LIFePO4 BALANCER Do you know the Volt Blocher ?

[Doctorbass]

Today, Frodus pointed me to a great simple solution about cell balancing.

It's a shunt type balancer that is used in few EV car project and that cost around 5.99$ each not assembled. (you need one per every 1s)

it can shunt up to 2A and is set to 3.6V but can be on demand seted to different voltages:

http://www.voltblocher.com/

It draw 2.2mA at 3.2V in standby mode and that correspond to few month or years for large Ah packs before it could draw wentirely the cells.

Doc

 

[biggs]

Today, Frodus pointed me to a great simple solution about cell balancing.

It's a shunt type balancer that is used in few EV car project and that cost around 5.99$ each not assembled. (you need one per every 1s)

it can shunt up to 2A and is set to 3.6V but can be on demand seted to different voltages:

http://www.voltblocher.com/

It draw 2.2mA at 3.2V in standby mode and that correspond to few month or years for large Ah packs before it could draw wentirely the cells.

Doc

Hi Doc,

i think it is the normal shunting circuit with tl431 with powermosfet.

i use this circuit in my first bms but with 8A current. irl3803 and 10mOhm shunt.
so it is very easy.

bg
biggs

 

[fechter]

2.2mA seems kind of high. It should be more like 2.2uA

One possible problem with this approach is at high charging currents, a cell could still go overvoltage. It also lacks low voltage protection. Still, the price is right.

 

[Doctorbass]

2.2mA seems kind of high. It should be more like 2.2uA

One possible problem with this approach is at high charging currents, a cell could still go overvoltage. It also lacks low voltage protection. Still, the price is right.

You are totally right, at higher current than 1.5 to 2.0A, the battery can still overvolt..

But i'm pretty sure that the mA is really 2.2mA..
From Frodus:

The standby resistance is 1.436kOhms so at 3.2v you should see about 0.00223 amp draw.

As they said.. this is a SIMPLE solution... :lol:

Doc

 

[GGoodrum]

Yes, it appears to be somethng that is to be used in conjunction with a "BMS" that does everything but balancing (are there really such units out there?).

Also, if you buy the assembled version, the price jumps up to $17 each.

-- Gary

 

[frodus]

yeah, its just a dumb shunt... you still need a smart charger that will not allow the voltage to go too high. Its the bare minimum you need for lifepo4 to get them to balance out while charging.

I'm planning on pairing this with a prototype 24-cell monitor that will do LVC and HVC... so I can disconnect the charger. A cheap and simple solution for now.

 

[AndyH]

Yes, it appears to be somethng that is to be used in conjunction with a "BMS" that does everything but balancing (are there really such units out there?).

Also, if you buy the assembled version, the price jumps up to $17 each.

-- Gary

I have one of the kits. It was inexpensive, went together quickly, and does work. It's a decent solution if one needs to shunt up to 2A and can get rid of the heat.

The designer uses 160Ah TS cells in a Honda S2000 conversion. He's using the Thunder Sky 'BMS', which is basically a monitor that can talk to the charger. There's no LVC or other pack protection.

I keep looking around for BMS options, and have yet to find one that beats Gary and Richard's board.

Andy