On Board Charger

Hey all, I have a Cabela’s gift card burning a hole in my pocket, and before I blow it on more Senko’s I am thinking about getting an on board charger for my trolling motor battery. I only run a 12 volt system so I don’t need a huge charger. My questions: First, are these worth the cost? I have been holding off for that reason. Second, do you connect it yours to your cranking battery as well, or just the deep cycle trolling motor battery. Any opinions welcome.
Thanks,
Dan

Dan Baker wrote:

First, are these worth the cost? I have been holding off for that reason.

Totally worth it. Come home, plug in, and you know you’re good to go next time out.

Dan Baker wrote:

Second, do you connect it yours to your cranking battery as well, or just the deep cycle trolling motor battery.

I believe best practice is to connect both. Get a 2-bank charger and connect leads to each battery. That way, you know your starting battery is always topped off.

Can’t hurt to put the starting on a bank, and if you ever have intentions of going up to a 24v system, or just having two batteries for your 12 volt system you’ve got that second bank already on your charger.

Great advice guys, thanks. Last question, the option are 8amp or 12amp. The price difference is about $30 between the two. Does the larger amp number mean that it will charge faster? Is there any other value of going with the bigger unit?
Thanks,
Dan

12 amp will charge faster. If you fish back to back days, go big. If not, an 8 amp should do the trick.

Make sure you look at the specifics of how those amps are calculated. Are those 12 amps PER BANK or 12 amps split across the banks. Some manufacturers display it one way vs the other. 12 amps per bank would be better than 8 amps per bank, but if its 12 amps split across the banks and 8 amps per bank the 8 amp one is actually better.
So just be aware of that difference.
yes, Ideally you would hook them up to all of your batteries. For me I only have a 2 bank unit that is connected to my trolling motor batteries, but I also have a Stealth DC alternator charger on my boat hooked in the system that will recharge my trolling motor batteries while I am on the water. It does this using the Outboard motor’s alternator once the cranking battery is fully charged. Its been an irreplaceable addon that I have done because of how and where I fish in remote Canada for a remote camping trip with no access to electricity.

Onboard Chargers are well worth it! The size depends on how often you fish back to back outings. I myself would not want to be lass than 10 Amps per bank, but know people that get buy with just 5 Amps per bank. I would definitely put the charger your starting battery, today’s electronics suck quite a bit of juice and if you fish at night you are running lights, along with other boat accessories. I do not know what size your outboard is, but because you are getting by with a 12 V trolling motor, it probably isn’t too big. My last 60 HP motor only put out 5 amps at WOT, so unless you are running a long ways you are not recharging your battery all that much. Plus with the onboard charger on your starting battery you will also be able to know that you started with a fully charged battery as they have lights that will tell you if your battery (when plugged in) is fully charged or not.

It’s simple, yes they are great. Get a 2 bank so all your batteries are covered. $30 to get more capacity, go for it. Assuming the numbers are equal.

I’ve got a 5amp/bank. They work for me. However that’s because I don’t hammer my batteries and have electricity on the dock.

When my newest boat starts going to Ontario then I’ll move up to a 10amp/bank to get more done quicker when I use a generator.

Problem with thinking about a 2 bank is that the charger has short leads. The charger does not operate correctly by simply adding extension to the charger leads. If both batteries are close to each other it works, otherwise it requires 2, single bank chargers to cover both your batteries. I use a 2 bank in the front of the boat for my 24 volt system and a single bank charger in the back for the starting battery.

SuperDave1959 wrote:

Problem with thinking about a 2 bank is that the charger has short leads. The charger does not operate correctly by simply adding extension to the charger leads. If both batteries are close to each other it works, otherwise it requires 2, single bank chargers to cover both your batteries. I use a 2 bank in the front of the boat for my 24 volt system and a single bank charger in the back for the starting battery.

I have not experienced this with my chargers. I’ve had three different chargers over the years (two and three bank) some extended leads, some not, no problems either way. There are extension leads sold to just plug and play for this purpose. I’ve always just sliced in longer wires, again without any issues.
The below info came from a FAQ page;
Can I extend the output of one bank 10 to 15 feet to the other end of the boat?
Country: United States
State: Minnesota
Age: 56-65
Gender: Male
2 months ago
by
BigSpaceMinnow
Answer this question

Yes. That can be done. Just be sure to follow the direction in the owner’s manual for doing so.
1 month, 4 weeks ago
by
Minn Kota Support

The smart chargers read resistance and that changes with length of the leads.

SuperDave1959 wrote:

The smart chargers read resistance and that changes with length of the leads.

Using the proper size wire, resistance won’t change enough to matter. I’ve done it on two different chargers according to the manufacturers’ instructions. Works fine. Here’s a quote from the MinnKota MK 318 PC manual”

“If the DC output cords are not long enough, they may be lengthened by splicing and soldering 12 AWG (minimum) wire. Each splice should be covered with dual wall adhesive lined heat shrink tubing to protect the joint from corroding. The splice should be made between the fork in the output cable and the fuse holder. The fuse holder should always remain within 7” of the battery terminals. The maximum extension length is 15 feet. You may contact the Minn Kota Service Department with any
questions.”

SuperDave1959 wrote:

The smart chargers read resistance and that changes with length of the leads.

Minn Kota replied that their charger leads can be extended. My smart charger leads are extended in accordance to the directions included with the product.

What brand are you using that can not be extended? Guys might want to steer clear of that brand.

I have a Promariner ProSport 20 amp charger with 3 banks, all 3 are extended with generic 12 AWG wiring, just spliced/taped them up, I haven’t had any issues in about two seasons. Definitely worth it, and I would always overdo it on amps if you can. My batteries get 6-7 amps a piece, and since the starting battery probably gets charged after the first couple hours or so, the TM batteries wind up getting most of the juice. This setup has allowed me to use them hard all day, charge overnight, and use hard again the next day for multiple days in a row without issue. You have to remember these batteries can hold/discharge 50-100 amps, and trolling motors tend to draw 10-50 amps an hour, so after doing the math it’s pretty easy to see why more is better.