Charging with tug

[curtis c]

I'm still a little foggy on what size fuse or circuit breaker should be used with a charge line. the battery in my trailer is a flooded group 24 from wally world. i was thinking of using ether 6 ga or 8 ga wire. Also do i run off of the + from the tug battery or from the alternator. I get the basic i idea of how this works but still need some advice. thanks. Trying to do it the cheap unplug way.

[floyd]

I'm still a little foggy on what size fuse or circuit breaker should be used with a charge line. the battery in my trailer is a flooded group 24 from wally world. i was thinking of using ether 6 ga or 8 ga wire. Also do i run off of the + from the tug battery or from the alternator. I get the basic i idea of how this works but still need some advice. thanks. Trying to do it the cheap unplug way.

With the size wire you intend to use, you can use up to a 30 amp breaker, A 20 will do .
I suggest attachment directly to the positive post of the battery or equivalent.
Also you can use a 30A toggle switch directly in line to avoid running the TV battery down when left not runnig and hooked up for extended lengths of time.
A breaker is preferable to a fuse but a fuse will do.
You must run the same guage wire all the way to the battery including both grounds. If not, the fuse should be small enough to protect the smallest wire in the circuit.
I have used 10Ga wire with a 20A breaker successfully for years even when running the fridge on 12V.

[curtis c]

i think that 6 ga may be a bit of an overkill. will 8 gage be sufficient? and would i still use a 30 amp breaker with that or go to a 20amp. Also is there anyway to estimate how much charge is going to the battery? i don't want to overcharge it if that is even possible? Like i said i get the basic idea but not all the specifics.

So basically run
8 ga from + battery through 20a breaker to the 7 blade. 8ga out of trailer side of 7 blade into + on trailer battery. aditional 8 ga. ground off of trailer battery? is that correct?
thanks for the help im just trying to do it right the first time.

[Parker Buckley]

i
So basically run
8 ga from + battery through 20a breaker to the 7 blade. 8ga out of trailer side of 7 blade into + on trailer battery. aditional 8 ga. ground off of trailer battery? is that correct?
thanks for the help im just trying to do it right the first time.

I would find a good grounding point closer to the hitch. Find a bolt going to the frame that you can put a wire lug under, or drill your own hole. Clean off the paint, add some Penetrox anti-corrosive, or equivalent, and ground it there. That saves running the ground all the way to the battery. All that steel structure provides a low loss path for the ground, as long as you pick a good spot to connect. Of course, there is nothing wrong with going to the battery, as long as you're using large enough wire to minimize the losses. Loss on the ground side is no different than loss on the positive side.

For circuit breakers at the battery (for me, one for the brakes and one for the charge line) I used in-line fuse holders that can accommodate bladed circuit breakers that plug in the same way a fuse does. I carry a couple of fuses to plug in there, just in case the circuit breaker fails. I got all this at the local NAPA.

Good luck. Fun project!

Parker

[curtis c]

ok so at the 7 blade on the truck side i run the ground to truck frame. and on the trailer end i run the ground frm the battery to the frame of the trailer. Using the 8 ga on all the connections. i dont need to run a ground wire from the trailer side of the 7 blade to the battery correct? I ordered a hopkins 7 blade that a 4 flat plugs into. but still has the other leads coming off of it for aux and trailer brake and ground.

[Bill MacDermod]

Unless your tow vehicle has a heavy duty alternator on it you may be wasting your time. With the standard alternator using A/C lights and all that stuff its already handling about all it can stand. Even the heavy duty is more money than its worth. I had one on a truck TV and it still worked itself to death trying to keep up. Your money would probably be better spent getting solar

[curtis c]

OK i started my charge line today. i went with 8 ga. i know its on the light side but i just didn't want to wrestle in the 6 ga at this time. My question is, Is there going to be a big difference in the amount of charge if i install an isolator or is it about the same as just running from the + side of the tug battery?

I don't have a fridge so when the trailer is in tow it draws no power, so I'm hoping ill get some topping off of the battery. The battery also only powers 2 led (from superbright) and one fluorescent light.

thanks, curt

[Joe MacDonald]

on a 4 hour tow, I can almost completely restore my AGM battery, from a weekends use.
How do I know this ?
I have a link 10 monitor on the battery that reads total usage from the battery, and total charge restored.
when parked, I use a battery water pump, lights and; if cold a furnace, but the furnace will kill the battery if left on overnight, the fan on the furnace really draws a lot.
My fridge does not require power to run.
I do not have an isolater, but I do have a #10 ground from the battery - to the 7 pin on the tow, and a #10 ground from the 7 pin on the tongue to the battery, a #10 + from the battery + through a 30 amp fuse to the 7 pin on the tow, and a #10 + from the 7 pin on the tongue to the battery

[Lloyd (aka Santa) Coltman]

Just for your information, in house wiring, per the Cdn Electrical Code (that's more stringent than any auto requirements) , #10 is good for 30Amp. If you protect the wire with a 30amp breaker, you will never have any heating problems, but will be able to push 30Amps to the battery, for charging. Also, in general, any vehicle equipped with A/C will have the heaviest alternator available for said vehicle. The heaviest drain will be when A/C is on, and fan is on Hi, any other setting will give you plenty of power to play with. The charge voltage is also, in general, slightly higher than optimal for deep cycle batteries, but will not cause any problems unless your vehicle runs for weeks on end. You should equip your vehicle with an isolation relay that is only operated with key on, to prevent draining of the vehicle battery, when parked. Otherwise, 'Hello,AAA?'. Diode isolators are not the best, because they introduce a constant voltage drop between the alternator and both batteries. Look under post 'Battery ignorance' (this forum) for a link to a wealth of info on 12v systems.
You will definitely need to run the ground from the plug to the trailer battery, but my preference would be from plug to battery, then battery to trailer frame (which probably already exists for light grounding) Although, being a F/G unit, you will have a continuous ground wire, and might not use the frame at all. That's an advantage of the F/G trailer. Manufacturers had to double wire everything, and not depend on the 'skin' for lamp grounds. That results in far fewer intermitant lights.

[Lloyd (aka Santa) Coltman]

[curtis c]

OK the way i did it was the ground on the tug side comes off the frame near the hitch into the blade. the ground on the trailer side of the blade i ran to the frame of the trailer. and i added a ground from the battery in the trailer to the frame. Your saying i need to run the ground wire from the trailer blade to the battery? isn't that pointless because the trailer is completing the ground circuit? I'm confused again. thanks for the help I'm trying to do it right.

also I'm talking about the dedicated ground for the hot lead not the 14ga ground for the trailer lights (4 way).

[Lloyd (aka Santa) Coltman]

OK the way i did it was the ground on the tug side comes off the frame near the hitch into the blade. the ground on the trailer side of the blade i ran to the frame of the trailer. and i added a ground from the battery in the trailer to the frame. Your saying i need to run the ground wire from the trailer blade to the battery? isn't that pointless because the trailer is completing the ground circuit? I'm confused again. thanks for the help I'm trying to do it right.

also I'm talking about the dedicated ground for the hot lead not the 14ga ground for the trailer lights (4 way).

What you did is fine, but I would tie the 4-way ground in too. I'm surprised your unit even had a ground to the frame, as the lights require ground wiring anyway. My old F/G 'CycleCamp' motorcycle tent trailer was wired using the frame as a ground, to save about 8 feet of wire, and it was a constant problem. When I rewired it, I ran 7-conductor cable (containing the ground lead) right back to the lights, where all grounds were spliced together. I never had any more problems with poor lighting.

[Kevin K]

[curtis c]

the trailer is wired both ways. i didn't even notice the ground to the frame until after i took the battery out a few weeks ago. it was not connected at the time and everything worked. Yea i figured i could wire the 4 way ground into the other ground but i didn't want to mess with it. i still have an open blade anyway. thanks for all the help i really appreciate it.

ill also change to a 30a breaker