Red Battery Light of Death

AC5L4T3R · Post by **AC5L4T3R** » Fri Jul 23, 2021 8:33 am

Yesterday I drove to football training and when I left, the battery light came on. After 20 mins or so of driving, I turned the engine off and on again and it went away for about 5 minutes then came back on. On the school run this morning, it was off until I dropped the kid off and then it came on again.

I did the in-car voltage test and it showed 11.9v with the engine off and 11.1v with the engine on. Turning the wheels dropped it down to 10v and crept under 10v briefly.

The battery is about a year old, maybe a year and a half. I still have my old one which is 3.5 years old so I'll try that and see what happens.

But given the age of the battery, does it sound like the alternator is on its way out?

enuff_zed · Post by **enuff_zed** » Fri Jul 23, 2021 8:37 am

Usually you'd expect the voltage to be much higher when the engine is running as the alternator is charging it.
Unless more electrically astute members can shed more light on it, then I'd be thinking alternator.

Zulu4 · Post by **Zulu4** » Fri Jul 23, 2021 8:40 am

+1 for alternator.

enuff_zed · Post by **enuff_zed** » Fri Jul 23, 2021 8:41 am

I'm sure I've read that it's possible to replace the brushes/diode pack rather than get a complete new alternator?
Maybe a search or two on here would clarify?

brillomaster · Post by **brillomaster** » Fri Jul 23, 2021 9:18 am

stop driving it! once the alternator goes, you've got about 45 minutes of juice from battery power alone, then your car is a brick!

bigwinn · Post by **bigwinn** » Fri Jul 23, 2021 9:23 am

+1 on alternator

Belts all ok I assume

AC5L4T3R · Post by **AC5L4T3R** » Fri Jul 23, 2021 9:39 am

bigwinn wrote: ↑Fri Jul 23, 2021 9:23 am +1 on alternator

Belts all ok I assume

Belt has some cracks but apart from that seems okay.

I'll replace the belt and alternator. €200 for a Bosch alternator.

firebobby · Post by **firebobby** » Fri Jul 23, 2021 11:01 pm

AC5L4T3R wrote: ↑Fri Jul 23, 2021 9:39 am
bigwinn wrote: ↑Fri Jul 23, 2021 9:23 am +1 on alternator

Belts all ok I assume
Belt has some cracks but apart from that seems okay.

I'll replace the belt and alternator. €200 for a Bosch alternator.

You can exchange the regulator whist the alternator is on the car, I did this and it's been fine since, about £30.

bigwinn · Post by **bigwinn** » Sat Jul 24, 2021 8:35 am

firebobby wrote: ↑Fri Jul 23, 2021 11:01 pm
AC5L4T3R wrote: ↑Fri Jul 23, 2021 9:39 am
bigwinn wrote: ↑Fri Jul 23, 2021 9:23 am +1 on alternator

Belts all ok I assume
Belt has some cracks but apart from that seems okay.

I'll replace the belt and alternator. €200 for a Bosch alternator.
You can exchange the regulator whist the alternator is on the car, I did this and it's been fine since, about £30.

Didn’t know you could swap the regulator out

Easy enough job?

firebobby · Post by **firebobby** » Sun Jul 25, 2021 6:09 am

Yes, there are quite a few threads on the forum around the issue. You can check the output and the actual regulator, again, check the forum or YouTube.
It took me about 30 minutes to change my one.

AC5L4T3R · Post by **AC5L4T3R** » Mon Jul 26, 2021 2:40 pm

firebobby wrote: ↑Fri Jul 23, 2021 11:01 pm
AC5L4T3R wrote: ↑Fri Jul 23, 2021 9:39 am
bigwinn wrote: ↑Fri Jul 23, 2021 9:23 am +1 on alternator

Belts all ok I assume
Belt has some cracks but apart from that seems okay.

I'll replace the belt and alternator. €200 for a Bosch alternator.
You can exchange the regulator whist the alternator is on the car, I did this and it's been fine since, about £30.

Interesting, I'll look in to it. Indie quoted me 300 euros today as it takes about 3 hours to change the alternator.

What would I have to check? Did you have to take the radiator off?

firebobby · Post by **firebobby** » Mon Jul 26, 2021 6:37 pm

AC5L4T3R wrote: ↑Mon Jul 26, 2021 2:40 pm
firebobby wrote: ↑Fri Jul 23, 2021 11:01 pm
AC5L4T3R wrote: ↑Fri Jul 23, 2021 9:39 am Belt has some cracks but apart from that seems okay.

I'll replace the belt and alternator. €200 for a Bosch alternator.
You can exchange the regulator whist the alternator is on the car, I did this and it's been fine since, about £30.
Interesting, I'll look in to it. Indie quoted me 300 euros today as it takes about 3 hours to change the alternator.

What would I have to check? Did you have to take the radiator off?

No, just removed the air cleaner to get more room. There are quite a few threads on here on how to do it
Or check out YouTube.

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