I made a portable battery-to-battery charger that I could use to charge the trailer battery when installed in the trailer (normal configuration) or when the trailer battery was carried in the back of my tow vehicle (TV) while the trailer was left in the campground (sightseeing configuration).
I use a Victron Orion-TR Smart 12/12-18 Isolated DC/DC Charger because I have only one lead-acid battery, and the 18 Amp charger was a good match. I used Anderson Connectors and 6 AWG marine wiring.
https://www.amazon.com/gp/product/B07H4LRJYV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
https://www.amazon.com/Marine-Duple...+Cable,+30ft+6+AWG&qid=1728858092&sr=8-4&th=1
When we go camping, we tend to go sightseeing and shoplifting rather than staying at camp. I figured as long as I was driving around without the trailer, I may as well recharge the trailer battery in the back of my TV, a Toyota Seqouia SUV. There is plenty of space and ventilation in the back of the TV.
When the trailer battery is carried in the back of my TV, I use a Ryobi 18V cordless power tool battery to keep the trailer refrigerator running. We always bring a Ryobi cordless drill, flashlight, lanterns, power supply and Ryobi battery charger when camping so no additional battery needs to be carried. The Ryobi battery powers only the refrigerator and has plenty of capacity and can run for hours with the refrigerator operating on propane
The first picture shows what I call the powerpack. It is mounted on nested slotted L-Angles that were bolted together to make a C-Channel. The Anderson Connectors fit snugly in the C-Channel. There is a crossbeam on top that serves as a handle. The base is plywood with oversized holes and washers for two studs in the floor of the trailer that hold everything securely to the trailer floor.
The second picture shows the back of the powerpack including a mounting L-Angle that holds the vertical arms to the base and a “battery box link plate” that connects the powerpack to a battery box that holds the trailer battery when it is in the back of my TV. Connecting the powerpack and battery box (with the heavy battery inside) together, provides a solid, difficult-to-tip, charging assembly in the back of my TV.
The third picture shows the powerpack next to the empty battery box. The battery box is also used to hold the powerpack when it is used in the trailer. The battery box has a 3.5 inch hole in the side to allow air from a cabinet mounted cooling fan to flow freely over the powerpack.
The fourth picture shows the powerpack next to the battery box with the lid installed. The lid covers the battery box link plate and firmly connects the powerpack and battery box together. The entire assembly is held in place with a stout bungee cord that runs along the top of long axis of the assembly and is hooked to pre-existing tie downs. The battery charger is mounted low enough on the powerpack, that the bungee cord does not touch it and thus does not put a load on it. The bungeed assembly is surprisingly stable, and though not crash rated, is stable enough for my use. The lid has a cutout to allow better access for the charging cable.
The fifth picture below shows the passenger side, rear dinette, storage area. There are power cables from the TV and to the trailer battery and the cabinet mounted cooling fan for the powerpack (an 80mm 12V fan). I added two studs to the floor to hold the battery box and powerpack. The studs use the same nuts as the trailer battery to cut down on fastener types I need to carry. The top of the studs are concave a little so I filled the concave with glow-in-the-dark paint to make it easier to align the mating holes with the studs; I was looking for white paint, not sure why I had glow-in-the-dark paint… Here is the link for the remote control switch I used. The leads are short, but I like having two remotes, one for the TV and one for the trailer.
https://www.amazon.com/gp/product/B093WM5SQL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The sixth picture shows the battery box, powerpack and assorted cables installed in the trailer. I ran the power cable from the powerpack to the trailer tongue through the bilge bulge on the passenger side. From under the refrigerator, just aft of the main door, I ran a steel nut with a string into the bilge (with the help of a piece of wire) and used a strong magnet from an old computer hard drive to pull the nut to a hole I drilled close to the front of the trailer. The magnet picked up an amazing amount of debris, mainly staples, from the bilge. I used the magnet to sweep the bilge of all the steel debris before running the wire.
I used Trailer Vision Anderson protective covers and plugs on the TV bumper and trailer tongue to provide a place to connect a 5 feet long wire harness to provide power to the trailer. Here are the links. The Anderson plug that came with the cover had to be modified to fit the other Anderson plugs I was using.
https://www.amazon.com/gp/product/B07ZX27CPZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
https://www.amazon.com/gp/product/B09KT99RFM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
The seventh picture shows the power cord in black and another cord that I made with left over wire covered in orange shrink wrap (for visibility). The orange harness is an extension cord so I could park my TV close (within 10 feet) to the trailer plug and top off the trailer battery by idling the TV.
The eighth picture shows the Ryobi battery power converter that I use to power the refrigerator when the trailer battery is in my TV. I use a male cigarette to SAE plug cable going into a SAE plug installed on the forward edge of the same cabinet that stores the powerpack and stuff. I can use the SAE plug to provide power to items like inverters if desired.
https://www.amazon.com/gp/product/B089JY71XG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B089JY71XG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I installed a diode upstream of the SAE plug so the Ryobi battery provides power to only the refrigerator. The Ryobi battery faults to an overload condition if this diode is not used.
https://www.amazon.com/gp/product/B007HRO4X8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
To provide power to the powerpack when I am using it in my TV, I ran a short cable with Anderson connectors on both ends from the TV rear bumper area, up through an existing rubber grommet, and into the factory built-in storage box in the back of my TV. The bumper end of the cable is tucked into the hitch frame when not used, and when needed, it is un-tucked and plugged into the Anderson connector on the rear bumper. I have two short pigtail cables with an Anderson connector on one end and different connectors on the other end. One cable has round connectors for the trailer battery posts, the other cable has a female 12V cigarette plug for whatever may need a bit of oompf for power, like an inverter.
The TV and trailer wire harnesses are protected with a fuse block shown on this link. Because the fuse block sits high on the battery, I double checked clearance with the hood closed using measurements and then with a piece of crushable foam to ensure no contact. I also cut the protruding stud a bit to increase clearance and zip-tied the dust cover in place.
https://www.amazon.com/gp/product/B09NP8431D/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Anyhow, it all works well for me and does what I need it to do. I don’t have a solar system so being able to charge the trailer at a pretty high amperage of 18 amps (using the Victron charger) versus the 7-plug cable amperage (which acts like a trickle charger) is beneficial.
I use a Victron Orion-TR Smart 12/12-18 Isolated DC/DC Charger because I have only one lead-acid battery, and the 18 Amp charger was a good match. I used Anderson Connectors and 6 AWG marine wiring.
https://www.amazon.com/gp/product/B07H4LRJYV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
https://www.amazon.com/Marine-Duple...+Cable,+30ft+6+AWG&qid=1728858092&sr=8-4&th=1
When we go camping, we tend to go sightseeing and shoplifting rather than staying at camp. I figured as long as I was driving around without the trailer, I may as well recharge the trailer battery in the back of my TV, a Toyota Seqouia SUV. There is plenty of space and ventilation in the back of the TV.
When the trailer battery is carried in the back of my TV, I use a Ryobi 18V cordless power tool battery to keep the trailer refrigerator running. We always bring a Ryobi cordless drill, flashlight, lanterns, power supply and Ryobi battery charger when camping so no additional battery needs to be carried. The Ryobi battery powers only the refrigerator and has plenty of capacity and can run for hours with the refrigerator operating on propane
The first picture shows what I call the powerpack. It is mounted on nested slotted L-Angles that were bolted together to make a C-Channel. The Anderson Connectors fit snugly in the C-Channel. There is a crossbeam on top that serves as a handle. The base is plywood with oversized holes and washers for two studs in the floor of the trailer that hold everything securely to the trailer floor.
The second picture shows the back of the powerpack including a mounting L-Angle that holds the vertical arms to the base and a “battery box link plate” that connects the powerpack to a battery box that holds the trailer battery when it is in the back of my TV. Connecting the powerpack and battery box (with the heavy battery inside) together, provides a solid, difficult-to-tip, charging assembly in the back of my TV.
The third picture shows the powerpack next to the empty battery box. The battery box is also used to hold the powerpack when it is used in the trailer. The battery box has a 3.5 inch hole in the side to allow air from a cabinet mounted cooling fan to flow freely over the powerpack.
The fourth picture shows the powerpack next to the battery box with the lid installed. The lid covers the battery box link plate and firmly connects the powerpack and battery box together. The entire assembly is held in place with a stout bungee cord that runs along the top of long axis of the assembly and is hooked to pre-existing tie downs. The battery charger is mounted low enough on the powerpack, that the bungee cord does not touch it and thus does not put a load on it. The bungeed assembly is surprisingly stable, and though not crash rated, is stable enough for my use. The lid has a cutout to allow better access for the charging cable.
The fifth picture below shows the passenger side, rear dinette, storage area. There are power cables from the TV and to the trailer battery and the cabinet mounted cooling fan for the powerpack (an 80mm 12V fan). I added two studs to the floor to hold the battery box and powerpack. The studs use the same nuts as the trailer battery to cut down on fastener types I need to carry. The top of the studs are concave a little so I filled the concave with glow-in-the-dark paint to make it easier to align the mating holes with the studs; I was looking for white paint, not sure why I had glow-in-the-dark paint… Here is the link for the remote control switch I used. The leads are short, but I like having two remotes, one for the TV and one for the trailer.
https://www.amazon.com/gp/product/B093WM5SQL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
The sixth picture shows the battery box, powerpack and assorted cables installed in the trailer. I ran the power cable from the powerpack to the trailer tongue through the bilge bulge on the passenger side. From under the refrigerator, just aft of the main door, I ran a steel nut with a string into the bilge (with the help of a piece of wire) and used a strong magnet from an old computer hard drive to pull the nut to a hole I drilled close to the front of the trailer. The magnet picked up an amazing amount of debris, mainly staples, from the bilge. I used the magnet to sweep the bilge of all the steel debris before running the wire.
I used Trailer Vision Anderson protective covers and plugs on the TV bumper and trailer tongue to provide a place to connect a 5 feet long wire harness to provide power to the trailer. Here are the links. The Anderson plug that came with the cover had to be modified to fit the other Anderson plugs I was using.
https://www.amazon.com/gp/product/B07ZX27CPZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
https://www.amazon.com/gp/product/B09KT99RFM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
The seventh picture shows the power cord in black and another cord that I made with left over wire covered in orange shrink wrap (for visibility). The orange harness is an extension cord so I could park my TV close (within 10 feet) to the trailer plug and top off the trailer battery by idling the TV.
The eighth picture shows the Ryobi battery power converter that I use to power the refrigerator when the trailer battery is in my TV. I use a male cigarette to SAE plug cable going into a SAE plug installed on the forward edge of the same cabinet that stores the powerpack and stuff. I can use the SAE plug to provide power to items like inverters if desired.
https://www.amazon.com/gp/product/B089JY71XG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B089JY71XG/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I installed a diode upstream of the SAE plug so the Ryobi battery provides power to only the refrigerator. The Ryobi battery faults to an overload condition if this diode is not used.
https://www.amazon.com/gp/product/B007HRO4X8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
To provide power to the powerpack when I am using it in my TV, I ran a short cable with Anderson connectors on both ends from the TV rear bumper area, up through an existing rubber grommet, and into the factory built-in storage box in the back of my TV. The bumper end of the cable is tucked into the hitch frame when not used, and when needed, it is un-tucked and plugged into the Anderson connector on the rear bumper. I have two short pigtail cables with an Anderson connector on one end and different connectors on the other end. One cable has round connectors for the trailer battery posts, the other cable has a female 12V cigarette plug for whatever may need a bit of oompf for power, like an inverter.
The TV and trailer wire harnesses are protected with a fuse block shown on this link. Because the fuse block sits high on the battery, I double checked clearance with the hood closed using measurements and then with a piece of crushable foam to ensure no contact. I also cut the protruding stud a bit to increase clearance and zip-tied the dust cover in place.
https://www.amazon.com/gp/product/B09NP8431D/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Anyhow, it all works well for me and does what I need it to do. I don’t have a solar system so being able to charge the trailer at a pretty high amperage of 18 amps (using the Victron charger) versus the 7-plug cable amperage (which acts like a trickle charger) is beneficial.
