Charging boat while on the highway.

[Halifax Shipfaced]

I'm planning to tow my boat 2100 miles and use it as a camper on the road for 4 or 5 days.
I want to connect the boats charging system to my F25O so we can keep the boat fridges (2 of them) on while in tow.
Any suggestions on how big an inverter should I be looking at?

Thanks.

 

[reelfishin]

Re: Charging boat while on the highway.

I'm planning to tow my boat 2100 miles and use it as a camper on the road for 4 or 5 days.
I want to connect the boats charging system to my F25O so we can keep the boat fridges (2 of them) on while in tow.
Any suggestions on how big an inverter should I be looking at?

Thanks.

You might want to check to see if your F250 is capable of powering two large inverters along with everything else it's already doing.

A small generator may be the best bet?

Most stock charging systems don't have the surplus power to run such equipment.
How does the boat keep those two refrigerators powered? Does the boat have a stand alone generator?

 

[Bondo]

Re: Charging boat while on the highway.

Ayuh,... Aren't these Fridges capable of being powered by the boat's 12V system,..??

If so,... Just run a 12V line from the truck, to the boat...

 

[H20Rat]

Re: Charging boat while on the highway.

I'd be REALLY careful just blindly connecting them together. You absolutely need to know two very key pieces of information, don't even think of doing it until you know those for sure.

a) how big of an alternator in the f250? (and how much spare capacity)

b) How much of a draw are you going to be putting on it.



Once you know those, that will tell you if its safe/possible, and how to do it. Keep in mind those fridges probably have some serious electrical draw if they both kick on, and unless you plan on burning the whole rig down when you overheat a wire, you are going to have some fairly large wire going directly to the battery of the truck.

just as an example, here is a tiny 3 way rv fridge. It draws ~12 amps on 12 volts.

https://www.makariosrv.com/products/Norcold-N260.3-3-Way-Refrigerator.html

So two of those are going to be sucking down 24 amps.

Now head on over to a wire size calculator...
http://beta.circuitwizard.bluesea.com/

I used 24 amps and 60 feet (has to go from your battery in the truck to the battery/fridges in the boat, plus turns, so size the length to whatever you think might be close. I have a feeling 60ft isn't too far off depending on boat) Keep in mind that length also must include a ground from the boat's negative ground to the trailer.


Anyway, 60 feet, 24 amps, some other standard variables, and it spit out a wire size of 2/0 gauge. (that is HUGE wire, but if you plan on doing it safely and not lighting the whole rig on fire, that is the only way)


The better option as far as wiring would be concerned is put a decent inverter in the truck cab, and then run an extension cord at 120v to the boat. Its far easier to transport higher voltage without needing massive wire. You lose a little in the inverter, as well the fridge being slightly less efficient on 12 volt, so you will need a little more spare capacity in your trucks alternator to go that route.


There always is a third option. Buy some ice! You can get dry ice at many grocery stores/butchers, it will last longer and is a lot colder.

 

[dvandsm64]

Re: Charging boat while on the highway.

on a camper the 8-10 pin elec. trailer connector provides 12 v. to certain things in the camper. i doubt your boat has this type of connector , though.

 

[PBJT]

Re: Charging boat while on the highway.

It is completely possible. Trailer RV's do it all the time. I would not use an inverter but only 12v systems and lights already in the boat. Inverters will suck down batteries in no time. Becarefull you don't leave the truck hooked up overnight and go out to start the truck in the morning and you have drained all the batteries.

 

[Gary H NC]

Re: Charging boat while on the highway.

Many of the RV fridges run on AC current or propane.
What type is on the boat?
I doubt it is propane....

 

[Halifax Shipfaced]

Re: Charging boat while on the highway.

My thought was to go from an inverter on the truck and then across the hitch to the shore power hook up on the boat (just like being plugged in at the marina) and thus charging the house batteries by on board battery charger.

The trucks alternator is a 200amp unit.
Each fridge runs on 3amps

Model Amps 120V/AC Amps 12V/DC
DE-0751 0.7 3.0



The boats fridges are DC and the boat has 4 batteries (2 for the house)

I thought this would be the easiest and most dependable. Yes i suppose there would be a waste of energy used to convert from DC to AC back again to DC.
But i thought with this amount of juice there would be no issues.

So if this set up is ok, what size an inverter do you guys suggest?

 

[Bob's Garage]

Re: Charging boat while on the highway.

RV fridges can be AC/DC and as such the batteries can be charged from the tow vehicle charging system.

I would think that you could change to a 7 wire plug, run the 12 volt aux. from the tow vehicle, to an isolator which can be used to charge your on board batteries, automatically switching the charging current to the battery that needs it. The on board batteries could be operating the fridges.

This would, of course, only work while the vehicle is running. The fridges would need to be plugged into an AC source at the campground, thru the boats shore power system, or they will run down all the batteries overnight.

What I would do is discuss the feasibility of the system with someone in the RV business as they would have the experience with setting up this type of charging system.

There may be some changes that would need to be made to my scenario but I think it is doable.

 

[mike343]

Re: Charging boat while on the highway.

One of the pins on the rear connector of your truck is a 30 or 40 amp fused 12v from the alternator battery. Just connect it to your boat battery terminal along with a heavy duty ground wire. Put the fridges on dc and travel.

 

[Frank Acampora]

Re: Charging boat while on the highway.

If indeed the refrigerators only take 3 amps each, do the math: If you drive for 8 hours at 6 amps draw, that's only 48 amp hours. If you have a couple of deep cycle batteries with, say, 750 reserve, why bother charging on the road at all?

Yeah--yeah--I know 750 isn't a real number, but that size battery will run a 24-30 amp trolling motor for a couple of hours so it should be good for your two fridges.

 

[bruceb58]

Re: Charging boat while on the highway.

If the fridges run on 12VDC, I would just run 12V through an ACR to the boat batteries. That is what I used to do with a horse trailer that had a deep discharge battery that was used for lighting.

 

[H20Rat]

Re: Charging boat while on the highway.

after thinking it through, I think you (we) are complicating it! Two decent sized house batteries should easily run those 2 fridges during the day if they truly draw 3 amps running each. (and considering they won't be running continously) Anyway, you said you are using it as a camper while on the road, so I'm assuming you are overnighting somewhere with electrical facilities, to recharge your batteries?

long story short, don't do anything! you have plenty of battery capacity if you are charging every night.

 

[bruceb58]

Re: Charging boat while on the highway.

If indeed the refrigerators only take 3 amps each, do the math: If you drive for 8 hours at 6 amps draw, that's only 48 amp hours. If you have a couple of deep cycle batteries with, say, 750 reserve, why bother charging on the road at all?

750 is not an amp hour spec of a typical size 27 battery(closer to 90 amp hours or less). 48 Amp hours is really going to deplete most size 27 batteries close to their 50% discharge point which is low as you want to go. I would not discharge them that deeply especially since it would be so easy to just run a cable from your truck to the battery. Just remember, a battery has a finit number of charge/discharge cycles and the more you do that, the less capacity they have.

 

[H20Rat]

Re: Charging boat while on the highway.

750 is not an amp hour spec of a typical size 27 battery(closer to 90 amp hours or less). 48 Amp hours is really going to deplete most size 27 batteries close to their 50% discharge point which is low as you want to go. I would not discharge them that deeply especially since it would be so easy to just run a cable from your truck to the battery. Just remember, a battery has a finit number of charge/discharge cycles and the more you do that, the less capacity they have.

48 amp hour is assuming it is running continously. A more real world case would probably have it running half the time, so 24 amp hour. A pair of group 27 batteries should have no problem with that.

 

[j_martin]

Re: Charging boat while on the highway.

Here's the problem as I see it.
1. You want to run 12v loads while you're driving, and maybe also top off the batteries.
2. Battery finishing voltages vary from one to another.
2. Any voltage drop between the truck system and the boat system will likely not meet that finishing voltage on the boat, especially with a load attached.

Solutions.
1. Ridiculous heavy wiring.
Cons are obvious, and probably won't work anyway.
2. Convert to 120 AC, send to boat, run charger.
Cons, inefficient, much equipment needed, possible 110 V electrical danger.
3. Just run on batteries, charge when parked.
Cons, weight, cost, and batteries get beat up when bounced around and partially discharged.
4. DC to DC converter/charger. (Yes, they make them for just this purpose.)
Cons - cost.

hope it helps
John

 

[Bondo]

Re: Charging boat while on the highway.

If the fridges run on 12VDC, I would just run 12V through an ACR to the boat batteries. That is what I used to do with a horse trailer that had a deep discharge battery that was used for lighting.

Ayuh,.... If ACR is a relay that only allows coupling of the tow unit electrical system to the boat's electrical system, When the tow unit is Running,....
I completely Agree....

Even a little 30amp/ 10ga. circuit between them will not only run the fridges,..
It'll easily keep the batteries topped off....
Especially if the boat's batteries aren't to discharged...aka; near Dead...

Goin' DC to AC to DC is way over-engineering at Great expence, for No good reason to Me...

 

[BUDDY123]

Re: Charging boat while on the highway.

I'am thinking a large ice chest to keep certain things cold and buy fresh things as you need them, after all its only 4 days and wont be used as a camper again, until your run home. No wiring, no blow alternator, no dead battery, no car or boat fires.

 

[sasto]

Re: Charging boat while on the highway.

I'am thinking a large ice chest to keep certain things cold and buy fresh things as you need them, after all its only 4 days and wont be used as a camper again, until your run home. No wiring, no blow alternator, no dead battery, no car or boat fires.

Hi Buddy....Do you mean camping without electricity? Sounds good to me. You have my vote. The subject is interesting to me and gave me some insight if ever needed.

Thanks.

 

[bruceb58]

Re: Charging boat while on the highway.

Ayuh,.... If ACR is a relay that only allows coupling of the tow unit electrical system to the boat's electrical system, When the tow unit is Running,....
I completely Agree....

That is what I meant. My father did the exact same thing. He had a Norcold fridge in his cruiser which he used to bring fozen fish back from the northwest. Just ran a wire from the truck up to the main house battery. I would put in a 50A automatic resetting circuit breaker on the truck side.