Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Battery charge while towing


medicdiver

Recommended Posts

Just wondering, My truck is set up with 7 prong plug. One plug is always battery voltage of truck, designed for campers lighting and such. It is a pretty standard set-up that most newer trucks have. Is it possible to run a wire from that extra prong onto the trailer and charge the boat batteries with the truck while driving down the road? I just figure I drive an hours or more to the lakes and wouldn't hurt to charge the batteries while towing.

Link to comment

Charging your batteries by driving down the road won't do you any good. They should be charged before you leave your house. What good do you think a 10 guage wire is going to do for your batteries anyways. At the most it would give them a small trickle and doubt it would even be a noticeable gain after only 1 hour on the road. I wouldn't recommend trying this.

Link to comment

doesn't work quite as well as you would think. Have tried it several times over the years. The battery voltage running to your 7 prong plug is only #10 or in some cases #12 wire. The truck manufactors circuit breaker or fuse this at 30 or some trucks 20 amps. This works if your batteries are just a little down. If they are way down they will try to draw 70 or 80 amps . Blowing fuses or tripping breakers. The second problem is voltage loss. batteries need 14 to 14.2 volts to charge. Your truck running makes 14.2 volts under the hood.But after it travels to the back of the truck then into what ever your rig up from the 7 prong to your batteries you will be down to 13.2 or as little as 13.

Link to comment

I will take a different view to this. While I have never heard this being done with boats, it is common on every towable RV going down the road. The charge line on the tow vehicle is designed to charge the batteries on the RV. I agree that it will not do much to a fully depleted battery, but to top them off or give them a small charge, you would be amazed. I have two golf cart 6 volt batteries on my RV and they charge up rather quickly while I am driving down the road. I would think running the charge line to the boat batteries would not be the greatest looking setup though.

Just adding another view....and real life experience!

Link to comment
Good to know. Just a dumb thought I had the other day to make sure batteries were charged.

It's actually a pretty good idea just not really worth the effort for the returns you'll get. If you rely on that method you'll be replacing batteries every year. Really important to top them off when you get home from the lake.

Link to comment
Good to know. Just a dumb thought I had the other day to make sure batteries were charged.

It's actually a pretty good idea just not really worth the effort for the returns you'll get. If you rely on that method you'll be replacing batteries every year. Really important to top them off when you get home from the lake.

I guess it depends on the electronics in the boat, because i have stock stereo and that is about it (other than PP), and I got 7 seasons out of the stock BU battery (just replaced it this summer just to be safe, and there was a good sale at West Marine). Boat sits on a lift, I charge the battery once at the begin of the season, once at the end of the season, once in the middle of winter. Other than that, it just charges from the alternator when we are skiing.

I also am on the original 2 batteries in my fish boat, and it runs Fish Finder, GPS, VHF and stereo (with a small amp). I do the same charge on that as the ski boat, and I am on year 4 on those batteries.

Link to comment

I use a solar-cell that plugs into one of the power plugs. It has a suction-cup and affixes on the inside of the windshield. I leave it in the window when we are pulling the boat and/or parked for long periods on the lake. We don't depend on it (making sure we have battery prior to leaving) but it can help reduce the drain.

Edited by Squag Mon
Link to comment

I hate to be the one with the obvious comment, but if your going to rely on the truck to charge your boats battery. Why don't you just rely on the boats charging system to charge the boat battery or upgrade the alternator to a higher output Dontknow.gif If you only have one battery, it shouldn't go dead, unless your running a pretty good size stereo system.

Just my opinion on the charging while driving thing :)

Link to comment

We have had two truck slide-in campers in the past and they were both set up to recharge the camper battery from the truck, which is essentially the same thing.

Three of the GM trucks that I have owned were all set up and pre wired from the factory for this type of hook up, be it a slide-in camper or a tag-a-long RV. We currently own a 32ft tag-a-long camper that is also set up this way and we have never had an issue with it or our other campers before.

In the slide-in campers, we ran the radio, interior lights and the furnace (fan) off of the battery while primitive camping a lot.

Of the times we would run the battery down without electricity, you can just start the truck for a while (if there is no generator available) and the battery would be good to go for a while again. We even made a small extension for this because the campers would be taken off of the truck while roughing it to launch a boat or run into town or what ever (10 gauge wire really is minimal).

This type of set up has a thermal overload breaker installed on the campers that is usually located just after the plug somewhere before the battery charging feed/terminal, the one we have now is 30amp.

It may be worth mentioning, every vehicle that we have utilized this set up with has had a stout alternator. Currently we are using a ¾ ton diesel Suburban which I’m sure has an adequate amount of charging capacity for both the camper battery and the vehicle battery(s).

It is also worth mentioning, that such a set up has an in line fuse (example: 30 amp) right after the battery on the vehicle to protect the line feeding the camper/trailer just in case it were to short out, it would be enough amperage to do some damage or start a fire if left unprotected.

My first hand 2 cents… (On the usage, not the fire part)

Edited by lakewaterjunky
Link to comment
I hate to be the one with the obvious comment, but if your going to rely on the truck to charge your boats battery. Why don't you just rely on the boats charging system to charge the boat battery or upgrade the alternator to a higher output Dontknow.gif If you only have one battery, it shouldn't go dead, unless your running a pretty good size stereo system.

Just my opinion on the charging while driving thing :)

If I forget to shut off the Perko switch when I get home, my batteries will drain in less than two weeks due to parasitic voltage draw from the stereo system. It sucks to get to the lake are realize both batteries are dead. Not that it has ever happened to me. Whistling.gif

Link to comment
I hate to be the one with the obvious comment, but if your going to rely on the truck to charge your boats battery. Why don't you just rely on the boats charging system to charge the boat battery or upgrade the alternator to a higher output Dontknow.gif If you only have one battery, it shouldn't go dead, unless your running a pretty good size stereo system.

Just my opinion on the charging while driving thing :)

If I forget to shut off the Perko switch when I get home, my batteries will drain in less than two weeks due to parasitic voltage draw from the stereo system. It sucks to get to the lake are realize both batteries are dead. Not that it has ever happened to me. Whistling.gif

What is that Dontknow.gif I don't have a perko switch on this boat but have in the my other ones, my starting battery has never failed me (knock on wood :) ) I only have to charge my stereo batteries about once a month if I use the boat every weekend.

Link to comment
I hate to be the one with the obvious comment, but if your going to rely on the truck to charge your boats battery. Why don't you just rely on the boats charging system to charge the boat battery or upgrade the alternator to a higher output Dontknow.gif If you only have one battery, it shouldn't go dead, unless your running a pretty good size stereo system.

Just my opinion on the charging while driving thing :)

If I forget to shut off the Perko switch when I get home, my batteries will drain in less than two weeks due to parasitic voltage draw from the stereo system. It sucks to get to the lake are realize both batteries are dead. Not that it has ever happened to me. Whistling.gif

What is that Dontknow.gif I don't have a perko switch on this boat but have in the my other ones, my starting battery has never failed me (knock on wood :) ) I only have to charge my stereo batteries about once a month if I use the boat every weekend.

Not sure what all is drawing current, but I assume the head unit, the three amps, and possibly the EQ. Never had the time to trace where it was going, but know for sure it is the stereo system. If I isolate the stereo battery from the rest of the boat, it will go dead in a week and the starting battery will be just fine.

Link to comment
I hate to be the one with the obvious comment, but if your going to rely on the truck to charge your boats battery. Why don't you just rely on the boats charging system to charge the boat battery or upgrade the alternator to a higher output Dontknow.gif If you only have one battery, it shouldn't go dead, unless your running a pretty good size stereo system.

Just my opinion on the charging while driving thing :)

If I forget to shut off the Perko switch when I get home, my batteries will drain in less than two weeks due to parasitic voltage draw from the stereo system. It sucks to get to the lake are realize both batteries are dead. Not that it has ever happened to me. Whistling.gif

What is that Dontknow.gif I don't have a perko switch on this boat but have in the my other ones, my starting battery has never failed me (knock on wood :) ) I only have to charge my stereo batteries about once a month if I use the boat every weekend.

Not sure what all is drawing current, but I assume the head unit, the three amps, and possibly the EQ. Never had the time to trace where it was going, but know for sure it is the stereo system. If I isolate the stereo battery from the rest of the boat, it will go dead in a week and the starting battery will be just fine.

Have you checked to make sure that your amps are turned off when you shut the key off? Just a suggestion, you probably already investigated everything!!

Link to comment
...... batteries will drain in less than two weeks due to parasitic voltage draw from the stereo system. It sucks to get to the lake are realize both batteries are dead. Not that it has ever happened to me. Whistling.gif

Sounds like your not using the boat enough! Rockon.gif

If I don't get on the boat for 2 weeks, I've got other problems to deal with!

Link to comment
  • 2 weeks later...

Jeramy, you must have something staying on. Your audio system when powered off should only pull enough to keep the clock on the head unit running and to hold the radio station presets.

The problem with a larger alternator on a boat of our type is that you generally are not turning enough RPMs for long periods of time. Most all alternators put out very little at idle (or barely in gear tooling around with the tunes on) no matter the size. They have to be spinning to create output. Generally if you get it to spin faster at idle (usually a smaller pulley) it is really zinging at high RPMs and can wear out the bearings prematurely.

Link to comment

OK, to clarify a little. I charge the batteries when I get home after a day out, and charge them the night before when I go out. So I am not relying on the truck to charge the batteries all the time. I do use a charger on the batteries as well. I have not ever had a no start to a dead battery. I did however have one in my waverunners once, and I did this to charge the batteries while traveling. Much smaller batteries though. I was just trying to make sure that the batteries were fully charged before I got to the lake. Nothing more embarassing that the boat not starting, or getting a jump on the lake.

Link to comment

There is no problem using the truck to charge the boat battery. The gauge of the wire will not matter as you will not be exceeding the maximum amperage that the wire is rated for.

Do it right........use an inline fuse close to the battery, no ghetto wiring jobs and all will be good.

I think it is a great idea and extra insurance against having a dead battery. Thumbup.gif

Of course if you want to charge your battery every time you get back AND every night before you leave go ahead....but seems like just another PITA thing to do added to the million other things you have to think about to get ready for a day on the lake.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...