Need Help (electrical)

[samuel pickens]

To one and all:

Getting ready to go on a trip and doing a check out. Seems I have no
charging circuit. There's a little blue box (looks like a rectifier) just
above the battery area and directly above the battery switching lock-out.
It's part number is GMC 706751. I can't find it in the book. But, it has 3
terminals and all is open between each terminal and ground. I apparently is
defective -- please confirm or deny. And, if so, who's a quick source to
get one?

With best regards; I'm
Sincerely,
Sam Pickens
picksam

 

[dave1]

>.... it has 3
>terminals and all is open between each terminal and ground. I apparently is
>defective -- please confirm or deny. And, if so, who's a quick source to
>get one?

That is the battery isolator. To check it out, start the engine and look
for voltage at the center terminal (measure to ground). It should be about
15 volts or so. Then measure each of the other terminals (to ground). Each
of them should be about .7 volts less than what you measured at the center
terminal. If the difference is a lot more (like multiple volts) then the
circuit is open. If the difference is close to zero then the circuit is
shorted. You can usually get replacement isolators at any RV supply store.
They have a good selection at camping world for example. I would use an
oversized replacement. Like one rated for 150 Amps. Not as likely to fail...

Dave
73 Sequoia

 

[samuel pickens]

Dave,

Thanks a heap. The difference is 0.20 V

With best regards; I'm
Sincerely,
Sam Pickens
picksam

- ----------
> From: Dave
> To: gmcmotorhome
> Subject: Re: GMC: Need Help (electrical)
> Date: Thursday, July 15, 1999 3:37 PM
>

> >.... it has 3
> >terminals and all is open between each terminal and ground. I
apparently is
> >defective -- please confirm or deny. And, if so, who's a quick source
to
> >get one?
>
> That is the battery isolator. To check it out, start the engine and look
> for voltage at the center terminal (measure to ground). It should be
about
> 15 volts or so. Then measure each of the other terminals (to ground).
Each
> of them should be about .7 volts less than what you measured at the
center
> terminal. If the difference is a lot more (like multiple volts) then the
> circuit is open. If the difference is close to zero then the circuit is
> shorted. You can usually get replacement isolators at any RV supply
store.
> They have a good selection at camping world for example. I would use an
> oversized replacement. Like one rated for 150 Amps. Not as likely to
fail...
>
> Dave
> 73 Sequoia

 

[mr.c]

Another problem is low water in one of the battery banks. I had a
problem with low water in the coach batteries. That caused the system to
always try to charge the battery that is weakest. I caused the engine
battery to get little charge. Try checking both batteries and see that
they are both up to the correct level on water. And use distilled water.

Al Chernoff
77 Eleganza II