alternator and voltage regulator Topic is solved

joebone · Post by **joebone** » 06 Sep 2005, 17:50

My battery keeps losing its charge. While the car is idling, the alternatro only puts out 12V and if I leave the car sitting for a few days the battery gets drained. I've already replaced the battery one month ago. My mechanic has recommended I replace the Bosch alternator with an OEM because of computer interface problems. Before I spend $450 on an OEM part, should I try to replace the voltage regulator first? Is it worth it to keep the Bosch Alternator in the car based on their recent history of poor craftsmanship?

greeselightning · Post by **greeselightning** » 06 Sep 2005, 19:59

I recommend before you replace the whole alternator ($$$), like you said, look into trying to replace either the voltage regulator or the alternator brush assembly. May save you some $$$ there.

What year and model do you have and what's your mileage? The brush itself might be getting too short or the brush spring might be weak already.

I was not aware of the poor history of Bosch alternators on Volvos. I think Bosch alternators are the OEM parts that came with the 850s. At least that's what I have on my '96 850 GLT. I haven't had any problems with it yet.

I've replaced an alternator brush assembly on my wife's Honda. Visually, you can tell if you need to replace the brush assembly. There's more wear and tear on the brush assy compared to the voltage regulator. That's why its more of a possibility it may just be your brush assy.

If anybody can explain what's the conneciton with what his mechanic said regarding the computer interface problem, I would sure like to know why that maybe a factor.

turbotim2 · Post by **turbotim2** » 07 Sep 2005, 06:18

Your alternator may only be able to make 12V at idle, there may be nothing wrong with it as most alternators need about 2,000 rpm+ on the engine to produce their full power. It sounds like you have something drawing power off the battery that shouldn't be when the ignition is off.