New Battery

[JJC]

Is 45 a/h enough for a battery ? I don't drive in dark and rain. Car starts every time first go. My original workshop Manuel suggests it is. JJC

[North London Mike]

Sounds like enough, charging rate is the key, if it keeps up with the draw you'll be fine.

 

The Amp hours are to help to starting the beast, max drain, no charge

 

If your still on a Dynamo the battery could supplement very high drain for a short period but not recommended

[peejay4A]

Isn't it cold cranking current that determines how good a battery is at starting? Amp hours is a measure of its stored energy and not an indicator of starting ability.

[Lebro]

+1

AH is the capacity i.e. how long it will supply a current for. 65 AH = 6.5A for 10 hours etc.

Cold cranking figure is a measure of the internal resistance of the battery, which if very low will allow lots of current, if higher will limit the current.

A CC figure of around 650A, & an AH of around 75 would be fairly normal for a TR. Go less on the AH, and you may run out of energy if it is not a good starter.

 

Bob.

[Ian Vincent]

My philosophy is to buy the biggest one that will fit in the tray.

 

Rgds Ian

[tim hunt]

+1 Ian. I currently have a Varta Blue Dynamic of 95AH capacity and a CCA of 850 Amps. I don't give a stuff that it doesn't look original, the comforting thought is that if it will start a big diesel engine with maybe 18:1 CR then it is well man enough for my 2.1L tractor engine. I also still run a dynamo and the reserve capacity is a reassurance on an all night drive when heater and wipers may be required with the o/d frequently engaged.

 

Tim

[TR5tar]

My philosophy is to buy the biggest one that will fit in the tray.

 

Rgds Ian

 

+2. I use an Optima Redtop on my 5 (815 cca,100 ah). Not cheap, but it has performed very well for me.

 

Cheers, Darren

[McMuttley]

I have a cheap old 'Lion' battery that has never been an issue - always fired.

 

The good news is that it is for sale - you just have to buy the rest of the car too !

[North London Mike]

+1

AH is the capacity i.e. how long it will supply a current for. 65 AH = 6.5A for 10 hours etc.

Cold cranking figure is a measure of the internal resistance of the battery, which if very low will allow lots of current, if higher will limit the current.

A CC figure of around 650A, & an AH of around 75 would be fairly normal for a TR. Go less on the AH, and you may run out of energy if it is not a good starter.

 

Bob.

+2 sorry, my point was badly expressed, it allows you to keep cranking until it starts (not the power of the cranking) tough crowd

[peejay4A]

Weeell not really. You could have a 100 ah battery with rubbish CCA and it will not start the car on a cold morning. You have to consider both figures. Sorry.

[North London Mike]

Everyday is a school day

[stuart]

Get the biggest one that fits in the space. I had a 3a in the week before that must have had a truck battery fitted as it took up the whole of the battery box and only just missed the bonnet! Interestingly enough it also had a high torque starter fitted too!

Stuart.