aerohead80

It's about time to change the battery on my 981 GT4 and I was hoping someone could tell me if they've done the swap without keeping power to the system with a host battery or other method? Are there any settings lost beyond what the manual talks about resetting after changing the battery (TPMS, windows, etc)? Also, if you did swap it and keep power, what method did you use? Is it ok to use a ctek maintainer plugged into the 12 V under the dash? Thanks!

KingSize.Hamster

I have unplugged the battery and put it back in. I just get the clock getting messed up. Other warnings tend to go off after another startup if at all. Need to reindex the windows as well. Otherwise it really is no biggies.

a Wall charger would work too. Otherwise, what my local battery shop does is he simply connects the new battery in parallel using smaller jumper cables to keep car powered the whole time during the battery swap. He does it so customers don’t end up losing random settings in their radios for their cars etc. that said, the guy at the battery shop said it’s mostly an issue with older car, especially Japanese cars. Somehow that throws off radio station settings and even trip odometers for some cars.

ICNU

Keep in mind your CTEK wont do anything to maintain power unless you have a CTEK model with a dedicated "supply" mode on it. Otherwise it will disconnect as soon as there is no battery seen on the other end. There is short term capacitance it seems, as many including myself have swapped the batt out within 5 minutes on these cars with no effect whatsoever on anything. Just plug and play

aerohead80

Good to to know and thanks!

aerohead80

Thanks, this is the kind of info that'll help me figure out a good way forward.

skl

Assuming the GT4 and spyder are similiar, I replaced the battery in my spyder a year or so ago with a H5 AGM battery with no issues. Just took out the old one and replaced it, reset the windows, etc but didn't do any recoding etc. Fit fine- like the H5 because it is a lot smaller than the H6 or H8 batteries. Would probably get an Antigravity next as that has to be one of the most awkward places to replace something that heavy!!

I also use a Noco Genius 5 charger/maintainer that has a setting for AGM batteries. I put it on a timer so it is only active for 4-6 hours a day if I'm not going to be driving the car for several days.

ahoy_mateys

Recently did an emergency replacement of my battery with a H6 AGM from Costco. I just set everything in place and swapped it in without any battery maintainer. I think I lost some PCM radio settings but besides that it was pretty straightforward. I didn't get any TPMS or window errors.

Diablo Dude

I swapped out my battery late last year in my GT4 and did an awful lot of research before I did.
I wound up purchasing an H5 VW automotive group battery (000-915-105-DE) from my local VW dealer for $143.
There's really no need to go for a bigger size and heavier battery. You can save easily yourself 20 lbs getting the H5.

I also spent $20 at my local Auto Parts store and bought a memory saver which was super easy to use.
After I did the swap, I took my car to my local indy mechanic for an oil change and had him "initialize" the new battery.
The cost to do so was half of what my Porsche dealer would have charged.
$140

Sgtfluffy16

best things to do, start the car and let it run while you do the battery change. Just make sure that the terminals do not touch anything after you remove them from the battery. That way you don't have to do any of the resets that are required. And then after that you can go in and code that it has a new battery. I need to do this as well as I am due for a battery, it is the original 5k0915105d but after all of the research that I've done I believe I'm going to go with the H6 battery as the h8 is overkill and the H5 seems to be a little underpowered some people even said you need an adapter for the H5 battery

okie981

You can leave the battery disconnected for months with no ill effects. Worst case effect is having to reset the power window limits by holding the switch in full down position until it stops and for another 2 seconds, then release the switch and quickly press full down and hold it for 2 seconds and release. Then repeat the same but for the full up position of the window. Make sure your doors are closed when you do this full up setting.

The "battery adaptation" procedure typically done with PIWIS (can also be done with Foxwell, Durametric, etc.) is only necessary if you have let the old battery degrade in performance to the point you have begun to see weird random faults appear on the dash LCD or if the auto stop/start function stops working. Never hurts to do the adaptation process, but not necessary except for the badly degraded battery situation.

Miles3719

I know this is an old thread but its mainly here for those googling (like I did) on batteries and this thread comes up pretty frequently. Just replaced the OEM (unavailable) 5K0915105D with a DIN65LH AGM with the following specs:

Length:276mm, Width:175mm, Height:190mm
Volts:12v, CCA:720, RC:120, AH:70, Weight: 20.05kg

Fits perfect, no need to additional hardware or brackets. Uses the 'middle' width bolt hole, posts were fine and venting hole location was the same as OEM. I am in Australia so you wont be able to get the same battery elsewhere, but mainly posting for reference in relation to size dimensions and what it looks like once installed, may help others while researching options. I was keen not to go overboard with the battery and thought one on the smaller side (yet still higher CCA and AH etc than the OEM one that did last 7 years) was appropriate. It lives on a 4a Redarc/DEFA trickle/maintenance charger anyway

DrBillyD

I used to connect my trickle charger to the pos/neg battery terminals too.

Then I read somewhere (probably one of the threads on RL) that there's a voltage regulator on the negative battery cable that doesn't like having outside current/voltage applied to it. Can't remember if it gets damaged or just reset in some way. In any event, I haven't had any problems, at least none that I know of. If you've been doing it for 7 years, you probably aren't having any problems either.

But now I have the negative cable from my trickle charger attached to the chassis ground. It's the same location that's used for jump starting the vehicle (2016 Boxster Spyder). Don't have my owner's manual in front of me right now, but I think the procedure outlined in the manual states that only chassis ground should be used for attaching negative cable when performing jump start; can't remember if it goes into detail as to why.

Miles3719

The battery lasted 7 years, but I am new to the car (a month now) so I will lookup and change this ASAP.. Thank you @DrBillyD

herbj

I need to replace the original battery in my 981 GT4. I would like to buy an AGM battery from Autozone. IT does not have the fancy QR code label with make and serial number. Can I just input AGM as the type and the amp hours or do I have to spend twice as much and buy a battery from Porsche (which would be a wet cell battery)?

DaveGee

I recently replaced my OEM wet cell battery with an AGM battery I bought at Costco. I had the car recoded so that the charging system would know I was now using an AGM battery. No issues whatsoever.

And before you ask, no, I did not use a temporary power supply while I swapped out the battery and yes, everything worked after the new battery was installed - other than the clock needing to be set to the current time.

DaveGee