Auxiliary Switches - Wire Ampacity Questions

[msiminoff]

Has anyone done any real world testing at or near the maximum current ratings of their JT's factory installed auxiliary switch fuses/wires? If so did you experience any blown fuses, excessive voltage drop, or other issues?

I know that the aux circuits are specified and fused at 40A (switches 1 & 2) and 15A (switches 3 & 4). However, the provided wires for each circuit don't appear to be appropriately sized for continuous use at these currents. I'm guessing that they're maybe 12ga and 18ga, which means max wire ampacities of somewhere around 30A and 14A respectively.

The reason for my question is that I'm considering running wiring to the bed of my '23 Mojave to charge an EcoFlow River 2 Pro portable power station. To get maximum charge rates I'll be stepping up the voltage with a Victron Orion Tr 12-30 which has a max output of 30A, so there's potential for current draw of as much as ~35A from the aux circuit.

Of course I'll run sufficiently large (6ga) wires from under the hood to the bed to handle the current and keep voltage drop to <3%. The Orion will be used in DC-DC converter mode at 15V and I'll use the Engine Shutdown Protection function to ensure that I don't drain the starter battery when the JT's engine isn't running. I also have the option to use an aux switch to actuate a secondary high current relay with dedicated wiring from the battery to the truck bed, but that's added complexity I'd prefer not to have. I'll add that the EcoFlow's max (solar) charge current is spec'd at 220W so my actual current may never exceed 20A anyway.

Thanks in advance for any input on this.
-Mark

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[ecidiego]

Great question. I installed my OEM aux switches after the fact and when I shoved those four wires through the firewall grommet I didn't understand how that was 2 15 amp and 2 40 amp circuits..

 

[Lost1wing]

I don't have the factory aux switch panel. I have STech switch panel that has similar amp ratings. I ran the 6ga wire to a solenoid under the hood and controlled the solenoid with the aux switch.

 

[HooliganActual]

+1 to this concept ^^^^

Personally, I would use an Aux Switch to enable a solenoid to do that charging.

Not that I don't trust the wiring capability of the Aux Switch harness, rather it would just be cleaner and you would be able to run your 6 gauge wire from the battery to the solenoid and then on back to the bed. It would allow you to also use Aux 3 or 4 and reserve 1 & 2 for larger loads that may not warrant a solenoid, such as a light bar or whatever.

 

[JRobes]

Also had my doubts when I was wiring some accessories to them... definitely seem too small

 

[johnchabin]

That’s crazy… I just posted a similar question! Looking to confirm switch amperage ?

 

[HooliganActual]

That’s crazy… I just posted a similar question! Looking to confirm switch amperage ?

Well…the switch amperage, effectively, is what the fuse size is: 1 & 2 are fused at 40a and 3 & 4 are fused at 15a. That answers your question; HOWEVER, what the OP is asking is really related to the wire size.

His point is that the wire size, esp. for 1 & 2, seems too small for continuous load at the 40a at which they are fused. Forgetting about the fuse size for a moment, that 12 gauge wire may allow you to put 100a through it but for how long before heats up to the point that it melts the insulation, starts a fire or acts like a fusible link and burns up.

Honestly, if you are putting any kind of serious amperage through those wires, it would be much wiser to use a solenoid/relay, which uses very low amperage to actuate, and then wire those large loads direct to the battery.

My Aux Switches 1, 2, and 3 are wired to solenoids to run winch, compressor and rock lights. Only switch 4 is wired direct to 2 LEDs for under hood lighting.

 

[EZRider]

+1 to this concept ^^^^

Personally, I would use an Aux Switch to enable a solenoid to do that charging.

Not that I don't trust the wiring capability of the Aux Switch harness, rather it would just be cleaner and you would be able to run your 6 gauge wire from the battery to the solenoid and then on back to the bed. It would allow you to also use Aux 3 or 4 and reserve 1 & 2 for larger loads that may not warrant a solenoid, such as a light bar or whatever.

I’m wanting to use a relay or solenoid for a 6 gauge wire to get power to the bed also. Any recommendations on a particular type or model solenoid or relay to use?

 

[HooliganActual]

I’m wanting to use a relay or solenoid for a 6 gauge wire to get power to the bed also. Any recommendations on a particular type or model solenoid or relay to use?

What are you running in the bed? Basically, you need to have a solenoid/relay that is rated for the amperage you’ll be pulling. For example, if you are just powering a fridge (my Dometic CFX 55IM rated at 1.1a continuous) that is rated for 1.1a continuous, you would “technically” only need one around that size; HOWEVER, the starting amp draw will be higher and you’d need to size appropriately. Realistically, something like this which is rated for waaaayyy more would work for probably anything you could throw at it.
https://www.amazon.com/Max-300A-Con...2&psc=1&mcid=b51e599dc9f0374da27916919fec015f

Something like this may be more appropriate for smaller things:
https://www.amazon.com/JD1912-Autom...tnluFkOZs-Y2Lfr3K6ei-wd7lZh6BbFBoCnAkQAvD_BwE

What are you going to power in the bed?

 

[BearFootSam]

Has anyone done any real world testing at or near the maximum current ratings of their JT's factory installed auxiliary switch fuses/wires? If so did you experience any blown fuses, excessive voltage drop, or other issues?

I know that the aux circuits are specified and fused at 40A (switches 1 & 2) and 15A (switches 3 & 4). However, the provided wires for each circuit don't appear to be appropriately sized for continuous use at these currents. I'm guessing that they're maybe 12ga and 18ga, which means max wire ampacities of somewhere around 30A and 14A respectively.

The reason for my question is that I'm considering running wiring to the bed of my '23 Mojave to charge an EcoFlow River 2 Pro portable power station. To get maximum charge rates I'll be stepping up the voltage with a Victron Orion Tr 12-30 which has a max output of 30A, so there's potential for current draw of as much as ~35A from the aux circuit.

Of course I'll run sufficiently large (6ga) wires from under the hood to the bed to handle the current and keep voltage drop to <3%. The Orion will be used in DC-DC converter mode at 15V and I'll use the Engine Shutdown Protection function to ensure that I don't drain the starter battery when the JT's engine isn't running. I also have the option to use an aux switch to actuate a secondary high current relay with dedicated wiring from the battery to the truck bed, but that's added complexity I'd prefer not to have. I'll add that the EcoFlow's max (solar) charge current is spec'd at 220W so my actual current may never exceed 20A anyway.

Thanks in advance for any input on this.
-Mark

Can you put the DC-DC converter under the hood? I realize heat is probably the worst thing so you'd wnat to mitigate that, but boosting the voltage even a few volts reduces the current through the wire, Ohms Law.

 

[chorky]

I’m wanting to use a relay or solenoid for a 6 gauge wire to get power to the bed also. Any recommendations on a particular type or model solenoid or relay to use?

Sounds like you're doing your own version of the genesis kit. I highly recommend 4ga wire, not 6. 6 will work, for some applications but due to the length of wire, 4 makes more sense. As soon as you run a compressor on that wire, with that length, your getting close to the max rating especially if running other things too.

Solenoids are not the best idea for this as well - also depending on what you are planning to be in the bed. Look for a battery combiner instead of a solenoid. They do not require constant voltage and many of them can handle up to 200a continuous. you probably want a capacity of at least 150a continuous.

 

[HooliganActual]

Can you put the DC-DC converter under the hood? I realize heat is probably the worst thing so you'd wnat to mitigate that, but boosting the voltage even a few volts reduces the current through the wire, Ohms Law.

Yikes! I’d advise against that. I don’t know about the Orion DC-DC Charger @msiminoff is using, but my Renogy shuts off around 149F to protect itself. Wouldn’t be hard to hit that temp in the engine compartment…

 

[msiminoff]

Hello, OP Here...
Looks like the consensus is what I had expected; the provided wiring is too small for high current loads, best to use a secondary relay.
I had hoped that somebody would have done some testing on this by now, or at the very least could confirm the actual wire gauge. I guess I'll be the one to do that (current/voltage drop) test and I'll measure the wire diameter too. Will report the results here.

I’m wanting to use a relay or solenoid for a 6 gauge wire to get power to the bed also. Any recommendations on a particular type or model solenoid or relay to use?

WRT the relay selection; There are plenty of 12V relays available, you just need to choose one that meets or exceeds you maximum current requirements (it goes without saying that you also need to use the appropriate fuse -preferably AT the battery- to protect your chosen wire gauge). This is the one that I will be using.

-Mark

 

[BearFootSam]

Yikes! I’d advise against that. I don’t know about the Orion DC-DC Charger @msiminoff is using, but my Renogy shuts off around 149F to protect itself. Wouldn’t be hard to hit that temp in the engine compartment…

Then again, isn’t there a duplicate set of aux leads in the passenger footwell?

or, just use the 15A lead to switch a solid state relay run to battery with heavier gauge wiring.

 

[ecidiego]

Then again, isn’t there a duplicate set of aux leads in the passenger footwell?

Yes

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