RV/Camper power converter question.

[KitchenKitten99]

Hopefully someone can help me out here.

Remodeling the inside of my horse trailer weekender area. Upgraded the power receptacle to a 30 amp (previous owner only had a 15amp installed with no ground!). I intended to purchase the 30 amp power converter but accidentally purchased the 40 amp instead not realizing I clicked the wrong model. I plan on running mostly on battery power but obviously if power is available, I will use it.

Is this 40 amp version ok to install/use or do I have to go with the 30 amp?

The model that I purchased: https://wfcoelectronics.com/product/wf-8740-40-amp/

The description of the unit makes it sound like it will be fine but as I am new to all this, I am looking for reassurance.

Thanks in advance!!

[icansayit]

I believe Gunny is the DP Resident Electrician. GOOD LUCK.

[Evmetro]

That unit shows 40 amps on the DC output side, which is not the same as the input side. It sounds like your shore power wiring and inlet were recently upgraded to 30 amps and I'm guessing that it is 110 volts ac like your house is.

Trailer shorepower input: 30 amps x 110 volts = 3300 watts
WF 8740 converter DC output: 40 amps x 13.6 volts = 544 watts

It sounds like you have plenty of shorepower available to run that equipment.

[KitchenKitten99]

That unit shows 40 amps on the DC output side, which is not the same as the input side. It sounds like your shore power wiring and inlet were recently upgraded to 30 amps and I'm guessing that it is 110 volts ac like your house is.

Trailer shorepower input: 30 amps x 110 volts = 3300 watts
WF 8740 converter DC output: 40 amps x 13.6 volts = 544 watts

It sounds like you have plenty of shorepower available to run that equipment.


Ok so from what I understand from what you wrote, the plug-in "shore power" Amp number (on my receptacle) is not the same as the Amp number on the unit (in this case, the 40), which is actually the output of DC power from the (soon to be installed) battery/batteries? When I was picking up a couple other parts at CampingWorld (one was the 30amp receptacle), I asked the parts guy what I would need to connect it to and what I would need to use the plug or the batteries I planned to purchase, and he showed me the converter I linked, except it was the next model # that which was the 30amp. Probably why I thought they had to 'match'.

My whole plan is to be able run a small AC-powered mini fridge, small .5 amp water pump for the sink, and have enough "shorepower" left over to use a phone charger and a portable convection burner and maybe a small fan without overloading the whole thing. Also possibly charge my laptop. My interior lights are already running off the same main battery that powers the electric jack and won't be connected to the converter because I want to keep them completely separate. They're LED anyway and with my sky-light, will rarely be used.

Thank you for your help in this...I am just trying to understand all this and do it right the first time - and not set my trailer on fire. Google and YouTube are helpful but only if you know the right terms to use for searching and I often don't know them right away. This is my first time dealing with any kind of portable power system that is more complicated than just rewiring a stock or flatbed trailer and upgrading the wire harness, lights, etc, which I have done.

[Gunny]

That unit shows 40 amps on the DC output side, which is not the same as the input side. It sounds like your shore power wiring and inlet were recently upgraded to 30 amps and I'm guessing that it is 110 volts ac like your house is.

Trailer shorepower input: 30 amps x 110 volts = 3300 watts
WF 8740 converter DC output: 40 amps x 13.6 volts = 544 watts

It sounds like you have plenty of shorepower available to run that equipment.My question would be did this 30@ upgrade consist of popping in a 30@ breaker. Have to run minimum #10 AWG from it to any outlet. The receptacle itself would have to be upgraded to handle 30@. Cheesy house receptacles handle 15 or 20. Under-size wiring and/or receptacles are a fire hazard.

Not to mention most homes are built on the cheap. I'd calculate my panel load so my house lights don't dim when it's charging. Electric companies don't leave much room for addition on homes. One reason I'm glad I worked only commercial. I've done enough service calls to see some really weird stuff.

As far as the equipment itself goes, if it's AC plug-in to charge, it should be fine, as you stated. 11-120 is converted by the internal transformer and is stored in the battery as 220.

I would be very concerned about the ground and was it mine, I would have 2 -- the internal that comes with the unit and I would run a separate external to the frame.

[Gunny]

Ok so from what I understand from what you wrote, the plug-in "shore power" Amp number (on my receptacle) is not the same as the Amp number on the unit (in this case, the 40), which is actually the output of DC power from the (soon to be installed) battery/batteries? When I was picking up a couple other parts at CampingWorld (one was the 30amp receptacle), I asked the parts guy what I would need to connect it to and what I would need to use the plug or the batteries I planned to purchase, and he showed me the converter I linked, except it was the next model # that which was the 30amp. Probably why I thought they had to 'match'.

My whole plan is to be able run a small AC-powered mini fridge, small .5 amp water pump for the sink, and have enough "shorepower" left over to use a phone charger and a portable convection burner and maybe a small fan without overloading the whole thing. Also possibly charge my laptop. My interior lights are already running off the same main battery that powers the electric jack and won't be connected to the converter because I want to keep them completely separate. They're LED anyway and with my sky-light, will rarely be used.

Thank you for your help in this...I am just trying to understand all this and do it right the first time - and not set my trailer on fire. Google and YouTube are helpful but only if you know the right terms to use for searching and I often don't know them right away. This is my first time dealing with any kind of portable power system that is more complicated than just rewiring a stock or flatbed trailer and upgrading the wire harness, lights, etc, which I have done.Each piece of equipment should have a listing that tells you how many amps it draws. Add them up. If they exceed 80% of 40@ (which I don't think they do), you'll need to go with a 60@.

[Evmetro]

My question would be did this 30@ upgrade consist of popping in a 30@ breaker. Have to run minimum #10 AWG from it to any outlet. The receptacle itself would have to be upgraded to handle 30@. Cheesy house receptacles handle 15 or 20. Under-size wiring and/or receptacles are a fire hazard.

Not to mention most homes are built on the cheap. I'd calculate my panel load so my house lights don't dim when it's charging. Electric companies don't leave much room for addition on homes. One reason I'm glad I worked only commercial. I've done enough service calls to see some really weird stuff.

As far as the equipment itself goes, if it's AC plug-in to charge, it should be fine, as you stated. 11-120 is converted by the internal transformer and is stored in the battery as 220.

I would be very concerned about the ground and was it mine, I would have 2 -- the internal that comes with the unit and I would run a separate external to the frame.

Indeed, there may be other wiring problems between the new 30 amp shorepower "inlet" and the device in question. To safely run that equipment, the trailer would need to have the appropriate size wire in whatever branch circuit it is in, if there are ever branch circuits at all, and of course proper grounding. I like your grounding to frame recommendation as well.

[KitchenKitten99]

Each piece of equipment should have a listing that tells you how many amps it draws. Add them up. If they exceed 80% of 40@ (which I don't think they do), you'll need to go with a 60@.


Thank you! This was VERY helpful and oddly enough no info I have read has actually said to do this.

[KitchenKitten99]

Ok Gunny... I have mostly connected the basic wiring but have not yet hooked up the battery (not yet purchased). (Photos below are the diagram on the panel and what I have set up so far. The 'black' wire going to the 'Chassis Ground' you see is actually not black/hot. It is the ground wire but I just wrapped it with electrical tape since I don't like the idea of the wire being exposed so close to the front.)

In the mean time... How would I hook up the other two breakers to be used - do I use the 'branch wire' coming off the first breaker?


I do know that my small 0.7amp water pump installation instructions recommended that it be on a separate circuit than other items. Is this accomplished by using a separate breaker or just one of the 6 lines coming out of the back?

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[Gunny]

One step at a time.

Take the black tape off your ground. By Code, only two (actually 3) colors are specifically dictated by code. The ground is ALWAYS green. The neutral is either white or "natural white" (a grey-ish color). There should be no reason for you ro reinsulate insulated wire. The "plastic" coating on the wire is the insulation. If it is new and free of nicks, it should be fine. If it makes you feel better, anywhere it passes through an opening that is bare metal which should not, couple of wraps of tape there.

The only time the ground is going to conduct heat (Volt-amps) is if the unit shorts. It should then trip the breaker and the charge go "to ground" (why it's called a ground :)

You have a 30@ and 2 20@ available for use. The one you have the green line drawn to that says available for a branch circuit is one of those available.

The bar on the left is your ground bar. Green

The bar on the bottom is your neutral. White or natural white

For each device you hook up, you should have a hot, neutral and ground. The hot could be any color wire. Usually black, red or blue for 120v.

Don't mess with the wires labeled "shore power" coming into the Main is they are your source of power.

If the water pump needs a dedicated circuit, you need to put it on one of the 20@ breakers by itself. That leaves you with 1 20@ circuit to do everything else so I would assume you would run a 20@ receptacle from it.

You will have to recalculate what I told you in my last post since you have a dedicated circuit that isn't drawing much. Add the amperage up and see if it exceeds 17@ (rule of thumb number as most 20@ breakers will trip pulling over 16.something amps). I know your electronics won't pull jack, but you mentioned some kind of cooking utensil. Heating elements suck amperage as they are nothing but open shorts.

I think I covered everything. If not, just ask.

[KitchenKitten99]

One step at a time.

Take the black tape off your ground. By Code, only two (actually 3) colors are specifically dictated by code. The ground is ALWAYS green. The neutral is either white or "natural white" (a grey-ish color). There should be no reason for you ro reinsulate insulated wire. The "plastic" coating on the wire is the insulation. If it is new and free of nicks, it should be fine. If it makes you feel better, anywhere it passes through an opening that is bare metal which should not, couple of wraps of tape there.

The only time the ground is going to conduct heat (Volt-amps) is if the unit shorts. It should then trip the breaker and the charge go "to ground" (why it's called a ground :)

You have a 30@ and 2 20@ available for use. The one you have the green line drawn to that says available for a branch circuit is one of those available.

The bar on the left is your ground bar. Green

The bar on the bottom is your neutral. White or natural white

For each device you hook up, you should have a hot, neutral and ground. The hot could be any color wire. Usually black, red or blue for 120v.

Don't mess with the wires labeled "shore power" coming into the Main is they are your source of power.

If the water pump needs a dedicated circuit, you need to put it on one of the 20@ breakers by itself. That leaves you with 1 20@ circuit to do everything else so I would assume you would run a 20@ receptacle from it.

You will have to recalculate what I told you in my last post since you have a dedicated circuit that isn't drawing much. Add the amperage up and see if it exceeds 17@ (rule of thumb number as most 20@ breakers will trip pulling over 16.something amps). I know your electronics won't pull jack, but you mentioned some kind of cooking utensil. Heating elements suck amperage as they are nothing but open shorts.

I think I covered everything. If not, just ask.

Thank you for this. Ok I have all that done. Removed the tape as you advised.

Here is where things get confusing to me ... I have the 12v DC connections (on the right)... I thought I connected the pump (and the power receptacles) to those, not the breaker directly? Can I connect outlets/receptacles to the 12v leads? Or are those for ONLY things that will be running off DC, not shorepower?

Back of the box:

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[Gunny]

Hook your DC outlets as your instructions show.

The 20@ breakers are in line before the converter, coming straight off the main. I don't see them doing anything else, so ... if you install it correctly you can run a 120v/20a rated device from each breaker. Oh, and yeah, that means a plug, if you like :)

[NightTrain]

When you get done lining KK99 out, Gunny, I'm going to need you up here for the 4th of July weekend to get my new shop wired up at the cabin.

Some good info here. I knew there was a reason we kept you sparkies around.

One thing I would caution you about, KK, is not to use any appliances off your DC system that produce heat in your RV. Things like a blow dryer, electric heaters, even a small 2-slice toaster. Plug a toaster into a 2000 watt generator sometime and you'll be very impressed with the way that toaster knocks that genny in it's ass. They draw serious amps.

That's really hard on your batteries.

But if you wire things up properly like Gunny said, your breakers will tell you if you're putting too much load on the DC system.

The size of your wiring is extremely important, pay close attention to what Gunny said about that. When in doubt, always go big on DC wire sizes. Bigger DC wiring actually makes your system more efficient.

[Gunny]

When you get done lining KK99 out, Gunny, I'm going to need you up here for the 4th of July weekend to get my new shop wired up at the cabin.

Some good info here. I knew there was a reason we kept you sparkies around.

One thing I would caution you about, KK, is not to use any appliances off your DC system that produce heat in your RV. Things like a blow dryer, electric heaters, even a small 2-slice toaster. Plug a toaster into a 2000 watt generator sometime and you'll be very impressed with the way that toaster knocks that genny in it's ass. They draw serious amps.

That's really hard on your batteries.

But if you wire things up properly like Gunny said, your breakers will tell you if you're putting too much load on the DC system.

The size of your wiring is extremely important, pay close attention to what Gunny said about that. When in doubt, always go big on DC wire sizes. Bigger DC wiring actually makes your system more efficient.Heating elements, or anything with a heating element, such as you mentioned, are open shorts. That's why I mentioned the cooking utensil (I don't recall what kk said she had). As you say, the suck amps. Ever notice it's ALWAYS a damned female hair appliance that trips the master bathroom GFCI?:laugh: I would definitely be checking the label on anything like that to see what it draws.
NightTrain I already got my Screamin' Eagle, red, white and blue outfit for the 4th. Won't be hard to find me. I'd be the one with a parka on in July :)

An edit to what I posted last; @kittenkoder You have 3, not 2, 20@ circuits in the box. The one you circled in green. It shows a tail coming from the main. Wire the hot to the tail. That's what it is for. They wouldn't put it there like that if they didn't want you to use it that way.

Also, you can buy rubber grommets that fit the knockout holes in the back of that can. Better than tape :) Definitely keep the wire from shifting.

[KitchenKitten99]

When you get done lining KK99 out, Gunny, I'm going to need you up here for the 4th of July weekend to get my new shop wired up at the cabin.

Some good info here. I knew there was a reason we kept you sparkies around.

One thing I would caution you about, KK, is not to use any appliances off your DC system that produce heat in your RV. Things like a blow dryer, electric heaters, even a small 2-slice toaster. Plug a toaster into a 2000 watt generator sometime and you'll be very impressed with the way that toaster knocks that genny in it's ass. They draw serious amps.

That's really hard on your batteries.

But if you wire things up properly like Gunny said, your breakers will tell you if you're putting too much load on the DC system.

The size of your wiring is extremely important, pay close attention to what Gunny said about that. When in doubt, always go big on DC wire sizes. Bigger DC wiring actually makes your system more efficient.


Thanks NT!

I don't plan on running a whole lot of stuff Mostly just a mini fridge, phone charger, and the water pump for the sink (no toilet). Occasionally an induction burner and maybe my laptop if we go out of town long enough since I can work from anywhere. It's just a "weekender" section of a 20yo horse trailer I bought so mostly a crash pad with a limited kitchen. Got a DEAL on it because it is a great brand, aluminum construction, and is fantastic shape other than the cabinets/interior of the LQ portion needed a complete gutting due to water damage from lack of roof maintenance by the previous owner, which I have been doing over the past couple months. I figured as long as I was completely overhauling the interior, I might as well make it even more useful (also increase resale ability should I choose to use it as a trade in later) and add a power bank to allow us to use it for more than just 1 or 2 day horse shows and allow for slightly more 'creature comforts' for power.

Progress so far. The only 'original' part left in was the turquoise carpet since it was fantastic shape and just needed a spot cleaning on a couple parts.

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[KitchenKitten99]

Found the pics of the original interior. The appearance in the photos looks better than reality. Most of the cabinets fell apart just trying to pull them out and ALL the paneling had black mold on a least a portion of it, with the worst of it being on the very front roof/ceiling panel over the sleeping area. We had a nice first bonfire this spring with it all.

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[NightTrain]

Thanks NT!

I don't plan on running a whole lot of stuff Mostly just a mini fridge, phone charger, and the water pump for the sink (no toilet). Occasionally an induction burner and maybe my laptop if we go out of town long enough since I can work from anywhere.

Yeah, those won't draw much. RV refrigerators and water pumps are designed to be as easy on the power as possible.

The other stuff, the cell phones & laptops, hardly draw anything at all. My DC computer that monitors the system at the cabin only detects cell phones plugged in and charging when there's 3 or more plugged in at once.

While you've got everything gutted, I would convert all your lighting to LED. They're brighter and draw the barest fraction of the juice compared to the old school incandescent bulbs, and your batteries will thank you for it. They even make the outside flood lights in LED now, too, and they're far superior in every way.

Also, there's some really cool outlets out nowadays that have built-in USB charger ports, which is handy in confined spaces like RVs - then you don't need those adapters hanging out getting caught on things.

[KitchenKitten99]

Yeah, those won't draw much. RV refrigerators and water pumps are designed to be as easy on the power as possible.

The other stuff, the cell phones & laptops, hardly draw anything at all. My DC computer that monitors the system at the cabin only detects cell phones plugged in and charging when there's 3 or more plugged in at once.

While you've got everything gutted, I would convert all your lighting to LED. They're brighter and draw the barest fraction of the juice compared to the old school incandescent bulbs, and your batteries will thank you for it. They even make the outside flood lights in LED now, too, and they're far superior in every way.

Also, there's some really cool outlets out nowadays that have built-in USB charger ports, which is handy in confined spaces like RVs - then you don't need those adapters hanging out getting caught on things.


Yes, LED lighting is in the plan. I already converted all my other lights in the horse stall area and exterior to LED 12v bulbs. Just gotta find a style of interior lamps that I like that goes with what I have going for interior. I found a video that shows how to wire up any fixture you want converting it to DC/12V and using the 12v LED bulbs. So that makes my options wide open. Which is also probably not good for my checkbook since that will dramatically increase the price-per unit and I will need a total of 4.

The switch I found on Amazon for my pump has built-in ports. I figure since the pump is on its' own circuit, a phone or two charging won't draw much more and it is unlikely I will have them all on at the same time anyway. Plus I like the fact it has a built-in volt meter is nice: https://www.amazon.com/gp/product/B083HRHN8V/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1