Is An 80amp Alternator Enough? And Which Are The Best Batteries To Use

[nige2009]

Hi, my alternator packed in and I bought an 80 amp new one. I have twin system batteries like below:

I need new batteries but am unsure of the best size? would 2 x 55ah be enough? Or should I go for 2 x 77ah's?

Also would it be ok to use silver calcium batteries? I have read that they need a higher charge rate of 14.9 instead of the usual 14.5 or something like that. anyone know?

thanks..

[nige2009]

there is a silver calcium Battery going for £50
it's 77ah
780 cold cranking power
5 year Warranty

would these be ok to use? they are the 096 size but do fit :)

Also would two 096 batteries be OK? the + 8is at the right side. I can extend the connection leads. does 1 Battery have to be - left + right .. and the other to be + left and - right.. Can they both be - left and + right..?

I've got until 4pm gmt to order, so any help would be great...

thanks

should I go for 2 x 77ah's?

Also would it be ok to use silver calcium batteries?

[davesyd]

i'm interested in hearing the answer as well

[nige2009]

Me too :)

Does anyone know the answers???

[MikeSh]

If it is a fairly unmodified vehicle why not just replace like with like (or as near OEM as possible)? If it's done 20 years with stock items why change now and make life difficult when there is no obvious benefit?

I think you should avoid silver calcium batteries. Even a brief web search suggests that older vehicles may not cope, and I'd certainly check with the car manufacturer (and alternator maker in this case) before trying it. Bear in mind that the higher charge voltage will also be applied to the rest of the vehicle electrics, so you may start killing off other stuff too.

On the other hand, if it has been heavily modified with things that will use a lot of power you need to publish that info here so people have something to go on.