trouble with trolling motor batteries

[buddy brown]

I'm having some trouble w/ my trolling motor batteries maintaining charge. Tested the batteries and one was at full charge and the other was toast. Also found a blown fuse (15 amp) which I replaced w/ a 20 amp fuse. Hopefully it was just the fuse..

[Rob Cummings]

What batteries do you have? (gel cell or lead acid?)
How old are they?
How often do you run them all the way down?
How long do you leave the charger plugged in for?
What charger do you have?
What was the fuse to/for?


Sorry for firing back with questions, but answering them will help people respond with more exact answers to your particular problem.

[scottsweet]

Replacing a 15A with a 20A fuse just because may not be a good idea. You should probably look in to why the fuse blew first. The 15A may be protecting something and going to the 20A may not do that any more.

As for batteries...there are lots of things to look in to. There are two things that kill batteries more than anything:

1. Overcharging - this heats up the batteries, potentially gases them and significantly reduces the life of the battery.
2. Leaving them uncharged for too long. When the batteries go below a certain voltage....the voltage corresponding with about 70-80% of capacity or so, they start to sulfate. Sulfication reduces the life, capacity and ability to hold a charge. Ever have that battery that says its fully charged and only 12.1V!? That's a fully sulfated battery.

Many people do not charge all of their batteries properly, especially their cranking battery. If you are running electronics and your livewell pumps over a weekend tourney and not fully charging your cranking battery, you are reducing the life of that battery by a whole bunch.

On trolling motor batteries, you really want to try to keep them as balanced as you can or you heat up the stronger battery more than it should (its pulling more current) and therefore ruin it in the process. Balanced batteries means that they are at about the same resting voltage after being fully charged and are fully cooled (sitting overnight after a full charge). If you have a more advanced battery analyzer, you can find out the capacity after a full charge as well.

The best way to check the balance of your batteries as a layman is to fully charge all your batteries and then let them sit overnight. Take a digital voltmeter and check the voltage (resting voltage)...they should be the same or within 0.1 V of each other or there abouts. More than 0.5V of each other means one of them is significantly weaker. If there not balanced, it is best to replace all the batteries at one time so that they are on the same "life" cycle. It's kinda of like replacing your front tires on a car...you should not replace only one if one has a lot of miles on it.

These concepts apply to all battery technologies we have available to us for our boats. The resting voltage will be different across the different technologies (AGM, regular lead acid, deep cycle) so it's best to use the same battery for all your trolling motor batteries. Keep in mind, you may not be able to use all brands/models of deep cycle batteries for your cranking battery as it depends on its CCA (Cold Cranking Amps) rating.

Personally, I really like the Lightening Series batteries from DualPro (Made by Northstar) ...especially the 31 series. They have the highest capacity of any battery available and can be both a trolling motor or cranking battery. The Series 31 have a 1500 A capacity. While they are quite expensive, they last a real long time and you would be hard pressed to drain one of these babies on a weekend tournament. Even the 27 Series (1100 A) outperform most other 31 series out there.

I know lots of people who just use the $60-$80 battery from Walmart and just replace them every couple of years when they die. Either way, just remember to keep them fully charged as best you can. If you want to be real efficient and be on top of the heap with charged batteries, use the Stealth Charger that charges your batteries every time you make a run on the lake or while driving home.

Hope this helps...

[Brian D.]

You should write an article on the subject..

[Brian D.]

You should write an article on the subject..

[buddy brown]

thanks for the replies. I'm running two everstart for the trolling motor batteries. They are a couple months old. The charger is a dual bank charger I don't know the make it's in storage, but it is standard on the 06 champ 187cx. I keep it plugged in all the time as well as a trickle charger for the cranking battery. the green light on the charger was green and I took it out to the silverwood and I was dead in the water w/ 25mph winds not good. I'm kind of a moron when it comes to technical issues, the fuse was the only one blown so I changed it. I wish I knew what was up..

[mark poulson]

If the fuse was the problem, you should put another 15 amp back. That fuse is sized to protect the circut/accessory from burning out. If you put too big a fuse in, you defeat the purpose of the fuse.
If the fuse was on your trolling motor circut, and your batteries are new, chances are you have a problem with your charger. Or maybe a bad connection at the batteries.

[DAKINE198]

I would check the battery condition with a volt meter. Keeping you charger plugged in 24/7 May not be the best idea. Follow Scotts recommendation, I run a '04 198 with a triple charger w/ 2x SCS225 Trojans on the troll and a generic brand 27 marine for the electronics(that one came with the boat). Before I plug in my charger I always check 2 things. 1. the water level in each cell. Charging a battery with exposed cell plates greatly reduces the life cycles of you batteries.
2. I take a volt test before and after charging. After a hard day of running they usually are aroung 12.58 on a volt meter which is borderline after charging its around 12.96-12.85. Also it would be wise to invest in a Hydrometer to measure the specific gravity of each cell. This way you know if one cell is going bad or has dropped off from the rest of the cells.

[19X]

I have always been told to charge your batteries to full power then unplug after each use. If you leave them dead to long they will slowly lose there charging ability. If you have green lights on the charger you might have a drain on system from somewhere else like pumps or lights... .02

[buddy brown]

Thanks for all the help. It appears to be the fuse. just checked both and they are both charging evenly. Hopefully that is it.

[Leroy_B]

Also check that all the wing nuts are tight, i had one semi-loose wing nut on one battery which caused its charge to be lower than the other battery. Thus, you lose power much sooner in the day can also cause a fuse to blow with one fully charged and one partially charged. Hope you get it fixed, these things can be frustrating.