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RV Battery Charging While Towing

lovegolf44

lovegolf44

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Any sense for how well our truck alternator system charges our RV batteries while towing? I have two deep cycle batteries in my RV with a residential frig. If the charging rate from our trucks is pretty decent, I'm thinking I can run my frig from the camper inverter for several hours without draining them down too far. I know the charging from our trucks is probably more along the lines of a trickle than anything else.
 
Do you not have a dual mode refrigerator? I just run mine on propane while towing, doesn't use much.
 
Not many options for what you want to do. The wiring from the truck alternator back is too small to flow any meaningful amount of current to the trailer, especially running an inverter. Unless you want to go with the suggestion above there is no way apart from a generator. That said, if you start out with a cold fridge and you don't open the door, the fridge will maintain a safe temperature for more than eight hour with no power. However residential fridges are pretty energy efficient so I don't see any issue with running the fridge inverter from your two batteries for an reasonable day's drive. Leave the trailer on shore power until you leave. Enjoy the trip.
 
My RV has a residential fridge. The truck does not provide enough juice via 7-way to keep batteries full. I have 540ah of lithium now and don't worry about it, Note, the truck charges the lithium batteries with less amps than the lead acid due to the higher cell voltage (13.2 vs 12.6). Get some 2awg jumper cables and wire them in the truck.
 
carlrx7 said:
My RV has a residential fridge. The truck does not provide enough juice via 7-way to keep batteries full. I have 540ah of lithium now and don't worry about it, Note, the truck charges the lithium batteries with less amps than the lead acid due to the higher cell voltage (13.2 vs 12.6). Get some 2awg jumper cables and wire them in the truck.
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To solve the voltage issue, I put a 8-40v to 13.8v 10A converter on the trailer. No matter what the truck gives, my batteries always get 13.8v

Before this, the truck would drain the RV battery down to it's "operating voltage" which is dependent on temperature and load. Usually I would leave with a 13.8v battery, and get where I was going with a 13.2-13.4v which is not bad if you don't boondock a lot. But we are about 50% unplugged camping.
 
Don't you have a 120V outlet in your truck bed? You could connect the shore line to that outlet? I do assume that nearly all modern trucks have 120V outlets in the cabin and the interior. Mine has 3 outlets and it worked great for our dometic cooler. Never connected the shoreline to our race trailer though.
 
fuchsroehre said:
Don't you have a 120V outlet in your truck bed? You could connect the shore line to that outlet? I do assume that nearly all modern trucks have 120V outlets in the cabin and the interior. Mine has 3 outlets and it worked great for our dometic cooler. Never connected the shoreline to our race trailer though.
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Most outlets in cabs are 400w max output. The only bed plug I’ve seen is on a F150 hybrid
 
Billcf7 said:
Most outlets in cabs are 400w max output. The only bed plug I’ve seen is on a F150 hybrid
Click to expand...
The 5th wheel and goose neck packages add 120V 400W outlet to the bed right beside the 7 pin trailer connector in the drivers side rear bed side.
 

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Put a frozen jug of water in your rv freezer before leaving and it wont draw much juice.
 
Lary0071 said:
The 5th wheel and goose neck packages add 120V 400W outlet to the bed right beside the 7 pin trailer connector in the drivers side rear bed side.
Click to expand...
I guess I need to buy a newer truck. Don’t have it in my 18
 
If the 400W is not working at all then I could see a few more options. These are just of theoretical nature and I have not tested all of that.

The internet shows that a residential fridges use about 1kWh per day. In your case it might be 2kWh per day since ambient temps can be higher in a camper van.
A 400W 120V outlet provides that in 5 hours (2000Wh/ 400W= 5h). The inverter uses some energy, so maybe a 6-8hr drive to the next campground provides enough energy for the fridge for a full day.

1) Working with just the 400W/ 120V truck outlet might just be enough. Just plug in your shoreline into the trucks outlet and that should keep your batteries loaded longer before the fridge drains them. But I do not know if the 400W outlet is turning off due to an overload, you can test if it stays on. I would give it a try and report back to the forum. Others might benefit from your feedback.
2) Put some solar panels on the roof of your camper. That might be enough to keep the fridge running and the batteries loaded. Maybe the trucks 400W outlet could support the solar panels on a cloudy day.
3) Add a 12V to 120V inverter into your truck to feed the campers shoreline. These are not very expensive nowadays. Just make sure the inverter is only working when the trucks engine is turned on to avoid any surprises. I would think that a 1-2kW inverter should do the job.
4) There are 12V to 12V systems to directly charge the camper battery from your truck but I do not understand them well and they seem pricey.

If I were you I might do the solar panels because that also protects your batteries from going below 12V during the off season. That could save you some years of battery life, low voltage in batteries due to parasitic discharge or just by self discharge (about 1% per day) damages a lot of batteries which would normally last many years. Assuming you park the camper outside in the sun.
 
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jadmt said:
Put a frozen jug of water in your rv freezer before leaving and it wont draw much juice.
Click to expand...

+1

We throw a bag of ice in the fridge and freezer before we set off for a camping trip. My fridge is dual mode though, so we'll set it up on propane before heading out.
 
lovegolf44 said:
Any sense for how well our truck alternator system charges our RV batteries while towing? I have two deep cycle batteries in my RV with a residential frig. If the charging rate from our trucks is pretty decent, I'm thinking I can run my frig from the camper inverter for several hours without draining them down too far. I know the charging from our trucks is probably more along the lines of a trickle than anything else.
Click to expand...

My truck does virtually nothing as far as charging the TT batteries. But I have about 1K watts of solar on the TT roof so when towing usually get fantastic yield. I don't have a residential refrigerator but if I did, I am pretty sure my solar would keep up with power to spare when towing. The only time my solar needs to supplemented with anything else is occasionally on cloudy winter days, or under dense tree cover. I have considered adding another couple of panels but the need is so infrequent, I just deal with having to use the generator a couple times a year when parked in unfavorable solar conditions. If the solar installation can be done yourself, than it is a cost effective and very helpful upgrade. If you need to pay to have it installed, it can get quite expensive upfront.
 
Will_T said:
My truck does virtually nothing as far as charging the TT batteries. But I have about 1K watts of solar on the TT roof so when towing usually get fantastic yield. I don't have a residential refrigerator but if I did, I am pretty sure my solar would keep up with power to spare when towing. The only time my solar needs to supplemented with anything else is occasionally on cloudy winter days, or under dense tree cover. I have considered adding another couple of panels but the need is so infrequent, I just deal with having to use the generator a couple times a year when parked in unfavorable solar conditions. If the solar installation can be done yourself, than it is a cost effective and very helpful upgrade. If you need to pay to have it installed, it can get quite expensive upfront.
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Appears my batteries were able to keep my residential frig going the entire trip. When I arrived at a campground, the batteries recharged overnight and I was good to go for another day of travel. Glad I have two deep-cycle EFBs.
 

this is a pretty nice video. there is a company which offers all sorts of stuff of electric equipment and also show the charging solution for the trailer. i looked at that battlebornbatteries webpage and they have reaonable priced 12v to 12v chargers and similar. maybe that helps, or call them for a solution
 
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