charging Batts from my pikup

[RixPlace1]

First thing..I plead ignorance of things electrical and prob mechanical.But I can design and build houses and leave the kiddie stuff to those who know electrical same with puters.
But I'm putting together a 7x7x16 CTC about 70% finished and will have some pix in a while. I'm planning a total electric unit 4 100W panels on roof 4 AGM batteries and that which go with all that.Don't want any gases; so I had an idea to run a wire from the pikup to the batt cluster, to charge batts while cruising hiways.my electrician said it can be done easily but not by him.So I'll take the idea to my whiz bang hood garage who solve all probs.But I'd like an idea before I get to the garage Ideas greatly appreciated

Not new to trailers and towing in aught03 bought a F 150 King Ranch to pull a 25" Airstream up and down hills to and from Alaska, Not a single problem not even a flat from SoFLA

[Jscwerve]

If you are towing with a standard 7 pin connector, one of the leads is positive. It will not charge very fast, but if you hook that into your battery system, it will charge. Oh, and don't forget to ground your battery bank to the trailer as well.

I would also check the size of fuse in your fuse panel for the proper size that is going to the plug.

[defjr333]

Highly do-able. Personally I would stay away from using the 7 pin plug to run a charge current through. Due to the Current level I would be concerned about melting and fires. To send 12vdc from the front of your truck where the alternator creates it, to the rear where it would connect to trailer is atleast 15ft or more. WAY to much voltage drop for small gauge wire and a tiny connector. Consider this:
Run a 2 or 4 AWG wire from the Positive AND Negative terminals to one of these at the bumper with enough slack left for "travel" as the trailer turns:
http://www.ebay.com/itm/175A-Power-Conn ... 2374064111
If you have a high amp alternator this would give you a great charge during travel. Had an ambulance with a 230Amp alternator hooked up this way to 8 batteries. Rarely needed alternative charge methods as it worked so well. You should also have a battery isolator on the positive side so you do not kill the start battery:
http://www.ebay.com/itm/NEW-160-AMP-DUA ... 2318748068
With that settup you will get around 150Amps of charge!!! If you dont feel comfortable doing this yourself, I would call around to car stereo shops, as they work with 100+ Amps of 12vdc daily and are familiar with all these components.
Doug

[tony.latham]

Due to the Current level I would be concerned about melting and fires.

However you tackle this, just make sure the charging wire is properly fused (or a beaker) near the alternator and you'll avoid any melting wires.

Tony

[Jscwerve]

Highly do-able. Personally I would stay away from using the 7 pin plug to run a charge current through. Due to the Current level I would be concerned about melting and fires.

Most modern vehicles have a fuse in-line with the 7th pin on the connector to prevent melting and fires. The current is also limited. It's typically fused around 20 amps and feeds 15.

I used to own a landscaping company. We would run our dump trailers hydraulics many times a day taking quite a draw on our trailer batteries. Rarely if ever was the truck charge while traveling to and from jobs not enough to keep the batteries charged. I can't imagine what in a travel trailer would draw more current than cycling hydraulic pumps except maybe if you are running a full sized house refrigerator or something like that.

If you need to charge 150A at a time, then yes, you need to go with a much larger setup. If you aren't actually powering a massive current draw, then the 7 pin is typically sufficient to charge while driving. Especially with 400w of solar sharing the work.

[defjr333]

Totally correct on the 7 pin being fused....IF FACTORY or installed properly. Buy I don't assume....too many backyard mechanics will just add it to any fuse in panel or direct to battery for the 12v connector. Anywho, I still would go the 2 or 4awg route as even at 15 amp at fuse due to length and gauge of factory wire will incur loss. Why only receive enough to run a fan, when u can get enough to run everything just by beefing up the wire thickness and connector? Would cost around 150 or so. Add a few solar panels to charge when parked and your set. Could even add a high idle unit to get rpms to 1500 to 2000 when parked to act as a generator....My old ambulance was set up that way and I never plugged into shore in 2 years. It did help it was a diesel.

[flboy]

Tell your garage mechanic what you are planning and that youd like him to install a "battery isolator" switch/solenoid which allows the truck to charge your trailer's "house" battery, but keep the trailer from running the truck battery down. Basically, it is a continuous duty solenoid wired to come on after ignition (run) to put the "house" batteries in parallel to the truck battery, then open up when the engine is turned off. It will need the proper gage wire and be fused at both ends for safety. Your mechanic/auto electrician should know what to do, proper gage wire, relay contact current to match charging system capacity, etc.. Good luck.

Solid state devices are also available in lieu of the solenoid, but the continuous duty solenoid is cheap and effective for this same purpose. Others noted solid state devices above. Can't go wrong either way.

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[hankaye]

defjr333, Howdy;

Highly do-able. Personally I would stay away from using the 7 pin plug to run a charge current through. Due to the Current level I would be concerned about melting and fires. To send 12vdc from the front of your truck where the alternator creates it, to the rear where it would connect to trailer is atleast 15ft or more. WAY to much voltage drop for small gauge wire and a tiny connector. Doug

From your statement above, I reckon that every RV on the road should be afraid of fire or melt down ...
they all run a charge to the batteries while on the road and if no shore power is available then they need
to be plugged into the tow vehicle in order for a 5th wheel to drop/raise the landing gear. I would also
think that the engineers that designed the system might have considered those problems and designed
the system to preclude those events from occurring.

hank

[pchast]

You are correct about th e RV side.... The TV needs fusing/circuit breaker close to the Supply for safety.

[McDave]

Pretty much all good answers you got on this go round. Since you won't be doing the work yourself, you need to be able to trust the tech. You have just got a crash course in 12v truck to trailer supply. So when you talk with the tech, it should sound a lot like what you just heard.
Key points, IMHO of course.
Use some kind of heavy gauge wire as suggested, I like 4g.
Be sure to fuse the positive at both ends.
Battery isolator to prevent discharging truck battery.
Also find out what the amperage of your alternator is, you want to be up around 150-185 at least.
You know what good clean work looks like, have the tech show you what he did so you are familiar with what and where. Wouldn't hurt to have him throw a meter on it to prove it's working and you will know what pin or connector is associated with this function.
Good Luck,

McDave

[defjr333]

While I am not trying to get any one riled up, I have and do see factory and modified charging systems melt and burn an rv to the ground. Many examples online. I tend to over build for safety in respect to power and propane. I never said can't be done, just gave my 2 cents to somebody that was asking. Maybe that's the Aviation Electronics tech from the Navy coming out? Anywho, I was simply trying to explain why one would rather have a set up that can actually charge a battery bank vs one that would barely maintain the current state of batteries. Ie: 15 amps vs 150 amps. Again just 2 cents worth. Not worth attacks. Thnx

[featherliteCT1]

My 2011 Silverado truck has a 145 amp alternator controlled by a computer with a very sophisticated 7 stage charging algorithm to charge the OEM starter battery and to maintain the proper amps in the system as various loads are applied to the system by the head lights, brake lights, fans, radio, air conditioner, heater, wipers, etc. When I installed a deep cycle battery (with an isolator) and tried to use the existing charging system to charge the deep cycle battery, as soon as the OEM battery was fully charged (which did not take long) the alternator stopped generating amps. Consequently, the OEM system would not adequately charge the deep cycle battery. After much research, I installed the Ctek 250S charger which can provide up to 20 amps utilizing a five stage charging algorithm. The unit was pricey at $238, but it works great.

https://www.etrailer.com/Battery-Charge ... 56676.html

My alternator, like most alternators, is designed to operate continuous duty at no more than about 65% of rated capacity (145amps x 65%= 94 amps maximum), otherwise the diodes in the alternator are at risk of will burning out. Before I bought the Ctek unit, I made sure that the extra 20 amps drawn by the unit would not exceed the 94 amp maximum.

I tested the alternator output with an amp meter by turning on the various loads one at a time. With every load turned on the alternator was outputting 76 amps. Consequently, I had about 18 amps to spare before installing the Ctek unit. I monitor my batteries with a Bogart Trimetric meter as I drive and am very happy with the Ctek units charging stages.

[flboy]

Wow... I had no idea that the newer vehicles had such sophisticated voltage regulators these days. Makes sense though... my wife's new Ford Escape shuts down at stops and restarts when the brake is released (all for little mpg gain). I am sure the computer has to keep an eye on the charge for that.

If it is all that trouble to charge while driving with newer vehicles, maybe best/easiest/least expensive just to get a few solar panels. Ussually not driving in the shade during the day. The generator can top them off at camp if needed. That's what I have been doing and no issues yet. I'll probably never wire up to charge while running. Could always use jumper cables in a pinch at camp if sun and generator let me down.

Btw.. you think a diode in line with the isolator to prevent draw from the house batteries would solve that problem? Sounds like the charging circuit in the truck is just satisfied and the house batteries may be supplementing the alternator. Just a thought. I'd have to get some shunts installed and do some playing around to figure that out.

Maybe not after re reading your post? Sounds like the trucks charge algorithm just is not adequate for deep cycle charging or the solid state isolator you have has issues. When house batteries are all inline with the truck battery, the charging system should just see one battery (bank)/load.

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[Padilen]

I didn't connect my pickup to my CTC battery. Since I did my own wiring, I don't know if I'm wired 100% correctly. So I'm not going to risk my pickups "brain".

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[featherliteCT1]

[quote="flboy"]

Good point about using the solar panels to charge while driving. However, I wanted the redundancy and ability to charge at night and during rain. Also, I suppose some guys might not have the roof space for enough panel(s) to generate 20 amps. Just brain storming with you.

My isolator was just an electric solenoid … no diodes.

I have no idea how the OEM computer knows that the OEM battery is full while the deep cycle battery is still low. Most of the literature I read about charging two dissimilar batteries at the same time (wired in parallel) using a conventional bench charger, said that the fullest battery would be over charged while the lower battery was still calling for charge.