You may consider two Group 27 batteries for your TM (either deep cycle or dual purpose). You don't have a huge boat, so that could be a lot of weight for you. If you are really trying to keep the weight down, you can probably make do with two Group 24 batteries for a boat that size. It all depends on how "into" the TM you typically get. Heavy user, Group 27, Lighter user, Group 24 will do. Unless you have a lot of electrical equipment, a Group 24 is fine for the starting battery as I'm sure you don't have a big V6 back there!

You didn't tell us what onboard charger you have. When you get a look at it, let us know and we will comment. You may already have one that is adequate.

Your Dual Pro charger is designed to be safely plugged in continuously. If it is not malfunctioning, it won't boil off a good battery. I don't remember the exact profile for the older Dual Pro units, but I do know they shut down and monitor battery voltage, so they aren't really charging 24/7. When a given battery's voltage drops below a certain point, the charger will turn on that bank to recharge it.

Now, if you have a failing battery that won't hold a charge very well, the charger will cycle a LOT more frequently than it ever should when connected to a good battery. These frequent charging cycles will eventually deplete the electrolyte level. This problem is caused by a failing battery, not the charger. This is why one should check the electrolyte level as part of regular boat maintenance.

If a battery is found to be consistently low in electrolyte level when connected to a smart charger, that's typically a sign of battery failure - or it's at least at the end of service life. Another clue is noting one battery getting hotter than another when they have been charging for a while. All batteries will warm up when charging, but one notably warmer is a clue it's not doing well.

Crappie Bait, thanks for bringing up this subject. It reminded me to check my batteries and sure enough the electrolyte was almost down to the plates.

Two words...deep cycle...sorry you didn't look at the battery I linked.

I will be running this battery for the next six years on a 36 lb trolling motor on my kayak. Good luck on yours lasting that long.

kickingback, my point was that it is not necessary to get AGM technology to get good batteries suitable for deep-cycle applications. I am aware he should use batteries intended for deep cycle applications, and that was mentioned in my post. AGM may offer no more reserve power, but it certainly will increase the cost - both absolute, and typically on a per-use basis when the cost is amortized over the service life of the battery.

While the battery you purchased is fine for your application (and probably even preferred when used in a kayak), it isn't a marine battery. Marine batteries have been mechanically reinforced to withstand the pounding and other vibrations of use in a powerboat on rough water. That difference is why golf cart batteries don't hold up in boats, for instance, even though they are good deep cycle batteries.

Your Welcome bush hog, looks like I'm gonna be buying some batteries, lol

The battery charger is a Charge Pro?

I don't know what your charger is - you tell me. I asked you previously what charger you had, but you never answered that question. I was asking so I could determine if you already had a good charger. If you want help, you're going to have to pay attention and answer questions, or the effort is just wasting my time.

As to the discussion of Dual Pro chargers, I was responding to Jacob, who has a "Dual Pro" charger made in 1997. We had a discussion about that charger while waiting on your to answer. The company that originally made them made only dual bank chargers in the early days, so their name was "Dual Pro" and they retain the website dualpro.com to this day. Now that they make many products with various numbers of banks, the company is now known as "Pro Charging Systems".

There are quite a few good chargers available today. By no means is Pro Charging Systems the only one. Look at yours and report here with info on brand and model. Or do you even have a true onboard charger?

My trolling motor batteries are in a tough place to check the water levels so I put sealed no maintenance voyagers . Not a bad price and three years no problems ! If you can easily maintain and check the water levels I have had good luck with auto zone dual purpose batteries. Great reserve on the biggest one

If you ever wanted to switch back to flooded cell batteries, there is a technology for "watering" batteries that will fill each cell to the correct level without overfilling any other cell. Basically it is a set of replacement caps for the battery that has a valve for each cell. As the electrolyte rises, the valve closes, preventing overfill. All the cells for two batteries can be tied together with tubing in a kit. A primer bulb and a container of water are used to fill batteries without access to the caps. It works very well and is easy to use. One time cost is about $30 per battery.

Marine Battery Watering

About 2 years ago I installed two of Walmart's best Batteries and a GUEST brand on board charger and have been trouble free...
The previous charger always over charged and my batteries would run dry quickly.

I leave plugged in all the time and rarely ever have to add water... maybe once in two years.

Thats a bunch of charges and dishcharges as I make at least 150 trips a year to the lake.

Have heard good things about Guest chargers from others.

Lots of good info here about batteries and chargers. Thanks for the lessons!

i got a free lesson again. thank you. special thanks to flippin-out

Glad to help. I hope I didn't confuse anyone with info since we had more than one discussion going in the course of this thread. If something seems off in left field, ding me and I'll try to uncross the wires.

One other thing I will mention that I may not have covered but should have: onboard (smart) chargers will sometimes fail to charge a battery that has been deeply discharged. The battery is so "dead" that the charger doesn't sense it at the end of the charging wires so it never turns on that bank. This is partly a safety thing so that the charger won't try to charge a shorted battery, which could get some things very hot. The charger isn't broken. If you think this has happened, connect a traditional battery charger for a while to manually get that battery's voltage up a bit. Then remove that charger and try the onboard charger again. You may then see it wake up on that bank and start charging where it would not before. If that battery does this frequently, it's time to buy a new battery.

I've come to this conclusion when it comes to batteries... You either purchase optimum or optimum.