28 replies to this topic

[BBZ]

Curious if there is a way to do this? Just want to add a way of trickle charging while driving without adding an isolator?? Is it possible? recommended or not? Why?

 

We have a set up that only power used is for led lights and fan, doesn't use much power. Spent 3 weeks in Baja and set up very small solar charger twice. Got home and had 50% battery life. Would be nice to get a little charge while on the road...

[OffTheGridMaps]

I can't speak to your setup, but I have a 2003 Tundra that I could charge the batteries using a 7-pin connector as we drove.  I just had a local RV shop set up extend the wiring and change it from a 4-pin (original) to a 7-pin.  Even at that age, the trailer charge was isolated from the main vehicle battery.

Edited by rkd, 30 January 2019 - 11:41 PM.

[esimmers]

Interesting idea: Charge camper battery while driving by using the truck's RV style trailer plug wiring. That's basically what people are doing when they tow an RV trailer, but there are several things to keep in mind. 

 

First, what's your source of power? You need a plug receptacle on your truck with a 12V charging circuit. One of the pins in a 7-pin receptacle provides this constant power but a 4-way doesn't (it only has brakes, turn signals and ground).

 

Next, check to see if the 12V charging circuit is on any time the truck ignition is on but off any time the truck ignition is off. If the charging circuit is still on when the truck ignition is off, you'll just run your truck battery down unless, of course, you add an isolator to the circuit.

 

Finally, remember that you'll be charging your camper battery through a very long set of wires that run all the way from your truck battery to the rear and then forward again to your camper battery. There will be a voltage drop that will not let your camper battery be charged anywhere near all the way.

 

Here's my situation: 2011 F-250 with 5th-wheel package including a bed-mounted 7-pin receptacle. I tested with my voltmeter and confirmed that the 12V pin on the receptacle goes dead when the ignition is off - no isolator needed. I bought a 7-pin plug and connected up the power and ground for the camper. I also connected the camper running lights to the tail/running lights pin on the plug. 

 

This works great for my needs but, honestly, I think my roof-mounted solar panel does a better job of charging the camper battery, even while driving. During daytime, of course.

 

It sounds like BBZ has a portable solar system that's not deployed while driving. So a connection to the truck's charging system is easy to try, assuming you have a 7-pin receptacle already. Even if it keeps the camper battery at 70%, that's something.

 

Good luck

[ntsqd]

I spent a bunch of time and money setting up to charge from the alternator, then I later added fixed solar to the roof. Had I it to do all over again I'd do the solar first and then assess how much, if any, charge I needed from the alternator.

 

With the new to us camper already having solar on it the decision was taken away from me and I've not yet needed to set up the alternator charging. I will do so, but I need to upgrade the wiring between the batteries and the load panel, and access to do that isn't easy.

 

I'd first put in a battery monitoring system of some sort. Both Trimetric and Victron seem to be popular here.

After you've had some experience with the monitor in place you can size the solar panel(s) appropriately.

Then you can decide on if you need an alternator connection.

 

Hint: If you suspect that the solar can do most of the job and you'll only need to "top off" with the alternator you might have a look at the Ctek Duo 250SA for your charge controller. The reason for mentioning this option is that it can handle two different charge inputs. One from the solar panel(s) and one from the alternator. This will naturally disconnect the batteries when the engine is off, and it will do a better job of charging your camper batteries than will the alternator's regulator.

https://www.ctek.com...on-board/d250sa

 

[esimmers]

Good points there by ntsqd, especially if you're willing to put some serious money into roof-mounted solar panels, battery monitoring and an isolator, CTEK or otherwise.

 

If you're just trying to get a bit of charging for minimal cost, your choices are limit to finding the easiest way to connect your truck charging system to your camper battery and installing an isolator (or remembering always to unplug the connection to the truck when not driving).

[ckent323]

I tried using the power from a 7-pin hitch connector to connect to the camper pigtail.  My camper has an Iota DLS-30 power converter connected to an IOTA Distribution/Breaker panel.  I had OEM 6V Golf Cart type house batteries connected to the power distribution panel which I have since upgraded to 6V Deep Cycle AGM batteries.  I used a custom made pigtail with appropriate connectors on each end to connect the 7-pin socket to the camper plug.

I found that the small wires that come from the truck to the 7-pin socket did not allow adequate charging of the batteries although it did manage to send some power.  For powering lights it is fine but it will be hard to keep up the batteries if you have a 12v refrigerator based on my experience.

 

I have since added 200 W of solar panels and a Victron charge controller along with a Victrron BVM-712 battery monitor setup which has kept the batteries fully charged.  I also ran 6 ga wires from the truck through a Blue Sea Ml-ACR to the camper house battery bank.  However, I have not needed the direct connection from the truck yet and the ML-ACR switch has been off since I installed it.

 

If I were doing the Solar knowing what I know now I would use a set of panels providing at least 300 W and use a Victron  Blue Solar 100/30 or 100/50 controller and a Victron BVM-712 Smart battery monitor.

 

Craig

Edited by ckent323, 31 January 2019 - 10:37 AM.

[Colorado Mark]

This what I am going to use for my new Grandby.  I have a GM truck.

 

In the under hood fuse & relay center, there is a 40 amp fuse and if you remover the cover, terminal lug #1 is for the rear 7 pin charge wire.  That 40 amp fuse is for terminal #1, trailer tow charge wire.

 

I added a new 10ga wire to the lug and ran it to the new connector in the bed of my truck for the new camper.

 

I don't tow a trailer that needs a battery charged.  If I ever do, I just need to be aware that it could pull too many amps and pop the fuse.

 

Key off and terminal #1 turns off.  Only activates with engine running.

Edited by Colorado Mark, 31 January 2019 - 01:24 PM.

[ntsqd]

A thought, mentioned here a lot on this topic, is what seems like it should be a large enough charge wire probably isn't. The reason is the length of the total charge circuit, have to include the ground path in the voltage drop calculation. I use this page and work for less than 3% Voltage Drop on charging circuits.

http://www.ancorprod...nt-voltage-drop

 

An insidious loss is trying to use the chassis as the ground path with high current. Every weld in the chassis has resistance. At low amperages this isn't usually too big of a deal. At high amperage it is a big deal and this is why the camper charge circuit from the alternator should include a ground wire/cable of the same size as the hot.

[smlobx]

Plugging a truck camper into your 7 pin connector is what most truck campers do.
I’m not familiar with fwc wiring but the rest of the industry uses this method and it will charge the house batteries very easily, usually in just a couple of hours of driving.

[esimmers]

ckent323 and others correctly point out that long wires and small diameter wires will severely reduce the amount of power sent from the alternator to the camper battery and certainly won't send enough to power a refrigerator running solely on 12V. Ask me how I know!

 

The original poster only uses the camper battery for LED lights and a small fan. If those are the only loads, it probably isn't cost effective to spend a bunch of money on solar panels, battery monitoring, etc. So powering off a 7-pin connector is an economical way to provide at least a fair amount of charging.