This discussion calls into question the sometimes suggested method for
charging aux batteries in Westys by using the fridge relay as the source
of charging current. At SDM a couple months ago someone had an Optima
connected this way that would not seem to hold a charge. When we
measured the voltage at the aux battery with the engine running it was
under 13 volts. When the fridge was turned to 12 volts operation the
voltage at the aux battery dropped to about 12.5 volts. When we checked
the voltage on the starter battery it was just under 14 volts at the
same time that the aux bat was seeing 12.5 volts. All that drop was due
to the wiring from the main battery to the dash and then to the fridge
relay. Obviously, a separate wire should be used to connect the 2
batteries for charging purposes or the Optima will never be of much use.
Using the fridge relay as a quick and dirty charging source is not a
good idea.

Mark

Derek Drew wrote:
>
> The charging voltage should be the pretty much same at the alternator
> and also at the battery terminals and also at the fusebox.
>
> If you turn on a lot of accessories (air conditioner, fans,
> headlights, etc.) you will notice that the voltage is lower as you go
> progressively forward.
>
> This is because the vehicle has inadequate wiring size between the
> alternator and the huge battery wire going forward from the starter,
> and also inadequate wiring size going forward from the battery to the
> fuse box. You can correct this deficiency yourself by adding more
> wiring at those locations in parallel with the existing factory
> wiring. I have done this.
>
> For long term use, I would measure the voltage at the battery
> terminals.
> .................