Smart charger drops to 0 twice a minute at peak solar

Q&A and troubleshooting
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1

My victron controller is dropping to 0 current twice a minute at peak output times. Victron’s engineering department suggested that i drop the current or voltage to correct the problem. This was to correct the problem of mismatched batteries and the bms was suspected of shutting down the controller. I bought 3 new sok batteries (wired in parallel) and spent a fair bit of time top balancing them (all cells are within .010v of each other). The volts and amps are well within the us parameters of the controller, and i’m trying to get MORE power not less. I did do variations from series wiring of the panels to series-parallel and also parallel with no change in the fluctuations. OCV is 87 (4 panels wired in series)and amps might make 40 on a great day. Absorption is set at 14.5 and 2 hours, float at 13.6. All else is victrons settings.

Someone should be able to figure this out i cant be the only one having had this problem. This is killing my solar output and we are boondocking in our 5th wheel.

2

Try dropping your absorb voltage to 13.8V and float at 13.6V.

3

My limited understanding was that this was the threshold that the battery had to meet to go into absorption. It seems to act up in both bulk and absorption and gets into absorption fairly easily. I changed the setting but can you briefly tell me your thoughts on why this is going to make the controller act normal?

4

3.45V per cell should be sufficient for internal balancing to kick in. When trying to charge at 14.5V, or 3.625V per cell, it’s quite likely that the battery bms will hit a high cell voltage limit and inhibit charging, causing the dropouts you are seeing. 3.45V is sufficient to fully charge an lfp cell, theres really very little capacity above that

1 Like
5

Thanks for that - i’ll check the cell voltages tomorrow to see what they are doing if it still drops to 0

6

At the setting of 13.8 for absorption the controller does not drop to 0 BUT it seem to limit the current into the batteries - like it cuts it in half, fro 500 to 250 watts or so. 13.9 gets the watts back up to 500 but it also drops to 0. Watching the cell voltage it doesn’t move to much and all cells are 3.333 +/- .010. How can i figure out if it is the bms that is dropping controller to 0 for a few seconds? Any further suggestions would be helpful - thanks