3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 10, 2021 18:54:30 GMT -5
Hi All, So I've spent all winter designing and building the mods to my 251VRK to allow the "camp anywhere" ability and it has been quite the challenge, but very rewarding. To be specific, I wanted to be able to "plug into myself" so as to use battery power to run a 3000 watt AC invertor to power my camper. I did much planning to determine the best layout and location to accomplish this with out making any "significant" changes to the factory build of the RV. First I searched and determined the wiring from the factory Furrion solar port that was factory installed. Turns out it is wired directly to the battery thru a 10amp circuit breaker at the hitch which made modifying it to connect to a solar charge controller easy. I had a new dual group 27 battery rail custom made and bolted onto the hitch A frame behind the factory single group 24 battery. I used the forward group 24 battery rail mount to install a custom made control box complete with a multifunction ammeter with a 200 amp shunt to measure all current passing to and from the batteries, along with the 100 amp MPPT solar charge controller as well as a 3000 watt AC invertor wired directly to the box mounted 30 amp RV receptacle, the same as would be used at any campground. In this control box is also all heavy duty 300amp terminal post as well as a DPDT 30 amp 125v Ac switch used to prevent a feed back loop (when powering your RV using internal batteries and an AC invertor, you DO NOT want to have the RV convertor also charging your batteries at the same time). This switch turns on the invertor AC output at the same time turning off the AC supply to the RV 12v convertor and vice versa. This allows me to either plug into a generator or shore power outlet and charge the batteries or plug into myself with the batteries not charging from AC. The batteries do charge from the solar port regardless of the mode I select. My single 180watt Coleman solar panel so far has provided 11.3 amps charging at almost full sunlight during testing. I can add more panels if I feel the need but so far its keeping up. I will be providing pics soon. If any of you are planning the same mod I'm happy to help!
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B&N
Seasonal RV’er
2021 272VRK
Posts: 229
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Post by B&N on Apr 11, 2021 7:43:46 GMT -5
Very cool and following... What type of fridge do you have? Our 2021 STT272VRK came with 12 volt and it pulls 8ah at 1/4 full and 50 degrees out and I hear it would be like 14 ah at hot peak times.
Also, what type of batteries did you end up using? Panel type? Etc...
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 11, 2021 8:50:47 GMT -5
Very cool and following... What type of fridge do you have? Our 2021 STT272VRK came with 12 volt and it pulls 8ah at 1/4 full and 50 degrees out and I hear it would be like 14 ah at hot peak times. Also, what type of batteries did you end up using? Panel type? Etc... The fridge is likely the same as yours. In AC mode it draws 30 amps DC through the invertor, so that would equal about 3 amps at 125v. When using the invertor to power the camper I run the fridge on LP gas which then only uses 1 to 2 amps DC. The batteries were bought from Canadian Tire (I'm in Canada) they are group 27 enhanced AGM type,12 volt connected in parallel, 92 Amp hour capacity each. They weigh 70 lbs each and cost $480.00 CDN each. 4 year full replacement warranty. The solar panel is a Coleman 180watt. Rated at 18v 10 amps DC, but as mentioned above, my solar charge controller has shown 11.3 amps coming in so far in almost full direct sunlight. I expect to average about 9 amps all day long on a sunny day but I havent tested it fully yet. Just finished the final install yesterday so I havent camped with the upgrades yet. Oddly, the small fridge in the outside kitchen only draws 6 amps dc through the invertor so it can actually be used without shore power. Tested all AC appliances, coffeemaker draws 100 amps DC, microwave draws 110amps, TV draws 2 amps, toaster draws 95 amps, all numbers are at 12v DC running the invertor. I basically have the equivalent of a 120volt 20amp AC hookup through my invertor so it easily runs any appliance except for the roof air. Won't quite start it. Everything else including the fire place runs fine though.
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 11, 2021 9:43:42 GMT -5
I should add, while I do have a quiet 3000watt Firman invertor generator which easily powers the entire camper (including the roof air) the obvious advantages of being able to run AC appliances from batteries is noise. On a bad weather day I can sit inside and watch TV without having to constantly bother other people with the noise of a generator running. I can wake up at 6am, switch on the coffee pot and not make a sound. If it's a clear sunny day the solar panel will easily recover the batteries. If not, then during dinner time when everyone is awake I can start up the generator, do all my cooking, all while recharging the batteries for the next day. This flexibility to be able to camp anywhere and quietly was well worth the time and money spent on this project.
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 11, 2021 15:45:22 GMT -5
Some pics: Wanted to make this box as serviceable as possible given the lack of space so it was built from the bottom up in layers. Here is the bottom with the terminal posts, wiring, and the 2 wooden cross pieces that act as a shelf for the AC inverter. Attachments:
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 11, 2021 15:46:47 GMT -5
Here is the invertor in place with the upper control panel folded open on its hinges to allow easy access to the invertor. Attachments:
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 11, 2021 15:54:15 GMT -5
Here is the control panel folded closed over the invertor. You see from the bottom: the multifunction ammeter/volt/watt meter, the solar charge controller, then a dual rocker switch panel, one switch for led box mounted work lights over the equalizer hitch bar mounts, and the other switch to power the camper's running/park lights for emergency or extra lighting. The household switch at the end is the DPDT 125vac 30 amp switch for feedback protection. And farther out is the 30 amp RV receptacle. Attachments:
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 11, 2021 15:55:47 GMT -5
Here is the unit running my 60 inch TV on a test run with the original group 24 battery and the led work lights on as well. Attachments:
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B&N
Seasonal RV’er
2021 272VRK
Posts: 229
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Post by B&N on Apr 12, 2021 6:40:33 GMT -5
So we're pretty novice on this electrical stuff but really want to get in done over the next year. So thoughts on where to start or YouTube videos?
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 14, 2021 19:34:17 GMT -5
So we're pretty novice on this electrical stuff but really want to get in done over the next year. So thoughts on where to start or YouTube videos? There are alot of videos on YouTube, search RV invertor mods. I saw one that was a very impressive mod that inspired me to create my build. Difference with his was with a total of 6 batteries in a different configuration than mine and dual solar panels. Same idea though.
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B&N
Seasonal RV’er
2021 272VRK
Posts: 229
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Post by B&N on Apr 14, 2021 19:53:16 GMT -5
Good idea.. thanks
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on Apr 27, 2021 21:41:15 GMT -5
Well one thing I've confirmed is a solar panel works best when its movable and periodically moved to point directly at the sun, as opposed to a fixed panel. I can maintain 10 amps from my 180 watt panel in full sunlight for at least 6 hours (as long as I've tested so far) which was longer than I needed to recover the 2 12 volt batteries after setting up, putting out the slide, firing up the furnace to warm up the unit after storage, running interior lights, heating up water in the microwave for 3 minutes, making a pot of coffee with an electric coffee maker, running the TV, making some toast, all off the 3000watt invertor. Shut everything down and let the solar recover the batteries while I was outside and within 4 hours the batteries were at 14.0 volts and solar charger stopped charging. I expect the one 180 watt solar panel will "just" keep up with normal use in full sunlight. A 2nd panel would pretty much guarantee no power worries.
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Post by wireman134 on May 26, 2021 20:09:16 GMT -5
FYI folks the RV converter is a piss poor charger. Bulk charges at maybe 14V for a few hours and settles down at 13.2V floating. Now enough for any lead acid battery. A converter will never charge let alone over charge a battery. Just turn off the charging 120v circuit to the battery and let the solar do it's thing. No back feeding issues if both are connected to the batteries. Just a false state of charge not letting the solar controller to charge properly. Watt hours output /12v = Amp hours needed for loads
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3rdof5
Weekender RV’er
Finally camping season!
Posts: 55
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Post by 3rdof5 on May 26, 2021 20:48:41 GMT -5
FYI folks the RV converter is a piss poor charger. Bulk charges at maybe 14V for a few hours and settles down at 13.2V floating. Now enough for any lead acid battery. A converter will never charge let alone over charge a battery. Just turn off the charging 120v circuit to the battery and let the solar do it's thing. No back feeding issues if both are connected to the batteries. Just a false state of charge not letting the solar controller to charge properly. Watt hours output /12v = Amp hours needed for loads Actually the convertor in my 251 vrk outputs 50 amps to my batteries, I know this because I have a multimeter unit in my control box that monitors voltage, amps, watts, kwh's, amp hour capacity both in and out of my batteries, so I would disagree that the convertor is not a good battery charger, in a feed back loop it would definitely cause issues. But, exactly as you said, turning off the AC to convertor, allows the solar charger to function properly. And that's exactly what I do.
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Post by wireman134 on May 26, 2021 21:05:21 GMT -5
50 AMPS IS NOT THE CHARGE CURRENT TO THE BATTERIES IT IS THE TOTAL SUPPLY TO THE BOARD. VOLTAGE IS THE PUSH THAT CHARGES BATTERIES. NO PUSH NO CHARGE. Most stock Converters will kill batteries if you let them. They will never properly fully charge a battery. The push is not there. No stock converter will give a group 24 battery a 50 amp charge current. That would burn up your little dual purpose battery that TT's are supplied with. I am a IBEW electrician and work on solar and UPS SYSTEMS I DO KNOW
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