LiPo battery not balanced after run

Raffa

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Hi all,

I recently upgraded from my BLS Raider to the latest BLX XL Raider and started to notice that both of my Venom Hardcase 2s 30c 5000mah LiPo batteries are starting to be unbalanced after running. I use a SkyRC B6AC+ v2 charger and when I plug the batteries in after running the first cell will read something like ~3.36V and the other cell will be up at ~3.54V.

But after either putting the battieries into storage mode or charging fully there might only occasionally be 0.01V difference.

I've seen some posts about unbalanced cells when charging but I have struggled to find advice for if it happens after running. Is it the Raider or is the battery that would be causing the problem.

Also if you have any reccomendations for any other batteries for the XL Raider please share! I'm interested in finding some with the cables that come out the end of the battery instead of coming vertically out of the top to make connecting easier as it's hard to tuck away the cables on the Raider.


Thankyou in advance!
 

lonee

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Is that a new battery? In the past I had some similar issues. After around 5-times charging it was better.
On the other hand, if you think the pack was damage from the factory, so give it back.

Regards,
lonee
 

Raffa

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Is that a new battery? In the past I had some similar issues. After around 5-times charging it was better.
On the other hand, if you think the pack was damage from the factory, so give it back.

Regards,
lonee

Unfortunately not, I've had it for around 12 months now...
 

lonee

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mmhmm,
It looks that one cell is not so good like the other.
A little drifting is normal, but not extremely after every run...
Do you charge all the time with the balancer? How many amps and how many mA can balance you´re charger?
Maybe the balancer can't reach the required mA to balance in relationship to the charge power.

In my case I do charge always with balancer. Except one S cell.
At the moment I create a circuit board for charging 2 x 2s and 2 x 3s serial with each balancer connector which is near at the xt90 located.
LiPo 1 has his connectors on the left and LiPo 2 on the right. The board itself is connected to the main + and- and also to the balancer connector of the charger. Finally just plugin the LiPos and push charge.
I do not how to explain it better, because english is not my main language..
So nothing can go wrong if my girlfriend try to charge their packs for the Nero. :)


Regards,
lonee
 

Raffa

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I always charge with the balancers, but the weird part is that I never have problems with charging and the cells always end up balanced when fully charged. It's only after running which confuses me.

Thankyou for your help
 

Unusual RC

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Note that you should always balance charge a lipo, unless ot is a 1S (single cell)only!

Approx. 0.5V difference is no issue!
It happens to most of my packs, now being over two years old.
As long as your balance charger brings it back to mint condition, there is nothing to worry about.
As soon as you start to notice significant shorter runtimes it becomes an issue.

Power output is different under load, so measuring while not driving will not give a correct state report of your batteries.
 

lonee

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Ah, Unusual RC are right.
Forget about it if the voltage of the cells are mostly equal after charging. Just charge with the balancer and have fun.
I had understood that the problem also is after normal charging...

Regards,
lonee
 

Unusual RC

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Ah, Unusual RC are right.
Forget about it if the voltage of the cells are mostly equal after charging. Just charge with the balancer and have fun.
I had understood that the problem also is after normal charging...

Regards,
lonee

My first thought was the same, @Ionee!
But after reading I noticed the difference.

What I do not understand is why there are not any ESC's around where you can wire the balance lead of your lipo in.
Now all ECS's measure the voltage of all the cells in series.
With 2S, this means it will monitor if the total voltage does not dive under the 6,4V (2x 3,2V) under load.
This way a heavy unbalanced lipo could slip the bill.
 

lonee

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I take the time to write some words while warming up from went outside with the dogs..

I think the reason for ESC´s without a integrated "each cell checker" are the less price.
Also you will need a circuit more inside and maybe also an processor if you want to make it perfect.

But be honest, in a Nero I would not have a balancer plug at the ESC. I am very happy with water resistent of these parts.
At begin with the Nero BR and no experience with the BLX200 I mounted small LiPo-checker on each pack (small board with a bright LED which starts flashing very bright).
After a while I found out that the cut off is a little low, but within range. If I realize leaking power, I stop running and change my packs to prevent a damaging of them. Specially if it is cold outside.

On my girlfriends Nero we have mounted a Lipo-checker with a buzzer on each battery box and also an extended cable to connect them to the Lipo´s. But just why she have not so much experiences with RC and the feeling that the car is becoming slower.
So we are on the secure side and can save money to change Lipo-packs to new ones! ;)

I had think about to modify the ttx300 transmitter to yeti to use the telemetry but I had no time to check if it is possible with these transmitter.
Also I could not find any suggestions to modify the TX. Will see what happens, first I have to make circuit boards to charge 2 x 2s and 2 x 3s in serial together with balancer connector. I do not like to charge parallel, cause these kind of packs are never selected like 2p packs.

Regards,
lonee
 
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