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diy solar

Troubleshooting help

HLP

New Member
Joined
Aug 18, 2020
Messages
3
Hello,

I started having a problem with my system one month after installation with no issues prior. Since moving to a warmer climate (where the average daily temperature is 100 degrees F), the numbers reading form the Renogy. bluetooth app and the charge controller, when compared to the capacity of the batteries, is not adding up. With a multi-meter, I cannot find a reason for the batteries being fully depleted, considering the demand.

We have the following solar set up in our converted van:
- 2 x 300AH, 24 volt LifePo4 batteries connected in parallel
- 2 x 365w solar panels
- 1 x 30amp Renogy Rover charge controller
- 1 x 2kw AIMS inverter/charger

The Renogy App reads the following:
- Panel - 27.4v, 0.18A, 5w from panels at 7:30pm (after sunset)
- Battery - 24.6v, 60%, 0.19A, 25 degrees C (the temperature never changes and it's most definitely hotter than that)

By 11:30pm the alarm goes off and the app says 0%, 21.9v, 0A

Test volts at connected battery is 10.2v when depleted
When sun comes up batteries go to 100% in less than 2 hours
Biggest draw is a 110v fridge drawing 0.8amps

Thank you so much for any responses or guidance, I'm new to this, and feeling a little lost! :)
 

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Your battery capacity is:

2*300*24 = 14.4kWh

Assuming no shading and optimal placement, your panels can provide:

2 * 365W * 5h = 3.65kWh/day

Your panels are undersized for your battery.

I see a few possibilities:
  • I suspect that you've been slowly over-using what your panels can supply, and after a month, you can no longer meet your overnight needs due to progressive battery depletion.
  • You have your charge controller improperly configured, should be something close to:
Absorp: 29.0-29.2V​
Absorp time: 30 minutes and a 12A cut-off current.​
Float: 26.4V​
  • Loose connection(s) somewhere between the charge controller and the battery.
  • A failed/failing batter(y/ies).
  • You have loads you don't realize you have.
Do your batteries have their own BMS?
 
Correct, 14.4kwh and being in Mexico we have about 8-10 hours a day of solid sun.

Yes the batteries each have a BMS.

Overnight we run an AirMaxx fan 70% speed, 2 small cpu fans which act as an exhaust for the bathroom and a 110v fridge drawing 0.8amps.

Connections are tight, no appliances seem to be draining, new batteries have only been in use for one or one and a half months.

Before moving for work from a town that was 12C/54F cooler then here, I would test with all 12 and 24 volt lighting, 110v fridge, fans, gas alarm and power tool chargers on at night for hours and they never dropped below 70% for multiple nights.
Now this is the fourth night they have dropped to 0% lowest 10.2v.

I dont understand how the batteries can be 0% 4 hours after the sun goes down and reading 100% 2 hours after the sun comes up?

much appreciate the help!!
 
I would disconnect all loads and start from the basics, looking closely at the SCC setup and BMS. Disconnect and test the batteries.
 
Last edited:
Your inverter + 110V fridge must use more than 0.8 amps from the battery.
 
Thank you for everyone's responses.

I changed some dip-switch settings on the inverter, and I'm going to change the batteries in my multi-meter, because I agree, it should be reading more than 0.8 amps.

Thanks again!
 
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