What are the best batteries to buy for using trolling motors, it's a duel battery set up and one blew up. Has an onboard charger that i left plugged in but was told they kick off and just keep the battery charged? I don't know why it happened but need to buy two new batteries and want to get what are the best. Also what is the best on board battery charger for keeping them charged? Thanks Crappiebait

So you have three batteries total? And the on-board charger you have now has how many banks? What model is it? I ask because there are a number of good chargers available, and you may already have one of them. Batteries can blow up due to reasons that are not the fault of the charger. A battery defect can do it, as well as letting them get dry. In order to know what battery to suggest, I'd also like an idea of your boat size/weight.

The best deep cycle battery Wal-Mart sells works just fine. Get a good on board charger and you may have one. You need a charger that conditions the battery as it charges and is a phased charger. Here's a link to one good brand. Best investment I made for batteries. These are also available from BatteryMart.com and some other places.
http://www.dualpro.com/

If the acid leaked out in the boat, look for problems where the acid got on anything. Especially the drain tube and plug.

My batteries went completely dry on me from leaving my charger plugged in all the time. The guy at the battery place said that the batteries aren't made to be left plugged in because when the charger senses a voltage drop, it will put full power into it until it goes back to fully charged. Every time it does this, you're boiling off a little more water. They told me to plug it in over night, then unplug it til the next trip so it won't keep cycling the charger on and off over time.

"The guy" at the battery place isn't always the electronics expert, either. If you have a "smart charger" (with digital electronics control), it will not boil out batteries as described. A "dumb charger" - you bet.

If a battery goes dry with a smart charger, it happens over a VERY long period of time (and was going to happen anyway from neglect), and the battery owner is at fault for not checking the batteries occasionally. Most good units go into a "float" mode where the required voltage is lower, avoiding frequent cycles of the charger. A bad battery will drop down rapidly, triggering the charger to try to recover it. So, quite often, it's the battery that is bad and causing the problem - not the charger!

A huge number of the bass guys (who work those trolling motor batteries hard) have theirs plugged in 24/7 and there is no chronic problem with people boiling batteries dry. I call "BS" on the "battery guy" when it comes to modern smart chargers. (mine need only a bit of water every 90-120 days.)

INTERSTATE BATTERIES.

Yes

Mine is a dual pro from 1997.

Thanks for all the advice! I have learned a lot and is my fault because I did not check them and left the charger plugged in all the time. Lesson learned for sure.

It's a 17ft. Lund, Im not home now out on the road working so I can't get the info. The batteries are continental marine/rv duel purpose but not sure about the charger.

Continental is a good battery also...

I'd buy Wal-Mart...they have a 3 year replacement guarantee and there's a Wal-Mart somewhere close by.

Years ago, there was a definite difference in battery life and quality...not so much anymore. The "good" Trojans are no more. the AC Delco maintenance free are gone. Sears has stopped selling their good battery.

Gman

Look at the Amp Hours on a battery to get the most time out of it. I bought a 100Ah battery from Amazon for $110. It weighs 62lbs but the charge on the battery can make it last 4 hours at full power for a 40lb thrust TM.
You want a sealed AGM battery. It will last longer and hold a charge better than standard cranking batteries.
If you run 2 or 3 in parallel you can conceivably be on the water all day for a couple of days!!
The price went up since I bought mine but you can still find them cheaper I am sure.
100 Amp Hour Battery on Amazon

"You want a sealed AGM battery." Why? Unless someone is seeking to skip the need to occasionally check electrolyte level in a boat's batteries, there's no compelling reason one should switch to AGM. The over-service-life cost WILL be higher, but there's no need to add water - that's about it.

When it's said that "AGM holds a charge longer" that doesn't mean that AGM technology lasts longer in use, it just means that if a battery sits dormant for months, the battery charge dissipates more slowly. How long a battery holds a charge once charged is typically of little concern to fishermen. Yes, AGMs do that, but we have chargers and power available to charge them frequently, so this minor feature isn't a game-changer.

An AGM battery doesn't last longer or provide more power than competitive batteries if similar models are compared. A battery with 200 minutes of reserve has more power than a battery with 180 minutes of reserve, for instance, regardless of the battery technology in use. (AGM vs. flooded cell) The same goes for cranking amps. There are batteries with good service specifications made with both AGM and flooded cell technology, and depending on which batteries are being compared, either may be the stronger battery with more power. An AGM batteries isn't just stronger and better because it is AGM - it just means there's no need to add water....

I set up a standard 24 hour timer to come on for an hour at noon and an hour at midnight and hooked up the onboard chargers via an extension cord. Batteries always seem to be fully charged though I will top them off the night before a trip just to make sure. This is the 3rd boat I have run this way. Last 2 didn't have an onboard charger so I used a manual charger. I had to find one that didn't require a switch being turned on manually and used the trickle charge selection. My Lowe pontoon had the trolling battery in the front and the starter in the back. So I made a "jumper" with an old 25' extension cord. Cut both ends off and put alligator clips on. Connected the charger to the front battery and then the "jumper" to the main. LOL seemed to work fine for the 5 years that I had the boat.