Attn: Everyone,

The 3-year old low-price, drained-several-times, weak-battery described
above is now replaced with a new 7-years warrantee battery. Let's see how
long this one will go. I have another similar alternator question for a
second car, if I may.

Recently my wife's '97 BMW 318ti's alternator was replaced and it shows
13.7V at any rpm with no loads. With loads it's 13.6V at 2000 rpm or 9-10V
at idle. Engine off it reads 12.6V. Alternator is Valeo, made in France.
Battery is two years-old. Is the alternator fine?
Attn: Battery experts! Thank you.
Tibur

>"L0nD0t.$t0we11"
> Roughly 12/27/03 21:47, Tibur Waltson's monkeys randomly typed:
>
> > 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?
>
> It looks like the alternator is OK, but the battery itself
> may be on its way to failure.
>
> You may want to try AutoZone or Sears for a quick check of
> your charging system and the battery itself.
>
> First make sure that all of the battery connections are
> squeaky clean and tight. If the cable posts are loose
> inside the battery might as well head to the battery store.
>
> You can load check the battery itself with similar test as
> above.
>
> With nothing connected, the battery should read 12.4 volts. If
> below that, it isn't charged fully or is defective. If you
> have a battery charger, try it.... but replace any battery that
> can't hold 12.4 volts or higher with no cables connected.
>
> Then make sure the battery isn't just taking a surface charge
> by giving it a load, then check the open circuit [no cables]
> voltage again. Turn on your headlights [with battery connected]
> for 15 minutes, then turn them off and wait 5 minutes. The
> battery should still show at least 12.4 volts. If it can't,
> it is getting old and is only taking a surface charge.
>
> With no-load and the headlight 15 minute load test, rough battery
> voltages for charge are:
> 12.0 volts = 25% charge
> 12.2 volts = 50% charge
> 12.4 volts = 75% charge
> 12.6 volts or more = 100% charge
>
> If the battery is 5 years old, swap it anyway if it is a premium
> model. If not a premium model, derate that to 4, 3, 2 years.
>
>
> --
> Fan of the dumbest team in America.
>