Gunter

'95 - 993

When installing a new battery, is it possible to keep ECU memory and radio code by plugging in a battery maintainer into the lighter socket?

Any harm in doing that?

Would there be power to the disconnected positive battery cable because of the plugged-in battery maintainer?

Thank you.

IXLR8

Yes.

Any 12V battery will do; I use my motorcycle battery for that purpose.

As for the cigarette lighter: center pin is positive in case you didn't know.

I also checked that my cigarette lighter socket was "hot" all the time before doing so in my 1995 993. You might want to make sure it is...maybe the fuse is gone if it isn't.

No.

I plugged in my spare battery first and when I disconnected the positive battery cable, I wrapped it in a rag and tapped it.

P-daddy

Haven't tried this myself but I recently saw at the autoparts store, a small device connected to a 9v battery and inserted in your cig lighter socket to maintain memory long enough to swap battery

Bouzoukikid

I beleive there is no power at the lighter. Some owners convert their lighters to have power with the ignition off so as to be able to use a trickle charger.
Apparently it's simple to convert.
Once done the trickle charger will hold the radio memory whilst changing the battery.
Regards.

IXLR8

Which is why I used a digital multimeter to confirm that the cigarette lighter outlet was "always on" even with the ignition off. On my car, it is ON all the time.

Others intending to use that outlet to supply power to the system while changing the battery, should do likewise...confirm, don't assume.

Rdelvalle

I use a BMW trickle charger connected to the cigarette lighter. It turns red then blinking green and finally solid green. I drive the car on average every three weeks 50 miles. Never had a problem starting. I have not checked the lighter to determine if it is hot; hoewever the fact that the trickle charger is changing colors I beleive is charging the battery. I have used it for about one year.
I have to change the steering wheel in the future and will be intrested in your outcome. I have an Alpine radio not the Porsche original so I do not know if there is a code. Is there any other codes that are lost when disconnecting the battery?
________________________________________________________________________ ___________

1997 993 Cab, Alpine radio, Targa wheels

Bouzoukikid

That's right, best check using multimeter. Cars from factory don't have power, but are easily converted at the fuse box. Mine doesn't, but I don't use trickle chargers so have no need to adapt it.
Thanks.

g_murray

I saw those "9V with gooseneck terminating in a cigarette-lighter' jobbies on the 'net one day
As a matter of fact I bought FOUR -- three were Christmas stocking stuffers.

Next time I've to change the battery or disconnect the terminal(s) ...it'll come in real handy to prevent the ECU from losing all those pesky readiness monitors!

Gerry

Gunter

I'll check it out but have to say that "easy converting at the fuse box" doesn't look so easy.
On the old 911, extra electrical work or wiring is easy because the fuse panel wiring is accessable; not so on the 993 where the wires are buried under the box out of sight.

How is the easy conversion done?

Thx.

rsr91128

Mine came from the factory with power all the time at the lighter. I think thats why they sell Porsche battery chargers that plug into the lighter socket.

2Many Cars

Seems like a lot of trouble just to swap a battery. How about just connecting your trickle charger to the battery leads before you remove them, or use jumper cables to another battery. Just make sure everything is turned off when you swap the leads and don't let the + lead touch anything metal. This doesn't need to be that complicated.

arjag

My 98 has power at the lighter with the ignition turned off. This why we hook up trickle chargers through the lighter in winter.

max911

If you already have a Battery Tender - get this : http://www.atbatt.com/product/19681.asp

Here is the 9v battery version mentioned above: http://www.pacificgeek.com/product.asp?ID=846054

Slow Guy

I believe this is incorrect.

Yes, I've used the trickle charger in the lighter in the past but now have a pig tail connected to the battery and charge from there.

Bouzoukikid

Maybe our UK cars are different from US cars. Here is a link on the topic.

http://911uk.com/viewtopic.php?t=593...garete+lighter