Domestic 12v batteries not going above 13.1v with 500w solar?

[davethedog]

Thanks all and now back in our home marina so got the batteries on shore power charger and that is only getting to 13/13.1v at present also. So looking like an issue with the batteries or one of them as the shore power charger circuit is separate to the solar circuit.

Have used the digital drop test meter device I have on each of the 3 batteries independently and all passed with good state of health but I do know that is not a true indication for house bank batteries.

Be interesting to see what the batteries get to by tomorrow morning after 12 hours on shore power charger.

Tomorrow going to see about getting some new batteries anyway as should really have a matched bank anyway, rather than the 3 x mismatched capacity and ages I have at present.

[davethedog]

Hi all and now in our home marina so on shore power and the mains charger is on so will see if that makes a difference overnight.

I did disconnect the batteries one by one and use a digital battery tester and they all were OK, but am aware that is not a true test for house batteries.

The shore power charger got the bank up to 13.1v easily enough but been stuck there for a long time and my battery monitor showing 4 to 8a going in to the batteries (as we are still running the fridge and freezer etc here in the marina).

So, starting to think that at least one of the batteries may be dead and so may be time to replace them all with the same size (as presently the 3 are differing amps capacity and ages and makes). May go for AGM if that is the case.

Will update tomorrow.

[Stu Jackson]

It may not be wise to consider AGM unless you solve your charging issues.


AGMs require complete charging regularly or they die a swift death.


There are many discussions about the limitation of AGMs.


marinehowto.com has good info

[Compass790]

If your shore power battery charger is only putting in 4 amps when the fridge isnt running & it jumps to 8 when it is it does suggest a battery issue. It should be putting in its max if the battery is only at 13.1v. What amperage is the shore power charger?
At 4 amps it would take a few days to fully charge a 480amp hr bank.
You probably should have at least a 20amp shore power charger for that size bank.


Have you tried testing with a hydrometer as earlier poster suggested?
You may easily identify a sick cell then & they are cheap.
+1 for post #18

[davethedog]

Hi the batteries are all sealed lead acid and after being on the 30a shore power charger (sterling power intelligent model) the battery bank is at 13.4v so not charged. So it must be the batteries as the bank does notnl charge well on either solar and wind or shore power.

[Compass790]

Yep sounds like batteries, sorry re earlier advice, assumed you were dealing with normal lead acid not sealed hence hydrometer recommendation.
You could put your car battery in the circuit briefly to test solar as well but given your shore power charger is ok it seems you've found the smoking gun.
As an aside we've found 6v golf cart batteries good bang for the buck if you dont mind watering batteries.

[hlev00]

Be sure to replace with something supporting deep cycle usage. We have been happy with FLA installed in 2018. Today I would consider another type but as mentioned you do need to look at your entire system. If you have the luxury of time then looking at options and cost makes sense.

Harry

[davethedog]

Hello all and as promised an update.

I have changed the 3 mismatched and mis aged domestic batteries for 3 x 140Ah AGM batteries and today they got to 14.4V before going to float under solar. I also re did the solar charger wiring and ran it through a bus bar instead of direct to one of the batteries for distribution (not that is should make that much difference but feels better going to all 3 batteries from the same point).

So, fingers crossed all sorted, but going to leave the batteries off the shore power charger tonight to see what they get to tomorrow morning and then how long they take to get to float charge (even though the weather forecast is a bit rubbish here for the next few days).

Thanks for all the advice!

[Compass790]

Thanks for the update,
Always good to hear the what & why. Bit hard to do a meaningful check if its cloudy & raining but I guess you'll see how little is coming from the solar & know what to blame.
Good luck with the new batteries cure.

[Pete7]

Don't be too alarmed if the new batteries drop a bit more than expected. Certainly my flooded batteries take a few charges and discharges before they assume full capacity.

Pete

[Pelican_38]

Originally Posted by Pete7

Don't be too alarmed if the new batteries drop a bit more than expected. Certainly my flooded batteries take a few charges and discharges before they assume full capacity.

Pete

Pete, how many cycles would you say your batteries needed to get to full capacity?