TC Battery infomation over load

The problem with a series diode is that it will drop .65 volts across it and reduce the charge voltage to the battery.

Look at the Park light diode, part # 690. In would be from relay, out would go to camper. In comes from relay.
These are rated around 30 amp and should handle the charge.
The standard diode #790 would not use one of the inputs.
Park light diode

enblethen wrote:
Wire would come off relay to the input side of the diode then to camper.
The light would be connected to the output side of the relay, same location as wire going to diode. Then other side of lamp would go to ground.
There should be no power then on the output side of the relay.

Oh... I was also confused, as connection at output of solenoid is also where aux batt connection is. But it sounds though as suggestion is a diode Inline on the feed wire to aux batt from solenoid? Then anything (light) hooked between diode and solenoid would only see power from truck when solenoid engaged.
Likely need a heat sink for a 40 amp diode and an isolated place to mount.
Actually not a bad idea-seems a bit of effort just to 'see' charge functioning, though thats all my amp gauge does.
But inline diode would also solve any backfeed from camper to truck battery when solenoid engaged. Which in my case because I have a manual switch, is when I stall truck or something, solenoid is on, truck batteries lower than camper that camper will send power-but its only for a minute at most until alt gets up to 14+.

40 amp diode
diode w/heat sink
Unless Im also still misunderstanding and muddying the waters further.

No the camper is on the oposite side of the diode. It is on the output, lamp goes on the input of the diode.

enblethen wrote:
Wire would come off relay to the input side of the diode then to camper.
The light would be connected to the output side of the relay, same location as wire going to diode. Then other side of lamp would go to ground.
There should be no power then on the output side of the relay.

I appreciate the time you are spending on this, however I just dont follow. If the light is connected to the same location as the diode which is the out put of the solenoid (going to the camper)isnt the diode being bypassed? sorry to be a pain.

Wire would come off relay to the input side of the diode then to camper.
The light would be connected to the output side of the relay, same location as wire going to diode. Then other side of lamp would go to ground.
There should be no power then on the output side of the relay.

enblethen wrote:
I would get one of these or the ones from Blue-OX. Should be available at most RV stores or direct from Roadmaster.
Diode

This may sound dumb, but how exactly would I connect this light.the diode will stop the flow of all voltage, unless it is inline with my charge wire, which couldn't work.

#8 wire should be fine. I would suggest replacing the solenoid with one designed for the purpose such as the Blue Sea 7601 or many others like it. They are voltage sensing, and will only contact when the system voltage exceeds around 13.5V (indicating a charging source). If the starter battery is very low, it will not switch on until the voltage is up and the starter battery mostly charged. This is the problem they are designed to solve, they do it well, are completely automatic, and don't depend on you remembering to do anything.

I would get one of these or the ones from Blue-OX. Should be available at most RV stores or direct from Roadmaster.
Diode

any idea what diode and where I could get one???
thanks