22 replies to this topic

[Wallowa]

I wired mine with 6 awg Ancor marine wire from the truck battery to the Orion 12/12-30 and it works fine. The voltage drop at 30 amps is small enough that the Orion’s engine running verification test cycling is not triggered. My wire run is about as long as anyone would have for a truck camper installation. My truck is a crew cab long bed and the battery compartment with charger is at the very back of the camper.

 

 

Jon,

 

I have seen, but can't find, a chart that lists voltage drop by distance vs wire gauge...do you have site for this?

 

Thanks,

Phil

[Vic Harder]

AC and DC Voltage Drop Calculator AS/NZS 3008 | jCalc.net

 

There are many out there... google is your friend!

[Jon R]

Sorry for not responding yesterday Phil. I went to Mt. St. Helens. The picture is from Johnston ridge. Why Mr. Johnston thought he’d be safe there i don’t get. Even in a vertical eruption that place is really exposed.

Ancor has data for their wire on their web site.

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Edited by Jon R, 30 October 2021 - 05:43 PM.

[Wallowa]

Sorry for not responding yesterday Phil. I went to Mt. St. Helens. The picture is from Johnston ridge. Why Mr. Johnston thought he’d be safe there i don’t get. Even in a vertical eruption that place is really exposed.

Ancor has data for their wire on their web site.

 

 

Great photo...I remember the chilling pictures of him "monitoring" the eruption from there and then being enveloped; I believe that was Mr. Johnston...sad indeed...

[rubberlegs]

I remember reading that charging straight from alternator wire loss makes a difference to the camper battery. Add a DC to DC charger then 10 gauge may not be a issue, but some have had problems with factory 10 gauge cycling on and off the DC to DC charger due to the loss in wire size and length.

 

Our truck was probably wired with 10 gauge. If I got a 30A sized DC-DC charger, then the voltage drop for 15' of truck wiring would be about 0.45V. I could improve that to 0.18V if I rewired the truck to 6 gauge. That's about a 0.3V difference. But there's still a voltage drop at 30 amps.

 

I'm exploring if it would work with the existing 10 guage truck wiring.

 

Can the DC-DC charger handle a half-volt input drop, say from 13.2 to 12.7, and work ok? Although there is loss in the line, would have full functionality? So I could procrastinate rewiring (or not bother if it works ok)?

 

Then again, maybe the 50A charger is the way to go... but we only use a 90W solar panel and don't think we need more than, say, 200W that I can ever imagine.

[TacomaAustin]

12.7 volts is the shut off threshold for my DC 2 DC charger.  Also, 30 amps through 15 feet of #10 gauge, I'm guessing the voltage drop will be closer 9/10ths of a volt.

[rubberlegs]

Thanks for the reply, TacomaAustin. I just found out that the one I'm looking at also cuts off at 12.7V -- which answered my question. https://www.renogy.c...0D1S-Manual.pdf

 

Also that manual says 8-10 gauge is ok for the 30A version, but you need 6 gauge for the 50A version. I got my voltage drop as follows -- does this look reasonable?

 

V = IR = (30A) * (0.9989 ohm/1000') * (15') = 0.45V

 

The 0.9989 value came from http://www.interface...resistance.html

Edited by rubberlegs, 28 November 2022 - 02:50 AM.

[Jon R]

Make sure you account for the total circuit length through the positive and return wires -not just one way. If your batteries are 15 feet apart you have 30 feet of wire.

[rubberlegs]

Ah, that would double it to TacomaAustin's 0.9V.

[pawleyk]

Just to answer the original question.. you don't JUST rewire from the truck, but internally to the batteries as well. 

 

A dual 6v system in a fwc can see as much as 50amps of charging from your alternator when discharged, with correctly sized wire. 

 

The rest of the wiring is fine, fuse block, solar etc. None of that is affected by this.