Battery Light Comes On And Kills Car

[muchogarcia34]

Hey everyone my battery light came on last night in my R34 while I was driving around town and I got to see it for a few seconds before all of a sudden my revs just died out and my car died, then immediately came back to life. The light would then intermittently turn on and off and the car died once or twice more then it stopped, and for about an hour nothing happened, it just drove normal. After this hour it happened again when I was just about home so I parked up and have left it alone today.

I tested the alternator this morning and it was charging at 13.8v and I checked my battery and that was holding 13.8v also while the car was running. Does anyone have any ideas of what this could be?

Mods:

RB25/30

ViPEC

Plazmaman Plenum

3076 on a 6boost Highmount

50mm Turbosmart Wastegate

Sard Injectors

Intank 044

Battery Mounted in boot (I checked the earths and connections on this and they looked good)

Any help will be appreciated.

Thanks

[Moodles2]

Sounds like an electrical connector is loose, I would start with the ECU

[markdem]

sounds dumb but check the battery terminals. they can come loose and make a dodgey connection

[luke gtr]

Also check your charge rate with your high beams, a/c fan, and brake lights on.

Need to see what the charge is doing under load.

Could still be a faulty alternator, possibly voltage reg on its way out.

But as mentioned, check your battery terminals, and earth points first.

Then go from there.

Good luck.

[GTScotT]

I think it will be close to the alternator or starter.

Look for loose wiring and possible shorts.

[kitto]

Sounds like the alternator or volt reg.

Really need a dc clamp meter to test it properly. Volt meters are handy but can give rricky/false readings.

[t_revz]

Sounds like the alternator or volt reg.

Really need a dc clamp meter to test it properly. Volt meters are handy but can give rricky/false readings.

if it was the alternator or reg the engine wouldnt die immediately as it still has the battery to run off. ecm would prob switch off between 8-10 so there would be ample time

sounds like something loose or even a short in batt cables

[sweefu]

Check the alternator charge wire, bolt on the back of the alternator.

[muchogarcia34]

Hey guys, checked all those things and everything seems fine. The light came back on yesterday and so I tested the alternator and it was only charging at 11v. So I'm going to get it replaced as it seems to be an intermittent problem with that.

[mr031]

check the belt tension aswell? could be slipping

[Odium]

check the belt tension aswell? could be slipping

Once more, intermittant alternator wouldn't cause the engine to cut out like the OP describes... It would continue to run just fine off the battery for many more km's until the battery voltage drops to something crazy low like 8v or whatever the ECU starts getting confused at.