Do you agree my batteries are on the way out??

[Jev88]

Fitted my preferred Victron Smartsolar unit on Sunday. Last two days show a healthy 13+ volts registered in battery bank. However, the handy history tab shows charge dropping to 12.5v each evening and there is nothing switched on bar alarm which I think is running off engine battery anyway.
Can I assume they are duff? They are at least 3 or 4 years old (previous owner) and he inherited them when he bought it.

I am ready to replace them (can fit up to three "normal" sized batteries but just checking in case I have missed something.

 

[Lenny HB]

Sound like they have had it. May be just one battery that's the problem dragging the others down. You don't know the history of how they have been treated so worth replacing them all.

 

[Jev88]

Sound like they have had it. May be just one battery that's the problem dragging the others down. You don't know the history of how they have been treated so worth replacing them all.

Hi Lenny.
I have switched my batteries over now. For interest I powered an old single clip on inspection lamp (halogen bulb) and after two hours the battery dropped to 11.5 volts. Does that confirm at least that battery is decayed a lot now?

 

[Lenny HB]

Looks like it.
What wattage was the lamp?

 

[Jev88]

Looks like it.
What wattage was the lamp?

I had to dismantle the lamp to see
3H 55watt bulb.

I tried a second battery and left on overnight. Battery down to 11.0 volt

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[Lenny HB]

Yep both knackered, one giving you about 9ah the other 50ah.

 

[Jev88]

Yep both knackered, one giving you about 9ah the other 50ah.

Cheers Lenny. I won't be selling them on then (I'm an honest chap). Scrap time or £10 voucher per battery at Halfords trade in then.
I have seen it recommended before to hook up a car headlight bulb as a test but couldn't recall how long a "good" battery should last etc....