Help me understand what went wrong .

[outboard1196]

I have a small solar system consisting of 2 4d batteries 195 AH 390RC 400w of panels . I have a consistent 2.5-3A load running my security system. And occasionally running lights for a total draw 15A . I have my low voltage cut off at 11.5v one battery is 5 months old the other is 3 months old . I never felt they performed well from the beginning but just kept going with the plan to add a 3rd because I will be using the system to run a well. With the 2 batteries over night 5pm to 7AM voltage would drop to 12v +/- .2v this is with a 3A load max normally around 2.5A so it never added up to me. I got a 3rd battery charged it and did a load test 25A down to 11.2v ( I didn't want to go all the way to 10.5v) took 6.5 hours and 130Ah so it passed with flying colors specific gravity when charged was 1.3 + . The old batteries specific gravity was 1.2 avg when charged I did the same load test on one of them today and got 3.5 hrs down to 11.2v 75 AH and 4.5 hrs down to 10.5v 120AH . did I get bad batteries from the beginning or did I do something wrong ?
With the new battery over night it only dropped to 12.5v at 7am well batter then the 2 in parallel.
Thanks

 

[time2roll]

Anything much below 12.1 - 12.2 volts is hard on the battery. What is the charging voltage? May need an equalization charge on those old batteries.

 

[Bluedog225]

I was under the impression you should not mix old and new batteries.

 

[OzSolar]

The old batteries specific gravity was 1.2 avg when charged I did the same load test on one of them today and got 3.5 hrs down to 11.2v 75 AH and 4.5 hrs down to 10.5v 120AH . did I get bad batteries from the beginning or did I do something wrong ?
With the new battery over night it only dropped to 12.5v at 7am well batter then the 2 in parallel.

Voltage is a poor indicator of SOC (state of charge) for both FLA and LFP.

Hydrometers are much better (for FLA only of course) but ideally it would would go to a 2nd decimal point. "1.2 average" doesn't mean much. 1.20 +/- .05 tells a lot more.

I'd disconnect the loads for at least few days and make sure all of the batteries get to 15v for at least a few hours for two days in row.

Investing in a Victron smart shunt and perhaps a better hydrometer will be tremendously helpful.

Using solar and batteries without a shunt is like driving a car without a dashboard. You can do it but there's a lot of guessing about how fast you're going, how far you've gone and how much gas you have left in your tank.

Keep us posted!

 

[outboard1196]

Voltage is poor indicator of state of charge.

Hydrometers are much better but ideally it would would go to a 2nd decimal point. "1.2 average" doesn't mean much. 1.20 +/- .05 tells a lot more.

I'd disconnect the load for a few days and make sure all of the batteries get to 15v for at least a few hours for two days in row.

Investing in a Victron smart shunt and perhaps a better hydrometer will be tremendously helpful.

Using a solar and batteries without a shunt is like driving a car without a dashboard. You can do it but there's a lot of guessing about how fast you're going, how far you've gone or how much gas you have left in your tank.

Keep us posted!

View attachment 199681

I'm using a smart shunt for the load testing .
I say 1.2 average over the 12 calls I can get all 12 readings .
I have taken them out of service and charged using wall charger up to 15.5 v and back down to float. The second battery will be load testing today . even after charging specific gravity didn't change .
Something weird was going on with the solar controller so I'm waiting for a victron to show up .

 

[outboard1196]

Waiting for the other battery to finish charging
The other specific gravity at 13.3v
1.200
1.190
1.200
1.180
1.190
1.200
I'm using a baster style hydrometer so its not as accurate as the one posted above .

 

[OzSolar]

Waiting for the other battery to finish charging
The other specific gravity at 13.3v
1.200
1.190
1.200
1.180
1.190
1.200
I'm using a baster style hydrometer so its not as accurate as the one posted above .

That style is fine but you do need to get all of those up to ~1.275 (check your battery's spec for exact).

15.5v at how many amps? Sounds like your batteries could be sulphated.

One mistake a lot of folks make with FLA is not enough solar amps for the size of the battery bank. My gut tells me that your solar is a bit anemic for the battery vs. the loads. What is the highest amps your see for an hour straight from the solar?

 

[outboard1196]

That style is fine but you do need to get all of those up to ~1.275 (check your battery's spec for exact).

15.5v at how many amps? Sounds like your batteries could be sulphated.

One mistake a lot of folks make with FLA is not enough solar amps for the size of the battery bank. My gut tells me that your solar is a bit anemic for the battery vs. the loads. What is the highest amps your see for an hour straight from the solar?

Yeah I have been thinking I need more panels , which is why I got a bigger charge controller . today was 25A charging which is normal for a good sunny day I have seen 30A
I'm currently running just one new battery till I get more panels.

 

[outboard1196]

Just something to add , I went back to November and December in the charge controller history before taking it out of service and the low voltage for the days was around 11.9-12.1v I switched out the group 31 battery's I was using at the beginning of November to the first 4d battery . so would it be possible they had issus from day 1? I'm dropping from 13.2v to 12.5 over night with the same load as November with the new battery now . I know voltage is not a good soc but this is an apples to apples test .

 

[JWLV]

Years ago I tried doing solar with two group 27 deep cycle marine batteries. Worked ok, but they never provided as much power as I expected. Then they died after about 6 months. Since it was under warranty, I got replacements for free. Then another 6 months and the new ones died. Lead acid batteries are good for up to 500 cycles. For vehicles, they generally stay fully charged with very little discharge. With solar, you are charging and discharging every day. The deeper the discharge, the sooner the battery will die. I came to the conclusion that lead acid batteries are terrible for solar. I went with LiFePo shortly after and never looked back.

LiFePo used to cost much more than lead acid batteries. But now, there is almost no difference in price with equivalent capacities. A single 100Ah 12.8V LiFePo battery is about the equivalent to two group 27 lead acid batteries in terms of usable capacity. Two group 27 batteries might cost you $100 each. A no-name brand 100Ah 12.8V LiFePo can be bought on Amazon for around $250.

 

[outboard1196]

Years ago I tried doing solar with two group 27 deep cycle marine batteries. Worked ok, but they never provided as much power as I expected. Then they died after about 6 months. Since it was under warranty, I got replacements for free. Then another 6 months and the new ones died. Lead acid batteries are good for up to 500 cycles. For vehicles, they generally stay fully charged with very little discharge. With solar, you are charging and discharging every day. The deeper the discharge, the sooner the battery will die. I came to the conclusion that lead acid batteries are terrible for solar. I went with LiFePo shortly after and never looked back.

LiFePo used to cost much more than lead acid batteries. But now, there is almost no difference in price with equivalent capacities. A single 100Ah 12.8V LiFePo battery is about the equivalent to two group 27 lead acid batteries in terms of usable capacity. Two group 27 batteries might cost you $100 each. A no-name brand 100Ah 12.8V LiFePo can be bought on Amazon for around $250.

I'd love lifepo4 eventually I will get some but these are being used in an unheated application through winter .

 

[outboard1196]

So an update , they warrantied the battery's. I added 2 panels for a total of 600w added a victron charger along with smart shunt . seems to be doing much better .
One issue I see is I get sun a bit later in the morning do to some trees so it doesn't get full power right away . did first equalization cycle over the weekend.