996 electrical problem

[GT03ROB]

My GT3 seems to have an electrical problem. Battery level seems normal based on voltmeter on dash. Been on CTEK charger which doesn’t show ant issue. But simply won;t start. It’s as if battery is flat. turn ignition & a click & thats it.

Put another battery charger on the battery & it shows as if flat. Starts perfectly off the charger, but stop it & it’s as if the battery is flat again. Another point I’ve noticed is there is a buzzing sound from the battery area when it is running which is definitely not normal.

Any thoughts or is it joist a dead battery. Battery is around 5yrs old & has mostly been kept on a ctek charger.

[Chris Stott]

Mine’s not a GT3, but it does seem to eat batteries if it’s not used regularly. No idea why.

Given a diagnosis by an Indy will likely cost more than a new battery I’d just stick one in it and see if that cures the starting issues.

[Hoofy]

It displays the battery has a voltage but can't jump start? Sounds like it doesn't have enough CCA, then. I'd test it with a new battery. I was told that even a well-kept battery will give up over time. Do you have a battery tester that can also test the health of the battery?

Edit: can't remember which brand (Yuasa?) does a 5 year battery warranty, but it might be worthwhile getting that one and claiming on the warranty after 4 years if you're keeping the car for a few more years.

[PTT]

Look if your battery ground strap mounting points are not corroded.

[M33KBT]

Mine was struggling to start recently and was diagnosed as a corroded/deteriorated cable from the battery to the starter. item 17 on this diagram

https://www.design911.co.uk/diagrams/d/41180/0

I had them replace the starter too while it was in the shop and it starts a lot perkier now

[IanSC]

Hi Rob,
I had a similar problem with my 996 turbo a few years back. The car was garaged with a CTEK charger, which I noticed was boiling hot when I unplugged it. The battery drained to completely flat in a few minutes, so I assumed it was a problem with the battery itself. Bought a replacement battery and exactly the same thing happened again.

The issue was diagnosed to a faulty alternator regulator, came in at just over £300 incl labour (5 years ago) and has been fine ever since.

Hope it’s an easy fix for you !

[cvega]

one easy way is to watch the Voltage gauge when car is running. if it's just above 12V, your regulator is toast.