[Andygoodbloke]

Hi all.
I'm finishing of the body work around the rear guards and so far so good.

The next job which needs addressing is a new battery.

I have a standard G13a motor and standard alternator and the tiny battery in the car needs jump starting more than it doesn't, plus I have added a kill switch from the starter adding resistance to the starting system but have up graded the wiring to be able to provide less resistance. The current battery is only 320 CCA, how big for a standard set up would people recommend? I am not running winches or anything accessibly draining on a battery but think for the standard alternator a 500 to 600 kind of range would suit as if you go too big with the battery the alternator won't charge it unless you drive Australian distances, and I don't plan to.

For a G13A motor and a standard alternator how big in terms of CCA are people going?

Thanks Andy

[fordem]

I've been in the habit of fitting the highest capacity battery that I can squeeze into the available space, and after forty plus years of doing this, I have no regrets - a larger battery costs more, but is less stressed and consequently lasts longer.

Having a larger battery does not require a higher capacity alternator to charge it - think of it as a tank of water, if you're using 10 liters a day, you only need to put 10 liters a day in to keep it filled - it could be a 100 liter tank or a 200 liter tank, if you only take 10 liters out, you only need to put 10 liters back.

The alternator is sized based on the running requirements of the vehicle with enough extra capacity to replenish the energy used to crank & start the engine and with a G13A and the stock alternator, that recharge typically takes 30 seconds to a minute, I had an ampere meter on my car and you would see the needle peak and then gradually drop as the battery recharged.

[Andygoodbloke]

Thanks Fordem
I have found a 620 CCA battery which is going to go in - a bit of a step up from the tiny 320CCA in there currently
As long as the leads go on, it should be fine then
Nice analogy with the water tank.

Cheers Andy

[Gwagensteve]

To clarify, CCA “cold cranking amps” is a measure of a batteries internal resistance. This is not a measure of the battery capacity. Some very small (low capacity) batteries have very high CCA ratings.

The capacity of a battery is measured in amp/hour.

To use the water tank analogy, amp/out is the size of the tank, CCA is the diameter of the pipe letting the water out.

A stock sierra with no additional aftermarket load doesn’t require much of either.

Note however the stock alternator is only just big enough for the load a standard car applies. Despite their rating, they become markedly less efficient when hot and typically won’t deliver over 35A peak once hot.

[Andygoodbloke]

Ahh I think you are mistaken Steve.

CCA does stand for Cold Cranking Amps but it is the measure of how many amps it will supply when could when the lead acid batteries struggle and fail to transfer ions due to the cold. Many European countries change battery acid to a stronger acid to help the CCA during long cold winters.

Ohms is the measure of resistance also not amps.

So Watts is Volts x Amps so 12x620=7400Watts
The old battery is 320CCA so 12x320=3840Watts

The new battery is near on double the output and it makes the vehicle spark into life a lot easier, time will tell how it goes over winter.

Thanks Andy

[Gwagensteve]

Sorry Andy, I’m afraid I’m right in this case. Output is not capacity. You can express CCA as watts if you like, it still doesn’t represent capacity, only ability to discharge quickly.

Yes, I know the measure of resistance is ohms. We can’t measure the resistance of a battery in ohms, we measure it in how many amps it can deliver against a theoretically infinite load for 30 seconds at -18 degrees c. (Note marine batteries are rated at 0 degrees C and the same battery in marine service will rate higher because batteries hate the cold.)

So yes, a battery with lower internal resistance and therefore higher CCA will crank your engine over faster. It has nothing to do with how LONG it can crank that engine over, that’s a measure of capacity, measured in amp/hour.

Some of the very very large batteries used for camping power sources etc have very low CCA ratings because they’re designed for long, slow discharge, not cranking.

In fact for a given case size, higher CCA generally results in lower capacity.

[Andygoodbloke]

I took the time to look this up as I had a feeling it had nothing to do with the resistance of the battery -

CCA is the number of Amps a battery can support for 30 seconds at a temperature of 0 degrees Fahrenheit (-17.778 C) before the battery drops to below a usable cranking power.

I will return to my original question.

What CCA levelled battery are people running for a G13A engine with a standard alternator. I have got one answer saying bigger is better - how big have people gone with their Sierra / Samurai's?

[UBZ]

Around 650-700cca in general is all you are efectivly going to charge it on a 65a stock alt (30a in reality at temp) but if you the. Slap a winch etc on that the stock alt is not going to keep up .

I would also suggest that before you refute with “chat gpt answers “about resistance related to CCA that you go bury yourself for a few days in the topic of C ratings in batteries and how that relates to battery usability over temperature range over chemistry type ……….

[Andygoodbloke]

Thank you UBZ
The information only please next time
I am not running a winch and do not plan to for a while
I did not use Chat GPT to get my answer I checked a few battery manufacturers and looked in my 30 year old auto electric text book.
Yes temp can effect batteries, so can many factors but they are lead acid batteries not fire alarm or security system back up batteries, I am in the South Island of New Zealand not the great western desert of Australia