Lipo balance problems

[AJH387]

Hey guys, I'm experiencing a weird issue with one of my Gen-Ace 2S lipos for my EB48SL. I have a 8000mah Hobbystar as my main lipo but I bought the Gen-Ace as like my practice / back-up. Since new, it seems like it never balances out. The first time I charged it, it was even and then 1 cell got to 4.20 while the other seemed to jump around at 4.12 and didn't fully charge. I took it off of the charger, as it just seemed like it was going on too long and I didn't want to damage it. My friend said to run it and then recharge and it should be fine. Same thing, only it got a little closer. Started out even and topped out around 4.15. I ran it and then again charged it last night and was about the same. So what do I do? Is this thing dangerous to use? Any input is welcome, thanks.

 

[Chevys10zr2003]

I have some Gens Ace batteries that are like that too and I have been running them. I do cut them off at about 3.6-3.7 volts per cell so that I don't risk any cells going under 3.0 volts but I do that with all of my batteries and not just the ones that don't balance perfectly. I would mark them with tape and keep an eye on them though.

 

[Cmbscx10]

That one cell seems wonky for sure. What charger are you using? How many cycles on the battery? On all my batteries the first 10 cycles are all over the place and then all of a sudden they come alive in the balance and power output. Maybe it is in my head but it is almost like breaking in a new motor. I personally set my LVC to 3.2 and 3.4 and run Alarms.

 

[Billl DeLong]

So long as any single cell never goes above 4.20V (or below 3.3V at rest) then you will not risk any permanent damage. I have always felt that within 0.07V of imbalance is acceptable... unfortunately I had a write up on how I came to this conclusion, but the thread is currently on URC and they have been offline for 10+ months. Anyway, I don't see any problem with your Gens Ace pack, the only issue is that they are not properly matched cells which means you will suffer longer CCCV charge cycles and slightly reduced peak voltage. Since this is just a practice pack then it's no big deal IMO.

If I was racing in a stock class then I would definitely select a higher quality pack with properly matched cells. Most quality brands I've used will match cells within 0.02V.

I would also increase the LVC to the highest possible setting to play it safe... check your cell voltages at the end of each run, that's more important.

http://batteryuniversity.com/learn/article/bu_803a_cell_mismatch_balancing

 

[AJH387]

I have 2 Traxxas chargers. The easy peak 6 amp and the newer 6amp dual ID. I bought them when I was strictly bashing and I know I could benefit from a better charger but it is what it is, for now. This was only the 3rd time charging it for me. I'm going to the track after work, so we will see what it does. I really like the Hobbystar 8000 as my main pack.
And in my 17.5 buggy, I'm running FTM packs, which is what 1 of the better local drivers also runs in his 22 4.0s. And they are great too. I do have a Gen-ace for that car also, as a back-up and i has been good.

 

[jump_it]

How many cycles on the battery? On all my batteries the first 10 cycles are all over the place and then all of a sudden they come alive in the balance and power output. Maybe it is in my head but it is almost like breaking in a new motor. I personally set my LVC to 3.2 and 3.4 and run Alarms.

I agree, I had talked about lipos wake up period in a thread over on URC a few yrs back, the owner of spc chimed in because I refrence a set of spc lipos, all tho he did not 100% agree with me that lipos have a wake up period, he also admitted he could not prove it wrong, specially once several other members chimed in backing my claim.

Like Cmbsx said give it a good 10 or so cycles, see if the balance numbers start too come in closer, my experience with the wake up period has been more power thru out the discharge of the lipo while running it, and the cells would either come in closer too balance, or an off cell will continy too drop.

So long as any single cell never goes above 4.20V (or below 3.3V at rest) then you will not risk any permanent damage. I have always felt that within 0.07V of imbalance is acceptable... unfortunately I had a write up on how I came to this conclusion, but the thread is currently on URC and they have been offline for 10+ months.]

I know you lost a lot of threads over on URC, I still find myself wishing I could grab some of my threads and transfer them somewhere else. I feel one of the most missed members from over their is El_Tonto, between him you and jang pretty much anything could be solved

 

[AJH387]

Awesome. I appreciate all of the good feedback, guys. Thank you. I'll probably put 2 cycles through it this evening, at practice. Hopefully it starts to come around.

 

[TBuggy]

I have noticed on multiple gens ace batteries go out of balance for me. They have all been the 5000mah 4s lipos and the sensor wires break at the soldering points. I have repaired them until the wires are too short and then shelved them. Probably can repair them if I got new balance connectors but haven't tried to mess with them again yet.

I don't think I will be using gens ace batteries personally anymore unless they are bullet connectors, their wire connections/soldering or the wire they use seams frail IME.

 

[Mongoose]

I just checked the levels on my packs that have been sitting and one of my 2S Lectron Pro’s checks at 3.77V and 3.52V....gonna have to balance it again.

This is not the 2S that I was talking about in my build thread if anyone knows what I am talking about.....it’s the 2nd of the two that I have like that. However, the battery I WAS talking about checked out at 3.77V per cell so it seems to be good.

 

[cordell12]

I am seeing the same thing on 2 of my 4s batteries. This is after I did a balance charge on them. Wondering if I should be worried about failure and or fire.

 

[TBuggy]

I am seeing the same thing on 2 of my 4s batteries. This is after I did a balance charge on them. Wondering if I should be worried about failure and or fire.

View attachment 572

Were they actually done charging or did they time out because of a setting on your charger? Those numbers look like they still have some balancing to be done. If your charger is working correctly they should all end up with the same voltage no matter how far out they are from each other. The thing is is they are really far out it will just take a long time to balance. A lot of chargers have timers so they don't over heat a battery too much. You may just need to run the battery for another charging cycle to get them all balanced up.

 

[cordell12]

Were they actually done charging or did they time out because of a setting on your charger? Those numbers look like they still have some balancing to be done. If your charger is working correctly they should all end up with the same voltage no matter how far out they are from each other. The thing is is they are really far out it will just take a long time to balance. A lot of chargers have timers so they don't over heat a battery too much. You may just need to run the battery for another charging cycle to get them all balanced up.

You know thats a good question. I just ran one of the batteries, but will throw the other one on again and see what happens.

edit..pretty sure my charger had timed out. two are now at 4.20 and the other two are making thier way up.

 

[TBuggy]

You know thats a good question. I just ran one of the batteries, but will throw the other one on again and see what happens.

edit..pretty sure my charger had timed out. two are now at 4.20 and the other two are making thier way up.

If you find your batteries are going out of balance and you don't balance them fully then they will become even further out of balance if used like that. I would suggest you get them all balanced correctly before they get too far out.

 

[TBuggy]

Don't be surprised if the voltage bounces around a little until they are all equal.

 

[cordell12]

Thanks, doing so now. I had always assumed that the charger had gotten the cells to the best balance it could do. The first cell always seem to be much lower than the rest, and as it drops while out bashing around, sometimes I only get half power (right before hitting LVC). Assuming this is that first cell dipping below that cut off and the esc shutting the motor off, then back on as the cell reads a bit higher? This only occurs on one of my batteries, and never when it is fully charged, or even half charged it only happens at the end. My other battery will ride full force up until it cuts off from LVC.

 

[TBuggy]

Each cell will always charge/discharge at its own rate. You can only hope that the cells all do it as close as possible thats why balancing is so important. Most batteries will have cells that have slightly different resistances and you want them ideally being as close as possible so they will charge or discharge at similar rates. This is when the cheap batteries start to reveal themselves...some manufacturers seem to just pair any lipo cells together and others pay attention to the resistance and pair the ones that are similar so they work together better.

 

[cordell12]

Each cell will always charge/discharge at its own rate. You can only hope that the cells all do it as close as possible thats why balancing is so important. Most batteries will have cells that have slightly different resistances and you want them ideally being as close as possible so they will charge or discharge at similar rates. This is when the cheap batteries start to reveal themselves...some manufacturers seem to just pair any lipo cells together and others pay attention to the resistance and pair the ones that are similar so they work together better.

These are HobbyStar batteries, not super cheap but much cheaper than the top dollar ones I've seen. I appreciate all the information here, all this battery stuff is somewhat new to me. The charger stopped and called the battery Finished. The 1st cell charged up to 4.19 I waited 10 minutes and started it again. After a few minutes the charger called it Finished again, the 1st cell was still 4.19 Looks like that's all it will take, still better than where it was and where it was going.


edit...my second battery ended up balancing perfectly!

 

[AJH387]

Ya, I'm still experiencing problems with mine too. Not sure what to do. I'm getting annoyed.

 

[TBuggy]

Ya, I'm still experiencing problems with mine too. Not sure what to do. I'm getting annoyed.

Time can depend on the charger you are using, but also if the voltage to the cells are off then it will take some time to get them balanced. There is a little back and forth with the voltage when the cells are balancing. It sounds like you need to just leave the battery on until its finished its. Let the charger do its job and run the full cycle.

 

[AJH387]

Time can depend on the charger you are using, but also if the voltage to the cells are off then it will take some time to get them balanced. There is a little back and forth with the voltage when the cells are balancing. It sounds like you need to just leave the battery on until its finished its. Let the charger do its job and run the full cycle.

Ok I'll try that next. Thanks.