7 Pin for charging + 4 pin for driving?

[dreadlocks]

id put some blocking diodes in the tow vehicle so you can feed both 12 and 36 volts back the trailer plug, put your booster on a switch so you can turn it on off and still tow other trailers safely without frying em.. with two blocking diodes like shown the higher voltage will always get passed through, and neither input can see any voltage from eachother.

 

[shade]

Looks like a Molex Eurostyle Two-Screw Terminal Strip in a wet location box.

https://www.newark.com/molex/39100-2203/terminal-block-barrier-3pos-8awg/dp/83X8205?ost=39100-2203&ddkey=https%3Aen-US%2FElement14_US%2Fsearch

 

[shade]

You can find em at your local hardware store in electrical section, I tend to favor the spring loaded push in ones but those are for solid copper.. these are much cheaper, but compared to 3 wire nuts in a junction box its much more compact.. try something like "3 wire coupler screw terminal".. I only said AC because its 3 wire, and DC is 2 wire so you might not find it in low voltage connectors.

Here's the whole kit-n-kaboodle: https://www.amazon.com/gp/product/B01IQUQF3Q/

$5? That's a heck of a deal if it doesn't leak or turn to powder from UV exposure.

 

[TantoTrailers]

$5? That's a heck of a deal if it doesn't leak or turn to powder from UV exposure.

Yep these little boxes are really cool, I used one to make my swamp cooler.

 

[luthj]

Note that those schottky diodes have current limits, and those current limits are based on some air flow for cooling. Soldering the diode to the wires helps to conduct heat away when running near the limit.

One option instead of diodes would be a DPDT relay. Put the solar panels on the NC pins, and then use power from the DC supply to flip the relay over to the DC supply when its activated.

 

[Buddha.]

id put some blocking diodes in the tow vehicle so you can feed both 12 and 36 volts back the trailer plug, put your booster on a switch so you can turn it on off and still tow other trailers safely without frying em.. with two blocking diodes like shown the higher voltage will always get passed through, and neither input can see any voltage from eachother.

I was planning on running separate wiring, 10/2 duplex with Anderson powerpole type connectors at the back. Running 36v back through the existing wiring is an interesting idea though.

 

[shade]

I was planning on running separate wiring, 10/2 duplex with Anderson powerpole type connectors at the back. Running 36v back through the existing wiring is an interesting idea though.

I know 36V isn't very high, but I also know if there's a way to cut corners on OEM wiring, it was done. Would 36V cause any problems with OEM connectors or anything else in the circuit?

 

[dreadlocks]

nah, amps is the limiting factor of wiring.. most wiring is rated for like 600v if you keep it within current spec.. and then I think that limit is more determined by insulation between conductors so you dont get arcing like a stungun.. 36v would be nothing I'd be concerned with.

The safest would be some andersons in a non typical keying so only your SC input that can handle the 36v would pluginto it.

 

[shade]

Fwiw,
60V DC is typicaly maximum for automotive ’spec conductors.
SAE J1127 for example.

Good to know. Thanks.

 

[shade]

nah, amps is the limiting factor of wiring.. most wiring is rated for like 600v if you keep it within current spec.. and then I think that limit is more determined by insulation between conductors so you dont get arcing like a stungun.. 36v would be nothing I'd be concerned with.

The safest would be some andersons in a non typical keying so only your SC input that can handle the 36v would pluginto it.

I know some circuit breakers are only rated to 48VDC, so that's the kind of thing I was wondering about.

 

[dreadlocks]

yeah those ratings are valid, breakers and fuses might not break far enough to prevent arcing at higher voltages, same with connectors being insulated enough from each-other.. fuses and breakers also have thermal limits that will be wattage limited.. the copper wiring dont care too much if the conductors are well insulated, circuits are usually always limited by fuses and connectors when changing voltages.

 

[luthj]

Typically the distance between pins in a connector determines the voltage limit. As opposed to the dielectric strength of the insulation, which is usually over 300V. Though sometimes the plastic thickness (dielectric strength) between the pins in tight connectors can play a roll.

 

[dreadlocks]

so your saying distance through air is not enough insulation for some connectors above a certain voltage?

 

[luthj]

Air is a dielectric/conductor just like the insulation on wires. However when air becomes plasma due to an arc or other event it conducts extremely well. Arcs in DC systems are much more difficult to extinguish than AC systems. You also have to deal with the chance of a finger or some other object bridging the gap.

There is also surface contamination and aerosols to deal with.

Here's a 500kv arc when a line wasn't de-energized prior to disconnect.

 

[Buddha.]

Btw, I think bigger concern is if solar controller is ok with (presumably) negative grounded input when its output to battery is likely be negative grounded also.

I'm unsure what you're saying. Should I not have a ground going from the trucks battery to the charge controller? There's already a ground in the 7 pin connection that I assume grounds the truck's and the trailers batteries together, but I thought I should add the additional ground since I was adding more power.