Replace 40ah battery with 70ah

[Andy_J_G]

Hi
My 40ah battery needs replacing and I have been offered a brand new 70ah battery free of charge, assuming it physically fits is it safe to do so? Assuming it won't fry any electronics?
Cheers in advance.
Andy

[QJumper]

If it fits and is the same voltage (eg 12v) it will be fine. Ah is just the capacity, so it will last longer before needing to recharge.

[GreenV8S]

Make sure it's the same battery type eg not switching between deep/shallow discharge type or wet/agm/gel and the CCA is as least as high as the one it's replacing. But if it's for a conventional car application then replacing a plain old lead acid battery for one which has higher capacity and similar spec for everything else then as long as it will physically fit and the terminals are compatible then there's no electrical reason not to do it.

[Andy_J_G]

GreenV8S said:

Make sure it's the same battery type eg not switching between deep/shallow discharge type or wet/agm/gel and the CCA is as least as high as the one it's replacing. But if it's for a conventional car application then replacing a plain old lead acid battery for one which has higher capacity and similar spec for everything else then as long as it will physically fit and the terminals are compatible then there's no electrical reason not to do it.

It's from a stop/start car, so an AGM, a no go then?

[Tony1963]

Andy_J_G said:

It's from a stop/start car, so an AGM, a no go then?

If the replacement is an AGM, it’s fine.

[Andy_J_G]

Tony1963 said:

If the replacement is an AGM, it’s fine.

The one being replaced is not an AGM, the new one is.

[donkmeister]

Andy_J_G said:

Tony1963 said:

If the replacement is an AGM, it’s fine.

The one being replaced is not an AGM, the new one is.

AGM requires a higher charging voltage than a standard "flooded" battery so have a higher alternator output voltage. You might get away with it... It won't damage anything and it's free.

[Andy_J_G]

Thanks for all those who replied.

[Polly Grigora]

donkmeister said:

AGM requires a higher charging voltage than a standard "flooded" battery so have a higher alternator output voltage. You might get away with it... It won't damage anything and it's free.

Agreed, free is good and it's worth trying

[Captain Answer]

Polly Grigora said:

donkmeister said:

AGM requires a higher charging voltage than a standard "flooded" battery so have a higher alternator output voltage. You might get away with it... It won't damage anything and it's free.

Agreed, free is good and it's worth trying

Could always use a Ring (or similar) smart charger on it to top it up. I've got the 8amp one from when we had a car with AGM on (lot of people use the 4amp for them but i already had a 1amp NoCo so decided to get the bigger one)

Not got that car now but still use the Ring about once a week on each car just to maintain the battery health

https://www.amazon.co.uk/gp/product/B082VBV2Z9/ref...