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Discussion Starter · #1 ·
Searched but could not get a definitive answer. First, while I'm on shore power (AC grid) the deep cycle battery on my RV will charge. That's perfect.

Now... when I hook up the 7 pin connector and am cruising down the road, will the truck supply power to charge to battery? The Winnebago is set up to allow this, but I have read so many scenarios. Like for example, would I have to add a fuse or uncoil a wire located near the fuse box and add it to a circuit? I'd think with the tow package all should be good to go? Can anyone verify that with the 2nd gens w/ trailer brakes will charge the RV battery?

Thanks
 

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Searched but could not get a definitive answer. First, while I'm on shore power (AC grid) the deep cycle battery on my RV will charge. That's perfect.

Now... when I hook up the 7 pin connector and am cruising down the road, will the truck supply power to charge to battery? The Winnebago is set up to allow this, but I have read so many scenarios. Like for example, would I have to add a fuse or uncoil a wire located near the fuse box and add it to a circuit? I'd think with the tow package all should be good to go? Can anyone verify that with the 2nd gens w/ trailer brakes will charge the RV battery?

Thanks
2nd Gens will send power from the truck to the trailer. As I remember, the alternator output is increased to support this if the tow/haul mode is selected.

I was thinking about this on my new trailer with my SIlverado - the issue is when I power up the trailer to "charge" the battery from the truck, the refrigerator also powers up. Great, so it is cold when we arrive. However, I wonder if the current draw from the refrigerator is greater than output from truck, if it will actually charge. I need to figure that issue out.
 
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I have heard, never hook up the 7 way trailer plug while shore power cord is plugged in and vice versa. I did it and blew two fuses in the Colorado Underhood fuse box. I remember not to do that now.
 

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‘17 Colorado CCLB 2wd 2.8L Duramax Summit White
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It’s possible to charge the trailer battery through the 7-pin as long as your trailer is set up to do that. However, without a dedicated DC to DC charger your truck won’t add much charge. More or less it’ll just maintain the charge and maybe add a little like a trickle charger. So don’t expect for you truck to fully charge a dead trailer battery after an hour long drive.
 

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Discussion Starter · #5 ·
2nd Gens will send power from the truck to the trailer. As I remember, the alternator output is increased to support this if the tow/haul mode is selected.

I was thinking about this on my new trailer with my SIlverado - the issue is when I power up the trailer to "charge" the battery from the truck, the refrigerator also powers up. Great, so it is cold when we arrive. However, I wonder if the current draw from the refrigerator is greater than output from truck, if it will actually charge. I need to figure that issue out.
Perfect. Was hoping all was in place. I just got the rig this past weekend. Sounds like we both have much to learn. lol Interesting as to whether it will run the fridge on DC power if it's available or the hierarchy will say propane? I've read some will pre temper the fridge with AC before traveling, place all the cold stuff in it with a few blue ices and just switch it off until back on shore power? Probably be fine for short runs.
 

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Discussion Starter · #6 ·
I have heard, never hook up the 7 way trailer plug while shore power cord is plugged in and vice versa. I did it and blew two fuses in the Colorado Underwood fuse box. I remember not to do that now.
Excellent advise. Thanks
 

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With the tow package you are good to go. Hitch up, plug in the 7 pin and go camping. We tow with a 2018 Colorado z71 v6. In 2019 we towed our travel trailer over 10,000 miles, spending most nights with no shore power. We always travel in tow/haul mode and the battery in our trailer was always fully charged by the end of the day. We found that trying to run the refrigerator on 12 volts did not work well. A 20 lb. propane tank will run the refrigerator for weeks.
 

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Discussion Starter · #8 ·
With the tow package you are good to go. Hitch up, plug in the 7 pin and go camping. We tow with a 2018 Colorado z71 v6. In 2019 we towed our travel trailer over 10,000 miles, spending most nights with no shore power. We always travel in tow/haul mode and the battery in our trailer was always fully charged by the end of the day. We found that trying to run the refrigerator on 12 volts did not work well. A 20 lb. propane tank will run the refrigerator for weeks.
Thanks. Just what I needed to hear. I don't think I'd even want to try and run the fridge on DC while traveling, believing the DC from the truck would in itself run the fridge and charge the battery. That seems unrealistic. If one wanted to run the fridge while in transit, I suppose the propane would be fine. To be honest I must read the owners manual. When we say the fridge can run on DC, I am assuming there is an inverter that converts the DC to AC?
 

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Depends on the model of your fridge. It could have separate heating elements for the AC and DC circuits. Or it could just have a DC heating element and uses a converter when plugged into AC. I doubt it uses an inverter as those tend to be less efficient and consume more power. The 2-way compressor fridge I have in my trailer uses a DC motor for the compressor and a converter for AC when plugged into shore power.
 

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As others have noted, the short answer is:

Yes, truck 7-pin has Truck Battery B+
Note: This is a direct Fused connection so if Truck engine is not running Trailer connected to 7-pin could drain your truck battery. On my vehicle I've installed an isolation relay. Other folks just unplug 7-pin

Next, Truck has smart alternator and in Haul/Tow mode it's output is held high. When Haul/Tow is off output can fall below voltage of trailer battery (no charging).
Note: Turning Headlights on also forces alternator to high output if your trailer size does not need Haul/Tow features.

Always assume Truck can only function as a low-amperage battery charger, 2-5 Amps, range. So takes a long drive to refill a low battery.
Note: For most of us if trailer 12VDC Fridge is on . . . all bets are off, Truck output is just too low.

If you need Truck to provide more Amps then the "slow charger" rate then you will need to add some type if aftermarket DC-DC Charger to trailer. Two or three brands on the market - - all expensive.
 

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2nd Gens will send power from the truck to the trailer. As I remember, the alternator output is increased to support this if the tow/haul mode is selected.

I was thinking about this on my new trailer with my SIlverado - the issue is when I power up the trailer to "charge" the battery from the truck, the refrigerator also powers up. Great, so it is cold when we arrive. However, I wonder if the current draw from the refrigerator is greater than output from truck, if it will actually charge. I need to figure that issue out.
Which Winnebago do you have? We have a Micro Minnie 2108DS (2018 model year). My Z71 Duramax charges while towing just fine. Our fridge is propane/110 volt evaporative, but I understand that new Micro Minnies are coming with 12 volt compressor. I would think that will add to the draw on your camper's 12 volt battery, and slow down the recharging while driving.
 

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Which Winnebago do you have? We have a Micro Minnie 2108DS (2018 model year). My Z71 Duramax charges while towing just fine. Our fridge is propane/110 volt evaporative, but I understand that new Micro Minnies are coming with 12 volt compressor. I would think that will add to the draw on your camper's 12 volt battery, and slow down the recharging while driving.
I have a Forest River, not a Wiinebago. No option for propane on this fridge like my old popup fridge had. Fridge seems to work well, including the freezer, on shore power. I have not towed enough to know.

I have been working on it during the off season, and I hooked up the truck with engine running to trickle charge the battery, but then realized on last trip the refrigerator was running, thus nullifying any charge I might have been able to do. Next time I hook up to work on camper, I will figure out how to turn fridge off.

Also planning to go camping in a month, hopefully I don't freeze my buns off. This weekend predicted in the teens around here with at least 1-2 days not above freezing.
 
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It’s possible to charge the trailer battery through the 7-pin as long as your trailer is set up to do that. However, without a dedicated DC to DC charger your truck won’t add much charge. More or less it’ll just maintain the charge and maybe add a little like a trickle charger. So don’t expect for you truck to fully charge a dead trailer battery after an hour long drive.
Run your truck in tow haul this will charge your trailer battery, it’s in the manual
 

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Run your truck in tow haul this will charge your trailer battery, it’s in the manual
Thanks, I have read the manual. I wasn’t implying that it wouldn’t charge. It just won’t add much if anything at all. Like others have stated, the truck only may only charge a few amps at a time much like a trickle charger and may not add any charge at all depending on if the trailer is using power. DC-DC chargers can be upwards of 60A and would be much more efficient to charge a dead battery.
 

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The 7 way charging basically is designed to keep the trailer battery topped off.
 

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Discussion Starter · #16 ·
Have my manual "Winnebago Fifth Wheel & Travel Trailer Owner's Manual". This is what is says about the fridge:

The refrigerator can operate on 120-volt or on LP gas (requires 12-volt to light). So I don't believe that having strictly 12VDC will work. There is no inverter to make this happen with the fridge.

Here is some info on the power converter (they say the nerve center of the 12v DC & 120v AC system:

1. The power center will supply 12v requirements when operating on 120v AC.

2. The onboard battery will gradually be brought to a full charge and maintained by the 6-amp battery charger as long as 120v power is available.
(And also it appears when you have the 7 pin connector plugged into the truck and in toe mode.

3. The propane leak detector and other 12v components continually consume small amounts of current even when switched "OFF". The trailer's battery will fully discharge within 72 hours if not recharged during that period of if the power center is not connected to a 120v AC source

DISCONNECT THE BATTERY IF YOU ARE NOT USING YOUR TRAILER
(I'll add that only if you're not on AC power. I have mine plugged in now and will probably leave it that way.)

Lots of good info in the manual. Gotta find a highlighter lol
 

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Thought I would provide some insight from 40+ years of towing/driving a number of RV's. The typical RV fridge is the ammonia absorption type and has been used for decades. They are generally 2 way-propane/AC or 3 way-propane/AC/DC. On DC they typically draw 15-20 amps, enough to drain a typical 1-2 battery setup in a matter of a few hours. Absent a DC-DC charger the truck is generally not going to be able to supply this many amps through the 7 pin mostly due to the wire gage used for the charge circuit. Some truck manufacturers this wire is as small as 14 gage, which is too small even with a DC-DC charger. At least GM tried to do it right as the charge wire in the Colorado/Canyon appears to be 10 gage and could supply the 15-20 amps but would be at the limit given the length of the run with or without a DC-DC charger. Voltage drop is the problem as you need about 13.6 or more at the RV battery to get any substantial charging. I have always run my fridge on propane while traveling, very low amp draw on the order of .5 amps or less for the igniter and control circuits. Running the fridge on propane is also preferred while boondocking for the same reason. Some of the newer RV's are being equipped with 12 volt compressor fridges. These are far better in amp draw department than the absorption type at 2.5 amps or so. That is still 60 amps per day, a lot if you are camping without hookups. Think a 100 watt solar panel in full sun charging at 100% efficiency (not going to happen) for 8 hours per day just to replace what the fridge used. I would caution anyone thinking of using a DC-DC charger to limit it to 15-20amps. The 50-60 amp units would need 4 gage wire at their rated capacity. Provided you run the fridge on propane while traveling the truck should keep the RV battery charged if you are driving 5-8 hours even without a DC-DC charger, this has been my experience over the years.
 

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Discussion Starter · #18 ·
Thanks Sgt H With that much windshield time you much have accumulated a ton of knowledge over the years. I'm brand new to the RV towing world. Towed several utility trailers over the years, but RV's are an entirely different animal. Again, I appreciate your input.
 

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also new to rv world myself. From what I have read and seen on YouTube. The fridge i have is 12v only. And it is supposed to run 50 hrs on one 850 cca deep cycle. I also have 150 watts of solar on the roof to help keep up. Being that there is no propane option I sure as hell hope the truck and solar can keep up. Who wants spoiled meat and warm beer 🍺 🤔
 
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This is going to depend on the wiring of the trailer. There is a lot of voltage drop over a long length of small gauge wire. For example a battery mounted closer the the truck will charge better than one in the back of the trailer given the same wire size.
Think about the 15 or so feet from the truck battery and alternator to the plug then the long wire through the trailer to it's battery. The more of a load (like a fridge) that it has the worse it gets too.
edit: see post #17.....just saw it.
 
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