Home Forums Truck Camper Adventure Forum How much current should an F350 be able to supply my truck camper?

  • This topic has 12 replies, 6 voices, and was last updated 3 years ago by Russ.
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    • #42549
      Matt Ellis
      Participant

      My 2018 F350 is only offsetting the 12A DC draw of the refrigerator by about 9-10A, meaning there’s always a negative 2-3A draw on the batteries which on a long ride knocks them down some. Is this normal? I would think that truck should be expected to recover the full load of the refrigerator to keep the batteries at full charge. Otherwise if I’m heading toward a location that does not have full hookups I’m starting at a deficit with the battery condition.

    • #42559
      ardvark
      Participant

      Sounds about right or more than I have seen on my meter at times from 2012 F350. The alternator senses the needs of the truck battery. The charge lead to the camper is secondary. Folks who have needs for more amps from the truck often run a separate larger lead from the truck battery or similar source under the hood. There are Youtube videos that show how to do it. Otherwise solar or more solar may be a suggestion.

      Operating the fridge on DC takes a load of amps for not much return.

      If you have a three-way fridge, how about operating off propane? Then the amp draw in negligible.

      Steve

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #42565
      ardvark
      Participant

      Matt,

      One of the guys on the Ford owners’ website has a 2020 F350 with dual alternators and he metered 14.1 amps to his batteries from his truck. I don’t know how much difference having dual alternators makes as I have no experience with that.

      In my experience the amp output from the truck can vary a great deal between trucks.

      Ardvark

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #42588
      ardvark
      Participant

      I just used my Fluke clamp meter and I have 9 amps to the distribution panel where my charge lead connects. That means I have a bit more given parasitic draws that are at the distribution panel like the propane detector. Anyone else checked theirs? 🙂

      Steve

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #42619
      Kyle Banerjee
      Participant

      If you have a three-way fridge, how about operating off propane? Then the amp draw in negligible.

      I’d only have propane hooked up when stopped. If you get into an accident with propane connected, the results could be disastrous.

      What kind/size fridge do you have? I have an electric Novacool 2.4 cf fridge — that thing takes very little juice. I have only a single battery that I charge via the outlet before I leave, I run it nonstop, and the 100 AH battery lasts 4-5 days before I need to recharge.

    • #42743
      ardvark
      Participant

      Propane systems have a device at the pigtail so if there is a line break the propane flow is almost completely stopped. If the accident is so severe it causes a tank breech (something I personally have never seen or heard of, but who knows?), having the fridge off will be the least of anyone’s problems. The reason the industry does not warn against the use of propane while underway is because they have surmised the liability risk is very small.

      I have actually worked on campers that were involved in accidents in one case having to replace multiple propane lines and in a couple of others a single line and other than the work involved there was no fire, etc.

      In the first case, the RV owner was hit on the Interstate and propane lines to the water heater, furnace, and oven were ripped partially off and left hanging. In the second case, the owner lost control, went off the road, and the water heater was thrown completely out of the camper. In the final case, a fifth wheel suffered a blow-out so severe the lugs nuts were torn off the drum and the wheel broke free taking out a portion of the sidewall and propane line to the water heater. A messy repair for sure, but came out well. I cite these instances only because they were dramatic and resulted in lines that were completely severed, but did not result in a fire.

      The refrigerator fires I am personally familiar with took place in refrigerators that did not have the recall kits installed and the majority took place in campers while in campgrounds.

      Not trying to tell anyone what to do. If you don’t feel safe using propane don’t. The RV industry in general has been moving away from absorption refrigerators for several years due to the convenience that comes with all electric models as well as increased cooling. 🙂

      Ardvark

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #42753
      Kyle Banerjee
      Participant

      I wasn’t aware of how the safety mechanisms worked. My worry was a violent crash causing a break right by the tank valve (or even ejecting it) and then igniting. Like you, I think a tank breach is unlikely — those things are tough and it would take a truly weird hit to do that.

      In my case, I’m all electric except gas and heat so there’s no need to be connected when rolling so at worst it’s an unnecessary step.

    • #42763
      ardvark
      Participant

      Hi Kyle,

      The only reason the current absorption fridges exist is the low amp draw technology was not around when Carrier developed it decades ago. All electric fridge just work better, no slant to worry about, cool down faster, etc. and eventually I suspect they will replace absorption models.

      At present the all electrics do require some added thought as to more batteries or Li+ batteries and maybe solar and those systems can get pricey. I sort of think about the current all electric RVs in the same way I remember the old bag phones for those of you who go back that far in time. They were expensive as the devil and a real pain to tote along, but eventually price came down to what it is today, support systems developed, and now everyone has one.

      Believe it or not, I actually had the opportunity several years back to drive a hybrid 40-foot motor home that ran only on battery power at slow speeds. It never made it into production, but that is the way the industry is heading.

      So once again great minds think alike! 🙂

      Ardvark

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #43879
      ardvark
      Participant

      I know this is an old post, but the question it raises comes up a lot on other sites so a couple of us set out to answer this question by using our meters to take some measurements. What I did was use my Fluke clamp meter to measure amps and my standard Fluke meter with alligator clips on the charge lead in the camper to simultaneously measure voltage over a variety of conditions. Now this is with a 2012 Ford Super Duty F350 with a 6.2 liter gasser for power. I have no idea if these findings apply to GM or Dodge products.

      First off, at the truck battery I found 14.1 VDC across all conditions. Voltage at the truck batteries did not change nor did engine speed increase amp output to the camper. We tested that at idle, 1,000, 2,000, and 3,000 RPM.

      Secondly, with no load on the charge lead other than the parasitic load from the propane detector and a small digital voltage monitor (.5 amp total) that same 14.1 voltage is also measured at the distribution panel. Batteries were disconnected in this trail so they not being charged.

      Third, with batteries at 12.4 VDC at the start and online with the charge lead, I measured 13.25 VDC and 4.6 amps from the charge lead to the batteries. Note: as soon as any significant draw is put on the charge lead from the truck voltage drops, however, the charge lead will still charge the batteries as long as demand is not excessive.

      Fourth, with the batteries now off-line so only loads on the distribution panel are measured the question is what happens when the fridge is running on the DC setting as would be the case with the all electric refrigerators and the 3-ways set on DC.

      Turning our Dometic 3-way fridge on using the DC setting, amp draw jumps to 12.5 and voltage drops to 11.50 VDC (not enough to charge the battery while the refrigerator is on DC). Add the furnace the mix and the amp draw jumps to 14 amps and voltage drops to 11.35 VDC.

      Now results similar to these are also showing up on bench testing suggesting if high amp draw appliances are in the plans, solar or a dedicated charge lead through higher ga. wire may be worth consideration. The truck alternator is not likely able to both supply the power demands of the refrigerator and charge the batteries at the same time.

      If anyone has done similar testing, it would be helpful to post those findings to increase the size of the database.

      Ardvark

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #44101
      Frank Mehaffey
      Participant

      Several years ago I was curious about the whole charging thing with our F250 with the camper package. The whole thing started when we would drain the single deep cycle TC battery when driving in hot weather with the fridge on DC. I must have written Ford 4-5 times, trying to go up the tech info ladder about the charging rates and what the amp rating should be in the camper package charging controller, and if there was some sort of algorithm governing draw and supply. Crickets could be heard. I got a few polite replies but no info. The other concern was that if I was not plugged into shore power, using the reico titan corner jacks, that I would often burn out the truck to camper 30 amp recharging fuse when raising the camper.

      Anyway, talking about electrical systems in any online forum was confusing and often like having a discussion about religion or politics!

      Mike replied to me and others in this forum, and had the most rational explanation on things here and in the articles he posted. There are many paths to electrical redemption!

      What we do now is run our fridge on propane when on the road. Very low propane consumption, no problems, no draw on the batteries, of which we have two now. We replaced all our lights with LED’s. Put two solar panels on the roof with a good controller. We have a big, dark TC with some mitigation of excessive heat with light vinyl squares and a white painted roof. But since the best ac we can get will only drop the inside temp 20 degrees, I can’t afford the new space shuttle batteries. Don’t want a generator to lower my weight load, just for daytime cooling. Maybe if I had a 450 duelie……

      Anyway, we try to stay in the shade wherever possible, when camping in the summer. If we went out west, which we hope to do, now that both of us are retired, we will go in the fall or the spring.

      I’ve done what I can, and now I am very purposely not going to worry about things, unless something needs fixing, for the truck or for the TC. What I want to know now is if I turn off the propane, at the tanks, why can’t I go thru the Baltimore tunnel, or any other posted tunnel. Huh??

    • #44102
      ardvark
      Participant

      We haven’t gone through the tunnel at Baltimore, but we have gone through posted tunnels with our tanks off without a problem.

      As to the having enough power issue, ability to recharge rapidly or at all is perhaps a greater issue for folks who have all electric fridges which seems to be the way things are going. 🙂

      Ardvark

      Steve and Andra
      2012 F350 6.2 gasser SRW LB
      Fab Fours front and rear in case we run into a rhino
      2019 Northstar Laredo SC

    • #45432
      Charles Hanna
      Participant

      Way late to the party here, and don’t even have a truck camper (have a Bigfoot 21 ft trailer) but newer vehicles use a computer controlled alternator that does not raise the voltage very high but for a short time, then drops it back to well below 14 volts. Most old school auto mechanics are used to an alternator running at a steady 14.2v or so, but to conserve power (and the batteries last longer as a result) the computer of mid 2000’s and up vehicles regulate at a much lower voltage. This coupled with the rather small wire supplying power to the 7 pin results in no measurable charge of a battery connected to it.

      I truly think that the sole intention of the charge line is to provide the small amount of power needed to charge a small sealed battery used in emergency brake systems on cargo and utility trailers.

      If you want to charge camper batteries from a newer vehicle, you need to have a DC to DC charger installed in the camper. Then you run heavy gauge (4 to 2 gauge depending on the size of the charger) from the truck batteries to the rear of the truck, and connect to an Anderson connector. Then you plug the camper up and the DC to DC charger has more than enough current to work with. DC to DC chargers will have a four stage charge program in them similar to many solar units or good power converters such as Progressive units. In addition, the DC to DC has buck/boost capability to raise or lower the current to the desired program levels of the charger. Basically you give it something in the 13v range and it does the rest. These units are built in 20, 40 and 50 amp and I think there may be a 60 amp DC to DC charger on the market. They will typically draw about ten amps above their output due to losses in the buck/boost of the current, and also have lithium charge profiles built in also. They prevent the lithium battery from sucking the power from the truck rapidly, which lithium would do if not restricted in some manner (which would destroy the trucks charging system).

      Also, the DC to DC units will not draw power when the vehicles voltage drops below about 13.2 or so. This way, when you shut off your motor, the truck batteries drop in voltage to a resting state of generally about 12.8 or 12.9 and the DC to DC charger will automatically disconnect to prevent discharge of the truck batteries. You can add a automatic battery separator on the trucks feed to the camper if you wish to safeguard the system but its probably not needed.

      Australian’s have been doing the DC to DC charging for some time now, if not having pioneered it. Redarc is one of the major players in this market with some very nice units that are environmentally sealed, and Renogy also makes similar units. I am sure there are others, but am not familiar with them.

      If installed, you would want to go into the camper and and find where the seven pin wire enters and disconnect the power input and secure it, so it is not attempting to charge the system in opposition to the DC to DC charging.

      Charles

    • #45973
      Russ
      Participant

      I installed lithium batteries in my Northern Lite and was frustrated by lack of charging from the 2017 F-350. The highest amperage I saw was roughly 7 amps when the batteries were at about half charge, but most of the time it was in the 4 to 5 amp range.
      So I installed a Renogy 20 amp DC-DC charger, and immediately got the full 20 amps to the batteries. I did not upgrade the wiring, however, and suffered a melt in the umbilical plug at the rear bumper. I bought a Amprobe to read the current on each side (inlet and outlet) of the charger, and found when it was outputting 20 amps, it was drawing 30, which I believe is the what the truck’s charge circuit is fused at. No blown fuse, but the melted umbilical (female plug end) had been very sloppily put together.
      One feature of the Renogy is the ability to run at half capacity, so I enabled that, and get a nice steady 10 amps to the batteries, with roughly 13 amp input to the charger. I’ll need to upgrade the wiring on the truck side before going back to the full power of the Renogy.

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