Re: [GMCnet] Isolator -- bypass? [message #326802 is a reply to message #326801] |
Wed, 06 December 2017 13:04 |
Emery Stora
Messages: 959 Registered: January 2011
Karma:
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Senior Member |
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Both batteries should NOT be connected to the same isolator post. Keep one that goes to the “vehicle battery positive pole”. Disconnect the other one. It should go to the second isolator post.
Most transmodes have a boost switch on the dash and a second battery (the “house” battery).
If you are certain that you don’t have a second battery (look in the back by the Onan) then you can connect the wire from the alternator (center isolator post) to the vehicle battery positive pole.
However, if you do have a second battery for the Onan or the house circuits that battery would not be charged.
Emery Stora
77 Kingsley
Frederick, CO
> On Dec 6, 2017, at 11:47 AM, Dave Stragand wrote:
>
> Hi All,
>
>
>
> Just started poking at the no-charging issue on our 1978 Transmode
> (403).
>
>
>
> Thanks to whomever created that great flowchart for troubleshooting
> charging issues. I was able to determine that the alternator voltage
> (center pole of the isolator) to battery terminal ground was 14.70
> volts, so the alternator seems within spec..
>
>
>
> However, both of the output poles on the isolator (top and bottom) are
> connected directly to the same point - the "vehicle battery positive
> pole". On a Transmode that may not have had a second or house battery,
> that kind of makes sense to me, but if that were the case, why would GM
> bother to install an isolator? In any case, the reading from either
> pole on the isolator is a dismal-but-steady 12.02V - and that's too low.
> It matches the 12.0 on the cheapo cigarette lighter voltmeter inside.
>
>
>
> That leaves me with a few questions, and I was hoping y'all might be
> able to help.
>
>
>
> 1) Is the low voltage on the battery sides of the isolator possibly
> caused by the fact that both the upper and lower outputs are connected
> together?
>
>
>
> 2) Considering I don't really have any house circuits at present (it's
> a Transmode with a partial homemade interior), can I simply bypass the
> alternator for the time being, connecting the alternator wire directly
> to the "vehicle battery positive" pole?
>
>
>
> 3) If my isolator is indeed shot, does anyone have a good used spare
> they'd like to sell, or should I just buy a new one from one of our
> awesome vendors?
>
>
>
> Thanks, All!
>
>
>
> -Dave
>
> 1978 Transmode (403)
>
> Pittsburgh, PA
>
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