The Battery Of My Rav4 Goes Flat If Not Used For A Few Days.

[voo]

It is a fairly new Battery that keeps going flat. Do you know how to test if it's the alternator or if I need a new Battery please?

[Raistlin]

Go to a motor factor and get them to test it, they will do it FOC if they think they are going to get a sale

[voo]

Thanks for replying Raistlin.

[pmb]

Petrol or diesel? Which model? The 4.2 petrol is well known for the smallness of its Battery and like most I have the bigger diesel one in mine. I found that once a Battery starts dying regularly it can't be fully recharged but others may disagree.

[voo]

Thanks for reply Paul. It's a petrol RAV4 2.0 engine. My son has tested Battery with a multimeter and says it's ok so it's more than likely an alternator problem. It started with a Battery jumper that I keep in back of car for emergencies.

[korat102]

A good Battery shouldn't go flat in a few days in an unused car unless there's a heavy current draw somewhere. Are all the lights going out when you close the doors?

[voo]

Hello Phil, yes all the doors are closed when I lock it and there's no lights on. Also the radio is turned off. I found an article online about parasitic Battery drain which my son checked for with his multimeter. As amateurs we don't think it's that. We've had a go a using the multimeter on the alternator which showed that it wasn't fluctuating. Might have to let a 'proper' mechanic have a look at it, thanks.

[gjnorthall]

You can't determine the condition of a Battery with a multimeter. If it reads around 12.4 volts then it's fully charged but it tells you nothing about the battery's ability to retain charge. Battery condition meters test the battery's condition by imposing a heavy discharge whilst measuring the voltage decay. Apparent Battery problems sometimes result from loose / dirty corroded terminals and connectors. An alternator in decent fettle should give around 14.2v across the battery with the headlamps on and the engine running at about 2000RPM.

[korat102]

You could try charging the Battery fully (with a mains charger) then leaving the car a few days to see what happens. If it goes flat, then you know there's either current being drawn or you have a dodgy Battery. Remember though, it doesn't take a huge current to flatten a Battery over time...

[voo]

Thanks for the advice Phil I'll try that. The mind boggles, it could be a dodgy Battery because I used a mains charger to charge the Battery and it was ok for a week but now it's let me down again by going flat.

[Mike169]

Like Raistlin said if you take you Battery to a local car spares shop they will test it for you, they will use a special tool which puts a load on the Battery. If it is faulty like others have said you may be better off fitting a larger Battery assuming there is spare space in the battery tray?

Mike.

[voo]

Thanks Michael will have to buy a bigger Battery, there's room for one.

[Mike169]

Hi Voo, very polite of you to reply, not everybody does so feedback is always nice. I totally agree with pmb's comment about fitting a diesel Battery to your car, i know you have a petrol but of course the Battery fitted to diesels is bigger and therefore has more reserve capacity. Yes it will cost a bit more but because of it's increased capacity it will last longer so in reality it is no dearer as it won't need replacing so often. Let us all know how you get on.

Mike.

[voo]

Thanks again Michael, it's nice to know your interested to know how I get on.

[Conrod]

Found this on the internet, a guide to fitting a bigger diesel Battery in a petrol Rav4....

http://forum.http://www.toyotaownersclub.com/forums/forum/79-rav-4-club//topic1090.html?hilit=New battery

[voo]

Thanks Conrod that looks just the job, I'll have to get saving. Thanks for the information.

[Conrod]

Thanks Conrod that looks just the job, I'll have to get saving. Thanks for the information.

Massive difference in the size of the batteries, difficult to understand why Toyota fitted such a small Battery for the petrol model.

[Mike169]

Voo i believe you can find a diesel Rav4 Battery for under £80 if you phone around and have you got the Halfords discount card?

[voo]

Thanks for that Mike, I haven't got the Halfords discount card but I'll look on the internet for a bargain.

[john21245]

Just replaced the original small Battery on my 10yr old rav. I've replaced it with exactly the same size from Battery Megastore for £35 with a four year Guarantee. I appreciate this length of service is unusual but if batteries are given an occasional boost charge and levels checked where appropriate they would give better service.

On this forum we are often advised to stick to the manufactures recommendations for oil etc, so why not batteries?

[Conrod]

Just replaced the original small battery on my 10yr old rav. I've replaced it with exactly the same size from Battery Megastore for £35 with a four year Guarantee. I appreciate this length of service is unusual but if batteries are given an occasional boost charge and levels checked where appropriate they would give better service.

On this forum we are often advised to stick to the manufactures recommendations for oil etc, so why not batteries?

Everyone that owns a car has a choice how they look after it, you could go down the route of taking it to a main dealer, and get them to fit standard parts, the whole life of the car.

All parts are made to a manufactures standard , I'm sure that standard is fine for some owners but the world of upgrading and modifying car is a massive one, it's the owners choice if he feels an upgraded part is the way to go.

A standard Battery could well be just fine and start the car summer and winter, by having a bigger Battery, it has more cold starting ability and allows more use of electrics in those winter months, other reasons are , you don't use your car every day of the week, or just weekends, and this can cause problems with alarms draining Battery power.

I have a diesel battery fitted to my petrol Aygo, as I'm just that person that can leave the car unused for a week or more, and the end of they day, it's down to choice, if you're happy with a standard battery ....that's fine :)

[Mike169]

Just replaced the original small battery on my 10yr old rav. I've replaced it with exactly the same size from Battery Megastore for £35 with a four year Guarantee. I appreciate this length of service is unusual but if batteries are given an occasional boost charge and levels checked where appropriate they would give better service.

On this forum we are often advised to stick to the manufactures recommendations for oil etc, so why not batteries?

Everyone that owns a car has a choice how they look after it, you could go down the route of taking it to a main dealer, and get them to fit standard parts, the whole life of the car.

All parts are made to a manufactures standard , I'm sure that standard is fine for some owners but the world of upgrading and modifying car is a massive one, it's the owners choice if he feels an upgraded part is the way to go.

A standard Battery could well be just fine and start the car summer or winter, by having a bigger Battery, it has more cold starting ability and allows more use of electrics in those winter months, other reasons are , you don't use your car every day of the week, or just weekends, and this can cause problems with alarms draining Battery power.

I have a diesel battery fitted to my petrol Aygo, as I'm just that person that can leave the car unused for a week or more, and the end of they day, it's down to choice, if you're happy with a standard battery ....that's fine :)

I have got to agree with Conrod on this. Voo has already stated that his battery is flat if he leaves his car for a few days so he obviously needs to upgrade this part of his car. It's fine having a standard battery with a 4 year g'tee but if the new battery keeps going flat and it is taken back to the place purchased they will test it and if it is just flat and needs charging they will just gives it back and say something like put a charger on it when the vehicle isn't being used which isn't always realistic. Fitting a larger battery will give more capacity so more reserve power, so this way if at any time Voo finds his battery flat at all, which i doubt, at least he can think to himself he did the job to the best of his ability and not blame himself for fitting a smaller one which has already been discussed as being too small for the car on previous threads. Go for the diesel one Voo, give yourself more peace of mind.

Mike.

[john21245]

Firstly a healthy Battery should not go flat after one week, so the Battery definitely needs testing. Also if it doesnt get sufficient use to keep it healthy then it needs an occasional boost. Remember too that the Battery is matched to the alternator hence my preference to keep to original spec.

[Conrod]

Firstly a healthy battery should not go flat after one week, so the battery definitely needs testing. Also if it doesnt get sufficient use to keep it healthy then it needs an occasional boost. Remember too that the battery is matched to the alternator hence my preference to keep to original spec.

You say "matched" as in both items are 12v, an alternator pushes out around 13.8v-14.5v and would charge whatever amp hour Battery is in place.

I'm not knocking what you say, we all have a choice, I decide to upgrade, as I could replacing half the items on my car, like better tyres, alloy wheels, upgraded brakes, stereo, Speakers the list goes on.....won't make it any better a car, it's just a choice :)

[john21245]

Firstly a healthy battery should not go flat after one week, so the battery definitely needs testing. Also if it doesnt get sufficient use to keep it healthy then it needs an occasional boost. Remember too that the battery is matched to the alternator hence my preference to keep to original spec.

You say "matched" as in both items are 12v, an alternator pushes out around 13.8v-14.5v and would charge whatever amp hour Battery is in place.

I'm not knocking what you say, we all have a choice, I decide to upgrade, as I could replacing half the items on my car, like better tyres, alloy wheels, upgraded brakes, stereo, Speakers the list goes on.....won't make it any better a car, it's just a choice :)

Why then are alternators rated differently? Rav 4 alternators have different amp ratings for diesel or petrol depending on the capacity of the Battery they have to keep charged.