I think I'd rather have a good battery!!
regards,
MP
----- Original Message -----
From: <europa-builder@ntlworld.com>
Subject: Re: LEDs
>
>
> > The "idiot" light tells you (when it is on) that the alternator output
> > voltage is lower than the bus/battery voltage. And nothing else.
> > When the light is out, the battery is not necessarily charging ( as
output
> > voltage may be below the c.13.4 volts required for charging).
> > My preference is for a voltmeter; which will tell the state of charge
of
> > the battery before start-up and whether charging is taking place during
> > engine run. The amount by which charging is taking place (as indicated
by
> > an ammeter), I find a little academic.
>
> I don't think a volt meter can tell you anything about the battery.
>
> 1) A cell goes open circuit after starting the engine (it does happen) or
> one of the leads falls off the battery. Your volt meter will show a >13V
> reading, but the battery is getting zero charge (an ammeter would show
this
> fault).
>
> 2) Battery not holding a charge. You arrive at the airfield and find you
> can't turn your engine, so you jump it from your car. When running, it
may
> appear to be charging and the voltage may be >13V, but it won't start the
> engine again (even an ammeter won't be much use here).
>
> 3) A duff battery may show a reasonable voltage but may have too high an
> internal resistance to let the current out (or in). It may even let the
> avionics work, but not quite let the starter turn the engine. You will
see
> the avionics die when you try to crank the engine though.
>
> I think I'd rather have an ammeter than a volt meter.
>
> Cheers,
> Mark.
>
> ________________________________
> Mark Jackson - +44 (0)7050 645590
> europa-builder@ntlworld.com
> http://harley.pcl.ox.ac.uk/~mark/Europa
>
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