Jim H.

Having recently re-acquired my GT3 I'm putting a few things back to where I wanted them. One was replacing the rennline/race battery combo with a full size battery (Sears diehard).

I took the car on a 2.5hr drive the other day and during the drive I noticed the electrical gauge showing a constant decline all the way down to 10 or so volts while traveling at a constant highway speed.

At my destination the car was seemingly dead but I was able to easily push start it. Immediately after push starting the car, the electrical gauge showed around 13 volts. I drove all the way home without a hitch. I did stop once and the battery had picked up enough charge to start by key (just barely).

Since being home the car has been on a trickle charger and shows full charge and starts immediately with the key.

For any of you electrical gurus out there, does this string of events point to where the problem must be? I'm thinking it's the alternator...

Jim

Boostin

I feel like it's something alternator related or a poor connection between the battery and the alternator. I'd be curious to hear what happens the next time you drive it. I'd even take it off the trickle a week before you drive it and then see what happens. I've got the Rennline setup in my car and the battery will easily hold a charge for a week.

I haven't done my research on 996TT vs. GT3 alternators but I'd assume they are the same unit, or damn similar. Anyway, I had the voltage regulator die on my TT so wasn't getting a charge to the battery. After replacing the regulator, she was good to go. The reason I mention this is because I'd start with the regulator before going for the whole alternator as the regulator is pretty damn cheap comparatively.

Jim H.

Thanks for the input.

I will probably take it in for diagnostics soon but it seems possible to isolate the problem beforehand somewhat. I was thinking connection too but in the front compartment all looks well, no corrosion and everything is tight.

85Gold

6GT3 alternator regulators are prone to failure. Easy do it yourself or less than $100 at an alternator repair shop. BTDT

Peter

993MAN

Wouldn't there be a warning lamp come on if it wasn't charging?
I reckon get a load test done on the battery. Sometimes a cell can be on the way out and behave like yours is behaving.

Jim H.

Thanks. Looking into just replacing the VR at home. I hate taking my car into the dealership for service...

911SLOW

These generators have a nominal output of 13.6v plus/minus 0.2.
I changed my first one when it failed under warranty. The newer one is a 997 part.
You can also change the regulator board that often fails with a lot less money.

You should check the alternator's output, the battery itself and lastly the ground cables. There's one on the right side of the engine's bottom bolted on the chassis that usually fails or gets unbolted.
I had mine changed a couple of years ago.

SH || NC

+1 (link)