Car immobiliser problems MEGATHREAD

[SHsheff 10]

After my son had been cleaning our car (a rare occurence, but worth a fiver so possibly to be repeated) I suspected he'd tampered with the immobiliser/attempted a drive-away 'cos the engine wouldn't start and the immobiliser bleeped strangely.

 

After much anguish (I'll spare the details because Childline say I shouldn't talk about it any more hehe) it turned out he'd flattened the battery due to having the car doors open and the radio on.

 

Bump-started it, and it saved me waiting til Monday (and £45) for someone to come out.

 

Just thought I'd mention it....

 

 

[cgksheff 44]

It isn't just the children that can do this (or switch the lights on)!!!!

 

 

............ but it can be convenient to blame it on them!

[Greybeard 10]

Originally posted by SHsheff

it turned out he'd flattened the battery due to having the car doors open and the radio on.

 

I wouldn't have thought the radio loaded the battery to that extent, - had he been winding the windows up and down ?

[ADC_28 10]

It sounds to me like the battery might be a little long in to the tooth if it discharged after such a small loading.

 

It might be an idea to consider replacing it or checking the levels of the liquid in the battery if its not a sealed unit. If the levels are down they can be replaced with deionised water.

 

Hope this prevents you being caught out again!

[SHsheff 10]

Originally posted by Greybeard

I wouldn't have thought the radio loaded the battery to that extent, - had he been winding the windows up and down ?

 

Of COURSE he'd been winding the windows up and down!

[SHsheff 10]

Originally posted by ADC_28

It sounds to me like the battery might be a little long in to the tooth if it discharged after such a small loading.

 

It might be an idea to consider replacing it or checking the levels of the liquid in the battery if its not a sealed unit. If the levels are down they can be replaced with deionised water.

 

Hope this prevents you being caught out again!

 

Apparently (I have just asked now, to write this post) he only wound the windows down once. How can I tell if the battery does need replacing, if it's a sealed unit (which I think it is)? Is there a test that a garage on do it?

[ADC_28 10]

OK, first of all. If a battery gets totally discharged it becomes damaged. The electrodes in the battery get furred up with deposits and the battery loses some of its efficiency. So, its usually worth replacing a battery after its been totally flattened.

 

If you can, look at the side of the battery and see if you can see the level of the electrolyte. This is a good indicator as to the health of the battery. If the liquid seems quite low (and the battery is a sealed unit so you can't top it up) then it will need replacing. However, some modern batteries are gel now rather than lead acid so you can't see the level of liquid as easily.

 

If the battery did discharge after such a small loading it does look to me like it's dead. If I was you I'd just buy another as it could easily let you down again when you least want it to. Battery testers are available from places like Halfords or you could take it to a dealer, but it's just added expense. And unless the dealer is totally honest it's worth their while to flog you a new one at a markup anyway.

 

A further, more sinister diagnosis is that there's a problem with the charging circuit. There may be something else in the car which is discharging the battery when the engine isn't running. Sometimes devices left plugged into the fag lighter socket can be the culprit.

 

Also, when you start a car is places a large drain on the battery which then takes a good couple of miles in most cars before it's replaced. If a car is constantly being used for short trips the battery doesn't have time to recover in between times and will gradually discharge. It's worth bearing that in mind.

 

In short (or, reading through what I've just written, long), I'd not take a chance and just part with £20 or so for a new one. The last thing you want is to be stuck in the rain in the middle of nowhere with a flat battery cursing yourself for not paying that extra few quid.

[SHsheff 10]

Hmmmmmmm.........I feel a new battery coming up!

 

Thanks for your comments, ADC_28.

 

[Strix 11]

It may also depend upon how he had the radio on.

 

Mr Strix used to have an annoying habit of only turning the ignition switch back to the first position when he stopped the car, coz turning the key full way turned the radio off.

 

This left the whole electric system of the car live, instead of just switching the radio back on with the key out so only the radio was on.

 

Needless to say, he pulled over for a nap one morning, and flattened the battery - requiring an AA call out

 

Of course - male civil engineers know far more about cars than female manufacturing engineers :rant:

[Grim 10]

Originally posted by SHsheff

Apparently (I have just asked now, to write this post) he only wound the windows down once. How can I tell if the battery does need replacing, if it's a sealed unit (which I think it is)? Is there a test that a garage on do it?

 

What i'd do is pop down to maplins and buy a cheap multimeter (£10), and measure the voltage, with the engine off. Below 12v, it's getting knackered. Then start the engine, give it a slight rev, and it should read 14v+. If it doesn't, the charging circuit is knackered (unlikely in your case, but possible for others reading).

 

If i drive my car short journeys with lights / heater on, i use more electricity than i generate, so after a few days my battery gets a bit low, even though both it and my charging circuit are fine.

[Tradescanthia 10]

My car has a AutoWatch immobiliser fitted, an old one, age unknown. The transponder only works when it has been warmed up in my pocket or by blowing on it. Does anyone local supply replacement transponders or does anyone know of an auto electrician who can remove the Autowatch alltogether?

[sarah2007 10]

sure its not the battery ????