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Battery for Toyota RAV4 - importance of amps?

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stevensfo
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Battery for Toyota RAV4 - importance of amps?

#428542

Postby stevensfo » July 18th, 2021, 5:40 pm

Our son left his large RAV4 diesel with us and when I checked it, the battery was flat. A few days with a battery charger indicates that the battery is well past its sell-by date and refuses to charge. Not surprising since it must be extremely old.

The figures indicate 12v, 80Ah, 800A. Dimensions are standard 30x17cm.

Plenty of batteries I've found in the shops are the same size and are 12v, 80Ah, but none are exactly 800A. I think the closest was about 740A and the only batteries with 800A were 90Ah.

How important is the 800A? I assume that the 80Ah is just the total energy and I could use a 90Ah if I want, but what is the significance of 800A?

Steve

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Re: Battery for Toyota RAV4 - importance of amps?

#428548

Postby swill453 » July 18th, 2021, 5:57 pm

The 800 is presumably CCA (cold cranking amps), which is a measure of its ability to turn over the engine at cold temperatures. So if it needs 800, best stick to it.

The 80 or 90Ah is the capacity, bigger being better. So if it's a decent make and the size is right, go for the 90Ah.

Tayna is a decent online supplier, and Eurocarparts often has good deals. Also Halfords can be ok and have good guarantees.

Scott.

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Re: Battery for Toyota RAV4 - importance of amps?

#428552

Postby 9873210 » July 18th, 2021, 6:05 pm

stevensfo wrote:The figures indicate 12v, 80Ah, 800A. Dimensions are standard 30x17cm.

Are these from the manual or the battery you are replacing?

Mike4
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Re: Battery for Toyota RAV4 - importance of amps?

#428556

Postby Mike4 » July 18th, 2021, 6:11 pm

swill453 wrote:The 800 is presumably CCA (cold cranking amps), which is a measure of its ability to turn over the engine at cold temperatures. So if it needs 800, best stick to it.


I'd say it is a little more subtle than that, AIUI. the CCA is not the max the battery can deliver per se, it is the max the battery can deliver without risking buckling the plates from overheating during that level of current delivery.

I'd also suggest there is a pretty big safety margin built into the 800A specification issued by Toyota and the starter probably only drags say 500A out of the battery during starting, so a 740A battery will probably work just fine. It's just that if it doesn't, the batt manu will reject a guarantee claim as will Toyota, as you ignored their paper spec!

Also, the old batt might be recoverable. Plenty of modern chargers are too clever for their own good and will refuse to charge a really flat battery. An old style 'dumb' charger* may well get enough charge into the battery to wake it up and then the re-charge can be finished with your (presumably) modern electronic automatic charger.

* A dumb charger comprising just a transformer and a diode will eventually overcharge a battery if left charging indefinitely. The electrolyte will start gassing and eventually all the water will boil away. Young people these days cannot be trusted with such a thing which is why all modern chargers are laden with safety devices, one being over-current 'protection', which prevents them charging a really flat battery.

Progress, eh?

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Re: Battery for Toyota RAV4 - importance of amps?

#428572

Postby 88V8 » July 18th, 2021, 7:03 pm

stevensfo wrote:The figures indicate 12v, 80Ah, 800A. Dimensions are standard 30x17cm.

I always buy the max cold cranking amps. That way it will still do the job on a winter's morning even if it's a bit flat.

The Tayna site will recommend batteries when you input the car model.
This is useful because.... if one just randomly buys a battery of a particular size / output, one can fall into the trap of buying one where the +/- terminals are transposed, so it won't actually fit into the car :oops:

V8

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Re: Battery for Toyota RAV4 - importance of amps?

#428592

Postby stevensfo » July 18th, 2021, 7:55 pm

9873210 wrote:
stevensfo wrote:The figures indicate 12v, 80Ah, 800A. Dimensions are standard 30x17cm.

Are these from the manual or the battery you are replacing?


From the battery in the car. It is an original Toyota battery.

The Tayna site will recommend batteries when you input the car model.
This is useful because.... if one just randomly buys a battery of a particular size / output, one can fall into the trap of buying one where the +/- terminals are transposed, so it won't actually fit into the car :oops:

V8
Top


Thanks. That's just the sort of thing that I wouldn't notice..... till too late!

I will add '+ve to the left and -ve to the right' to my notes.

Steve

PS The battery in my Volvo XC60 has half of it hidden underneath a separate cover, and I learned the hard way that it's easy to mistake two metal connectors for the +ve and -ve when they're nothing of the sort......especially after an evening with wine. :oops:


Steve

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Re: Battery for Toyota RAV4 - importance of amps?

#428608

Postby Mike4 » July 18th, 2021, 8:49 pm

88V8 wrote:
stevensfo wrote:The figures indicate 12v, 80Ah, 800A. Dimensions are standard 30x17cm.

I always buy the max cold cranking amps. That way it will still do the job on a winter's morning even if it's a bit flat.

The Tayna site will recommend batteries when you input the car model.
This is useful because.... if one just randomly buys a battery of a particular size / output, one can fall into the trap of buying one where the +/- terminals are transposed, so it won't actually fit into the car :oops:

V8


Oh so you've done that too eh?!!

The other trick batteries like to play on you even if you get the terminals right is the new one is an inch shorter (or taller) so the bracket that holds it in place won't fit.

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Re: Battery for Toyota RAV4 - importance of amps?

#428638

Postby DrFfybes » July 18th, 2021, 10:58 pm

As V8 says, just go to the Tayna website, look up the battery with the reg number, and just buy one with the same spec as the one you have at a price you are prepared to pay.

It will arrive quickly, it will fit, and you'll struggle to beat them on price.

Paul

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Re: Battery for Toyota RAV4 - importance of amps?

#428703

Postby jfgw » July 19th, 2021, 9:48 am

It is not a simple "it works" /"it doesn't work" decision. Fewer CCA may mean that the car takes a bit longer to start. The strain on the battery will, therefore, be greater and this may shorten its life.

I have known a "correct" battery to fail after a year.


Julian F. G. W.

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Re: Battery for Toyota RAV4 - importance of amps?

#428737

Postby 9873210 » July 19th, 2021, 11:23 am

88V8 wrote:I always buy the max cold cranking amps. That way it will still do the job on a winter's morning even if it's a bit flat.

Battery design is a compromise. If you maximize CCA you will be losing somewhere else.

If you live in Edmonton winter starts may be of overwhelming importance, but do you live in Edmonton?

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Re: Battery for Toyota RAV4 - importance of amps?

#428754

Postby jfgw » July 19th, 2021, 12:09 pm

Batteries with more CCA usually have longer guarantees. They do cost more though.


Julian F. G. W.

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Re: Battery for Toyota RAV4 - importance of amps?

#429161

Postby 88V8 » July 20th, 2021, 6:38 pm

Tayna have 5% off website purchases until 4th August.

Use the code FIVEOFF at the checkout.

V8

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Re: Battery for Toyota RAV4 - importance of amps?

#429189

Postby richlist » July 20th, 2021, 9:21 pm

I find cars with stop/start technology have hardly any cranking time i.e. they start almost instantly, even on a cold day.


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