Dis connecting battery Question

Normally, you have to re-enter the security code for the radio.

With most modern vehicles it is really inadvisable to disconnect the battery or let it go flat. The radio is often the least of your problems. Computer controlled engines, gearboxes and immobilisers are much more of a problem. For instance , I once changed the battery on an XR2i, afterwards the car would not tick over, I had to drive it in a certain sequence of so many miles at about one speed then varying speed etc. so the system could relearn the engine parameters. Afterwards everything was fine, but what a palarver. Either make yourself up a connector with crocodiles or buy a plug in device to keep everything going while you change the battery. (a 9v PP3 is sufficient, but 12 volt is better)

IME a good quality low amp battery charger is quite safe to use without disconnecting the battery. But preventive maintenance of checking the battery every few months and before winter is the real cure. (no need till the battery is about three years old)

MrCheerful

Yes there will be a special procedure to go through if your car has an immobiliser/alarm/central-locking: if you don't do this you can easily end up with the security-system getting itself confused [happened to me on a Nissan - one C/L motor got de-phased from the rest].

I never bother disconnecting batteries when charging them - any modern regulated charger worth the name will have overvoltage-protection built in.

Thanks for replies chaps bit confused tho as handbook , under battery maintenance section says * If re charging with the battery installed on the vehicle , be sure to disconnect the ground cable * No mention of potential damage etc. Mixed messages eh ?

Not really. The manufacturers are covering themselves against the faint chance you will connect up a monster, unregulated charger and fry everything. A good example is brake fluid: must be changed every two years ! I agree it is a good idea and I recommend it, but I doubt if 1 in a thousand cars has it done, none of them come to grief because of it. (although the eventual life of parts like master cylinders is reduced, there are no catastrophic failures AFAIK)

MrCheerful

MrCheerful

The message from PJML contains these words:

Perhaps his extension cable won't reach!

I would have a problem doing that living in a 2nd floor flat :-) Stuart

Apologies if I did not make myself too clear ... what I meant by * no mention of potential damage * was the damage or problems caused to the electrical management system . Surely they would not refer to the battery charging as being an owner/ maintenance function if it caused the severe problems that have been suggested .

Well, perhaps your vehicle does not have any electronics that have a KAM (keep alive memory) in them.

My advice would still be: don't disconnect all battery power on a modern vehicle unless you really, really need to.

My sister slings an extension cable out of her third floor flat if she needs power to her car for hoovering or battery charging.

MrCheerful

MrCheerful

Thanks for advice I'll just have to try and get more info from my local Toyota garage ..... tho it's like getting blood out of a stone ...... unless they can make a sale of course !