Battery Amps

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edd_barker
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Battery Amps

Postby edd_barker » Fri Jan 04, 2019 11:24 am

Hi all,

There was an excellent article in the most recent minor matters, on batteries suitable for higher compression engines that might need a little more oomph. Sadly my copy has already fallen victim to the recycling police! Can anyone advise on a suitable battery? My engine has 12G940 head so is a high comp ratio than standard. I think it is Amps I need more of rather than amp hours? Electrics are not my strong point.

I suppose I will be heading to Halfords to buy it.

Many thanks,

Edd

Ian Jones
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Re: Battery Amps

Postby Ian Jones » Fri Jan 04, 2019 8:38 pm

Hello Edd

Can't answer your question directly but hope I can help a bit. Amp Hours (Ah) is a measure of how much electricity the battery can hold. Cold Cranking Current, or Cold Cranking Amps is a measure of how much electricity the battery can supply in a given time. Sorry if this is a bit too simple for you but if you imagine the battery to be a tank of water, the Ah is the size of the tank and the CCA is the size of the pipe coming from it. As long as you have about 45Ah, and the battery will fit the space, the higher the CCA the better. I've used Tayna batteries https://www.tayna.co.uk/ for a while now for various vehicles. Good prices and quick delivery. Just check that the pos and neg connections are the right way round. The one on my Traveller has the terminals towards the front of the car and a bit too close to the clamp for my liking. When I need a new one I'll buy one with the terminals at the back. Not sure which is "correct" as in original. No doubt someone will advise.

Regards

Ian

JOWETTJAVELIN
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Re: Battery Amps

Postby JOWETTJAVELIN » Fri Jan 04, 2019 9:17 pm

For period look you can buy hard rubber open bar batteries from LinCon. Can always specify a more powerful one from them too. I bought one for my Morris Oxford MO and have had it on my Humber Snipe which it turns over very quickly.

Otherwise an 065 would perform admirably.
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IslipMinor
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Re: Battery Amps

Postby IslipMinor » Sat Jan 05, 2019 10:06 am

I am pretty certain that the original design has the battery terminal at the rear, next to the bulkhead. If it didn't then it should have! Having the terminals at the front brings them much too close to the battery clamp.

For starting it is the 'CCA' (Cold Cranking Amps) that matters, although you will find that with CCA and Ah (Amp Hours) one increases as the other does.

The BMC Workshop Manual quotes around 40 Ah as the battery capacity, and for positive earth an 038 (with Terminal Layout 1) is often stated as the current equivalent, but this is actually a bit small, as the capacity is around 35 Ah and 265 CCA (there do not seem to be any definitive standards for battery codes, as different suppliers quote a range of Ah capacities for the same battery reference).

To give a bit of reserve capacity, particularly with some electrical extras, I would suggest a minimum of 50Ah (065) is better, or even more, especially if the car is not used on a daily basis. It also means that the battery can lose a bit of capacity without immediately compromising the starting capability. Our Minor is garaged and dry, and not used very much in the winter, but I expect it to start as normal as and when required, which it does.

For a negative earth car, the terminals need to be 'Layout 0', and for positive earth 'Layout 1', as in the diagram below:
Battery Terminal Layout.jpg
Battery Terminal Layout.jpg (18.9 KiB) Viewed 534 times
After the restoration was completed 20 years ago, we fitted an 075, which generally comes with lifting handles and is for a negative earth car, and has a capacity of around 60 Ah and 550 CCA. We fitted the 3rd 075 battery a couple of years ago, with the first 2 lasting around 9 years each, and with no real problems even then - it just seemed to be tempting fate to push too much longer! This time Yuasa were offering a good price, so that is what is now fitted. So far no problems.

As a note, fitting a battery bigger than an 075 increases the weight significantly, which means getting it out could be an issue (going in, gravity is on your side!).
Richard



edd_barker
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Re: Battery Amps

Postby edd_barker » Mon Jan 07, 2019 9:38 am

Many thanks for the informative replies! I will have a measure and see what I can fit in there. My car is negative Earth, the current battery is fitted backwards, keeping the terminals at the rear, and leaving a handy blank side to fix my own period logo rather than something modern and inappropriate!

Edd

edd_barker
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Re: Battery Amps

Postby edd_barker » Thu Jan 24, 2019 2:17 pm

To finish this thread, I have just ordered a 075 battery from a Cheshire-based seller on ebay. It cost me £55 with next day delivery, which seemed pretty reasonable. My sole reason for choosing it was the 'LUCAS' branding, which I thought would sit quite nicely in the car!

Mine is negative earth, with the battery fitted backwards, which keeps the terminals away from the fixing bar nicely. Whoever fitted the last battery and did the positive-earth-to-negative-earth conversion did this, and so I have never seen any reason to change it.

Thanks,

Edd


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