Recharging trolling batteries

[NHBull]

I suspect I know the answer to this, but how do people recharge their trolling batteries if they keep their boat on a dock without AC?

Can a solar panel work?

 

Thanks in advance

Al

[Choporoz]

I'd love to hear that solar has improved the past few years.  I used to have a 5 watt (I think...maybe 7.5w) panel, but it took most of a week to charge a 1/2 drained, size 27 battery.  For maintaining charged batteries, they're probably decent enough, but it was way too slow for me. 

[Angry John]

It will take a decent size panel to charge a 31 group battery and most I would think are running 24v systems.  The cost of that panel would worry me for theft

[Al Wolbach]

Small generator may be only hope but theft could be a problem.

[RoLo]

 

Good question.

In fish camps without electric docks, I generally wind-up foregoing the electric motor.

This summer for instance, we're renting a boat in Manitoba that has no electric motor,

much less a live dock.  We vacationed a few times at a lodge in the Thousand Islands

that had dead docks.  There we'd take a long lunch at a waterfront restaurant with live docks

where I'd plug to the onboard charger.

 

I've had no experience with solar panels, but they're getting more efficient by the year.

As Al mentioned, a portable generator and 100 ft extension cord should fill the bill,

but I'd also be concerned with theft.

 

Roger

[Firefish Alumacraft]

If your main engine has a alternator you can get Minnkota 12vdc-2-3 bank 12/24vdc charger. you just have to keep your main engine running for it to charge. 

 

http://www.minnkotamotors.com/Battery-Chargers/On-Board-Chargers/DC-Alternator-Chargers/

[Scott F]

I've had this happen. It was a pain, but I've had to take the battery out of the boat, bring it up to the room and charged it there. It all depends on your location. I've also run a 100 foot extension cord through a window in the cabin down to the dock.

[Way2slow]

To properly charge your battery, a charge rate of 10% of the rated capacity should be used.  For the average TM battery that's approx. 10 amps.  For two batteries in parallel, that would be 20 amps.  For two in series, it would be 10 amps but would require a 24V charger or a two bank charger with 10 amps per bank @ 12V.

To get this kind of power from a solar panel you are looking at 240 watts of solar panel or 120 watts and charge one battery at the time.  I have seen 30-45 watt panels that can be used as a maintainer when storing the boat in places with no power but that would not be sufficient to charge a discharged battery.  Anything less than that would pretty much be a waste.

As for using the motors charging system, unless you are running one of the newer motors that has a 35-60 amp charging system buying something to use the motor would be a waste of money, unless you spent all day running the big motor.  The smaller charging system will not put you enough free power to charge the TM batteries more than a very small amount.

A small 800-1200 watt generator running a good charger would be your best bet, plus those small ones are usually very quite.

[WestBranch]

I have an 80W solar panel with built in charge control I got from northern tool.

It'll fully charge a size 27 battery from just under half in a day, if the sun does it's part.

 

 

[Jay B.]

I have a seasonal campsite for my 5th wheel with no room at the site to park my boat.  I keep it in an open field on the campground and hook the TM battery up to a 100 watt Renogy solar panel (approx. $110) with a Flexcharge PV7D charge controller ($67) with a 10 ga. quick disconnect.  I lay the panel on a couple of cheap sawhorses and the sun does the rest.  This setup will top off a 1/2 discharged TM battery in about 1 to 3 days, depending on the sun.

 

The PV7D charge controller will handle two batteries independently, so it could be used for 24V applications.