Charging batteries while in vehicle

Heya, I'm no sparkie, but I've heard you can damage things like frisges doing that. Gotta disconnect it. You can leave it in the tray, but disconnect anything first.

Cheers.

Well I am no auto elec but have been doing this myself to my cars and to the trucks at work for years and years and so far never had a problem. The battery absorbs any spikes from the charger. Its the same reason why you can run a gennie to charge your battery while still running fridges and other appliances off the battery.
I have even done this with Kenworth prime movers that are fully computer controlled, had the charger connected up to the rear battery overnight and never had a problem in many years of doing this.

Hi Austravel
When you think about it, there is no difference if you charge your battery/batterys with a 240 volt charger than if your engine was running, using the alternator. The condition of the battery and the load will determine the current draw on the charger, but provided the voltage doesn't exceed 14.2 volts, you'll have no problems. A flat battery will draw heaps of current and keep the voltage low, but as the battery comes up, the current drops and the voltage rises to the maximum of the charger. If your not sure, put a voltmeter on the battery while you charge it and when the voltage reaches 14 volts, turn it off. The charger will only put out what the battery can take, unless there is a fault/short in the battery or an external load on the charger eg. fridge or other accessory.
The short answer to your question is no, you can not damage your alternator, but I would be more concerned about vehicle electronics, however as already stated, the battery will filter out any voltage spikes.

Good Luck
Chaz
http://members.bettanet.net.au/~conody/index.htm

Hi Austravel, I was allways told that you could damage the vehicles electrical system eg. alternator diodes, computers ect.
but have have been to many cars that have been charged that way without any problems.
I think the case would be very, very different if you attempted to start your vehicle with the charger on and connected.
By the way make sure that you loosen the caps on the battery to let any gases escape a little easier and turn off the charger before taking off the leads to minimise any sparking. (battery gases are explosive and from personel experience when a battery explodes it goes off like a bomb)
Will

Thanks all.

Heres one - I once got told that when jump starting a car with expensive ECUs etc that you can overcome the problem of not having spike controlled jumper leads by switching on the the car headlights - I don't really understand but the globes apparently will blow first thus preventing computer damage.

There may be something in this - maybe you could switch your lights on overnight whilst charging the battery still connected thus making the charging process safe.

Oh, there seems to be a problem with my theory I just noticed - what if you were camping and wanted it to be dark?