I've got two "less than a-year-old" interstate deep cycle trolling motor batteries. I've got a built-in pro mariner charger that charges both of them. The charger says it's charging. The batteries say they are taking a charge, but after using the trolling motor for 20 minutes, they are dead. Any thoughts???
You may have a dead cell on one of your batts. Quickest way to confirm/deny is to do a simple load test on them. The fix is easy - new batt.
You would be well-served in checking the output on our charger, too. I had an issue this year where all of the lights said batts were charging but the output on one bank was dead. A voltmeter will quickly tell you the output of each bank. This fix is a lil more involved, expensive (as I had to learn the hard way).
A couple things to keep in mind when buy batts:
- Always, always, always check the manufacture date. Sometimes it's a sticker on the side, sometimes it's a punch-out on the top (month/year). You'll often find batts that are a year or more old sitting on shelves. Buy the newest batt available. Don't do like I did and buy the 2-year-old unit that's been waiting on the shelf for some dummazz who's in a hurry to come get it. Just sayin' . . .
- Make checking water level in your [wet cell] batts a part of your pre- and post-launch routine. Water can seep out as temps rise and fall. It can also seep when you're riding on ruff water. If a cell is low add a lil [distilled] water.
- Check your connections routinely. This includes in-line fuzes!
Take a multimeter with you after there fully charged check each battery for volts. Then run trolling motor for the 20 mins and when they poop out on you check them then for volts. I had this happen to me last fall with a 36volt system and I had one bad battery. It worked for me . Hope this helps