done 500+ near full discharge cycles on this pack or around 7500km over a one year period with zero issues up until the last week or so where one cell has developed a fault and no longer charges > 4v and the cell voltage delta is getting worse with each cycle. I'm going to retire this pack from daily use and the faulty battery will go in the trash this weekend, however I think I have more than got my monies worth.

Before I bought the Adaptto (which I would HIGHLY recommend) I charged with a powerlab8. This is one of the higher end "RC" chargers. I used reconfigured server PSU's as the power source run in series to provide 24v @ up to 60a. I would reconfigure the pack for each charge by disconnecting from series and re-connecting in parallel before charging as effectively a 4s 50ah battery. I would strongly recommend against this . You don't want to be unplugging or reconfiguring your pack on a daily basis because inevitably you will frock it up one day when you can least afford it. It's a simple statistical certainty. Buy a bulk charger set to a suitable end voltage (83v is a good point for 20s) and then balance charge periodically. Or better yet buy the Adaptto controller and throw the lyen stuff in the bin.

Regarding terminating wiring with bullet connectors, this is dead easy. Strip back just enough insulation to reach the full depth of the bullet connector, ~4mm. Tin this exposed wire thoroughly. Heat up your bullet with a decent soldering iron and half fill the 'cup' with solder. Insert your pre-tinned wire into the molten solder and wait until it all melts together. This is key - you can easy insert cold wire in molten solder, release and have it 'hold' in place but it will not be a great electrical connection.
Click to expand...

Some good advice here.. I charge at 1c though but hey if it's at 500+ cycles..whatever works. I'd basically do or have done everything he is suggesting.

Like some one pointed out there's no pint in a balance charger if you're doing bms route .. Just bulk charge with a power supply like from meanwell.

I personally don't like bms.. The discharging to balance oout the cells means shorter battery life.. By how much I don't know.

There's a very good balance charger bc168., which charges each cell individually .. No discharging involved

I'd personally go with bulk charging and just monitor ing the cell for when/if it goes oout of balance
 
I just realized something very interesting. With the 5.5mm 10awg to (4x) 4mm 12awg parallel harness, to put them in series I do not have to make or solder any wires. Unless I want to place certain packs on the sides of a rack or whatever. Soldering 10awg wire to 5.5mm connectors are waaaay easier!

 
How did this build turn out? I am currently trying to build a 20s2p pack, did you ever use a bms like the adaptto, or are you running naked?
 
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