High quality balancing board 22s

[Merlin]

Aloha electric junkies

I am building a 22s battery pack and I need a good balancing board that is just for charging.

With this bike a normal bms would be useless because we have to bypass the (high) load for security reason.
(400-500a battery current)

Bluetooth to monitor cells would be really great.
But not necessary at the end.

I only find bestek who offers 22s balancing boards right now.

Any ideas where I can get a BT balancing board?

 

[amberwolf]

Remember you can use a normal BMS for your purpose, but simply run the discharge leads directly from the pack directly, not going thru the BMS at all.

The charging and balancing wires would be run as normal.

 

[Merlin]

that is my plan "b" =)

but i needs also some space in the Battey Place. Space is very limited. 22s9p takes the whole space.
and going 8p maybe is less Riding time + more stress to the cells.

lets see if someone know a balancing board =)

 

[flippy]

why not use a regular BMS that has the option for a external current sensor? i use the tinybms often with the 750A external LEM sensor that you just put a wire tru.

you might need 2 of them (only one with the sensor) for getting beyond 16S. but that would give you the proper protection such a expensive battery would require.

otherwise should not be hard to use another aliexpress one with a modded shunt to divide the reading until you get within spec of the current range of the bms. you probably need replacing the mosfets with proper stuff and/or fit a contactor instead of the mosfets. i use this trick just to keep the OCP of a bms and use any bms i want, just dialing in the shunt takes some trial and mathz. the main advantge is that you can use the BMS's data for the proper capacity and other fun stats like temperatures so you dont end up in a ball of fire in a ditch.

 

[Merlin]

the "Problem" is that every possible BMS fail could kill the guy. No matter how quality it is.
It for an FMX Bike. And you dont want a fail/cutoff jumping 40 feet in the air.

 

[flippy]

then bypass the mosfets and other stuff and make a direct connection between battery>controller.
put a loud beeper on the BMS (you do need that) so if there is a error he can stop when he is back on terra firma.
having a correctly set LVC on the controller is paramount to prevent damage.

bms only handles charging and balancing duty, not actual driving. but it can still warn if stuff goes bad. but its up to the driver to stop.

 

[billvon]

the "Problem" is that every possible BMS fail could kill the guy. No matter how quality it is. It for an FMX Bike. And you dont want a fail/cutoff jumping 40 feet in the air.

If you can't handle a sudden disconnect, and a fire is preferable - then why would you use a BMS at all?

BMSes can really only do one thing in response to an out of range parameter - disconnect the pack. The other functions (like balancing) can be done by the charger so you don't really need them in the BMS.

 

[Merlin]

I asked for a balancer board. Not really a bms.bypassing is only plan b
Yes bms do only disconnect if parameters hit a setup value.
And sometimes they fail. And this sometimes case is not welcome
Of course a fire is the better option. Sounds weird I know but
Fires starts while (over) charging or shorting cells. Bad insulation about vibrations and stuff like that. Not on a normal discharge within specs. That's why blutooth would be welcome.
No hassle with beepers. Just a quick check on your phone before you start your show ride.

A charger can balance?
That's new to me.
Link?

Looks like plan b is necessary

 

[amberwolf]

An RC charger can balance. A common bulk charger cannot.

Individual cell-voltage chargers can also balance. No big sngle charger is used, just one small charger for each cell (group) is used. Each charger must be electrically isolated from input to output, as their outputs will all be connected in series when attached to the pack. If main charging is done this way, you need larger cell-group wires out to this charge connector than you would with just a balancing system.

The other functions (like balancing) can be done by the charger so you don't really need them in the BMS.

Unless you want to minimize the number of connections coming out of the pack, for whatever reason.

In that case, a built-in balancer would leave you with only the main + and - wires.

 

[billvon]

A charger can balance?
That's new to me.
Link?

Here's one that will do up to 6 cells:
https://www.amazon.com/Tenergy-Balance-Charger-Discharger-Connectors/dp/B00466PKE0
You can use several of these to charge 22 cells. Or you can roll your own; get 23 very accurate (.1%) resistors, build a long divider, and then get 21 high voltage (~100V) op amps. That allows you to convert any charger to a balance charger.

 

[Merlin]

4x 6s charger 200+ dollars, wiring mess....okay =)
I think plan b using a 22s BT BMS bypassing discharge sounds way better to me