Alternator shot?

[clickman]

Long story short, I managed to hook up the battery the wrong way round. For a couple of minutes.

I've had the battery out of the car for a couple months. (It's been hooked up to a battery maintainer until a few days ago while I moved it to another car.) After I hooked the battery up in the car backwards, I corrected that and then measured the voltage across the battery terminals at just under 13V.

I started the car and ran it for half an hour. (Stereo dead, but no CEL). The voltage across the battery dropped from just under 14V at the start to around 13.25V at the end of the half hour. Alternator toast?

Edited December 17, 2009 by clickman

[Tool Pants]

A few years ago I asked one of the mechanics what happens when you hook up a battery backwards. The alternator and radio. Check the fuse on the back of the radio. Your alternator may have somehow survived if you are getting that much voltage.

[clickman]

Yeah, I've already got the radio pulled and the fuse out. Unfortunately the fusible part isn't visible and I don't have a continuity checker. Now I need to figure out where to get a replacement! (Porsche part number 996-blah-blah $322.99 ;) )

I just wonder if it's normal for the voltage to go down like that...

Edited December 17, 2009 by clickman

[goldenwarrior1]

Yeah, I've already got the radio pulled and the fuse out. Unfortunately the fusible part isn't visible and I don't have a continuity checker. Now I need to figure out where to get a replacement! (Porsche part number 996-blah-blah $322.99 ;) )

I just wonder if it's normal for the voltage to go down like that...

13.25 volts is a normal reading for the Alternator. If you don’t have any lights you should be ok. DO NOT disconnect the battery while the car is running to check operation of the alternator. It can seriously damage the car control modules from the power fluctuation. If you suspect it bad take it off and take it to a shop and have them run it on the bench. Places like auto zone will do this for free. If it is bad, an electrical repair shop can repair it for you at a fraction for the cost of a new one. Hope this helps.

R/GW

[goldenwarrior1]

Yeah, I've already got the radio pulled and the fuse out. Unfortunately the fusible part isn't visible and I don't have a continuity checker. Now I need to figure out where to get a replacement! (Porsche part number 996-blah-blah $322.99 ;) )

I just wonder if it's normal for the voltage to go down like that...

13.25 volts is a normal reading for the Alternator. If you don’t have any lights you should be ok. DO NOT disconnect the battery while the car is running to check operation of the alternator. It can seriously damage the car control modules from the power fluctuation. If you suspect it bad take it off and take it to a shop and have them run it on the bench. Places like auto zone will do this for free. If it is bad, an electrical repair shop can repair it for you at a fraction for the cost of a new one. Hope this helps.

R/GW