Final LFP Charging settings with Batrium BMS?

[Zwy]

Banding is the "width" of voltages the balancers will work on simultaneously.

In my case, when I deployed my NMC bank, the total deviation was about 0.25V. 12 were pretty close, one was way low and one was way high.

Set gap to 0.02V. If I set banding to 0.01V, it would have only worked on the cells with the highest voltage within 0.01V, i.e., the single high cell.

If I set banding to 0.25V, it would have done all cells 0.02V or higher from the lowest cell. In my case, I needed 13 of 14 cells burned off. This could have over-worked the heat sink on the WM5 if I didn't have active cooling. In this case limiting the banding would have reduced the strain on the balancers.

Thanks, makes it much easier to understand. With the Core and K9's, there is a heat sink on each battery. When I was just using Bypass without the Auto Level and the current settings, the balancing would be on multiple cells, usually 8 cells, even then odds, and the K9 temp would rise quite fast. It would bypass cells that had lower voltage and it seemed a waste to me, plus it would heat up the K9 rapidly. The result was it took extended time to get balance.

 

[callmeburton]

As an experiment I just reset the SoC to 85% (where my ramp down starts) to see what it does after it settles back down.

Same old 3.3 settled voltage state, not being able to climb past with the .1A at 98% SoC.

Will now set to the non-longlife setting, ramp start / end voltages match, set SoC manually to 88 to trigger a charging cycle given the battery is at 3.3 right now, and selected default settings for charging (as I had them modified slightly for cell hi cutout. Will report in another 24 hours with new settings to see where the battery ends up and what it does. Final ramp is set to 98% and .1A still.

 

[callmeburton]

Beginning to think something is "wrong" if you will ... pack went through a charge cycle and settled down, only 2.5Ah went in during that time based off the telemetry I am seeing. It is still at 3.3-3.32 :/

I set the SoC manually to 88% so I wouldn't get a huge cutoff behavior from the start from having it below 85% which would request 112A ... looking at the reason the charging stopped it seems the bypass session mAh amount was exceeded for each cell. The SoC never got beyond 90/91 so the request was 6A when it "finished" and reset the SoC to 100% for the pack.

 

[sunshine_eggo]

What are your settings now?

 

[callmeburton]

basic defaults at this point. I went through most screens and defaulted them after selecting typical LFP BUT the ramped I kept my personal settings and only updated the voltage to match the default voltage.

EDIT: Looks like my settings screeshots are compressed ... sec will fix this ... mental note, the form doesn't like wide images. @sunshine_eggo

 

[RotEvery]

when

Please where in Victron did you do the 0.1A current setting. I'm new to Victron. Thanks.

 

[sunshine_eggo]

Please where in Victron did you do the 0.1A current setting. I'm new to Victron. Thanks.

This is a Batrium BMS discussion.

 

[RotEvery]

This is a Batrium BMS discussion.

Okay thanks.

 

[Zwy]

basic defaults at this point. I went through most screens and defaulted them after selecting typical LFP BUT the ramped I kept my personal settings and only updated the voltage to match the default voltage.

EDIT: Looks like my settings screeshots are compressed ... sec will fix this ... mental note, the form doesn't like wide images. @sunshine_eggo

A few things I see with your setting I don't like, the high voltage cutoffs are too high. This is what have set.



As for your ramped charging (which I don't use), the limits are set too high.

 

[callmeburton]

As for your ramped charging (which I don't use), the limits are set too high.

Thanks for the thoughts, which limits?
I think my settings are default "long life LFP" right now ... in your settings it looks like the only active options which are different is the high shunt voltage cutout, and the cell hi cutout

 

[Zwy]

Thanks for the thoughts, which limits?
I think my settings are default "long life LFP" right now ... in your settings it looks like the only active options which are different is the high shunt voltage cutout, and the cell hi cutout

Yes. I'd lower the cell high voltage cutoff to 3.65V supply high cutout.