Finally found a LiFePO4 BMS with Low-temp Charging Protection

[Stupid Monkey]

Oh i had full intention of a proper top balance, and with hindsight could have used my time parked up at a mates better - doing a charge closer to full as a 12v battery, then the top balance, rather than from new voltage to top in one go was what i should have done. It might have been a 10A power supply but at 3.4v it wasnt 10A - and 24 cells to balance ....

Now I'm back on the road in the truck i just cant do that - maybe if I'm parked up next winter I could. Time and space limitations of vanlife eh?

I've ordered a "
1.2A 4S Active Equalizer Balancer with LED For Li-ion Lifepo4 Lithium Battery Energy Transfer
Current: 4S
(HeltecBMS Store)" which should help.

 

[Sgt Raven]

It took me a little more than 5 days to top balance my eight 280ah cells. IMO it was worth every minute of it. I used the 12 amp version of the Riden.

The latest version of the Overkill manual is awesome and explains top balancing. There are many other sources and well. One of my favorites is Nordkyn Design. That one should be required reading for all beginners...lol.

It might be an interesting experiment. The difference between 2 sets of 4 vs 8 at once. I don't know if it would be any difference or not.

^^^ your results might lead someone else to do a proper top balance the first time.

 

[Gazoo]

I don't think it makes any difference. Even fully charging individual cells to 3.65 and then connecting in series would work. Yeah I know there would be some self discharge doing it that way, but it would be very small.

 

[Gazoo]

Oh i had full intention of a proper top balance, and with hindsight could have used my time parked up at a mates better - doing a charge closer to full as a 12v battery, then the top balance, rather than from new voltage to top in one go was what i should have done. It might have been a 10A power supply but at 3.4v it wasnt 10A - and 24 cells to balance ....

Now I'm back on the road in the truck i just cant do that - maybe if I'm parked up next winter I could. Time and space limitations of vanlife eh?

I've ordered a "
1.2A 4S Active Equalizer Balancer with LED For Li-ion Lifepo4 Lithium Battery Energy Transfer
Current: 4S
(HeltecBMS Store)" which should help.

The link doesn't work for me but I have looked at those. It can't hurt to try given your circumstances. I hope you will report back with your results. ?

 

[Stupid Monkey]

I found a screeny of my initial top-balance, 28th April 2020 - just for completeness/comparison

 

[TGPB]

I installed the Heltec 3S 4S 5A Active Equalizer Balancer
It seems to have resolved my balancing issues. My cells are now within 0.004 on my troublesome battery.

 

[Sgt Raven]

I found a screeny of my initial top-balance, 28th April 2020 - just for completeness/comparison

Those look pretty good. I wonder what the voltages difference were between the cells in series.
Part of the problem may come from you having 6 cells in parallel. That may be too many cells in parallel for the BMS to handle.
IIRC, there has been a lot of discussion about how many we should run in parallel. You might be better off with 4S3P-2P.
FYI, you said 6P4S, which is backwards. Series cells first then Parallel groups of cells. Yours is 4S6P

ETA: I didn't think about the total number of cells in each parallel group before now.

 

[HRTKD]

I think he had the nomenclature right. 6p4s would be six cells in parallel, then for of those in series. 6p would certainly be unusual, but not unheard of.

 

[Sgt Raven]

I think he had the nomenclature right. 6p4s would be six cells in parallel, then for of those in series. 6p would certainly be unusual, but not unheard of.

Google 6P4S and 4S6P and see which gets a return about a battery. The standard is Series first the Parallel.
His nomenclature is ass backwards. This slipped by me the other day and I didn't notice it.
You may build your battery by paralleling the cells first, but it doesn't change the order in naming it.

 

[HRTKD]

4s6p = six separate 4s batteries (six BMS)
6p4s = what I said before (one BMS)

I have 4s2p in my trailer, but considered 2p4s.

He explicitly listed his setup as 900 Ah. 150 Ah cells x 6 = 900 Ah.

 

[papagyo]

I installed the Heltec 3S 4S 5A Active Equalizer Balancer
It seems to have resolved my balancing issues. My cells are now within 0.004 on my troublesome battery.

TGPB,

Is this balancer installed alongside the normal BMS(with balance leads)? Does that mean two sets of balance leads? Or how does install? Thanks

Brian

 

[Sgt Raven]

4s6p = six separate 4s batteries (six BMS)
6p4s = what I said before (one BMS)

I have 4s2p in my trailer, but considered 2p4s.

He explicitly listed his setup as 900 Ah. 150 Ah cells x 6 = 900 Ah.

Either way for the nomenclature. I think part of the problem is 6 is too many cells in parallel for the BMS to regulate. I think it wold be better to split it up to two batteries of 3 parallel cell groups and two BMSs. Also he would have the redundancy of two separate batteries.

 

[HRTKD]

Either way for the nomenclature. I think part of the problem is 6 is too many cells in parallel for the BMS to regulate. I think it wold be better to split it up to two batteries of 3 parallel cell groups and two BMSs. Also he would have the redundancy of two separate batteries.

I completely agree with you that 6 is too many to parallel.

 

[linkcat]

Hi folks! I'm waiting for the BMS delivery and just figured out one thing... I have two batteries wired in parallel 12v (4s) + 12v (4s), because I need 12v and a high amp (200A), so I got 2 120A 12v BMS, both with Bluetooth



With the App, do you think I will be able to change between both batteries and saw the info of each? Or every time I wanted to saw the other bms if I will have to configure it again? Thanks!

 

[Sgt Raven]

Hi folks! I'm waiting for the BMS delivery and just figured out one thing... I have two batteries wired in parallel 12v (4s) + 12v (4s), because I need 12v and a high amp (200A), so I got 2 120A 12v BMS, both with Bluetooth

View attachment 32372

With the App, do you think I will be able to change between both batteries and saw the info of each? Or every time I wanted to saw the other bms if I will have to configure it again? Thanks!

The app should see two different signals. Not sure how to switch from one to the other.

 

[HRTKD]

Within the app you can switch between the two batteries. On the Android app, it's kind of goofy. Select the BMS, wait a couple seconds. It if didn't work, go back and select the BMS again, then it will go through. Also, when you change parameters, don't forget to commit the changes. I missed that step, at least once. Definitely a WTF? moment.

 

[linkcat]

Within the app you can switch between the two batteries. On the Android app, it's kind of goofy. Select the BMS, wait a couple seconds. It if didn't work, go back and select the BMS again, then it will go through. Also, when you change parameters, don't forget to commit the changes. I missed that step, at least once. Definitely a WTF? moment.

Nice to know! Thanks for the answer!

The app should see two different signals. Not sure how to switch from one to the other.

Thanks for the answer, will post when I got it.

 

[Sgt Raven]

Nice to know! Thanks for the answer!

Thanks for the answer, will post when I got it.

In the Android app, when I open it, it shows a BT signal, but most times it auto connects. If it doesn't auto connect, then I have to click on the BMS. I only have BMS in use, not sure how it looks when there are multiple BMSs.

 

[HRTKD]

I don't recall what the default names of the BMS are. In the app you can change the name of the BMS. The BMS bluetooth "dongle" will turn blue when the app is actively connected to that BMS. That's how you can tell which one is which.

 

[linkcat]

Thanks @HRTKD and @Sgt Raven