which is the power wire from the harness

[Juiceman]

I have upgraded to Lithium and with that, I need to pass the power wire from the harness (connected to truck while towing) through a voltage booster.

I can see a bunch of positive wires connected to a bus bar with various size fuses in the compartment near the battery. Without disconnecting each of them and doing an ohm test, can someone tell me which one of these wires is coming from the harness?

That would sure help my patience level.

[A.Texas.Yankee]

I can't help your with your request in where is the wire, but I must ask why you think you need a voltage booster. Are you going from 12v to a different voltage?

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[John303]

I can't help your with your request in where is the wire, but I must ask why you think you need a voltage booster. Are you going from 12v to a different voltage?

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I think he is referring to a DC to DC charger. I did the same thing last year when I replaced my AGM with a Battle Born. Working from memory here since the trailer is in storage, but I think the biggest wire will be the charging circuit. In my case it was a 10 gauge. Be sure and match your charger current rating to what the truck can provide. For my RAM the charging wire is protected by a 30amp fuse. When the hooked up, the DC-DC charger had a little over 8 volts on the input, and was pulling ~25 amps from the truck (from memory). That is why I chose a Victron Smart charger with the lowest rating of 18 amps supplied to the battery. Anything more and I would have been popping fuses. Some folks do go to the expense and trouble of running a separate charging wire from the truck to to the camper, but I did not see the need in my situation.

[Juiceman]

The Lithium battery solution does require that you evaluate each and every DC component in the trailer. The harness is also important as that is an important charging element from the truck when towing. Flooded and AGM batteries charge at around 13.5V. Lithium with BMS systems charge starting around 14.5V. Some alternators will work, but the voltage my draw down as the current is pulled just as John303 experienced.

I am using a Renogy DCC30S 12V 30A DUAL INPUT DC-DC ON-BOARD BATTERY CHARGER WITH MPPT that handles both the solar and the incoming alternator power. It isolates the truck battery so it will not discharge when engine is not running and boosts the voltage for the Lithium charging Battery Management System (BMS). This Renogy will limit the power from the truck to 15Amps.
The solar panels are working great.

I agree with the 30 AMP fuse and have an ANL fuse waiting to connect the harness power. Fun fact, after the main trailer battery is fully charged, the Renogy unit will trickle charge the truck battery.

Sadly, I see 8 wires with 4 of them of the 10gage size on my positive buss bar with little breakers. I will start disconnecting the 10ga wires and checking which one it is with a meter.

[A.Texas.Yankee]

I think he is referring to a DC to DC charger. I did the same thing last year when I replaced my AGM with a Battle Born. Working from memory here since the trailer is in storage, but I think the biggest wire will be the charging circuit. In my case it was a 10 gauge. Be sure and match your charger current rating to what the truck can provide. For my RAM the charging wire is protected by a 30amp fuse. When the hooked up, the DC-DC charger had a little over 8 volts on the input, and was pulling ~25 amps from the truck (from memory). That is why I chose a Victron Smart charger with the lowest rating of 18 amps supplied to the battery. Anything more and I would have been popping fuses. Some folks do go to the expense and trouble of running a separate charging wire from the truck to to the camper, but I did not see the need in my situation.

Ah, that makes sense. I was thinking he had a 24v battery bank so I was going to ask him about it.

The Lithium battery solution does require that you evaluate each and every DC component in the trailer. The harness is also important as that is an important charging element from the truck when towing. Flooded and AGM batteries charge at around 13.5V. Lithium with BMS systems charge starting around 14.5V. Some alternators will work, but the voltage my draw down as the current is pulled just as John303 experienced.

I am using a Renogy DCC30S 12V 30A DUAL INPUT DC-DC ON-BOARD BATTERY CHARGER WITH MPPT that handles both the solar and the incoming alternator power. It isolates the truck battery so it will not discharge when engine is not running and boosts the voltage for the Lithium charging Battery Management System (BMS). This Renogy will limit the power from the truck to 15Amps.
The solar panels are working great.

I agree with the 30 AMP fuse and have an ANL fuse waiting to connect the harness power. Fun fact, after the main trailer battery is fully charged, the Renogy unit will trickle charge the truck battery.

Sadly, I see 8 wires with 4 of them of the 10gage size on my positive buss bar with little breakers. I will start disconnecting the 10ga wires and checking which one it is with a meter.

Thank you. I am in the middle of planing a lithium upgrade and I don't expect much out of the 7 pin for charging, but to keep the batteris topped off is my goal when on the road. My factory alternator will be 400A so I will be running a dedicated wire eventually to take advantage of the full capacity of the truck's alternator.

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[Juiceman]

For completeness for the site, here is what I found.

On my 2020 Reflection, there is a bundle of white wires that have color stripes on them. The 10 gage white wire with the red stripe is the one from the harness. Always use a meter to prove this on your trailer as it may be different.

It is attached to a 30 amp breaker with the rest of the inputs/outputs for the DC buss bar. I disconnected this wire and ran it through the Renogy DC-DC converter.

[MarkVer]

Hi Juiceman, do you know what the 30amp relay is for? On the far left side of the same bussbar. (2021 Reflection 310RLS, new Lithium install)
I'm trying to locate the truck ignition wire for the Renogy DC-DC converter. This will enable truck alternator charge when the truck is running.


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