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Discussion Starter #1
Hey Guys

I am sure someone has done this or figured away.
Before my brother bought his PSD he would just put the battery in the truck and it would charge while driving to the water.
Now he wants to rig up some kind of system that will charge the boat battery. There is no power where the boat is stored so a trickle charger is out. What would you need to run a wire or wires to the back of the truck and charge it there or .....in the boat even ?????
Can it be done? What would it take? It needs to be safe, of coarse.
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If you have the factory 7 way trailer light plug, you can charge off that. I can't tell you right off hand which one is the hot wire, but it's labeled on the outlet and in the owners manual. This is set up charge the battries of a travel trailer. It charges slowly, so it'll tale a long while to charge an really depleted battery. You just have to make the connections from hot spot in the truck plug to the positive side of the battery with a ground to the negative side.

Another method would be to wire in some sort of DC to AC inverter. This is commonly done to run TV's, VCR's, etc. The problem with doing this for a battery charger would be having enough watts to do the job. The more watts the invertor puts out, the more amps of 12 volt you have to put in. This requires adquate alternator output, heavy wiring, etc.
 

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I did wonder about your first idea. I'll check into that.

Your second ideal was another. Like you said, I have no idea of what size wire would be acceptable. Would a larger alt be in order.

I hope some more smarter people than I will chime in. /ubbthreads/images/graemlins/grin.gif



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Using and inverter would be silly, since you already have a 12 volt source. The inverter is if you need to run an AC appliance. Sure a battery charger is AC, but it takes that AC and either by switching or transforming it turns it into guess what.. 13.6v DC. So, I would say run off the trailer connector, or just run a fused hot right from the truck batteries to another connector at the bumper.

If you run a 4 gauge cable you won't even need to regulate the current.


Now, don't forget thats the completely wrong way to go about having good battery life. You really should pull the battery from the boat and leave it at your house on a trickle charger, then bring it w/you to the boat.


Joe
 

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Why does he have to charge it all the time, is it for a trolling motor? You can do like the others have said and use the charge wire in the 7 prong rv plug or another idea, at work we have small solar chargers on our hydraulic trailers that sit out in the yard all year and they work great that is if the boat is outside /ubbthreads/images/graemlins/grin.gif Good Luck
 

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It's been some tears now sinceI worked at an RV Shop, but the Idea of 12V off the 7-way plug in the rear of the truck is what we used to keep trailer and 5th wheel batterys charged, although it is not the fastest chargin method. we also would install a "Battery Isolator" so that the truck could charge what was being towed but the towed vehicle could not drain the truck batteries.I hope this helps a little. Ted
 

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I've seen a few different solar chargers at Harbor Freight and other places, why not just run one of those when its stored. That way its ready to go whenever you need it and doesn't require a particular setup on any one vehicle.

Even if its stored inside of a building, you could run a solar charger outside the building and extend the wires some.
 

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either the solar charger in storage or a little 1000 watt Honda generator with the 12v output while you are driving to the water, would charge the batteries faster and be much simpler to deal with at the boat ramp.
 

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[ QUOTE ]
You really should pull the battery from the boat and leave it at your house on a trickle charger, then bring it w/you to the boat.


[/ QUOTE ]

That is the best idea and also solves getting to theboat and finding thieves have made away with the battery.
You can also have it load tested periodically. Breaking down on the water as a storm approaches is not fun.
 

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4 gauge cable jumper ends some heavy duty connectors and you can charge anything run the cable from your battery to the connectors you put by your trailer hitch then create a jumper that will reach the boat battery
 

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The PSD must have a 7-way plug on the back, get a 7-way trailer end from an RV store and hook up a #10 2-conductor wire to the marked terminals-- Black (battery positive) and the White (battery negative) and put a couple of large clips on the end of the wire-- Black wire to Red clip and White wire to Black clip. That way you would know you have the correct polarity when clipping to the battery. Another way is take a long jumper cable (if it would reach the battery) and cut the clips off one end and hookup to the trailer end plug as above. This is a very safe way, if you fasten the cable to the boat so the wind don't blow it off when traveling. Also if he does'nt use the 7-way now you have to plug in the fuse (30 amp) and maybe relay at the fuse box.

OLDBULL /ubbthreads/images/graemlins/smokin.gif /ubbthreads/images/graemlins/smokin.gif /ubbthreads/images/graemlins/warmsmile.gif
 

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I have a little solar charger I use to keep my horse trailer battery up. It works great. If I recall correctly, it was about $30 from Orchard Supply Hardware. When we go camping with my brother's family, they bring a small boat with a trolling motor and we fish in the morning and evning. During the day I throw the solar charger on it while we take the horses out.
 

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I have a couple of different trailers with batteries in them that I charge from my tow vehicles. One is a horse trailer with an on-board battery for the fans and lights, and the other is a large flat-bed that has a winch and hydraulic dovetail.

There is a pin on the 7 pin RV trailer connector on the back of the truck that is hot when the ignition is on. I think that it's the center pin, but double check the wiring schematic (it's usually engraved onto the dust cap).

Your biggest challenge with this system is that this is a relatively low fused lead (I think 30 amps), so if your boat battery is really drained you might pop the fuse or breaker on your truck. Most of the time I don't have problems with my trailers unless the batteries are really drained.

If you use it, be sure to add a circuit breaker in your trailer wiring. I concur with the recommendation regarding 10ga wiring.

The advice regarding using a solar charger is very sound - a better quality of charging and the batteries will always be hot. Northern Tool sells a good unit from Batteryminder - it has the added feature of having a "pulse" charger built in which will desulphanate the batteries - thus extending their usable service life.
 

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I was told a vehicle alternator is not designed to charge a battery from dead. If done too often (how often is too often), it will kill the alternator. True?

Sounds like the OP is looking to routinely charge a dead battery with truck alternator.

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Devo
 

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It is not that it will kill the alternator, it is that the charging voltage is too low to recover a weak battery back to full or near full charge. Batteries that get only 13.2-13.3 volt charge will not live as long as they should nor power devices as long as they should. It takes 13.9-14.0 or even a little more to bring it full charge. When charging from the trailer plug you will have voltage drop. It will charge the battery but not to a full charge.
The charger linked to up the thread is a charger that is electronic and can take lower voltage and increase it up to 13.9-14.0 V needed to get full charge. It will not be a fast charge using that charge but it will get battery up to full charge.
 
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