36v 10s9p battery bms

[Garry Hallam]

Your DMM might be inaccurate?

Checking Multimeter Calibration at Home

One of the most important tools in an e-biker's toolbox is a multimeter (aka Digital Volt Meter or DVM). It is sometimes needed to be used to measure voltages with a high degree of accuracy, for example looking at the output of a charger to tell if it is set up to the correct voltage or not...

www.pedelecs.co.uk

I have used two different meters and both show the same 41.2

 

[guerney]

They now have an all in one unit that is BMS and active balance combined. However, I doubt that I could fit one of those into the battery case.

100 BALANCE 100BALANCE 60A 8-17S Smart BMS with Active Balancer and Integrated Bluetooth APP/UART for Lithium Battery NCM/LFP/LTO Pack https://amzn.eu/d/bGSO5L5

Drill appropriate holes into the battery case, glue on another case containing the active balancer?

 

[Garry Hallam]

Drill appropriate holes into the battery case, glue on another case containing the active balancer?

It did cross my mind. I have been thinking of getting a semi pro 3d printer to compliment my laser cutter for doing such as that!

 

[guerney]

It was after reading something online. But, I'll give them the benefit of the doubt and use along with my own build battery. It is finished now and working fine.

How did they get the strips off so cleanly? Hope you've got a well matched set of cells.

 

[Garry Hallam]

How did they get the strips off so cleanly? Hope you've got a well matched set of cells.

Good point. I will contact Cell Supply and ask that very question!

If I did it again, and I will not. I would buy new stock. I feel strongly that there should be restrictions on who can buy these cells!!

In fact, If I could I would go so far as to ban all youtube video's promoting the building of these packs!

 

[Nealh]

So I have done some runs with this new battery mostly on the Canal paths with 3 sometimes 4 setting of the five available. It cuts out charging at 41.2v so must not be fully balanced or the BMS is not quite right. So far I have accumulated 50 miles and is now at 36.2v. What is the best voltage to recharge at?

Any time you plan on going for along ride , 36.2v is approx. 38/40%. If riding locally I wouldn't bother charging unless the battery is below 39v.

 

[saneagle]

So I have done some runs with this new battery mostly on the Canal paths with 3 sometimes 4 setting of the five available. It cuts out charging at 41.2v so must not be fully balanced or the BMS is not quite right. So far I have accumulated 50 miles and is now at 36.2v. What is the best voltage to recharge at?

The best time to charge is when you don't have enough charge for you next ride, if you can figure out when that is.

 

[harrys]

Thanks for posting the Dewin BMS link. There is no balance current specification listed, so it's a good bet that it doesn't balance. Balance currents would be listed for a balance BMS and are typically 40-50 ma.

That's not the end of the world. A lot of ebike packs don't use balance BMS, primarily to save a little money, but it's a tradeoff.

 

[Garry Hallam]

Thanks for posting the Dewin BMS link. There is no balance current specification listed, so it's a good bet that it doesn't balance. Balance currents would be listed for a balance BMS and are typically 40-50 ma.

That's not the end of the world. A lot of ebike packs don't use balance BMS, primarily to save a little money, but it's a tradeoff.

Thanks for pointing that out. As this was my first and only battery build, I have learned that the cheap BMS boards rarely have a balance function. Knowing what I know now, I would certainly not have used a cheap BMS such as this.
I find these battery packs both Intriguing and scary at the same time!

 

[lenny]

Monitoring the Balancing of a Pack

Been meaning to post this for some time but not got around to it so here goes while I have a moment spare. I think it's worth looking at as the results are quite interesting. I posted this back in November last year: Here is a dismantled Yose power pack, generic Chinese cells, crappy 20A BMS...

www.pedelecs.co.uk

 

[Garry Hallam]

Monitoring the Balancing of a Pack

Been meaning to post this for some time but not got around to it so here goes while I have a moment spare. I think it's worth looking at as the results are quite interesting. I posted this back in November last year: Here is a dismantled Yose power pack, generic Chinese cells, crappy 20A BMS...

www.pedelecs.co.uk

Very Interesting read. Thank you.

I just wish there was a reputable company out there that leased the batterys and who would take care of all the technicalites. Maybe that would improve safety for everybody and let us all get on with enjoying getting out and about on our bikes!