Forum Discussion

campermama's avatar
campermama
Explorer II
Apr 12, 2023

Need Solar Guru Help!

This is my system...

570w solar panels (parallel)
?2 100ah BB lithium (parallel) (12v)
Victron smartsar 100/50 controller
Renogy battery monitor
Renogy 2000w inverter

Victron goes through bulk mode until it reaches absorption V, then goes to absorption mode for 1 hr (recommended by BB), (highest V I have seen on the monitor during absorption mode is 13.5, while mppt reads 14.4)then it goes to float (mppt reads 13.6v, monitor reads 13.4v), the amps never go down to 0, it sticks around at 2-4 amps. So to me it seems batteries are never "fully" charged?

V always drops to 13.2(something) v when it gets dark. According to charts I have seen that is only 70%!
ALSO, discharging amps at night seem really low....TV, inverter on, led lights on, it shows - 1.8 amps, how can that be?

Here is a "drawing" of my set up....

My 12v System
  • So there was one connection wrong that was affecting the amps reading....the Neg of the inverter was not on the shunt! I have now switched them.
    Now it's just the charge issue, I think.
  • I'd suggest checking/verifying load/discharge (-) and charge (+) current separately by measuring current on the appropriate wires/cables with a DC clamp-on ammeter (during the day and at night). Your battery monitor only provides the sum total of both, which doesn't give you a clear picture of what's going on. It's also possible your battery monitor is inaccurate or mis-calibrated. A DC clamp-on ammeter would help confirm the accuracy of the battery monitor's current readings.
  • The 1.8 amps sounds more like the 120v side. 13.2 is more than 70% on any chart I've seen. I did not know any Li battery needed absorption.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,203 PostsLatest Activity: Feb 22, 2025