Radio power source?

L

lw8000

Member
Jul 30, 2012
217
14
18
Hello all,

I have the original AM/FM/8-track radio and recently we were using it, when I noticed that I can use it when the ignition key is not on. This is
actually great as we would like to use it this when parked and engine off. My question is, does the radio draw from the engine or house battery?
I've looked over the 12V wiring diagrams that I have, and searched other posts, but I have not been able to confirm one way or the other so far.

Thanks as always!
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
 
The radio usually runs off the house battery. But on my coach, it runs off
the engine battery, and I think that is original. So, go figure.

Rick "noting the radio fuse in the chassis fuseblock" Denney

> Hello all,
>
> I have the original AM/FM/8-track radio and recently we were using it,
> when I noticed that I can use it when the ignition key is not on. This is
> actually great as we would like to use it this when parked and engine
> off. My question is, does the radio draw from the engine or house battery?
> I've looked over the 12V wiring diagrams that I have, and searched other
> posts, but I have not been able to confirm one way or the other so far.
>
> Thanks as always!
> --
> Chris S. -
> 77 Kingsley, 3.70 FD, mostly OEM -
> S.E. Michigan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
 
Disconnect the house battery and try it again. If it doesn't work, it's
connected to that one.
If it does, it's probably connected to the coach battery, but not through
the ignition switch.

ronC

On Sun, 13 Aug 2017 21:28:18 -0600 Chris S.
writes:
> Hello all,
>
> I have the original AM/FM/8-track radio and recently we were using
> it, when I noticed that I can use it when the ignition key is not
> on. This is
> actually great as we would like to use it this when parked and
> engine off. My question is, does the radio draw from the engine or
> house battery?
> I've looked over the 12V wiring diagrams that I have, and searched
> other posts, but I have not been able to confirm one way or the
> other so far.
>
> Thanks as always!
> --
> Chris S. -
> 77 Kingsley, 3.70 FD, mostly OEM -
> S.E. Michigan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II
 
> Hello all,
>
> I have the original AM/FM/8-track radio and recently we were using it, when I noticed that I can use it when the ignition key is not on. This is
> actually great as we would like to use it this when parked and engine off. My question is, does the radio draw from the engine or house battery?
> I've looked over the 12V wiring diagrams that I have, and searched other posts, but I have not been able to confirm one way or the other so far.
>
> Thanks as always!

Chris,

The wiring diagrams that I have looked at always have the radio on the chassis (main engine) battery. It is not switched with the ignition, but that
is where it is and it is(was) on a 10 amp fuse in my coach. The real issue here is that the normal car radios cannot draw enough power to
significantly drain that battery in a reasonable time. But even still, when I put in the new radio, and the cell repeater and the CB (now gone) and
the two extra DEC mouseholes, I also added an extra fuse block to the space behind the glove compartment to be distribution for a run from the house
bank. It has been good.

Are you going to make Elkhart? Even if you can only get there for Saturday and Sunday, it is still very worth your while.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
The OEM wiring is: The radio powered by the engine battery and powered all the time no matter what position the ignition key is in. Some people
have changed them to the house battery side instead.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
My 76 was connected to the chassis battery . I relocated to the house battery. The easiest way to do this is to connect the radio wire to the isolator
house battery terminal also connect the cigar lighter when you do it. Don't forget be sure they are fused.
--
Roy Keen
Minden,NV
76 X Glenbrook
 
Thank you everybody for the information, that helps a ton.

Matt, I like your idea of having an alternate fuse panel up in front that feeds from house battery. Would make it easy to switch over one circuit at
a time from one to the other. I might look in to that as we have a house battery hot connection close to there under the dash with a cigarette plug.
Unfortunately we cannot make Elkhart this year.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
 
> Thank you everybody for the information, that helps a ton.
>
> Matt, I like your idea of having an alternate fuse panel up in front that feeds from house battery. Would make it easy to switch over one circuit
> at a time from one to the other. I might look in to that as we have a house battery hot connection close to there under the dash with a cigarette
> plug. Unfortunately we cannot make Elkhart this year.

Chris,

Even if you can't make it to Elkhart (even for a day), be aware of the fact that there is a community of owners that are all in striking range and if
any one of them can't assist you with your questions, he can probably point you at some one that can.

The first International we attended at all was the last day of Berrien Springs in 2006 when we were greeted by none other than Emery Stora and I would
say we were made to feel like family, but in my case, that might not be great. It was maybe more like long separated old friends. At that time, I
had owned the coach (soon to be named Chaumière - say Show Me Air) for about 159 hours.

You should put an international on your list of things to experience.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
My experience with radios and engine batteries is that low current draws can discharge a battery in short order. The older 70's era radios used class
A audio amplifiers and consumed several amps no matter the volume setting (remember the heat sinks and how toasty warm they got). Consider a 2 amp
draw from a radio that was ON from 9am to 9pm = 2amps x 12 hrs = 24AmpHrs, that's 50%+ discharge of a typical cranking battery. Compare that to
cranking the engine for 30 seconds at 300amps = 300Amps x 1/120hr = only 2.5AmpHrs

We are a Motorola communications dealer. Older crystal radios consumed about 1/4amp while new microprocessor controlled radios can consume about 1 amp
on standby. This is enough to kill a battery over the weekend in the summer or overnight in the winter. So we designed a power-down timer. It detects
the vehicle starting and turns ON power to the radio. After the key is turned off, it will keep the radio alive for a period of time (usually 4 hours)
then shuts the power OFF. Restarting the engine resets the timer. This keeps the radio ON all day, but will power off by 9pm in most commercial
applications, leaving the battery with enough power to start the vehicle the next day.

http://www.gmcmhphotos.com/photos/electrical/p28712-12-volt-accessory-power-down-timer.html

I moved my accessories power to the house battery to prevent draining the engine battery.

Just my experience from 40 years of doing this stuff.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
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