trouble sourcing 12s bms/balancer

[ejonesss]

i have a 12s chevy volt battery i am using and i looked on ebay and the only 12s bms that would work is $200+ in price.

the cheaper ones for ebikes come in 1, 2, 3, 4, 5, 6, 8, 10 13, 14 and 15 s i was wondering the bms modules like the ones used by hoverboards can the last cells be omitted so it will only recognize and charge 12s on a 13s bms for example? or would the missing cell be detected as a faulty cell and wont charge?

another option is to series connect 2 6s bms modules but if the voltages are not even wouldnt 1 bms draw unevenly and cause an imbalance in the charging?

also does the P+ and P- have to be connected or can i connect the charger directly to the battery and use the bms to balance will the bleeder circuits turn on from the battery or do they need power to the P+ and P- wires to activate? and power the charge controller?

i could possibly order from ebay a chevy volt bms module that was part of the car but being proprietary it is possible that the car's brain box or ecu or what ever the car's computer is called may be controlling the bms making it useless

verses

 

[jonyjoe303]

Did you look at the chargery bms16, I saw those for 109 dollars with the 300 amp shunt. That one can do any series between 2s and 16s. I been using the chargery bms8 with 100a shunt (86 dollars)on my 220ah 4s lifepo4. It can do all the lithium chemistries and the voltage cutouts are fully programmable. The chargery bms8/16/24 are basically the same, only difference are the shunts and the series it can accommodate.

You just need to supply your own contactors, I been using a 30a automotive relay (4 dollars) as a contactor. It can also balance at 1.2 amps and includes temp sensors, and a audible/flashing alarm. After a month of use, it has been working great. Its better then the cheap BMS but its not a small unit like for use on a bike. If you got the room for it, its probably the only bms you need.

bms8t, the bms16 looks the same but has a larger control box.

 

[ejonesss]

where do i buy one?

i hope not some chinese company because i want to keep the stock here in the united states

i looked on ebay and china is the only source i want to stay away from china as it could take weeks or even months as most shipping is done by sea and especially now with the tarifs put in place on china.

and another problem is a lot of chinese products are either in chinese or the translation is severely broken.
and the only ones in the united states are over $200.

right now i have used fritzing and sketched out a balance circuit based on fechter/ggoodrum bms 2.x from back in 2005.

i can get away with using cell logs as lvc or hobby king battery alarms.

update i found on ebay for $1 + $10 shipping a bunch of broken chargery bms so i have an email into the seller asking what is wrong if it is just the bms box that is burned and the display still works it may be something i can fix.

does anyone know if the chargery bms has reverse polarity protection and what method it uses if it a diode in series or parallel set to blow an internal fuse narrowing the possible damage to just the bms box

 

[john61ct]

Pretty funny trying to avoid China for LI batts and BMS.

Even the biggest most successful Euro suppliers do joint ventures in order to be able to locate the factories there.

Yes separating the wheat from the chaff is harder, yes a local-country warranty return point would be nice, yes paying extra for fast delivery is a pain.

But limiting your choices to stuff resold by an actual local-country company holding stock near you, will eliminate 99.9% of what's actually available on the market.

 

[fechter]

How much current are you trying to get on discharge?

Most of the cheaper 13s or 14s BMS boards can work fine with 12s by tying the unused balance wires together with the B+. Put the unused channels at the + end of the BMS. I used a 14s board on a 8s pack and it works great. With some models there may need to be a jumper change on the board.

The "Smart" or Bluetooth BMS units may not work like this, but I haven't reverse engineered one to see.

 

[ejonesss]

the main use for the bms will be to charge and balance.

i will be using hobbyking battery monitors for lvc because of their alarms.

the problem was no one makes 12s bms that are not expensive.

and john61ct i would have no problem with foreign if they would ship by air or if it was in mexico or canada as it is drivable.

once i bought from australia a ceramic life size head of Marilyn Monroe made by flesh pots and it was shipped by sea and took 2 months as it had been packed in a container and went through customs that had to run tests for lead paint.

however i ordered a ceramic joker bust book end from the uk and it came in a week by air with no customs checks.

if engineers would build that roadway and bridge that connects all the world together then sea would no longer be the cheapest option and stuff could go by ground as they could drive around the world

 

[john61ct]

Hmm I thought most Ali and eBay vendors ship by air if you pay for it.

Neither Canada nor Mexico make BMSs afaik.

The threads here have all the documentation and support you need, just have to be willing to read through the relevant threads.

 

[fechter]

You can frequently find places in the US stock and ship the chinese boards. It will cost more, but not much more.

Here's an example. I got one like this and it works fine.
https://www.ebay.com/itm/14S-45A-50...=23296406732495eb6dc425d048f2b5f3bc495de2a33f

 

[ejonesss]

that's the one i had bookmarked after finding out that you had success with tying off the remaining wires at the + end of the pack.

i was told by the folks of http://vruzend.com forum that it would not work as the bms units would detect the missing cell as a faulty battery and not charge.

it is possible that their bms units are from a different manufacturer or are the cheap ones used by the hoverboard scooters

now i have to wait until i get the money together so i dont over draw on my bank account.

 

[fechter]

that's the one i had bookmarked after finding out that you had success with tying off the remaining wires at the + end of the pack.

i was told by the folks of http://vruzend.com forum that it would not work as the bms units would detect the missing cell as a faulty battery and not charge.

it is possible that their bms units are from a different manufacturer or are the cheap ones used by the hoverboard scooters

The "Smart" or Bluetooth versions might not work but I'm sure even those can be reconfigured somehow. I've used several of the cheap ones with fewer cells and they all worked. When you short the unused channels, they have no power to send a signal to trip the BMS. I found it does not work to just leave the unused wires disconnected.

 

[ejonesss]

that is maybe what the folks of vruzend was trying to say