I was a bit slow getting through Aggieland. Class of '96. I'm not as young as that might lead one to believe; I worked my way through and could only take a couple of classes at a time. Them beans weren't gonna crawl on the plate by themselves :)
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Just wanted to come back to this thread.
It does seem correct to combine the grounds on a 12 and 24 volt system.
I know this has already been established, but after a month of further research, it Is correct.
Ground the 24 volt and the 12 volt systems together, or even through the frame.
What had caused my concern with this design, was corrosion and galvanic/ dielectric damage that I have experienced with some 12 volt driving lights, that I "had" installed on my truck. ( now replaced with new ones )
I had "thought" that the voltage differential
was causing the corrosion.
I'm still not sure what caused it, but it only formed on the "ground" side of the bulb bases.
All in all, it is correct to join the grounds together, and should not be a problem.
what caused my issues?
I do not know.
all 4 lights were installed at the same time, were the same age , but with two different designs.
One set was wired direct 12 volts with an isolated ground, run off battery # 2 ( the 24 volt battery when combined into a bank )
and the other set used the ground of the truck, and was tapped off the 1st battery, to only proved 12 volts.
here are some pics of the lights and the damage.
they were totally SEALED with clear silicone, and were not "under water" or cracked in any way.
I still don't know what caused this corrosion.. but it sure looks electrical or even GALVANIC in nature.. especially where it formed, and how it was limited to the negative part of the bulb bases, in both lights on that circuit.
The other two lights are still fine, and have developed NO corrosion.
these have been replaced with new ones... and I will keep an eye on them closely.
So , Long story short...
YES... it is correct to tie your grounds together in a dual voltage system, and I have another issue here that still remains a mystery.
[IMG]http://i1279.photobucket.com/albums/...ps46298f63.jpg[/IMG]
[IMG]http://i1279.photobucket.com/albums/...ps713c259b.jpg[/IMG]
All sealed... clear silicone.
[IMG]http://i1279.photobucket.com/albums/...ps81304bc8.jpg[/IMG]
HI Guys, Not on here much but, I am also looking to do a 350v8 swap and a turbo 400.
But as Barrman said above, I am doing a 24 volt starter. 12 volts to HEI. In my 24 volt system, I run a battery charger for my phone right now off the front(1) battery. If I am missing something I don't know. As of yet it seems to be working fine. Without going through both batteries I can get 12volts.
Blitz, just now reading this as I am considering running a dual charging system so I can run a 12v winch and accessories. Anyway, I have a theory your DIY sealed lights corroded because of the acetic acid (smells like vinegar) fumes produced during the out-gassing of the silicone while curing.