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Old 01-12-2019, 03:39 PM   #1
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Do the batteries recharge while towing?

We are newly retired and are now the owners of a 21 foot travel trailer (FR 21FBRS) and we love it! We are very experienced with boondocking, water conservation and limited electricity after many, many years of camping in a tent and pop-up, but we have never had a gas refrigerator or gas heater before.
We are planning a Fall New England trip, staying mostly in State Parks with no electric hookups. I understand that the gas refrigerator and gas heater will still draw electricity from the batteries. I am guessing that we will probably have to run the gas heater at that time of year. How many days would you think we could get from 2- 6 volt batteries while we conserve as much electricity use as possible? We are thinking of staying 3-4 days at each campground. Will the batteries recharge during the 2-4 hour tow to the next campground? We are hoping to not have to buy a generator. Any advice would be appreciated.

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Old 01-12-2019, 03:47 PM   #2
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With conservative furnace use, you can get 3-4 days out of the 6 volt batteries.

That is the same setup I have.

I use a Mr Buddy Heater if it's really cold and we need more heat. I crack two windows and have not had a problem as it's rated for indoor use.

I keep the hot water heater off and only use the water pump as need (I don't leave it "on").

LED lights help but I still keep the light use to a minimum. A battery powered lantern comes in handy if you really need to conserve power.

I few hours behind the truck WILL NOT RECHARGE the batteries. It will help, but will not give them a full charge.

I recommend a gen if your moving from one boondocking site to another so you can maintain the batteries properly. I'm looking at one as well.

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Old 01-12-2019, 03:49 PM   #3
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Most tow vehicles only provide a trickle charge at best.
Your furnace will be the biggest power drain. Fridge and water heater will not use much.
We are also experienced dry campers but we wouldn't be without our trusty Honda 2000i.
2-4 hours of towing will NOT fully charge depleted batteries.
I think you're going to need a generator or solar panels.
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and Zoe the Wonder Dog(R.I.P.)
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Old 01-14-2019, 07:59 AM   #4
Join Date: May 2018
Location: Brandon Fl
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We added two 100 watt solar panels to help recharge the batteries while on the road as well as parked. We can get about 15 amps on a good day plus the trickle from the trucks alternator. Using two 6volt golf cart batteries and a solar controller. We keep the converter off most of the time to keep from cooking the batteries.
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Old 01-14-2019, 12:56 PM   #5
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I added an extra 6 gauge wire from the power distribution box under the hood of the truck to the battery. I hope that I get a better charge due to the heavier wire. I will be checking the charge rate when I borrow my friends amp meter this weekend.
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Old 01-14-2019, 01:29 PM   #6
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Understand that when you plug in your tow vehicle it puts all the batteries in parallel. If the trailer batteries are low, they will draw down the TV battery and all will equalize. The alternator senses SYSTEM voltage so it will not sense a real low battery and hit the system with its full amps. The initial "hit" will bring them up some but it takes a LONG time to get them to peak charge as the alternator drops off. This is also the case with a standard converter when you plug in to shore power or run a generator; initially the amps are high and the voltage jumps up pretty fast but as you approach "full" the converter will back off. With the better after market converters they will stay at high discharge longer. I was amazed at how much better my last trailer charged after I switched to a PD 60 amp converter from the stock POS 40 amp. So yes, you'll need some help.
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Old 01-14-2019, 01:56 PM   #7
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Suggest buying this voltage meter below ($12) and plug it into your 12 volt outlet in your trailer.. With the vehicle engine off, the meter will read your battery voltage (around 12.3 volts).. Then start your engine, check the voltage and it should read around 14 volts if charging properly..

(Amazon sell the same meter but $40)
2015 F350 4x4 gasser.. 2017 Rockwood 2506S TT
Ardenvoir, Washington (near Wenatchee)
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Old 01-14-2019, 01:59 PM   #8
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X2, 3 & 4 on the TV not fully recharging your TT batteries. Also, if you haven't already checked, you should check to see if the 7-way receptacle at the rear of the TV has a live 12v power from the alternator. Depending on the manufacturer, some ship the vehicle with fuse/relay for that circuit already in place and some are supposed to be installed by the dealer as part of the "towing package" prep. (if it came equipped) before you take delivery. On my old Chevy (2002) even though it had a so called trailer package, I had to install my own 40 amp. fuse in the power distribution box under the hood in order to feed the constant 12v power to the 7-way trailer receptacle.

If you want some peace of mind just in case, you might consider either of the 2 economical (& quiet) inverter gensets below.
"PT Crew Members Since 9/2010"[/I][/B]
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Old 01-14-2019, 02:11 PM   #9
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I have a 2017 21FBRS and have found the following by applying an amp meter to the trailer to get an idea on what the draw is for the different systems. Here is what I recorded. Keep in mind that each item includes the parasitic draw.

Base parasitic draw - 0.17 ah
Refer (on gas) - 0.58 ah
Furnace - 2.6 ah
Hood Fan - 1.23 ah
Hood light - 1.38 ah
Bath Fan (on high) - 2.67 ah
Ceiling light (1) - 0.45 ah
Ceiling lights (all) - 2.54 ah
Lights on JN Sofa (1) - 0.27 ah
Scare Lights - 1.14 ah
Porch Light - 1.52 ah
Hot Water Heater (on gas) - 0.78 ah.

For what it is worth to you.
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Old 01-14-2019, 03:06 PM   #10
Join Date: Jun 2010
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Suggest you check your tow vehicle fuses, my 04 Silverado is fully wired for towing, however the fuse for the battery circuit that feeds the trailer connector was missing.

Also be careful when you are boon docking to unplug the trailer from the tow vehicle, I spent the night at a Loews and left the trailer plugged into the tow vehicle, had to get a jump to get it started the next day. My cpap discharged 3 batteries to the point the tow vehicle would not crank.

Jerry & Sally Martire
Culpeper, VA
2008 FR Flagtstaff 831RLSS
2004 Silverado 2500HD diesel
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