Okay, I see a few misconceptions here. Let's take them one at a time.
As part of my winterization (for Alaska) I want to get away from using the front battery only for my 12v source. I have the resistor delete set up right now.
Okay, first problem. The resistor bank ONLY affects the glow plugs. It has nothing to do with the 12v for your cab, lights, etc.
I read the CUCV-II's use a step down transformer instead of the resistor.
I found an old thread with a link to this:
Low cost 24 volt to 12 volt DC-DC reducers 400W, suitable for automobile electronics.
www.powerstream.com
That's not a transformer. Transformers only work on AC circuits, not DC. What you are looking at there is a CONVERTER. Not the same thing at all. That's not just being picky - they are completely different. It's like saying transmission when you mean transfer case.
I understand I'll need to do a bit of rewiring, that's a given
Not much. All you would have to do is to disconnect the 12v feed that currently goes to the diamond-shaped terminal on the firewall, and connect that to your converter output. And of course, connect your converter to the 24v supply.
Just have a few questions:
How big does the transformer need to be? (Or how big is it on the CUCV-II's?)
Dunno about the CUCV-IIs, but here's how to figure it out: What is the total current draw of the 12v system? If you are NOT including the GPs, then I think it's about 30 amps max, based on remembering a post by AntennaClimber. 30 amps at 12v = 360 watts. You want some cushion here, so call it 400 watts. AND, it's really not 12v, it should be ~14, so 30*14 = 420. Add some cushion and that's 500.
That's if you don't add any goodies, like a stereo, lights, etc.
Now, if you want to include the GPs, you need to bump that quite a bit. They pull around 80 amps, which is 960 watts. But for some reason, I'm remembering someone giving a number of 1500 watts. And again, it';s not really 12v. 80*14 = 1120.
You definitely want to go bigger than you need, because if you run at the limit all the time, your converter won't have a long life. If I were doing this, I'd want at least double what I calculated.
So, if my numbers from memoroy are correct, then witout the GPs you need 420, so maybe a 1,000 watt unit (420 * 2 = 840, and round up) IF you want to run the GPs as well, you have 1120 + 420 = 1540. 1540 * 2 is 3080. But, the GPs are not used a lot, so maybe a 3,000 watt unit.
Not sure of the proper terms, but if I need a jump, can I hook the other vehicle (12v) to the output of the transformer and run it backwards? Or is that a no-go?
I have heard some people say there are converters that will do that, but I have never encountered one, and I'm skeptical. Certainly it would be a special purpose unit, and therefore more expensive.
Keep in mind, the factory CUCV electrical system, by design, is imbalanced. It pulls the cab load (heater, lights, etc.) from the front battery in its stock form. It's not a problem. Then if you delete the resistor, you add the imbalance of the GPs to a system that is designed to be imbalanced.
If you had a single 24 alternator, I think you'd probably run into problems. But each battery gets the charge it needs from its own alternator. The front battery gets topped up with normal driving. Yes, the front battery goes through a few more discharge/charge cycles. Big deal.
Is it really a problem that needs to be solved? I don't see it, myself. But suit yourself. I hope this helped.
- TRANSFORMER: AC TO AC, normally bi-directional.
- INVERTER: AC to DC or DC to AC. Normally NOT bi-directional, but that option does exist.
- CONVERTER: DC to DC: Normally NOT bi-directional, but some say that option does exist.
