GM documentation on how the auxiliary battery works

[RogerKoop]

I found this documentation in the 1969 GM service news bulletins that came about every month to the GM dealers. It explains how it works

[jjzepplin]

Thank you so much. I wonder what type of relay. Are they reproduced or can we just use one off the shelf. I guess I will be pulling out my camper harness and trying to figure out how to use it with my dual battery setup. Maybe I will go psycho and have a three battery setup. That'll show them campers!

[firedemon]

looks like theyre using a 10 guage wire with a 14 guage fusible link so a standard 30 amp relay should work

[Killer Bee]

battery isolators are the only way to go, keeps yer crankin battery ready..

we have the best results from Sure Power 1315 series and Cole Hersee 48525/48530 series..

good luck!

[RogerKoop]

Originally Posted by jjzepplin

Thank you so much. I wonder what type of relay. Are they reproduced or can we just use one off the shelf. I guess I will be pulling out my camper harness and trying to figure out how to use it with my dual battery setup. Maybe I will go psycho and have a three battery setup. That'll show them campers!

I have some NOS relays. $40.00 shipped.

[RogerKoop]

Originally Posted by jjzepplin

Thank you so much. I wonder what type of relay. Are they reproduced or can we just use one off the shelf. I guess I will be pulling out my camper harness and trying to figure out how to use it with my dual battery setup. Maybe I will go psycho and have a three battery setup. That'll show them campers!

The camper wiring is a separate harness and is not integrated into the dual battery harness.

[RogerKoop]

I also manufacture the dual battery harness. Cost is $95.00 shipped.

[RogerKoop]

Originally Posted by firedemon

looks like theyre using a 10 guage wire with a 14 guage fusible link so a standard 30 amp relay should work

I don't think there is a fusible link. The 14 guage wire goes from the battery to a junction block where the aux battery harness ties in.

[Killer Bee]

the dual battery harness schematic illustrated does not identify any load connections..

body upfitters installing campers, wreckers, utility bodies, emergency services bodies etc. would do that..

the base chassis has no use for an aux battery, it's installed for external 12vdc loads..

winches, spot lights, emergency lights, camper interior lighting, sound systems, etc.

the separation scheme for the two batteries prevents those external loads from draining cranking battery..

a camper would likely have a home run from the aux b+ back to a distribution block..

the schematic only illustrates that connection as a terminal block..

I don't want to interfere with anything you sell but modern 'smart' isolators work great..

they have status light outputs and a bypass trigger for a switch to connect both batteries for jumping..

they're also voltage sensitive and function proactively regardless of key position..

for a restoration, OEM harness should work well for the loads it was intended for..

If anyone needs any help with isolators, happy to help..

good luck!

[jjzepplin]

I actually have a dual battery system designed with double solenoids and an isolater. It gives both batteries at start position and in ACC position goes back to separate batteries and on the isolater for charging. It works GOOD! I used to have a hot start problem but now it starts no matter how hot.

[firedemon]

Originally Posted by RogerKoop

I don't think there is a fusible link. The 14 guage wire goes from the battery to a junction block where the aux battery harness ties in.

the 14 guage wire is the fusible link . most fusible links are just 4 wire size smaller than the wire on the rest of the circuit so that burns first . the rest of the circuit is 10 guage so 14 gauge fusable link its the same on the passenger side

[jjzepplin]

Can you find anything on how the camper harness is supposed to be connected?

[jocko]

Great info, thanks for sharing Roger.

[RogerKoop]

Originally Posted by jjzepplin

Can you find anything on how the camper harness is supposed to be connected?

I have one listed. See http://67-72chevytrucks.com/vboard/s...d.php?t=585200

At the firewall the production intermediate tail light harness is unplugged and the camper harness is plugged into it. The unplugged intermediate harness is plugged into the camper harness. The white wire goes to ground and the the red wire goes to the junction block on the fender. The balance of the wiring goes thru inside the bed and plugs into the camper. I've included a copy the factory wiring diagram.