LivinDaDream
Member
Over the last 4+ years I've been working through the challenges of getting my rig better suited for extended off-grid camping with the goal being limited only by water and food supplies and not having to run my truck or generator other than in very rare circumstances. I've learned a lot from this forum and the general research I've done...and aided by a well grounded theoretical and practical knowledge of power systems, both AC and DC.
I hope others will find what I've learned useful in their own systems, so I'll share what I've learned in this post. I'll say at the outset...data is king...you really need to start with an accurate accounting of your power needs...and in many ways, when it's used is as important as how much is used, especially if you're using Lead-Acid batteries.
The rig: 2013 Chevy Silverado 2500HD, Duramax, EXSB, 4X4 - 2008 Lance 815 Camper - Customized utility trailer to haul motorcycle(s), kayak, bicycle, tools, extra water/fuel, gear as needed depending on trip.
The original setup had a 100AH, FLA deepcycle battery that was ok for a couple days as long as I ran my 3-way refrigerator off propane (only 1 20lb tank) and limited the use of my bigger laptop (used for photo and video editing). I tried running the Refer off DC when driving, but the current draw was so high (about 11amps) that the voltage drop from the Truck power system resulted in voltage in the camper system that was too low to charge the battery properly. Running the refrigerator on propane while driving was iffy at best. Installing 6GA wire from the truck battery to the camper jack in the truck bed helped, but was still not a workable situation. Swapping out all the incandescent bulbs in the rig to LED also cut down nighttime power consumption and that helped, but bottom line, it was almost impossible to go much more than a couple days without running the truck, plugging in or running my 34 year old 650W Honda generator...which still starts 1st or 2nd pull, btw. Not where I wanted to be...but it was at this time that I bought a couple power monitor modules to get some hard data on where my power was going and when. That was extremely useful and started me down the path to where I am now...which is a really workable solution and not outrageously complicated or expensive, though I suppose expensive or not is relative.
Here is a schematic of the current system...
The truck charging system is stock with dual batteries and 160A alternator, so I haven't shown anything but the batteries. I do see 14.4V or a little higher when the charging system is in boost mode or sees a heavy load on the system. Found some good info on the GM charging system in a tech reference. I've added wire gauge info on key wiring.
The key changes that got me to where I am today include replacing the power hungry Norcold 3-way refer with a Vitrifrigo compressor based unit, addition of solar panels (up to 400W) and controller, BattleBorn LiFePo4 100AH battery and the aforementioned power monitor modules.
The Vitrifrigo unit has a current draw when operating of about 3.5A and a duty cycle ranging from around 25% to 50% depending on ambient and how often I'm in it...overnight is usually 25% or less, especially if temps are below 50F. The old Norcold drew 11A almost continuously. I went from around a 3000Wh requirement to run the Norcold off DC alone, down to 270Wh to 540Wh by changing the refer alone.
As noted on the schematic, I mounted 2 panels on the camper...they are hard mounted, but can be easily detached if I want to relocate them to a sunny spot. The other two panels are not mounted and depending on where I'm going and the length of the trip, weather, etc., I may or may not take them. If I'm not moving, I have space on the roof to locate all 4, but the only time I could see doing that would be during multiple days of rain or cloudiness. A 40A Renogy MPPT controller is mounted inside the camper, but I also have a second one that is mounted on a board that I can hang under the wing of the camper near the battery compartment...I've installed a 40A power jack to take it's output into the battery, through the power monitor. If I use remote panels, this secondary controller will handle them. I thought about rewiring to allow the remote panels to also feed into the controller in the camper, but that gets complicated due to the rooftop units being wired in series. As it is, I have backup with the second controller. I have considered replacing the two panels on the roof with a large, 300W+ residential panel and may yet do that, especially if I can score one at a great price. I have another use for the 100W panels, so they wouldn't go to waste.
The operation of the system is simple and whether driving, plugged into shore power at a campsite or boondocking, it all just works and keeps me supplied with ample power for my needs. When driving and there is enough sun, the rooftop solar panels will supply all the power needs for the camper for charging the battery and operating the refer...in fact I have seen some power flowing back into truck batteries at times, so on long, all day drives when it's sunny, I'll disconnect from the truck batteries. The MPPT controller is set for a LiFePo4 battery, so the charge voltage will run up to 14.4V as the battery nears full charge and that's higher than the truck charging system is putting out, so you'll see some backflow. Having power monitors that I can read via Bluetooth let's me see what the system is doing at all times. If it's cloudy, the truck can supply plenty of charging for the battery. As you can see, I don't have a DC-DC charger in the system and with the wiring I'm using, I don't see the need for one. The max current I see going into the battery from the truck system max's out at about 35A due to resistance in the wiring from the truck batteries to the house battery. As the battery charges, the current drops and the voltage goes up, of course, so I am able to get a full charge from the truck. Wiring gauge is large enough that I'm not overloading any of the wiring. Also, it seems the LVD built into the camper disconnects the house battery from the truck whenever I start the truck as it sees the voltage sag when the starter kicks in...I was a little surprised at that, but again it's in the middle of the wiring path (about 16' per leg) between the truck and house batteries, so will see a lot of the voltage drop.
This system would not work anywhere nearly as well (if at all) as it does with Lead-Acid batteries, the LiFePo4 technology made this possible and in the long run will save me a LOT of money. First off, I don't have space for more than a single Grp31 battery, unless I put a couple along the sides of the truck bed ahead of the wheel wells between the camper base and side wall of the bed...and that would be a real PITA to install whenever I was putting the camper on the truck. Even with that, charging LA batteries properly is voodoo science and I'd have had to add a costly DC-DC charger into the system to properly charge via the truck system. Secondly, most days I can recharge the LiFePo4 in 2-3 hours if I have some decent sun. On a recent trip I was camped in an aspen grove and it the time the sun was overhead above the clearing, I was able to recharge using just the rooftop panels. If I have 3-4 panels hooked up, I can recharge from 50% or more very quickly...great for those days that are only partially sunny. With 4 panels hooked up on a cloudy day, I can see 70-120W output most of the day...enough to keep me ahead of the usage curve.
I've had no issues with the battery itself in the 2+ years I've had it and being a "drop-in" type unit with a fairly bulletproof BMS I can pretty much let it manage itself. I do have to be careful when it gets down to freezing temps, though BB told me that the BMS will not allow charging if temps are too low. I have a temp monitor on the PowerMon module that's mounted to the side of the battery, so I am able to keep an eye on the temps in the battery compartment...which is insulated and the inner walls are within the shell of the camper. If I do much camping in colder weather, I may add a heating pad...time will tell on that.
By using the Bluetooth data access into the MPPT controller, Bluetooth readings from the Thornwave PowerMon and a cheap Amazon power monitor module that keeps track of the usage of the refer, I have a very good handle on what the system is doing and can adjust accordingly. I don't have a large inverter in the system, but I can connect a 1200W Pure Sine Wave unit at an Andersen Power Pole plug that comes directly off the battery. I have a small, 200W inverter that I use to power my laptop or low-power charging modules for cameras, etc., and that just plugs into one of a couple 12V accessory plugs inside the camper.
That's about it...questions are welcomed.
Cheers!
I hope others will find what I've learned useful in their own systems, so I'll share what I've learned in this post. I'll say at the outset...data is king...you really need to start with an accurate accounting of your power needs...and in many ways, when it's used is as important as how much is used, especially if you're using Lead-Acid batteries.
The rig: 2013 Chevy Silverado 2500HD, Duramax, EXSB, 4X4 - 2008 Lance 815 Camper - Customized utility trailer to haul motorcycle(s), kayak, bicycle, tools, extra water/fuel, gear as needed depending on trip.
The original setup had a 100AH, FLA deepcycle battery that was ok for a couple days as long as I ran my 3-way refrigerator off propane (only 1 20lb tank) and limited the use of my bigger laptop (used for photo and video editing). I tried running the Refer off DC when driving, but the current draw was so high (about 11amps) that the voltage drop from the Truck power system resulted in voltage in the camper system that was too low to charge the battery properly. Running the refrigerator on propane while driving was iffy at best. Installing 6GA wire from the truck battery to the camper jack in the truck bed helped, but was still not a workable situation. Swapping out all the incandescent bulbs in the rig to LED also cut down nighttime power consumption and that helped, but bottom line, it was almost impossible to go much more than a couple days without running the truck, plugging in or running my 34 year old 650W Honda generator...which still starts 1st or 2nd pull, btw. Not where I wanted to be...but it was at this time that I bought a couple power monitor modules to get some hard data on where my power was going and when. That was extremely useful and started me down the path to where I am now...which is a really workable solution and not outrageously complicated or expensive, though I suppose expensive or not is relative.
Here is a schematic of the current system...
The truck charging system is stock with dual batteries and 160A alternator, so I haven't shown anything but the batteries. I do see 14.4V or a little higher when the charging system is in boost mode or sees a heavy load on the system. Found some good info on the GM charging system in a tech reference. I've added wire gauge info on key wiring.
The key changes that got me to where I am today include replacing the power hungry Norcold 3-way refer with a Vitrifrigo compressor based unit, addition of solar panels (up to 400W) and controller, BattleBorn LiFePo4 100AH battery and the aforementioned power monitor modules.
The Vitrifrigo unit has a current draw when operating of about 3.5A and a duty cycle ranging from around 25% to 50% depending on ambient and how often I'm in it...overnight is usually 25% or less, especially if temps are below 50F. The old Norcold drew 11A almost continuously. I went from around a 3000Wh requirement to run the Norcold off DC alone, down to 270Wh to 540Wh by changing the refer alone.
As noted on the schematic, I mounted 2 panels on the camper...they are hard mounted, but can be easily detached if I want to relocate them to a sunny spot. The other two panels are not mounted and depending on where I'm going and the length of the trip, weather, etc., I may or may not take them. If I'm not moving, I have space on the roof to locate all 4, but the only time I could see doing that would be during multiple days of rain or cloudiness. A 40A Renogy MPPT controller is mounted inside the camper, but I also have a second one that is mounted on a board that I can hang under the wing of the camper near the battery compartment...I've installed a 40A power jack to take it's output into the battery, through the power monitor. If I use remote panels, this secondary controller will handle them. I thought about rewiring to allow the remote panels to also feed into the controller in the camper, but that gets complicated due to the rooftop units being wired in series. As it is, I have backup with the second controller. I have considered replacing the two panels on the roof with a large, 300W+ residential panel and may yet do that, especially if I can score one at a great price. I have another use for the 100W panels, so they wouldn't go to waste.
The operation of the system is simple and whether driving, plugged into shore power at a campsite or boondocking, it all just works and keeps me supplied with ample power for my needs. When driving and there is enough sun, the rooftop solar panels will supply all the power needs for the camper for charging the battery and operating the refer...in fact I have seen some power flowing back into truck batteries at times, so on long, all day drives when it's sunny, I'll disconnect from the truck batteries. The MPPT controller is set for a LiFePo4 battery, so the charge voltage will run up to 14.4V as the battery nears full charge and that's higher than the truck charging system is putting out, so you'll see some backflow. Having power monitors that I can read via Bluetooth let's me see what the system is doing at all times. If it's cloudy, the truck can supply plenty of charging for the battery. As you can see, I don't have a DC-DC charger in the system and with the wiring I'm using, I don't see the need for one. The max current I see going into the battery from the truck system max's out at about 35A due to resistance in the wiring from the truck batteries to the house battery. As the battery charges, the current drops and the voltage goes up, of course, so I am able to get a full charge from the truck. Wiring gauge is large enough that I'm not overloading any of the wiring. Also, it seems the LVD built into the camper disconnects the house battery from the truck whenever I start the truck as it sees the voltage sag when the starter kicks in...I was a little surprised at that, but again it's in the middle of the wiring path (about 16' per leg) between the truck and house batteries, so will see a lot of the voltage drop.
This system would not work anywhere nearly as well (if at all) as it does with Lead-Acid batteries, the LiFePo4 technology made this possible and in the long run will save me a LOT of money. First off, I don't have space for more than a single Grp31 battery, unless I put a couple along the sides of the truck bed ahead of the wheel wells between the camper base and side wall of the bed...and that would be a real PITA to install whenever I was putting the camper on the truck. Even with that, charging LA batteries properly is voodoo science and I'd have had to add a costly DC-DC charger into the system to properly charge via the truck system. Secondly, most days I can recharge the LiFePo4 in 2-3 hours if I have some decent sun. On a recent trip I was camped in an aspen grove and it the time the sun was overhead above the clearing, I was able to recharge using just the rooftop panels. If I have 3-4 panels hooked up, I can recharge from 50% or more very quickly...great for those days that are only partially sunny. With 4 panels hooked up on a cloudy day, I can see 70-120W output most of the day...enough to keep me ahead of the usage curve.
I've had no issues with the battery itself in the 2+ years I've had it and being a "drop-in" type unit with a fairly bulletproof BMS I can pretty much let it manage itself. I do have to be careful when it gets down to freezing temps, though BB told me that the BMS will not allow charging if temps are too low. I have a temp monitor on the PowerMon module that's mounted to the side of the battery, so I am able to keep an eye on the temps in the battery compartment...which is insulated and the inner walls are within the shell of the camper. If I do much camping in colder weather, I may add a heating pad...time will tell on that.
By using the Bluetooth data access into the MPPT controller, Bluetooth readings from the Thornwave PowerMon and a cheap Amazon power monitor module that keeps track of the usage of the refer, I have a very good handle on what the system is doing and can adjust accordingly. I don't have a large inverter in the system, but I can connect a 1200W Pure Sine Wave unit at an Andersen Power Pole plug that comes directly off the battery. I have a small, 200W inverter that I use to power my laptop or low-power charging modules for cameras, etc., and that just plugs into one of a couple 12V accessory plugs inside the camper.
That's about it...questions are welcomed.
Cheers!
