Can I fit a bigger battery

[Chasgunter]

My RAV 4 Petrol XT3i gives excellent service but the Battery goes flat after about 5 days. It is not a Battery fault as I replaced it with a good quality one of the right size. There is no excess drainage (I've had it checked) and the alternator is working properly. The thing is, the Battery looks, physically, quite small. Obviously, the physical size of a battery will affect the amount of energy it can store. I would like to fit a larger one but the available space doesn't look as if it will take a bigger one. 

I would be interested to know if anyone has tried this, successfully.

 

 

[Chasgunter]

I should have said, after 5 days without use.

[FROSTYBALLS]

Moved to the Rav4 club.

[alan333]

The Battery shouldn't go flat after 5 days, or 5 weeks for that matter.  Either your Battery is knackered, or there's something draining it, or the car is running for too short periods to charge it.  

[Chasgunter]

Thanks alan333. I hear that a lot, and it sounds right, but I am afraid it doesn't seem to be the case. The Battery was replaced with an expensive new one because of the issue but no improvement. The meter is showing no unusual drain but, nevertheless, after 5 days of not being used, it won't turn the engine over. Interestingly, my wife's Peugeot has a similar problem and she's had it from new. No vehicle electrician has been able to find a reason for either car. I also have an Avensis diesel and that give no trouble at all - but it is a big Battery.

It seems I may just have to live with it.

[IanML]

How, and with what, are you measuring the drain?

[alan333]

Disconnect the Battery and see what happens after 5 days.  If it starts the car you have a drain, if it doesn't then your Battery is duff.

[IanML]

Good idea.  It is possible for a  Battery to have an internal partial short circuit, which results in the Battery running down even if nothing is connected to it.

[Chasgunter]

Thanks IanML. Unlikley to be a Battery fault as it has been changed - same problem persists.

Alan333. Drain was measured by three different people. 1. A  mobile auto electrician; 2. an auto electrical specialist garage; 3. RAC. An Ammeter has been used (in series) to check the drain.

The Battery was recently replaced by a good quality Battery because of this problem but didn't fix the problem. As long as I use the car every 3-4 days it is OK. It's obvious something is draining it (if only the alarm light) and think a larger battery would might help.

 

[craggle]

My Range Rover a few years ago was exactly the same. 

Fortunately I always had petrol Range Rovers but they were all made to fit the Diesel engine so you could take out the small petrol specification Battery and fit the bigger Diesel Battery filling up the Battery tray to the max. You can't have a battery too big. 

If your battery fits the battery compartment though there is little you can do except fit another battery in the boot or somewhere else under the bonnet. I know people who have multiple batteries in campers and they all charge from the same alternator but you can turn a big red key and use the auxiliary batteries to start the engine if needed. Turn the key off again once started and they still charge on the split charge circuit but don't get used for starting again unless the key is used again.

Failing that get yourself one of those booster packs and connect it when you start after leaving the car for a while although that is a pain to be honest. 

On the Range rover the issue was the key constantly transmitted on a common frequency like 2.4Ghz which Wi-Fi and remote doorbells use. If you parked near a building with Wi-Fi the car would stay in a state of readiness thinking the key was nearby and never fully went to sleep and so it drained the battery more than it should. Not sure if that issue would apply here?

Craig.

 

[Chasgunter]

Thanks craggle. That sounds eminently sensible. Sadly, RAV's battery is not only small, there is no space to fit a bigger one. I'll talk to an auto electrician about fitting a reserve (at the moment I keep a spare in the back with jumper leads, but as you said - it is a pain).

Thanks again.

 

[pmb]

There have been threads about this before on here. Many people (including me) have fitted the diesel sized Battery to a petrol 4.2. Be wary of which way round the polarity is as I recall it's different between the two fuel sources. If you have the terminals the wrong way I think you can still fit it but there is more strain on the cables. You will have to move the Battery securing rods at the bottom and top to the other holes. Oh , and don't get me started on the Battery cover clips. The part nos. of those have also been a topic, £10 a set from Mr T when I bought them. I had this going flat issue after several days of not using the car and once the battery needed recharging it never seemed to recover properly but I thought it strange.

[Chasgunter]

Thanks pmb. That sounds useful.

[pmb]

Just done a search on this forum for petrol Battery and within the first 4 pages there are several threads you may wish to read.

[Steve 2017]

I have had the same problem in the past.  Left my RAV at the airport for 10 days and Battery flat.  RAC told be they are regularly dealing with the same problem at airports.  I now disconnect the Battery if I go away for any length of time.  I also bought a solar panel which plugs into the diagnostic socket (under the dash on the offside) and plug it in if I am leaving the car for more than a few days. Obviously it needs to be parked outside, preferably where it gets some sun but it certainly does the business for me.