Battery in our Verada is nearly 5 years old and need to fit a new one. Is it OK to keep power going to the car from another car battery while I change the old battery? I was going to just connect jumper cables from our Land Cruiser to avoid losing the settings.

I wouldn't think that would be a good idea. Just spare the 5 minutes to reset your settings, rather than risking electrical damage :)

Thanks mykhverada, will that be all the settings ( those in the instrument cluster ) or just the clock radio etc ? Last time an autoleccy did it and I wasn't there at the time to see what he did. Tried 2 places yesterday but neither were that fussed on selling me a new battery !!!!!!!!! Not worried about how much it costs, just wanted someone to fit the best battery they had, one was too busy, the other said he only kept Holden and Falcon batteries in stock.

There are devices that you can buy to do that. RAA use them when changing batteries.

Settings are just really S/W (sedan/wagon) and 3.0 vs 3.5 for engine; all of your odomoeter etc will be remembered.
But you may need to "retrain" the transmission, idle speed controller etc., basically just by driving normally for a while, making sure you put all sorts of loads on the engine (eg. high beam while braking with aircon on and turning the wheel) to train the ISC as to what kind of revs it needs to maintain for different situations. Basically just drive around like normal for a while without pushing it, and it should sort itself out fine.

i cant see an issue with doing this.. ive seen it done with a battery not connected to another car so dont see why this is any different..

If the alternator is ok the car should keep going once you disconnect the battery.

call someone like budget batteries they fit on site in brisbane if thats where your located get a bosch S5

If the alternator is ok the car should keep going once you disconnect the battery.

DON'T DO THIS!!! YOU CAN FRY ALL SENSITIVE ELECTRICS! If you're lucky you might *only* nuke the diodes in the alternator, which still means a new alternator!

Info sources:

http://www.troubleshooters.com/dont_disconnect_battery.htm
http://jgdarden.com/batteryfaq/carfaq9.htm#cautions - Section 9.2.12

Basically without the battery there, the alternator does a shitty job of power regulation. If your fan (or any electrical load) is on and then switches off, you can get a huge voltage spike before the alternator drops its output back down to 12 volts. In that short amount of time - bang goes your ECU, your BEM, etc.

I don't think there would be any problem with it as the battery in the landcruiser would take any spikes from the alternator. It's no more risky than jump starting the car. Just connect the negative terminal first to somewhere on the engine, same as jump starting. Or if you have a jumper pack use that.

Don't be lazy. Hell, if you're quick enough (<10 seconds) settings may stay stored. I think I've unplugged the centre trip computer (with everything turned off, no key in ignition etc) for a very brief period of time, when i plugged it back in it still had the previous counters.

What's better, destroying expensive electrical components, or spending 10 seconds choosing sedan or wagon, and 3.0 or 3.5 litre? Go for a drive for 20 minutes, or something, everythings fine.

Thanks everybody, for your help. I'm actually a retired mechanic but didn't do much on cars that had a lot of electronics on board. I think I may take the car to battery world or somewhere similiar and get it done. I'm located in Cairns and there are a couple of battery mobs here. Have jump started hundreds of earlier model vehicles, tractors etc. but am wary of crashing the whole works in the later models . I tried auto electricians first because they normally check the charging rate etc when they fit a new battery.

I don't think there would be any problem with it as the battery in the landcruiser would take any spikes from the alternator. It's no more risky than jump starting the car. Just connect the negative terminal first to somewhere on the engine, same as jump starting. Or if you have a jumper pack use that.

Sure, *that's* OK - I was referring to starting the car and then removing the battery so there are NO batteries connected. That would be a potential fatal error.