Honda Car Forum

>"wß" <wb@notmail.com> wrote in message
> "Tibur Waltson" <Toush@hi.com> wrote:
> > Today I load test the alternator by an instruction in an aftermarket
> > repair manual. The instructions says to turn on headlights, defoggers,
> > fan, radios, cigarrete lighter, etc and measure the voltages. It reads
> > 13.6V at 2000 rpm or 11.2V at 750 rpm. It's within normal range
> > according to the book. But the headlight seems a bit weak unless rpm
> > is above 1300 rpm or sometimes it just too weak for the starter. We
> > hardly drive in the highway. It has an alarm system. Is the alternator
> > fine? TIA Tibur
>
> Once you do this if you turn off all the loads does the voltage quickly
> float up to 13.6 volts?

Good question, I didn't include this information because I thought
everyone assume if it reads 13.6V with load at fast idle then the
voltages should jump up to 14.4V without load at fast idle. Which
it did and I was wrong to assume. I regret not including this info
because the other BMW measures 13.6V with load at fast idle
and 13.7V with no load at fast idle.

Based on many advices the Beamer's alternator is broken, but it's
newly rebuild and it works. It'll be impractical to yank it out in the
freezing cold when it appears to work fine, unless I'm, otherwise,
convinced.

> How old is it and of what quality?

About the battery, it was a cheap`o Wa1-Mart one-year free
exchange battery rated at 650 cranking amp max. I'll be sticking
with the Sears 7-years free replacement Die-Hard or Duracraft
or something.
Tibur

Randolph wrote:
> When it comes to judging the health of the alternator, the magnitude of
> the ripple is not as important as the shape. Normally it will look
> something like:
> _ _ _ _ _ _ _ _
> / \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
>
>
> If you have a failed diode (open) in the rectifier you will have
> something like:
> _ _ _ _ _
> / \_____/ \_/ \_____/ \_/ \_____
>
>
> If you have a failed diode (short) in the rectifier you will have
> something like:
> _ _ _ _ _
> / \__ __/ \_/ \__ __/ \_/ \__ __
> V V V
>

Thanks for the reply Randolph. If I remember correctly, the voltage on the
scope looked something like:

/\/\/\/\/\/\/\/\

with sharp peaks (+/- 0.2 volts) spaced out evenly. Does the above wave signal
any problems your fimilar with?

Thanks,
- Dave

> Thanks for the reply Randolph. If I remember correctly, the voltage on the
> scope looked something like:
>
> /\/\/\/\/\/\/\/\
>
> with sharp peaks (+/- 0.2 volts) spaced out evenly. Does the above wave signal
> any problems your fimilar with?
>
> Thanks,
> - Dave

No, not to my knowledge.