Travel Trailer Electrical Upgrades

This is the 300Ah lithium battery I am looking at picking up. That said, if I want everything to communicate seamlessly through the app I'll likely have to switch to the Victron Phoenix 12V/1600W 230V Smart Inverter.


I've been looking hard at their 460Ah battery.
 
Here's some data to demonstrate why I'm going all in on 100A of DC-DC chargers.

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With heavy overcast, we're not producing much at all. We're connected to shore power right now, but have the current limit set at 0. If I need it, I can spin the knob on the DMC to 30 and set the inverter to top up the batteries.

I really like the idea of just starting up the truck in a Cracker Barrel or brewery parking lot. I'd probably only use it when the batteries were nearly drained, and just enough to make coffee, check email, etc.
 
I don't see any advantage to sharing a ground with the truck. The seven pin still has a ground for the brake circuit and running light circuits, that are not part of the trailer house battery circuit and should not be used for charging the lithiums. The seven pin hot should not be connected to the trailer house battery hot, as it would be, in the junction box, if lead acid batteries were being used in the trailer. The Lithium batteries have a different charging profile and voltage than the lead acids in the truck. Isolate them from the truck. On my last install with 480 AH of Expion lithium batteries and 660 watts of solar, I used a 30 amp isolated Victron dc-dc charger. #4 wire and a 60 amp marine circuit breaker next to the battery on the plus wire. I ran plus and negative wires to an Anderson plug on the rear bumper and then on inside the trailer to the dc-dc charger. No upfitter switches should be used for this, just go straight to the battery with the charging wires and get much higher amperage. The Victron is voltage sensing and turns on when the voltage hits about 14 volts (indicated by the truck starting) and off at about 13 (truck off). No switching wire or extra relay is needed. All of the charging parameters are adjustable through bluetooth and your phone.
 
I don't see any advantage to sharing a ground with the truck. The seven pin still has a ground for the brake circuit and running light circuits, that are not part of the trailer house battery circuit and should not be used for charging the lithiums. The seven pin hot should not be connected to the trailer house battery hot, as it would be, in the junction box, if lead acid batteries were being used in the trailer. The Lithium batteries have a different charging profile and voltage than the lead acids in the truck. Isolate them from the truck. On my last install with 480 AH of Expion lithium batteries and 660 watts of solar, I used a 30 amp isolated Victron dc-dc charger. #4 wire and a 60 amp marine circuit breaker next to the battery on the plus wire. I ran plus and negative wires to an Anderson plug on the rear bumper and then on inside the trailer to the dc-dc charger. No upfitter switches should be used for this, just go straight to the battery with the charging wires and get much higher amperage. The Victron is voltage sensing and turns on when the voltage hits about 14 volts (indicated by the truck starting) and off at about 13 (truck off). No switching wire or extra relay is needed. All of the charging parameters are adjustable through bluetooth and your phone.
Victron has yet to announce an isolated version of their 50A Orion XS.
 
Victron has yet to announce an isolated version of their 50A Orion XS.
I think the only difference is that the plus and negative on the input side of the dc-dc charger, have no continuity with the connections going to the House battery, in the isolated model. So, the the house circuits have no connection the the trailer frame. The seven pin ground connection is usually attached to a bolt on the trailer frame and is where the brake circuit connects. Also, there can be current through the trailer hitch. I suppose, with a load connected to the house batteries (interior lights, or fridge, for instance) there could be a higher potential in the trailer frame than the truck frame that might lead to power going to the truck, or affect the truck charging circuit. Just guessing. But as long as the dc-dc charger output to the house batteries is not grounded to the trailer frame, or the house batteries are not grounded to the trailer frame, there should be no problem. And with lithiums, I see no reason that the house batteries should be grounded to the trailer frame. The house and the truck, when using lithiums, have different voltages and the seven pin should not be used to charge the lithiums. But the seven pin sends truck power to the trailer for brakes and lights. No problem, because the house lithiums are not grounded to the trailer frame. Thoughts?
 
I think the only difference is that the plus and negative on the input side of the dc-dc charger, have no continuity with the connections going to the House battery, in the isolated model. So, the the house circuits have no connection the the trailer frame. The seven pin ground connection is usually attached to a bolt on the trailer frame and is where the brake circuit connects. Also, there can be current through the trailer hitch. I suppose, with a load connected to the house batteries (interior lights, or fridge, for instance) there could be a higher potential in the trailer frame than the truck frame that might lead to power going to the truck, or affect the truck charging circuit. Just guessing. But as long as the dc-dc charger output to the house batteries is not grounded to the trailer frame, or the house batteries are not grounded to the trailer frame, there should be no problem. And with lithiums, I see no reason that the house batteries should be grounded to the trailer frame. The house and the truck, when using lithiums, have different voltages and the seven pin should not be used to charge the lithiums. But the seven pin sends truck power to the trailer for brakes and lights. No problem, because the house lithiums are not grounded to the trailer frame. Thoughts?
On our trailer the batteries have to be grounded to the chassis because most all electrical components in the trailer pull their negatives from the chassis (brakes, factory converter, lights, fans, slide, etc.). The entire 12V fuse center gets it's negative via the chassis ground between the batteries up front and the panel in the back of the trailer. Our trailer came from the factory with the chassis grounded at each end.

I simply removed the trailer's 12V+ wire in the 7-way cable junction box. Now the 12V+ wire from the 7-way cable only powers our TPMS signal booster and the rear camera when we hook up.

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On our trailer the batteries have to be grounded to the chassis because most all electrical components in the trailer pull their negatives from the chassis (brakes, factory converter, lights, fans, slide, etc.). The entire 12V fuse center gets it's negative via the chassis ground between the batteries up front and the panel in the back of the trailer. Our trailer came from the factory with the chassis grounded at each end.

I simply removed the trailer's 12V+ wire in the 7-way cable junction box. Now the 12V+ wire from the 7-way cable only powers our TPMS signal booster and the rear camera when we hook up.

YGfNwtf.jpg
Disconnecting the seven pin plus should isolate the charging systems sufficiently. The brakes, as far as I know, only use the seven pin brake hot and ground for their power source, even though they are normally grounded on a frame lug too. The only reason I know of for the brakes to need a house battery ground connection at the frame, is if the emergency breakaway is powered by the house batteries and the switch is pulled. So it must be retained for that purpose.

However it's done, we just don't want lithium voltage leaking to the truck, or truck power charging the lithiums directly.
 
Sigh...

My next project:
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We have very similar setups. I have 1200w of solar into a victron mppt charge controller (70/150), 2x270ah battleborns, multiplus 12v3000, cerbo s gx, 7” display…I have a separate 100ah battery in the box of my truck and victron dc-dc 30 amp sitting on the shelf to go in for that one with a smaller 800w inverter, second cerbo, victron charger for shore power on the truck side etc.

Trailer has a quick connect for 12v starlink with a starlink cable modified to cat6 on that end and a 5v router and 150w poe that it runs through. I keep a gen 2 starlink in one of the storage lockers and just throw it up when I arrive.

Truck has an additional flat mount starlink magnet-mounted on the roof…gen 3 so a bit different than the trailer with voltage requirements but it is also running through a 5v router which eliminates the starlink router. Its on all the time if the truck is running and on an up fitter so I can run it when the truck is off if I want. I get 60-100mbps on he highway in most places which is nice when there’s no cell reception.

I might change the trailer side to work with the gen3 dish and I can remove it from the truck and run it from the trailer when setup. If I do that I’ll just get a 57v DC power supply and run it right into the starlink router and permanently mount that in the trailer. Then I don’t need to bring the additional gen2 to have internet if the truck leaves camp.

i know there’s plenty of resources for 12v converting this stuff but if you have any questions happy to help if I’m able.

One other nice thing I did is replace the wireless camera on the trailer with the ford camera. So I don’t need the aux screen. It is really nice to have it on the ford infotainment. Well worth it!
 
What kind of voltage readings are you guys seeing on your RV battery when the truck is hooked up to it and running. I a, seeing between 14.1 and 14.2, it keeps that AGM pretty topped off.
 
What kind of voltage readings are you guys seeing on your RV battery when the truck is hooked up to it and running. I a, seeing between 14.1 and 14.2, it keeps that AGM pretty topped off.
The stock truck voltage is fine for charging an AGM. 14.1 or 14.2 will do the trick. Once the smart charging system in the truck sees that the batteries are fully charged, the voltage output will reduce to about 13.2. The voltage reading at the trailer battery can be misleading because of the load of a discharged battery and because of the various charging steps. So you might only see 12.5 at the trailer battery connections while charging, but it will be charging. Fully charged and rested will be about 12.6. Float will be about 13.2.

The problem is with lithium batteries. The truck voltage can spike to over 14.5 and that is not good for lithiums. Also, they have a higher rested voltage than AGMs so the truck's flooded lead acid batteries can look like a load if tied to a lithium when not charging.

The seven pin wiring will never charge a battery fast, so a dedicated dc-dc charger in the trailer works better and should be fed through an Anderson plug wired directly to the truck batteries. You can do AGM charging without the dc-dc charger, but still use the Anderson plug, if you'd like, by running the charging wires directly to the trailer battery. I did this a lot before the lithium upgrade, but you have to manually disconnect so you don't pull the truck battery down with loads in the trailer. The dc-dc charger disconnects as part of its function. With lead acid bats, don't let the rested voltage fall below 12.2 volts. That is the 50% point and lower voltage will damage the battery through sulfation.
 
The stock truck voltage is fine for charging an AGM. 14.1 or 14.2 will do the trick. Once the smart charging system in the truck sees that the batteries are fully charged, the voltage output will reduce to about 13.2. The voltage reading at the trailer battery can be misleading because of the load of a discharged battery and because of the various charging steps. So you might only see 12.5 at the trailer battery connections while charging, but it will be charging. Fully charged and rested will be about 12.6. Float will be about 13.2.

The problem is with lithium batteries. The truck voltage can spike to over 14.5 and that is not good for lithiums. Also, they have a higher rested voltage than AGMs so the truck's flooded lead acid batteries can look like a load if tied to a lithium when not charging.

The seven pin wiring will never charge a battery fast, so a dedicated dc-dc charger in the trailer works better and should be fed through an Anderson plug wired directly to the truck batteries. You can do AGM charging without the dc-dc charger, but still use the Anderson plug, if you'd like, by running the charging wires directly to the trailer battery. I did this a lot before the lithium upgrade, but you have to manually disconnect so you don't pull the truck battery down with loads in the trailer. The dc-dc charger disconnects as part of its function. With lead acid bats, don't let the rested voltage fall below 12.2 volts. That is the 50% point and lower voltage will damage the battery through sulfation.


Good info, thanks for the detailed reply! I am looking forward to an eventual lithium upgrade but it definitely appears that there's a lot more care and prep that goes into them versus an AGM.
 
Good info, thanks for the detailed reply! I am looking forward to an eventual lithium upgrade but it definitely appears that there's a lot more care and prep that goes into them versus an AGM.
The lithiums have the advantage of twice the usable amp hours in the same size battery. For instance a 100 AH AGM only has 50 AH of available power before the battery will get damaged by repeatedly running it down below 50% charge. The lithium can be drawn down to 5% without damage, thousands of times. So it has 95AH available in the 100 AH size. However, they cannot be charged below 35 degrees F internal temp, or discharged below about 15 degrees F. So they should be mounted inside the trailer in cold weather. They do not outgas, they have consistent voltage throughout the discharge cycle, they are about 50% lighter and should last much longer than an AGM. But they do have a slightly different voltage and charging program than AGM, so it is best to charge them with a dedicated dc-dc charger in your trailer. Solar charging also works well, with the proper controller. My last trailer had 660 watts of solar and 480 AH of lithium and I rarely ever plugged in. Mostly an off grid trailer. My new trailer, a Roamer 1, has 1,240 watts of solar and 1,080 AH of lithium. It has induction cooking, 12 volt air conditioning, full time Starlink, A 2,000 watt inverter, etc, all from solar and the batteries. I will never go back to lead acid batteries. But charging lead acid bats is simple from the truck, especially with an Anderson plug. If you are considering switching to lithium, you can look up Battle Born Batteries, in Reno Nevada. They have been very helpful in the past and they have lithium bats that are designed to be direct replacements for lead acid bats. A flooded lead acid battery and an AGM battery use the same chemistry, it's just that the AGM has little or no liquid inside. The plates are called Absorbed Glass Mat, or AGM, but they are the same thing. There are Gell, AGM, and flooded. Same chemistry and same characteristics. The lithiums are a huge leap into the modern world and much more powerful, while being lighter and longer lasting.
 
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The lithiums have the advantage of twice to usable amp hours in the same size battery.. For instance a 100 AH AGM only has 50 AH of available power before the battery will get damaged by repeatedly running it down below 50% charge. The lithium can be drawn sown to 5%. without damage, thousands of times. So it has 95AH available in t e100 AH size. However, they cannot be charged below 35 degrees F internal temp, or discharged below about 15 degrees F.. So they should be mounted inside the trailer in cold weather. They do not outgas, they have consistent voltage throughout the discharge cycle, they are about 50% lighter and should last much longer than an AGM. But they do have a slightly different voltage and charging program than AGM, so it is best to charge them with a dedicated dc-dcd charger in your trailer. Solar charging also works well, with the proper controller. My last trailer had 660 watts of solar nd 480 AH of lithium and I rarely ever plugged in. Mostly an off grid trailer. My new trailer, a Roamer 1, has 1,240 watts of solar and 1,080 AH of lithium. It has induction cooking, 12 volt air conditioning, full time Starlink, A 2,000 watt inverter, etc, all from solar and the batteries. I will never go back to lead acid batteries. But charging lead acid bats is simple from the truck, especially with an Anderson plug. If you are considering switching to lithium, you can look up Battle Born Batteries, in Reno Nevada. They have been very helpful in the past and they have lithium bats that are designed to be direct replacements for lad acid bats. A flood lead acid battery and an AGM battery use the same chemistry, it's just that the AGM has little or no liquid inside. The plates are called Absorbed Glass Mat, or AGM, but they are the same thing. There are Gell, AGM, and flooded. Same chemistry and same characteristics. The lithiums are a huge leap into the modern world and much more powerful, while being lighter and longer lasting.

Yea I know the advantages and inner-workings of lithium, I just hate that it requires more systems and to some degree care in order to properly charge them. For now I only have a 200W solar suitcase to help keep the batteries topped off but we don't plan to boon dock more than three nights at a time so I should be ok with the setup I have for the time being considering how little we use stuff inside of the trailer while camping. LED lights, the MaxxFan, the water pump when running the sinks or a single shower over a few days, charging a cell phone or two. None of that has a lot of draw that would risk pulling the batteries down to a level where I might be in trouble, especially if the solar is able to help out during the day.

I am pretty set on the Epoch 300Ah battery for my move to lithium, tie-in a 1500W inverter in-line and repurpose the current exterior battery box to storage for wheel chocks and other small items. The WFCO converter I have is lithium capable so I am good to go there. I just need to figure out dedicated solar for the roof to go along with the switch to lithium as I'd like to set everything up all at once.
 
Disconnecting the seven pin plus should isolate the charging systems sufficiently. The brakes, as far as I know, only use the seven pin brake hot and ground for their power source, even though they are normally grounded on a frame lug too. The only reason I know of for the brakes to need a house battery ground connection at the frame, is if the emergency breakaway is powered by the house batteries and the switch is pulled. So it must be retained for that purpose.

However it's done, we just don't want lithium voltage leaking to the truck, or truck power charging the lithiums directly.
The 7-pin ground must be maintained for brake power to complete the circuit. You should be able to connect the DC to DC charger without an issue if you leave the 7-pin hot wire disconnected and leave the 7-pin ground intact as it will not complete the circuit to the truck.
 
The 7-pin ground must be maintained for brake power to complete the circuit. You should be able to connect the DC to DC charger without an issue if you leave the 7-pin hot wire disconnected and leave the 7-pin ground intact as it will not complete the circuit to the truck.
I agree, but it's the truck ground, the seven pin ground, that completes the braking circuit with the brake hot from the truck, not the trailer ground. The trailer just happens to be grounded with the same wire that goes to a bolt on the frame. That bolt completes the braking circuit too. Plus and minus come from the truck to act as a braking circuit. The truck also runs the marker, turn and brake light circuits. The breakaway can be done using house batteries, or a separate battery. The service brake ground does not have to be connected to the trailer as the brake coils are isolated and have no polarity. Usually the truck ground goes to a bolt on the frame and so do the trailer grounds. So if the trailer circuits require a ground wire instead of using the frame, then the frame could be isolated, except for the very poor grounding that would happen through the hitch. Normally, the charging circuit from the seven pin is grounded to the frame too, but with an isolated dc-dc charger, there would be no need to ground the batteries to the frame for charging. Plus and minus from the truck would go to the dc-dc charger input and plus and minus from the batteries would go to the output side of the isolated charger. The main thing is to isolate the plus side of the truck charging circuit and the lithium plus from each other, if the ground is still continuous to the truck. Otherwise the dc-dc charger will be trying to charge the truck batteries and the truck will look like a battery load on the lithiums when the truck is not running. If you must run a non-isolated dc-dc charger, disconnect the battery plus from the seven pin. Or check for continuity from the dc-dc input and output to be sure they are not bonded together.
 
The 7-pin is grounded to the trailer frame as is the trailer brakes ground as is the clearance and brake lights. Your truck provides power to work all of these through the trailer frame and it's separate from the trailer 12v system because the positive wire is separate. You can run a DC to DC charger using the trailer frame as a ground provided you run a big enough wire from your truck to the trailer frame or run a separate ground to the charger it doesn't matter. So long as you have a separate 12v positive wire from your truck to the charger input wire it doesn't matter. You can't separate the ground between the truck and trailer if you wanted to because it would try to ground the two through the hitch.
 
I haven't touched the 7 pin on the truck and no issues with my batteries.
 
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