Battery replacement procedure - Page 2 - Porsche General - PistonHeads UK

I've just ordered a battery from eurocarparts for my Cayman. When I got the battery replaced a couple of years ago at halfrauds the guy went through a procedure of ignition on and did other things to save the radio code or something. Is there a correct procedure somewhere for a battery swap ? Used to be back in the day it was battery out battery in ! If I need to have power on I could connect my battery tender to the leads while I swap out the battery ??

Leave ignition on when disconnecting, that way the car doesn't think it's being stolen and won't trigger the alarm. Ignition on when refitting too. From my experience you'll only need to teach the windows to one touch up/down again and the radio should be happy still.

...just as an aside, Halfords usually operate a no-quibble battery replacement guarantee, which in my experience they honour without quibbling. Is yours not still under warranty?

Wouldnt turn the ignition on - don't think all those complex electronics would like the battery being taken away like that. - just make sure the car is unlocked and open - the alarm will be disabled at that point - did that with my boxster and had no issues. Simes.

If it's anything like the 996, you need to leave the key in the ignition, but it does not need to be "on". However I put it "on" just so the car knows the key is there, then turn it one back to the "off" position. Otherwise if you just put the key in I suspect the system may still technically be "key out". If the battery is disconnected for extended periods (weeks) the alarm battery may drain and you may get the alarm going off just after you start (due to the voltage drop). Under such circumstances I charge the (main) battery for an hour or so (with the battery connected). I guess that just leaving the battery connected for a couple of hours before starting up probably works just as well.

Didn't need to leave the ignition on like in the 986. Instead, I used a jump battery to bridge the terminals to ensure there is still power to energise the car in standby. Or, use the spare pole in the fuse box to do the same.

On my 996.1 you just leave key in ignition, turned to position 1 so no lights etc. if you don't the alarm will sound when you disconnect battery and it's bloody loud. Literally hurts your ears if you're in a garage.

LOL! About 4 different methods advised! Do you feel lucky OP? Well, do yer?!

996tt - key to position 1 and change battery. No alarm but did lose the radio code - but had it at hand.

I know that when I had mine changed the car decided to show a whole variety of disturbing messages. ABS Failure, Drive Off Assistant Failure etc. Quick spin round the block though and they all cleared.

Key in ignition but not turned, car knows key is in. Disconnect neg then positive. Battery out , new battery in , connect neg then pos. Started car, faults on dash, reversed car down drive and back up, faults cleared. Job done. Thanks for the tip re key in ignition.

Update for the archives: Replaced the Moll battery in my 997 with a Bosch one yesterday - really doable DIY, though I did have a couple of questions myself as to process before I attempted - mainly re ignition/alarm. I switched the ignition on (1) for a bit, then switched back to off (key left in) to perform the installation, and this worked fine - no alarm issues. On restart with the new battery connected, I had a Traction Control Failure error which cleared itself after a short drive. Simples

Just read this thread, I see the OP said disconnect the positive terminal 1st and connect the positive terminal last. From experience I'd not do this. If the spanner accidentally contacts any metalwork when disconnecting the +ve terminal then you can have a spark and damage paintwork or even worse. I'd always disconnect the -ve terminal first then the +ve and connect the +ve terminal first.

mikecassie said: Just read this thread, I see the OP said disconnect the positive terminal 1st and connect the positive terminal last. From experience I'd not do this. If the spanner accidentally contacts any metalwork when disconnecting the +ve terminal then you can have a spark and damage paintwork or even worse. I'd always disconnect the -ve terminal first then the +ve and connect the +ve terminal first. This^^^^^

Pistonheads Battery Brain Trust needed! (aka another battery maintenance thread) My 997 gets stored for several months, and shocker - the battery becomes heavily discharged. I try to trickle it from time to time (no sniggering) but I cannot leave the charger connected for long periods unfortunately (due to car park location). So I would like to keep a spare battery charged indoors, then swap it in periodically. At the same time, I would like to keep charge CONSTANT to the vehicle's electronics while I remove the depleted battery (so that I don't lose ECU settings etc, the alarm still works, and so that I'm not constantly breaking and reconnecting power). Plan would be to connect second GOOD battery via jump leads to the car's connectors, remove depleted battery, then swap it back in later once reconditioned (and repeat...). This means two batteries of differing voltage would be briefly connected at the same time. Will the voltage difference between the two batteries cause a problem if they are only connected for a short period? I have read this might not be a good idea. I won't be trying to start the car with both batteries connected. The other solution might be to use an ODB2 memory saver to maintain settings, but I'd still be yanking and reconnecting a live battery every month. Perhaps I'm being over sensitive on that part, i don't know? Many thanks as always

Fl0pp3r said: Pistonheads Battery Brain Trust needed! (aka another battery maintenance thread) My 997 gets stored for several months, and shocker - the battery becomes heavily discharged. I try to trickle it from time to time (no sniggering) but I cannot leave the charger connected for long periods unfortunately (due to car park location). So I would like to keep a spare battery charged indoors, then swap it in periodically. At the same time, I would like to keep charge CONSTANT to the vehicle's electronics while I remove the depleted battery (so that I don't lose ECU settings etc, the alarm still works, and so that I'm not constantly breaking and reconnecting power). Plan would be to connect second GOOD battery via jump leads to the car's connectors, remove depleted battery, then swap it back in later once reconditioned (and repeat...). This means two batteries of differing voltage would be briefly connected at the same time. Will the voltage difference between the two batteries cause a problem if they are only connected for a short period? I have read this might not be a good idea. I won't be trying to start the car with both batteries connected. The other solution might be to use an ODB2 memory saver to maintain settings, but I'd still be yanking and reconnecting a live battery every month. Perhaps I'm being over sensitive on that part, i don't know? Many thanks as always But if your battery goes flat you will lose all settings anyway. Once your battery goes really really dead, I found out that you need a really powerful 12V on to the internal terminals to get the bonnet to release. There was time once when I'd left the car that long it just wouldn't release the bonnet. Local indy advised that this can happen and the next fallback plan is to jack up the front of the car, remove passenger side wheel, remove wheelarch lining and pull manual release wire. Moral of the story ... try not to let you battery get very dead!

My old 987 the radio code is from memory stored in the ecu in the rear boot. So no issue taking the battery off at all but i did put the key in the ignition prior to disconnecting. Also the front trunk, when connecting a power supply to the pin in the fuse box, sometimes it wouldn’t open but try both the remote key and the switch on the sill. Again I can’t remember which normally wouldnt work but the other one always did.

987.2 S battery change...everything off key out door open, disconected the battery and removed it, new battery in re-connected, switched on started traction control light remained lit which went out after driving. However I asked at the OPC (where I bought the battery) if my Cayman needed coded, no they said only the later models with Stop-Start, so thats some info to remember. The battery was dead in mine, I tried to jump it which blew the Bose raido fuses..???, just be careful jump starting these cars. Edited by Klippie on Sunday 22 January 14:56

James44 said: Fl0pp3r said: Pistonheads Battery Brain Trust needed! (aka another battery maintenance thread) My 997 gets stored for several months, and shocker - the battery becomes heavily discharged. I try to trickle it from time to time (no sniggering) but I cannot leave the charger connected for long periods unfortunately (due to car park location). So I would like to keep a spare battery charged indoors, then swap it in periodically. At the same time, I would like to keep charge CONSTANT to the vehicle's electronics while I remove the depleted battery (so that I don't lose ECU settings etc, the alarm still works, and so that I'm not constantly breaking and reconnecting power). Plan would be to connect second GOOD battery via jump leads to the car's connectors, remove depleted battery, then swap it back in later once reconditioned (and repeat...). This means two batteries of differing voltage would be briefly connected at the same time. Will the voltage difference between the two batteries cause a problem if they are only connected for a short period? I have read this might not be a good idea. I won't be trying to start the car with both batteries connected. The other solution might be to use an ODB2 memory saver to maintain settings, but I'd still be yanking and reconnecting a live battery every month. Perhaps I'm being over sensitive on that part, i don't know? Many thanks as always But if your battery goes flat you will lose all settings anyway. Once your battery goes really really dead, I found out that you need a really powerful 12V on to the internal terminals to get the bonnet to release. There was time once when I'd left the car that long it just wouldn't release the bonnet. Local indy advised that this can happen and the next fallback plan is to jack up the front of the car, remove passenger side wheel, remove wheelarch lining and pull manual release wire. Moral of the story ... try not to let you battery get very dead! Cheers James, yeah normally I’ve been able to stop the battery falling below a critical level, but for some reason the last Varta dropped to 3v which was not helpful (probably the recent cold snap). Played the bonnet release game of course and it is worth noting that I had to use the remote rather than the flap release button inside the car for it to work (per other comments above). Anyhow I’d like to keep a second battery ready-to-go and swap it in periodically before we get to that critical point, then recondition the extracted one as I say. The question is how to do that swap safely. Any thoughts?

Could you not buy a solar powered trickle charger?

Why don’t you buy one of those rechargeable starter packs and spare battery plus maintainer. They have enough juice to open frunk and get it started from flat or then change it out.

Fl0pp3r said: Cheers James, yeah normally I’ve been able to stop the battery falling below a critical level, but for some reason the last Varta dropped to 3v which was not helpful (probably the recent cold snap). Played the bonnet release game of course and it is worth noting that I had to use the remote rather than the flap release button inside the car for it to work (per other comments above). Anyhow I’d like to keep a second battery ready-to-go and swap it in periodically before we get to that critical point, then recondition the extracted one as I say. The question is how to do that swap safely. Any thoughts? Perhaps have a 3rd battery and attach that to the internal terminals while you swap the battery. That may keep 12V on the esentials to keep your settings, though whether there are other unintended consequences I don't know! (you'd have 12V on the battery terminals as you swap over, so wouldn't want the positive lead to hit the bodywork!)

7184c said: Why don’t you buy one of those rechargeable starter packs and spare battery plus maintainer. They have enough juice to open frunk and get it started from flat or then change it out. Yeah I hear ya - but I’m trying to avoid the situation of having a flat battery altogether to be fair. Not good for the battery ultimately - killing it and resurrecting it constantly. I already have a ton of kit - including 2 CTEKs and a spare full size battery, I was just hoping to find a safe way of swapping the main battery in/out without damaging the circuits while retaining ECU settings etc. Think I might look at these ODB2 memory savers for the settings issue, but that still won’t stop the main battery dying. Another guy suggested a battery isolator switch which would alleviate any pull down on the battery while stored, but the problem then is you have no alarm etc and you cannot apparently use a trickle charger on the battery. :-| TBC

James44 said: Fl0pp3r said: Cheers James, yeah normally I’ve been able to stop the battery falling below a critical level, but for some reason the last Varta dropped to 3v which was not helpful (probably the recent cold snap). Played the bonnet release game of course and it is worth noting that I had to use the remote rather than the flap release button inside the car for it to work (per other comments above). Anyhow I’d like to keep a second battery ready-to-go and swap it in periodically before we get to that critical point, then recondition the extracted one as I say. The question is how to do that swap safely. Any thoughts? Perhaps have a 3rd battery and attach that to the internal terminals while you swap the battery. That may keep 12V on the esentials to keep your settings, though whether there are other unintended consequences I don't know! (you'd have 12V on the battery terminals as you swap over, so wouldn't want the positive lead to hit the bodywork!) Cheers James - yes I think using the spare battery in parallel on the terminals is doable - with care. I believe one of NOCO’s chargers has a “supply function” which would fulfil the same task, with lower charge and security circuits, but that means buying more equipment….

mikecassie said: Just read this thread, I see the OP said disconnect the positive terminal 1st and connect the positive terminal last. From experience I'd not do this. If the spanner accidentally contacts any metalwork when disconnecting the +ve terminal then you can have a spark and damage paintwork or even worse. I'd always disconnect the -ve terminal first then the +ve and connect the +ve terminal first. Exactly as my Dad taught me: never have the -ve terminal connected on its own.