Charging a trolling motor Battery

[anchor man]

Does it work to hook up my deep cycle batt. to my Yamaha F150 (instead of the starting batt.) to give it some charge while cruising? I know this motor kicks out 35amps, so I thought an hour or so of cruising might give it some decent charge.

Thanks

[Dances with Walleye]

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Does it work to hook up my deep cycle batt. to my Yamaha F150 (instead of the starting batt.) to give it some charge while cruising? I know this motor kicks out 35amps, so I thought an hour or so of cruising might give it some decent charge.

Thanks

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I've had times on long camping trips where I've got no power, and I went through my 3 trollng batteries faster than I thought... Hooked them up to the battery of my F-150, and just letting the truck idle, it recharged the battery in about 45 mins.

[marine_man]

It would work... but you would need to be running at 1/2 to 3/4 throttle at a minimum to make it worthwhile for that hour or so.. depending on how discharged your trolling motor battery was - the 35 amps is at WOT...

marine_man

[BobT]

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I've had times on long camping trips where I've got no power, and I went through my 3 trollng batteries faster than I thought... Hooked them up to the battery of my F-150, and just letting the truck idle, it recharged the battery in about 45 mins.

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One should be careful here. The truck running at idle didn't likely fully charge those batteries or even one of them in 45 minutes. Most likely they drew their charge from the truck's batteries. You do this too much and you could find yourself unable to start your truck.

Another consideration. The power output of an alternator is not designed to restore dead batteries on a regular basis. Using the truck to maintain your boat batteries plus operate your truck's electrical circuits is inviting problems with your truck's charging system by overtaxing it.

It might work in a pinch but it is best to use a charger and not rely on your truck to do the work.

Bob

[pfluemis]

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Does it work to hook up my deep cycle batt. to my Yamaha F150 (instead of the starting batt.) to give it some charge while cruising? I know this motor kicks out 35amps, so I thought an hour or so of cruising might give it some decent charge.

Thanks

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Search: Dual Pro - Pro Xtra II Charger

Or search: Trollbridge24

[Ufatz]

Very refreshing to see a direct and correct answer! BobT is dead-on correct. Heed his words.

[Dances with Walleye]

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Quote:

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I've had times on long camping trips where I've got no power, and I went through my 3 trollng batteries faster than I thought... Hooked them up to the battery of my F-150, and just letting the truck idle, it recharged the battery in about 45 mins.

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One should be careful here. The truck running at idle didn't likely fully charge those batteries or even one of them in 45 minutes. Most likely they drew their charge from the truck's batteries. You do this too much and you could find yourself unable to start your truck.

Another consideration. The power output of an alternator is not designed to restore dead batteries on a regular basis. Using the truck to maintain your boat batteries plus operate your truck's electrical circuits is inviting problems with your truck's charging system by overtaxing it.

It might work in a pinch but it is best to use a charger and not rely on your truck to do the work.

Bob

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The first time I did it...

I was watching my truck's battery gauge... The night before I'd been playing my radio, and used the head lights to tie up some lindy rigs... So when I started it my Battery gauge was reading lower than usual...

Hooked the Trolling battery up to it jumper cable style... I sat there watching it to make sure... And my battery gauge climbed back to it's normal position while I had the trolling battery on.

Granted it was slower than past times when I've drained doing night tasks.

But it lead me to the conclusion that the Alternator and the 5.4L engine were capable of charging two batteries at once.

I've only done it a handful of times, as I only use it for rather tough circumstances like this where I'm out in the bush.

*****

QUESTION:

What then is going on with these Tow-Charger Kits you can have installed into your truck to charge your boat battery... Such as you will find on a HSOforum like Fishhousesupply (Contact Us Please) com?

[Scott K]

By using your truck to charge the batteries, I would only do this if you had to. When you hook up a dead battery to your truck and charge it that way, the alternater will get very hot, it is hard on it. If you do it a couple times it will be ok, but if you do it a lot, you will be replacing your alt. and now days they are not cheep!

I really dont know what type of alt your boat has, but Im sure its not intended to run that way either!

[anchor man]

My trolling batt. isn't dead, probably around 35-40%. Makes sense that the alt. is made for maintaining a fully charged battery vs. re-charging a low/dead one. I'm racing up to the cabin tonight and won't have time to re-charge before hitting the water. Thought maybe a 40 minute boat ride to my fishing spot would give it a bit of a boost for the night's trolling.

[pfluemis]

The alternator in a vehicle is designed to operate the cars power, and charge the battery. The more power the vehicle uses, the alternator should be proportionately larger. This is why those kids cars with big "thumper" stereos run 140 amp+ alts, and offroad trucks with a lot of offroad lights too. The same can be done to tow vehicles. There is a percentage of "room" designed into the system to allow for add on's, but usually not much. In order to set up a charging system correctly, you would have to increase the amount of amperage output of the alt by the amount of extra amperage needed plus a little extra. Alternators by design, are meant to put out power. The percentage of power vs. max output, will dictate how long the alt will last (under normal circumstances).

RV's have been doing this for many years. Years ago Ford made a truck called a "Camper special" and a special one ton called a "super camper special". These trucks had 2 batteries. One for starting, and one with an isolator that ran the camper. The alt maintained/charged both batteries, but isolated the camper battery so it never effected the starting battery. This is the same concept that the "charge while you drive" systems are using today. As long as you have a large enough alt, the system will work fine.

Yes, you will wear out the alt faster than normal, but at $200-$450 for an onboard charger, you would have to go through 2 extra alternators over the life of the truck in order to come close to costing more money. Not likely if the system is set up properly in the first place. With lifetime warranty's on replacemet alt's, it's not likely you will need to buy more than one anyway's.

As far as the question about directly hooking a dead or low battery to an outboard, you might be looking for trouble. If you have a newer motor, you might be alright as a lot of them put out much more power than the older ones. The older ones, on the other hand, were only meant to "top off" a battery that was used for starting and running navigation lights. Disconnecting the starting battery, and hooking up a low battery could be too much for the older system. Use caution, and plan for a failed charging system if you attempt this. It's all dependedent on the condition of the charging system. Everything might go ok, then again.....

[anchor man]

pfluemis,

It's a 2004 Yamaha 4stroke 150hp. I don't like the sound of putting any extra strain on my still new toy, so I'll probably just use the remaining trolling charge and fire up the big motor for some cranks later tonight

[BobT]

I suppose if one is comparing the cost of replacing a truck alternator to the cost of on-board chargers you have an argument. However, when you can get a simple battery charger for less than $50 things change and where do you get an oversized alternator for less than $200 these days not to mention the inconvenience of finding yourself stuck at some remote destination with a fried alternator.

Personally, I think I would go with spending the money on a charger and leaving my truck alternator to handle what it is designed to handle.

Bob