How can I charge that battery pack?

[razenxd]

Hello,
it's not a laptop/desktop related question but I figured that someone here will have the right knowledge.
At work we use a few Aldebaran(now Softbank/United Robotics group) Nao Robots which they use some custom 6S li-on battery packs.
Nao robots tends to draw from the battery even if they are shut down, and the BMS tends to be a little aggresive, if the pack stays on a turned off robot for 3 months it's gonna lock and will refuse to charge.

Now, I have noticed a few things.
The "dead" battery, while connected to charger and NOT Charging will power up the robot but when the robot tries to activate its joints, it shuts down(I guess not enough voltage).
BUT, while the robot is booting the charger lights changes and looks like the battery starts to charge, but this stops when the robot shuts down.

So I was wondering if :

A. Can I put a known working battery in parallel with a non working battery and try to charge it?
B. Based on the assumption that the battery charges while the robot tries to boot, meaning that it's possible to charge it under some load, could I artificially make that load and charge the battery?

2 of those battery packs are 1year old, and 1 is a rebuilded pack which also rebuilded last year.
I'm trying to avoid a rebuild and if possible opening up the packs.

you can see pictures of the battery pack here
https://www.bartneck.de/2021/02/03/r...-battery-pack/

Any other idea/recomendation would be great.

Thanks a lot

[rumpumpel1]

Look for someone who has an NLBA (battery analyzer).

[razenxd]

Look for someone who has an NLBA (battery analyzer).

Unfortunately I cannot find anyone with an NLBA.
The only option is to ship them to a different country, but I could just rebuild them for cheaper.
Also don't know if there's the pinout available.

I guess my ideas will not work?

[rumpumpel1]

post your problem in the NLBA forum.

[razenxd]

post your problem in the NLBA forum.

Thanks for the suggestion man.
But on their forums they provide support only for NLBA customers

[stj]

i would open the pack and charge each cell using a tp4056 module and some crock-clips

[rumpumpel1]

so you were not able to register?
Then the only suggestion I have: call every repair shop in you region and ask them whether they use an NLBA. I'm pretty sure, you will find one.

[sam_sam_sam]

The first issue is that if the robot needs power to not lose its parameters this is a poor design because in reality when it is power off it should be off not sleeping now what you might be able to do is how is just power the data retention system and make sure that the battery pack does turn on but in order to verify this you need to have access to the battery system power leads and see what the current draw is when supposedly off and see if the current draw is micro milliamperes if not why not

Now depending on how rough the robot is on the battery pack you could have an issue with using too much current and heating up the battery cells continuously and degrading them over time and then you could have self discharging cells that in about a month or sometimes more than a month the battery voltage between cells is noticeably different which will cause the BMS protection board to refuse to turn on and if the voltage is below a certain voltage refuses to charge the battery cells with any real current and need to be charged at the battery cell rail which would mean that you would need to open the battery pack in order to do this

[sam_sam_sam]

You do not need to find someone with a NLBA laptop battery unless is a computer battery pack that it is using and then maybe

There is a battery tester that I use and will tell you everything you need to know about your battery cells but you have to use the computer software for this information to be available you can use the battery tester with out the software but you can not look at charging and discharging curve graphs over time which what you need to determine weather or not the battery cell is very good fair or bad

This would require you to test each and every battery cell to determine this

The model number of this battery tester is

EBC-A10H you can find on eBay Aliexpress Bandgood and several other online sellers

They run around $75.00 or more depending on what site you go to

[petehall347]

you could try giving it a second or a few seconds with a good battery pack to get the voltage up to get it to start charging . i have done this a few times now with garden tool packs .

[sam_sam_sam]

It would help if you posted a picture of the battery pack and where it connects to the robot and the charger