Trolling Motor Batteries going bad?

[Black]

Fishing this weekend, and I noticed that around the 6 hour mark that I started losing power in my trolling motor (MF101#). I figured it was just out of juice and the day was wrapping up, so wasn't too concerned about it.


Then I got home, plugged the on-board battery charger in and two of my 3 trolling motor batteries jumped to flashing green within the first 5 minutes of charging and my 3rd battery was showing 80% remaining. Any ideas why I lost power? I was on 100 on the foot pedal at one point and barely moving the boat. I at least figured if there was a bad battery, I wouldn't have shown charged so quickly when I plugged them back in. And all batteries were showing full charges before heading out.





Question 2:

I just picked up a X2 as a new cranking battery. It was down to 10% left on it at the end of the day....did I run it too low? Guy at BatteriesPlus had me nervous telling me something about discharging it too low


Thanks for the help guys. Oh, and for reference:

2009 Ranger Z520 w/ 250 Merc ProXS
101# MinnKota Fortrex TM
X2 AGM 31 Cranking battery
2 Interstate AGM 31 Batteries, and 1 Walmart AGM Battery for TM

[Bradrodfish]

The guy at Battery plus could be correct. On board charger will charge batteries, but there is a limit. If a Battery has a bad cell the charger could give you an indication that the battery or batteries are good, but in actuality they fail under load. Get a manual charger and charge the batteries up to full charge state with the charger. Then do a load test on each battery. Auto Zone or any of the car parts places has testers and should be able to do that. Check connections too from front to back of the boat. Report

[Black]

Thanks. I'll try that out.


And i'm pretty sure we are in the same bass club.....lol

[Bradrodfish]

You are either jimmy or Black from Coastal. LOL

[CatFan]

Your onboard charger is 100% fine for charging the batteries. It does exactly the same thing as a manual charger except it shuts off when the batteries are fully charged. A manual charger is a good way to destroy an AGM.

What specific charger do you have? Your next step should be to measure the voltage on each of the batteries.

[catdude28]

For the X2, when you say 10% left (or 90% discharged), did you measure that with a voltmeter? That would be around 11.9 volts left. If so, repeatedly deeply discharging it like that will shorten its life span significantly.

[Black]

You are either jimmy or Black from Coastal. LOL

nah, i'm a newbie.....almost a legit member and not a probationary

What specific charger do you have?]

Dual pro 4 bank charger

[Ann-Marie]

The idiot lights on chargers indicate percentage of AVAILABLE charge. This means if age, and in particular deep discharge, has reduced your "available" charge capacity in a battery from 100 amp-hours down to 50 amp-hours they will charge in half the time.

If two of your batteries charged in 5 minutes after a day's running then assuming an average of 10 amps each (although it is probably less) their capacity is 10 amps x 5/60 hours = about 1 amp hour or down to 1% of the initial capacity. Time for new batteries.

[billnorman1]

Since you got 6 hours use from your batteries it's safe to say they were charged fully. Lights are for the basic device user. You should check the actual voltage delivered to the batteries when the charger is started and also look in the batteries for water UNLESS they are sealed.