Solar panel charge doesn't seem to be flowing to batteries...help, please

DIY
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1

My batteries won’t seem to charge from solar. The batteries charge fine when Inverter is connected to shore power.
I am in Los Angeles if anyone has a good resource that I could take the van to diagnose.
Thanks

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2

How much PV do you have on the van ? … can you access the PV plugs / connections? 15V PV is not much …

Perhaps the DC disconnector is defective … Can you measure the voltages before and after the fuse?

3

The PV voltage needs to be 5V higher than the battery voltage for the panel to start charging and once charging it has to stay 0.5V (or 1V I can not recall exactly) above the battery voltage.

I notice in the picture what looks like the top of a pair of resettable breakers, these cheap breakers have a really poor reputation for poor connection with high resistance. You have all the hallmarks of a poor connection somewhere in your system not allowing the power to flow. You need to check the voltage at every connection with a multimeter to see where the voltages change on both the solar panel side and the battery side. Check for voltage drop over these breakers using your multimeter. My money is on a poor connection on the solar side which is dropping voltage so the MPPT gets a low input voltage and very little current (essentially zero). It is seeing battery voltage on the outlet, but again that does not preclude a high resistance connection.

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4

The PV voltage as mentioned above needs to get to 5V above the battery voltage as mentioned above, it will then operate down to 1V above the battery voltage. if you have 2 solar panels, then these should be connected in series for the higher voltage, otherwise you should change the MPPT controller for a PWM type.

5

Thanks for the reply, I will test the voltages before & after.

6

Thank you for the reply, I’ll check the voltage at the recommended locations.
Can you elaborate on the breakers and also suggest alternatives?
Thanks

7

Here is one thread on the cheap breakers as an example. I have lost count of the number of DIYers
using these and reporting problems, there was another a week or so ago.

Personally I use fuses but a good brand of breaker such as Blue Sea may work if you can avoid the clones.