Recharging boat battery's while towing....

Harvey, I talked to my brother, an Electronic whiz, (electronic technician by trade) about this first, as I was worried about to much current and all. He said if I'm going from almost 14 some volts from the car altenator, to a battery with 12 volts, that is only a 2 volt difference and the amperage draw would be very little. The fact I have not blown my 5A fuse shows I'm transferring less than 5 Amps thru my system. I have used both C-pap and my Webasto heater at night on the road, but never seen the battery below about 11.9 in the morning, (usually with a load on it, and as indicated on one of my chartplotters voltage readout.) More normal is about 12.1 volts with no load. I also have a 10 amp fuse on my accessory (cigarette) outlet at the helm. After driving all day, my boat house battery is back to about 13.2 volts. (Probably back up sooner, but I don't check it until done driving in the evening. ) I fabricated my system for about $10. The cost of the plugs at both ends of the wire, that I already had! :) BTW, FWIW, I've left the system hooked up, and ran the heater with no ill effect. I don't know what kind of current the glo plug pulls, but I'm sure it's more than 5 amps. However, I also think the boat battery is providing the current necessary, so still little draw on the "tow" system. I believe I remember my brother saying that the length and size of wiring would also act somewhat limiting on the amount of current traveling thru. I'm just a layman at this, so don't remember everything he explained to me. I just know it's working for me. Colby :D
 
Back to this:

I am looking at their website now. (John, maybe they read you post and just bumped the price) but I am seeing $89.95 for the 60 foot version. I don't think I could make it from the truck, (over under and round and through) and up from the hitch to the deckpipe and then back to the batteries in the aft Lazuretts with a 40 foot run.

Also, I am wondering if the 12 gauge wire is heavy enough for that length. Seems like if the 40 ft is 12 gauge, then the 60' should be heavier wire.

If anyone else is interested, If I do this it will be soon.

Harvey
SleepyC :moon

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Sea Wolf Joe said:
"Just a question: Would a solar panel on the boat with the proper regulator, recharge the boat battery and eliminate this charging via the tow vehicle connection? Plus, you'd have recharging at anchor or during dry storage, too!"
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I like that idea Joe, but seems it would be more expensive (especially to have a quality system) and not have big panels running all across the roof. I really like what Greg did on Ari, with his panels running along the side roof, out side of the hand rails. Low profile, and unobtrusive.

Thanks for reminding me of that idea.

Harvey
SleepyC :moon

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ssobol":dj6qonea said:
A couple of observations/questions.

The hookup as shown could lead to the tow vehicle battery becoming discharged. It would be better if this system was powered through something switched by the ignition switch.

While I could see it being useful when towing my boat long distances, like when we are using the refrigerator. However, it seems designed to charge the battery of a vehicle towed behind a motor home. How much utility does it really provide? AFAIK, the only thing that would be a demand on a towed vehicle battery might be the brake lights. At least with my vehicles, they can be undriven for at least 3 weeks (often longer) and will start right up without the need to charge the battery. If I was towing a vehicle behind a RV it'd probably be used at least once a week, so keeping the battery up shouldn't be an issue.
Click to expand...

The issues in a "TOWD or TOAD" as called in the RV world also include at times the engine computer and other systems being left on, but often the main load is the auxiliary braking system. For example the brake system I use uses an air compressor and compressed air to apply the "TOAD" brakes. The issues are when "TOAD" is towed day after day as in across country, and not used, or only have the engine run for 5 minutes each day to lube some of the running gear. There are only a very limited number of vehicles which can be towed 4 down.

These charging systems are designed to be used only when the RV is underway, and the alternator is charging the start battery. They are not run off the RV house battery.

I am not using a charging system currently--and the refrigerator/freezers are running off the 200 amp Li ion battery bank--and could not be charged safely by the vehicle.
 
SleepyC will have a "Toad" system soon. It will be a modification of the system Colby is using. Taking the charging power from the battery charging pin of the 7 pin connector and running it back to a bus on the helm station bulkhead that have a 4 or 6 gauge wire that runs from there back to the battery switch. There will be a plug pigtail near the 7 pin truck outlet, and that line will run into the V-birth via the deck pipe.

I will be testing this week to see how the voltage maintains. Will report back.

Harvey
SleepyC :moon

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It is in, My boat, SleepyC :moon is now somewhere along the lines of a toad (Towed) and a boaterhome. I towed to Portland yesterday and the system is working great. The pickup did not have a hot pin on the 7 pin plug for charging a battery, SO, we had to run the wire through a solenoid and fuse and then run a #10 wire back to the hitch 7 pin plug. From there a new pigtail for the 2 wires (Hot and ground) to a dual contact plug. Then on the boat, a line (again a #10 wire pair) from the helm bus, forward and with a loose end so it can go up and down through the deck pipe, At least now that is serving some purpose. I would have liked to have an extra couple of feet of slack, but it will work the way it is. AND it charges the battery and I can run the camera without worrying about running the battery down.

Colby, it is like your system somewhat, although I think the toad system that John gave the link to might have been a better (fewer $$) deal at least I have heavier wire :lol:

Happy boater homing.

Harvey
SleepyC :moon

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Sounds like you'll have a good system. I think my wire was 14 gauge, but having the heavier wire can't hurt. I also had to run a positive wire back to my trailer hitch as well. The F150 apparently has the wiring there, if you have their expensive brake controller, however I don't think it was as heavy as the what I ran. I also used 10 gauge wire going thru a CB from the truck's battery to the rear trailer harness pin.
I have decided I'm going to try using my new Engel Frig/Freezer on my Alaska trip. I'm going to try it out first on some local runs. Since I'm going solo, and don't have a lot of cockpit room, I found a way to set the Engel in the front passenger seat. (I first put a board down in front of that seat where a cushion goes to make it into a bed.) Everything is strapped down nicely. My plan is to see if I can run the Engel while traveling, without running my boat house battery down. Ideally, the "toad" system I have set up, will provide enough current to maintain the boat's house batteries while the Engel is also running. I don't expect the Engel would run the whole time, but rather cycle off and on. I expect the boat's house battery will provide the load, but then the truck will continue to charge the battery back up when the Engel is cycled off. If my 5 amp fuse don't blow, I'll be happy. If not, back to the drawing board if I want to run the Engel also. Colby
 
A constant 5 amps for 10 hours gives you 50 amps. The Engel will require about that in 24 hours. We have a group 24 AGM as the second battery in our GMC. We ran the Dometic (about same power draw) for 6 months continuously in the truck. We probably averaged less than 2 hours a day...but had full 30 amps to the battery while the engine was running and the battery was low. Our longer trips topped off the battery. This was with southern heat--a trip up North would require less power.
 
Did you actually measure 30 amps while charging your boat batteries from your TV?

I would have thought that with 20' of run to the back of the TV from the alternator plus another 20-25' in the boat, 10 gauge wire would cause such a high voltage drop (more than 2 volts at 30 amps) that it wouldn't supply that much current, unless the battery was nearly dead.

I have never measured more than 15 amps or so to my RV trailer with the battery at 50% SOC.

David
 
I think my worry about rather or not my "Toad" system could handle the Engel portable refrigerator/freezer, is a non-concern. I ran the freezer today on 12 vts, and it never drew more than 3 amps. I also checked and found I've actually got a 10 amp fuse in my charging system between the truck and boat, and the wiring should easily handle 10 amps. Harvey, I think you are going to find your system is more than ample to handle keeping your boat batteries charged while towing. Colby
 
USE REPORT:

I towed to Portland and back last week. The charging system worked perfect. I just need to remember to keep the battery switch in the "Both" position. I wish I had a bit more slack in the wire from the boat to the plug. 2 feet of slack would have been nice to allow for a bit of play in positioning but the charging system works.

Harvey
SleepyC :moon

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Bringing this thread back to life as I learn a little more about my F150's charging system. I have the factory installed AGM battery in the pickup. And after doing a lot of research (as I am thinking about replacing this battery with a standard lead acid battery), I find that the truck is only feeding about 13.2 volts into the AGM. Apparently the AGM's don't need or like the higher charging voltages. If and when I replace this battery with a standard lead acid, I can use Fortran to recode the truck's computer to charge for a regular lead acid battery. The lower charge rate on an AGM may explain also why I wasn't getting more voltage back to the boat through the toad cable. (Along with the voltage loss in the cable.) I've been having some other problems lately with my Ford's Sync system as well. This is the system that runs the FM/AM radio and other electronics. And a couple of times where the battery appeared to not have enough voltage to start the truck. Usually after I had been running and the engine was hot. None of this may be related, or it may all have something to do with the battery. I'll do some tests including a load test, on the battery this week. But thinking about all this, I wonder how reverse voltage affected the battery. Over night when Boater homing I usually leave the toad cable plugged in. So there is some drain on the truck battery overnight from the boat house batteries. I've also ran the boat's generator a few times, thus putting that voltage back through the cable to the truck. However, voltage loss in the cable would likely lower the voltage traveling into the truck battery. Just thinking out loud..... Colby
 
Colby,
What side cable are you running? As I recollect you put in a "Toad" system or something similar.

I don't leave the boat plugged into the truck battery, for as you note, the chance of running down the truck battery. Many pickups have space for.a second battery. In the F250 I did install a second battery.

Protection of the boat/truck battery integrity can be achieved by a VSR between the boat and pickup.
 
Hi Bob,
I ran 10 gauge wire from my truck battery back to the trolling motor style plug in the back of the bed. Initially I was unplugging the trailer toad cable, but then started just leaving it plugged in. Probably not a wise choice.... Colby
 
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