Toyota RAV4 Battery Keeps Going Flat :(

Hi

My Mum has had a Toyota RAV4 for over ten years. Some time ago the original battery was replaced with another which would go flat very frequently, so she replaced that one with another and that one goes flat just as often.

The batteries seem to go flat if the car is not being used even for quite short periods. She has to take her RAV4 out every day just to make sure the battery is kept charged.

She has tried to get the original battery as supplied with the Toyota in the first place but for some reason that does not seem to be possible.

I had thought that maybe there is a problem with the alternator but then, it seems that the battery does charge up when she is out driving.

She does use the car frequently but always short journeys.

It seems that the batteries go flat very easily on this car.

I wonder if anyone here might have some suggestions for a solution to the problem?

Thank you.

Reply to
Patrick James
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Patrick James wrote on 15/12/2010 :

You need to check the level of discharge when the car is parked up. It should be less than around 60mA, after being stood for an hour - once all of the electronics have fallen into sleep mode. A short term fix, might be to disconnect the battery everytime it is to be parked for a period unused.

Reply to
Harry Bloomfield

If the battery is going flat that quickly, something is very wrong. Modern cars have electronics that draw current even when everything is switched off - but should be able to cope with at least 3 weeks of not being started.

As Harry says, you need to get the quiescent current measured. It's likely several amps in your case. It should be perhaps 0.05 amps

Reply to
Dave Plowman (News)

battery was replaced with another which would go flat

just as often.

short periods. She has to take her RAV4 out every day

first place but for some reason that does not seem to

seems that the battery does charge up when she is out

Conceder any after-market devices that you might have had fitted as possible suspects. I'm thinking of alarms and hands free kits.

Also make sure you haven't simply got a "fridge paradox" going on with a festoon bulb in the boot, or under the bonnet.

Reply to
Graham.

As others have said, the most likely problem is something draining current when parked, but it is also possible for an alternator to fail in a way that it produces enough current to extinguish the no-charge light, but insufficient to keep the battery fully charged. Another possibility is a slipping auxiliary drive belt, but you can usually hear that. (The belt is actually a service replacement item on the RAV, rather than just something to be checked.)

Both problems are easy to check if you have a multi-meter, and the skills to use one. Otherwise, perhaps it might be worth trying to find a mobile auto electrician to check it out. The cost can be offset against having to drive the car every day!

Chris

Reply to
Chris Whelan

Thank you Harry and also the other replies from Dave, Graham and Chris.

I get the picture I think and I am going to ask my Mum to contact a car electrician with these suggestions, the main one being to see if something is draining the battery when the car is parked.

My Mum is in Northern Ireland whereas I am in England so I can't easily do this myself but she is well up to it she just needs a general idea of what might be wrong and I now have this.

Reply to
Patrick James

Get her to ask the auto electrician for a 'quiescent current check' on the battery. If he doesn't know what you mean, find one who does.

Reply to
Dave Plowman (News)

Will do :)

Reply to
Patrick James

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Patrick James saying something like:

Two main causes that I see as possible...

  1. Chances are the batteries she's getting are calcium ones, which have a charging spec of 14.8Volts. An old alternator/regulator doesn't put that much into them, more like 14.3Volts and this is compounded by the short journeys, so the battery is never fully charged and is further drained by the stop/start nature of the trips. It's possible to get a replacement regulator to match the calcium battery, but you have to piss around a bit trying to find one. Otoh, a decent auto-electrician should know about it and be able to sort one out.
  2. There might be a fault in the existing regulator or a duff diode which is allowing battery discharge through the alternator when the vehicle is parked up.
Reply to
Grimly Curmudgeon

IMHO, an urban myth. Very few car batteries are ever at 100% charge - except after a long run. So the few percent difference between a so called calcium type and normal isn't going to make any difference. If it did, companies like Halfords wouldn't sell them due to excessive warranty claims.

Reply to
Dave Plowman (News)

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Dave Plowman (News)" saying something like:

Nonetheless, it is true, and allied with stop/start behaviour, simply compounds the problem. It seems that calcium/calcium batteries don't take kindly to slight undercharging and sulphation becomes a problem sooner than it should. A decent calcium-matched charging system should keep the battery going for well after the warranty period. In my case, a calcium battery in my Tranny is now nine years old and still cranking away like a good'un. Happily for Halfords and the like, the owner just buys another one from them. Even if the battery fails within the warranty period, the no-quibble replacement policy of many battery chains just hoovers them up. I would suppose by now the majority of Halfords customers are actually driving calcium-compatible cars, so the odd older car with lower voltage charging system doesn't impact the the returns all that much.

As for the rest of us with older alternators on our ShiteOldClassics, we need to replace the regulator or occasionally give a proper 14.8V top-up charge to keep the battery happy. As you know, the Aldidl charger does just that.

Reply to
Grimly Curmudgeon

The calcium battery in my 25 year old SD1 is 7 years old and still ok. Despite having been run pretty flat on a number of occasions. ;-)

FWIW, any time I look at the actual charging voltage on my BMW which has a pretty massive alternator, it's 13.8. Just what I'd expect with a fully charged battery.

Reply to
Dave Plowman (News)

=A0 London SW

Hide quoted text -

I had a Cavalier on which battery kept going flat, turned out to be the heated rear window relay was sticking 'on' and not releasing when ignition or its own switch were turned to off position.

Reply to
4square

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