Looking for thin bms

I’m sure someone directed me to a bms before but I lost that thread from weeks back.

I’m looking for a 14s iron bms. Not ion. And thin. I’ll be potting it along with the cells and my mold leaves very little extra room so the thinner the better. And don’t want to wait eternity for it to come from China. I need two.

I’d like all the bells and whistles but that comes second to it being no more than maybe 2-3cm thick.


Can’t you just shave one like a Daly down with a belt sander??

Worked so well with the 4.12 VESCs


haha. but it did work… grind it down and then acid to eat any possible connections.

Daly. thats the brand i heard
if i get this can i work around the discharge limit by working around the bms for discharge?
Amazon.com: DALY BMS 14S 48V 60A Li-ion 3.7V Battery Protection Module PCB Protection Board with Balance Leads Wires BMS for 18650 Battery Pack 48V: Home Audio & Theater
or is the discharge limit good for 90 amps from the battery?
ive never worked one of these things and looking for a guide as to what id be best with. just want to balance the cells really, or maybe i want other features and dont know it

ill only charge at 15amps so maybe its good for charging through too? talk to me like i have no idea please. what should i do? theyre for a bike and vesc6 set to 90 amps from the battery max. and regen used.

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du and this one i posted above is for ion. any lifepo4 14s bms around? i dont see any by daly.

Wasn’t it a Flipsky 6.6 :thinking:
Good old times…


think it was flipsky but its been a loooong time

Active Balance Battery Protection Board Bluetooth BMS 13S 14S 15S 16S 17S 20S 120A RS485 GPS APP Lifepo4 li ion LTO JK 48V 60V|Battery Accessories| - AliExpress

Lifepo4 BMS 16S 48V 18650 Balancer 120A 100A 80A 60A 50A 40A 30A 20A Lithium Battery Protection Board for Electric Vehicle Ebike|Battery Accessories| - AliExpress

any advice on what to get? trying to find something in usa so shipping is quick

Daly has iron for sure, just send them a message if they dont have it listed, if you menage to remove the plastic case without breaking anything it should be thin enough.

Also you bypass the discharge on any bms, just with going directly from battery to vesc, skipping the bms

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does the bms need to have a rated discharge current above what i would do or since im bypassing the bms while discharging i could use a much lower current bms? will contact Daly @Acido doing 14s and vesc6 discharging at 90amps max

If you want small, have you considered using just balance boards instead of a BMS? They are absolutely tiny and the LiFePO4 is much more tolerant to overcharge and abuse in the event of a fault condition.


Not LiFePO4:


If you plan on charging at 10a get a 10a+ bms, you can discharge as much as your battery can handle, as the discharge current is not going through the bms only the charging current from the charger

So you can get the smallest bms they offer ( i think its 15A)


I bought those balance boards at one point long ago and think I have them to @evoheyax abd they killed his battery. You never know what it was that killed the battery so not sure

Any bms use bulbs to burn off the extra voltage so you can see it working?

But I’ll just get the smallest then

got these
3S 4S 6S 10S ~17S Li-ion Lifepo4 LFP Battery Active Equalizer BMS 1.2A Balancer | eBay

Any naysayers?

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I personally would not use the active balancers like that.

You probably want passive balancing. I would, anyway.


Active seems good to me. Why u think passive better. http://mocha-java.uccs.edu/ECE5720/ECE5720-Notes05.pdf @b264

I don’t have much experience with active balancing but the couple folks here that tried it, I think I remember it wasn’t the greatest thing.

It’d probably be a great thing to use if you were a battery builder balancing a new pack that’s out of whack… but I don’t know if I’d want it permanently installed. If you had some serious P-pack capacity variances and for some reason still wanted to use the battery, maybe they could be good? I don’t know.

@Battery_Mooch do you have thoughts about active versus passive balancing?

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Active balancing is great for huge packs because the energy lost if passive balancing can be substantial. The relatively tiny packs used for esk8 don’t lose a lot of power with passive balancing so the higher cost, larger size, and increased susceptibility to vibration can make active balancing the less attractive option. Both methods can move a lot of current or a little, depending on their design and the conditions of the pack.

The tall electrolytic capacitors or the inductors used in active balancing circuits are particularly sensitive to vibration and shock due to their size/weight. IMO those components must be firmly anchored to the PCB (via appropriate RTV or epoxy) if the balancer is being used in an esk8 setup. The soldered pads for those components will not hold them!

Either active or passive balancing can be used, of course, but the advantages and disadvantages of each need to be carefully considered. Active balancing isn’t the best option for every application and pack size.