Pytes V5 Charging Profile Confusion

DIY
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1

I’m trying to understand my Pytes V5 charging behavior. This is a new system and only up and running for a week or so. No PV. System is currently a UPS/backup configuration. Pic below. Closed loop with DVCC configuration as recommended by Pytes manual.

Being a novice with this system I am, of course, obsessed with the data VRM produces.

I really cannot make sense out of the charging curve for my battery bank. Perhaps I should just relax and let the Pytes BMS do its thing? I have attached voltage chart for last three days with notes and VE Bus State state for same period.

Thanks for any insights!!

Equipment:
2 x Multiplus 5 kVa split phase
Cerbo GX
3 x Pytes V5

3-day-charging-curve
3-day-charging-curve2986×1882 228 KB

3-day-state
3-day-state2986×1882 177 KB

System
System1280×960 164 KB

2

It is normal for a bit of battery voltage drop under inverting.

High resistance to (or in) the battery bank can cause voltage rises and drops like that under load.

With them daisy chained, i am not surprised.
Second observation the gauge wire from the battery bank to the bus is not grater than or equal to the gauge from the two inverters to the bus bar.

Increase the gauge or add another connection to the bank. It may help a bit.

1 Like
3

Thank you LX. Yes, I understand the dramatic voltage drop when going from full charge idle to inverting. I’m really interested in the variance in idle voltage and that VRM shows bulk or absorption and never float. For the last 12 hours VRM shows the battery bank @ 52.18 v and bulk charging with battery at idle.

Battery bank to Power In cable is 4/0. Power In to inverters cable is 2/0.

4

The 2/0 is great for 0-5m (return) but your return looks like it is longer than that. Then 2x 2/0 is 140mm 4/0 is not quite that.

That being said, to get into float, the systen has to finish the whole charge cycle without interruption.

CC to target voltage. CV for set period (absorption), then drop into float. Your charge cycle is pretty interrupted there.

You can get different voltages on idle depending on cell balance SOC etc.

5

Thank you LX. 2/0 distance ( Power In to Inverter ) is 2 x 0.61 m ( 2 ft. ). 4/0 distance ( Battery to Power In ) is 2 x 1.83 m ( 6 ft. ).

I think I ill just relax and let the Pytes BMS do what it thinks is best.

Thank you again.