24s BestechPower BMS Thread

[dnmun]

how did you determine that the fault that causes the BMS to shut off the output mosfets to be on channel 18?

did you measure the voltage across the sense wire pins on the BMS for channel 18? and each channel adjacent?

 

[tenutso]

I'm getting the right voltage across all the sense wires. 3.85 across the board totalling about 69.3. At first glance each channel appears to be happy with correct voltate when walking up with a volt meter. What I did find surprising is that resisters 12 & 13 are hot while all others are cool. This channel appears to be discharging for no reason.. I'm preplexed at this point so I'm going to break the pack apart and check parallel cells for a mismatch in voltage. I'm thinking one the cells is trying equalize causing some current flow... but would that cause the BMS to fault at this point? Otherwise I'm not sure why this channel is constantly discharging.

 

[dnmun]

i have no idea of what you think a BMS does or how you imagine it should behave.

if there is 3.85V on all channels then it should be bypassing the cell and your charging current should be only the balancing current.

i think i asked why you decided that channel 18 was dead. maybe that was another since now you are talking about channel 12 and 13.

 

[tenutso]

The resisters 12 and 13 are hot when no charging current is applied. It's running the cell down as if it's trying to balance. Like I said I'm getting the correct voltage on all 18 sense wires and the output terminals have voltage as well... just no current.

 

[tenutso]

The resisters 12 and 13 are hot when no charging current is applied. It's running the cell down as if it's trying to balance. Like I said I'm getting the correct voltage on all 18 sense wires and the output terminals have voltage as well... just no current.

I swapped d131 units and it worked. something must be shorting on this unit.. I resued the same wire harness. Both were pulled out of the wrapping this week. Too bad.

All is good now. I wouldn't haven tried this any of this if it wasn't for all your efforts dnmum.

 

[zlagger]

Hey dnmun. You mentioned having two Power boards linked for more current handling. Do you have a diagram or picture of how you did this. I would like to use two of my D131 boards to do the same thing.

henry will not sell you the balancing board alone. i was able to talk him into sending me one so i could show it so that is why there is a picture of it.

i have separated the top from the bottom and use the bottom as a balancing board as you were asking.

it is mounted under a power board but the connection between the two pcb is separated by cutting all the pins between the two.

i use the power board on that setup as a slave BMS and it is controlled by another D131 which acts as the master board.

this allows me to use two D131 to handle the max current from 44Ah of lipo and the two balance boards provide 350mA of balancing current.

by using one D131 as the master and wiring the two BMS power boards in parallel it will handle more than the 120A peak of one. i have pulled a total of 185A from that pack with the current split equally between the two BMS. 95A from one and 90A from the other.

 

[dnmun]

no pictures. i just connected the gate drive for the discharge and charge mosfets from the master to the slave. they are the 4 pins on the end, doubled. the other pins are for other functions the slave does not need.

if your slave does not carry charging current then it does not need the gate drive for the charging mosfet.

also i wire the two BMS in parallel connecting the B- spot and the P- spot and the C- spot too.

 

[zlagger]

no pictures. i just connected the gate drive for the discharge and charge mosfets from the master to the slave. they are the 4 pins on the end, doubled. the other pins are for other functions the slave does not need.

if your slave does not carry charging current then it does not need the gate drive for the charging mosfet.

also i wire the two BMS in parallel connecting the B- spot and the P- spot and the C- spot too.

The concept makes sense. I'm still noobish enough to be unsure of what pins the 4 would be to connect. We need a picture with all of the pins labeled with their functions. That would be a great reference.

 

[scpmi]

HI All,

PLease don't flame me as I'm a bit of a newb when it comes to batteries and BMS solutions and this is probably something that is easy to answer! I have read through this thread as I have a HCX-D131 for 6s Li-Po and I'm having some issues with charging it and getting it to balance.

I have an iCharger 3010b. How do I need to set it up to use it with the HCX-D131 so that the battery fully charges and balances?

How is everyone finding the reliability of the D131? I bought two and whilst the first seems great, when I connected the second to a 6s pack it only output a really low voltage, (maybe 4 or 5 volts,) so I think it's probably faulty.

I haven't been able to get a reply out of Bestech for weeks now. Anyone else having a similar problem getting responses out of them?

 

[dnmun]

you do not use a balancing charger with the BMS. there is nothing wrong with the other BMS. they test every single one during final test. they do not engage in endless discussions with novices as to whether they are responsible for the operators actions. they are only selling these to people here because i was able to convince henry to sell us BMSs in small quantities since they would only normally deal with battery manufacturers or resellers.

do not expect them to reply, i find it embarrassing now that my efforts are now clouded by this type of behavior where novices who know nothing about and have never used a BMS before can send emails back to the company stating that their product is defective.

if you are using a 6S lipo pack then you need to use the 6S balancing chargers. these 24S lipo BMSs are for normal sized battery packs charged using a normal bulk charger.

if anyone else is interested in going on another shared shipping order to the US for a batch of these D131 then let me know by pm.

i am gonna see if i can get him to do a special order to build a batch of D131 24S lipo with a balancing voltage around 4.17-4.18V. i think if i can order 8-10 of them he would put that into their production schedule.

i also have to order some more of the D131 24S lifepo4 BMSs too so if someone needs another lifepo4 BMS you should also contact me if you are in the US so the order to you can be forwarded by 1st class mail from here. they will have the normal 3.60V balancing voltage too.

 

[agniusm]

Dnmun, i have this dilemma now. Got 8 modules of Leaf cells for 16S2P pack but i only can get waterproof charger at 66V so cell end voltage will be 4.125V. My question is what is happening with cell balancing, does it ever kick in or does it just keeps the cells in relative balance, say one cell reaches 4.2 while others are at 4.120v?

 

[izeman]

if no cell reaches 4.2v then no balancing will happen. that's the main disadvantage of these bms. they are hardware coded and not 'smart'.
i'd also like to charge to storage voltage and balance at 3.85v. but this will not happen.
but on the other hand: there normally is absolutely no need to balance every time. so if you're on the road and don't discharge too low (where imbalance happens) and then charge to 4.12v all your cells should still be balanced. and latest when you are back home and do a full charge balance will happen again and your fine

 

[dnmun]

yes, no balancing if the balancing voltage is 4.20V.

i got to thinking about how i have my lipo pack in parallel with the lifepo4 pack and i am thinking that if i drop the cell balancing voltage to 4.17V then i give up the top 2-3% of charge storage capacity, but i do not end up pushing the voltage of the lifepo4 pack up as high currently 88.2V/21S. so i can charge them both to about 87.5V/24S or 3.64V on the lifepo4.

maybe you can hack the charger voltage up. it should be possible, and maybe if we try to order something around the 4.17V level we can talk henry into including that in his production schedule.

imbalance doesn't really happen because of the use of the cell down to low voltage. that has not been demonstrated, just conjecture.

becoming unbalanced is a function of the self discharge rates imo. each cell accumulates a deficit of charge over time and the balancing current has to be sustained long enuff and often enuff to keep the cells with the highest self discharge rates close enuff in available capacity to allow the pack to store that amount of charge. so then the cell with the lowest voltage during balancing is the limit on how much the entire pack produces, or saves depending on how you look at it.

in effect the BMS 'pays for itself' by allowing you to store the maximum amount of charge possible in the battery by providing a balancing function.

 

[agniusm]

Just got of email with charger manufacturer. The weight of that on board charger is 8kg so no go. Will get some off board charger with proper voltage. I ciuld go for a BMS but the ones I am buying do not discharge throuh fets, rather disconnect accelerator handle, only charging is done through fets up to 15a.

 

[scpmi]

you do not use a balancing charger with the BMS.

We know the BMS is self balancing, it's one of the principal reasons we are evaluating them. The issue we have is that when we use a 3010b charger and try to run a standard (non-balanced) charge cycle it regularly throws a battery connection error at the start of the charge cycle. It's an interesting issue, we'll try one of our other chargers with it and see if we get a similar result.

On a more general note, perhaps you might want to slightly wind your neck in. As far as I'm aware you aren't a representative of BesTech, nor are their units only available because of your activity. It's great to see people using them and there's some useful info in this thread but don't get ahead of yourself

 

[mj2412]

Just got of email with charger manufacturer. The weight of that on board charger is 8kg so no go. Will get some off board charger with proper voltage. I ciuld go for a BMS but the ones I am buying do not discharge throuh fets, rather disconnect accelerator handle, only charging is done through fets up to 15a.

Dear Agniusm, what Kind of BMS you are talking about?

Thanks Martin

 

[agniusm]

Its modified bestech power BMS:

 

[Xtr6]

Does annyone have a good drawing how to connect the BMS to 4 packs of 6s lipo. And remaining the balancing connectings one ach pack. I am building a extra battery pack So i like to have two packs of 4 times 6 's lipo and each pack wil have his one BMS. Btw i have 2 Bestech BMS 24s bought whitouth anny problems.

 

[Matador]

Sorry to revive an old thread, but I see a lot of wisdom here and I'm kinda stuck with this HCX-D131 80A 14S

https://endless-sphere.com/forums/viewtopic.php?f=14&t=87134#p1273091

Matador