ANT BMS QUESTION - please help!!

[TerrySavace]

All,

I have an ANT BMS connected to a 72Volt battery. I have left it plugged in for a couple of weeks, just checked it today and it seems the first cell (#1) is being drained faster than the rest? I have attempted to do a manual balance and it doesnt seem to be making it any better. Any idea why its doing this? Does the ANT BMS only really use one of the cells blocks for powering itself? Why is a self balance not bringing this cell bank back up to the match the rest?

The cell difference is now 0.100 - it was 0.005 when i first built this battery. I have not yet charged this battery.

 

[BobBob]

Guessing the BMS is drawing power from the first bank only. I believe this is quite common.

 

[TerrySavace]

Well, thats a poor design! I best charge it up soon

 

[Andy_L]

is this quite common? The ANT BMS was on my list of potentials

 

[goatman]

what happens if you lower the start balancing voltage to 3.0v

just curious if that would "solve" draining p-group 1 down when putting the pack into storage or if it would just take the whole pack down at the same time, as p-group1 goes down the bms burns off the other p-group voltages to match with the potential of "bricking a pack"

 

[tmho]

is this quite common? The ANT BMS was on my list of potentials

I am using an older version (with App for android phone only) of the ANT smart bms. It is not drawing power from just 1 group of cells. I said so because after storing for several months, the voltage difference is still just 0.003V like before.

 

[Jonno]

what happens if you lower the start balancing voltage to 3.0v

just curious if that would "solve" draining p-group 1 down when putting the pack into storage or if it would just take the whole pack down at the same time, as p-group1 goes down the bms burns off the other p-group voltages to match with the potential of "bricking a pack"

You've hit the nail on the head with that.
I've been running all my ANT bmss like that , 1 for over a year with no problems,

Jonno

 

[j bjork]

I have another kind of ant bms, those that are available in 24s and 32s versions.
I have not noticed anything like that, but I usually turn it off when the bike isnt used for a while.

I think the extra red wire to the last positive cell is for powering the bms.

How do you self balance?
If you are trying to get the bms to drain all the other cells down to that level it will take a long time..

It depends on the Ah of the cells of course, but I assume it is not 3-5Ah.
Draining with maybe 180mA, overheating and stop. Start again and so on.

If you charge that group to the same voltage or slightly higher than the others it will probably work better, but maybe there is a problem with that cell group?

 

[Frank]

Just to confirm - this method keeps the pack in balance but does nothing about the unequal power draw.

Isn't there a way to totally disconnect the BMS to eliminate power draw during storage? I'm asking as I have one of the older ones (just installed, just downloaded the app today) and the newer version apparently offers some way to do this.

Any info appreciated!