ValveBounce

Hi,

I'm about to change the battery on my S2000.

To avoid all the hassle with losing fuel trims, ECU recalibration etc can I simply leave a battery charger connected to the battery leads to keep +12v on the car while I change the battery over? Then, simply remove them once the terminal have been re-tightened on the new battery?

Are there any issues I need to be aware of putting a battery charger directly to the leads without the battery connected in the system?

Thanks for any advice.

seatonsurfer

Not really a good idea as the battery acts as a buffer against any spikes the battery charger may give out. If you get a voltage surge it will damage electronic parts like the ECU. Not a good idea.

Normally the ECU will relearn all settings very quickly, so if you change the battery normally, which takes about 10 minutes at the most, all should be OK.

flanders

What kind of charger do you got? Some models has a supply feature for cases just like this.

richmc

You won't lose fuel trims, just the radio code, I changed my battery a long time ago by jump leading the old and new one together, before I had the code. A modern smart charger will detect there is no battery and switch off. Anyway unless you have an exotic ECU and are non NA, it just takes a drive to reprogram it anyway.

ValveBounce

Thank you for your replies.

The battery charger is not new/modern. It's a very simple device with a switch that selects 6v or 12v and that's about it.

From all your suggestions I think the best plan is just to jump a battery onto the battery leads while I swap the batteries over. Hopefully that will work but if not the car will just be a bit lumpy until the ECU has sorted itself out. It's the standard Honda OEM ECU on a regular NA engine, nothing fancy.

flanders

It will most likely work fine with that charger connected during the swap, I would just check the open circuit voltage and make sure it's not too high before using it.

lovegroova

I disconnect my battery each winter while the car is SORN. There are no problems at all with lumpy idle or anything else after reconnection. All that's required is a clock and radio reset.

Chuck S

Do not mess with a battery charger here, dealers and other shops change batteries daily without losing ECU settings. You will need to reset the clock and radio. Notice that all your mileage data on the dash stays the same as it's in permanent memory as is the bulk of all data in the car. The radio losing settings is an anti-theft scheme.

-- Chuck

Daytona-Dave

AS above just swap the battery and stop piss balling about with something that may create a spike if you arc it out or slip, you will only need to reset the radio code,
after you start it let it idle till warm and the fan has cut in a few times to relearn the idle and your good to go, it actually does them good to reset once in a while you are worrying over nothing but have the potential to cause problems by going down your route,

eriktheredd

Tried this battery charger trick so I didn't have to re-code the radio when I changed the battery, however, knocked one wire off and thought "bugger" but the radio code still held, phew!! great relief.
so maybe there is a time lag built in between disconnection and re-connection of battery voltage
?