Roof top Solar panels ( charging issue)

[Rich W.]

Rich,

Your comment about measuring voltage is not a good way to measuring anything surprised me.
Not an electrical engineer but what other method is used to determine a battery is bad?
Never heard of another method to check a battery. Even under a load test, it is voltage that tells the story.
Been in aviation for 54 years and voltage has been used on all the craft that I have flown.
Please enlighten me.

I was referring to testing battery health. If its all you have its better than nothing (12v batteries should be around 12.6v at rest) but it wont give you state of charge or capacity. When testing panels of course its fine. Having read all of this now, I agree with Kevin that removing the bad battery is paramount and ypu probably don’t need it anyway. Sorry for any confusion I caused.

 

[B52Bombardier1]

Hello,

Rich W is correct. A measurement of the battery voltage only reveals half of the power equation - volts x amps = watts or . . . power . . . the ability to do useful work. You need to take your batteries to a well equipped auto parts store for a "load test". Charge them up first to whatever you think is a full charge. Then go to the auto parts store to run the test that will show how many amps they can deliver within a short amount of time. This is usually a free test.

At three years old, I think you have at least one bad battery.

Rick

 

[forty_caliber]

Sounds like a bad cell to me as well. Are these lead acid chemistry? If you have to spend time and money on batteries, is it time to consider LiFeP0?

 

[LMHS]

... I would rather replace it later as it’s $700...

Wow. And my daughter thinks the two 6V 200AH SLA batteries that I'm ordering for her truck camper is expensive at $180 each. And this time we got free shipping! This new set of 6V 200AH SLA batteries are cheaper than what I bought last summer (currently $220 ea on Amazon) when I upgraded the single 12V battery that was on the used camper when it was bought in 2022. But then the cheap battery bank is on a cheap used truck camper, charged with two cheap (about $50-$60 on sale with coupons stacked with 20% employee discount) Harbor Freight 100W mono solar panels (I love that parking under a light fixture in the parking lots can keep the batteries "up" overnight with no loss even with the refrigerator running) with a cheap ($20) 30amp MPPT solar charge controller and the 2000Watt inverter is a cheap Harbor Freight inverter (it was a return that the buyer said didn't work - I think it was a "dispose" one that was tossed in the trash. I also have a 1500W inverter that I got the same way - works but not needed for now). The most important thing we run on the camper is the cheap Thomson 7.5cf refrigerator/freezer (on sale plus we used our "Sam's Cash" to get the price down to $70). And the cheap 700W microwave. And the cheap TV. And the cheap region free DVD player. We got a theme here! A cheap battery system so we can park in cheap/free places and parking lots. The camper has been plugged in one night so far this year and four or five nights total for last year. Threads like this make me think I have no business being on this forum. I'm either too poor or too cheap. Who knows, one day I might get serious and put what I have learned from my cheap system into a more acceptable/expensive system. But probably not.