Trolling Motor Battery question

[Rizzo]

I rarely use the trolling motor on the front of my boat, but did put it into use earlier this summer. I noticed the battery (3 years old) really did not hold a charge well. I do tend to keep the battery charged (don't run it down much ...except this summer because it went dead quite fast).  I will admit I have never once added distilled water. Since I plan to use the trolling motor a bit this fall, should I just go ahead and replace a 3 year old battery? Or if I add water (assuming it is low after 3 years?) could this salvage it. Since it only gets used maybe 4 or 5 times a year, the battery I purchased was a lower end one (Nautilus, Cdn Tire, size 27 with 90 amp hours) and cost around $175 I think.

[Fisherman]

Lets put it this way,  it can't hurt to open it up and check the levels AFTER it has been charged.  Then if it's low add distilled water,  I use a turkey baster tool.  Once it's up to the proper level, use the baster to suck up and squirt the fluid back in to stir it up.  Then recharge.  If you have a smart maintainer, it may bring it back to life for a few more seasons.   I leave mine connected ALL the time to do the job it's intended for,  ATV and boat.

[Brian Gavin]

Yes definitely pop the caps and check  acid levels and fill to proper levels but not too high. Give it a full charge and check the charge with a multimeter. Should be 12-13 volts.

[Rizzo]

time to buy a batter tester I think!

[Rizzo]

got me a tester...said battery is bad. Popped the caps....ya she was dry not sure how much water was in there. Added some De-ionized water and now charging again. Might have wasted 6 bucks on the water but want to see if it can recover. Other than that, buy new battery and make sure to check it once in a while for water levels!

[Terry]

If you have an old battery charger , it would work best as it is helpful to boil the battery a bit to bubble off crap that will be stuck to the plates from being dry

[Rizzo]

the charger is old. I read on line to charge it on trickle for 12 hours. If there are bubbles coming up after 12 hours the battery can be salvaged, if no bubbles then the battery is toast

[Fisherman]

What Terry said,  you "equalize" the cells by getting it to bubble hard for a while,  if your charger has a manual/auto mode, go with the manual for a couple hours.

[Rizzo]

this charger only has manual (did I mention it was old?). I have left the caps off so I can see what is going on (yes...I am being safe). But right now it is probably just still water in there anyways hasn't formed acid yet possibly! Seeing the odd bubble come up every 10 seconds or so. It has been on trickle for 2 hours approx.

[Fisherman]

Leave it on for a day, trickle charge won't do any damage.

[Rizzo]

Been charging 6 hours on trickle...bubbles getting a bit more frequent maybe this will work

[Rizzo]

so after 11 hours I tested it and it had gone from bad battery to weak (10.6 volts showing), this morning (at the 19 hour mark) it is now showing good battery (13.4 volts)! The interesting thing is when I tested it the first couple times the battery tester got hot. Even smoked the first time. Now that that battery seems to be recovering the tester did not get hot while charging

[Fisherman]

Now comes the real test, will it hold.  Once you turn off the charger, don't hook anything up to the battery, let it sit for 24 hours and then check with your meter to see what the voltage is.

[Rizzo]

Yes that will be the moment of truth. I have now bumped it up from trickle charge to 6 amp charge. Plan to do that for a couple hours as apparently that overcharging will help equalize it

[AKRISONER]

I had a battery that was “bad” I would turn over the boat and my electronics would all cut out due to the voltage drop. I refilled them and put them on a smart charger and sure enough I ended up getting 2 more years out of it. There is still hope.

If you do end up buying a charger, I’ve had incredible luck with the noco genius line. Never had a single issue with one in over 5 years.

[Rizzo]

rats....you can read into that however you want

[Rizzo]

but it ain't good. One thing I don't understand is why you have to enter the CCA amount into the tester before testing the battery. If anyone knows the answer for this I would love to hear it

[Fisherman]

The tester will adjust to the level of the battery it needs to test, otherwise you get an inaccurate reading.

[captpierre]

Can someone tell me if it’s ok to charge a battery in an ATV, Honda generator or Yamaha outboard with a charger at 2 or 10 amps with the battery cables to the motor still attached?  Or should they be disconnected?  

[Fisherman]

Key off, yes you can.  Most of the ATV batteries have 2 rates, something like 10 amps for 1 hour or 2 amps for 5-6 hours.  I like the slow method.  Don't overcharge AGM batteries, they don't like it.

[Rattletrap2]

It wasn’t until a couple of years ago that I learned you can damage a lead acid deep cycle battery by discharging below 50 %!! I have had trolling motor and RV batteries for like 35 years, but somehow missed this point! DOH!! So your 90 amp hour battery is really only good for 45 amp hours. I am very careful about this now! Especially with the RV!!

I use my electric bow mount probably way more than the gas engine, but do not run the battery down. It goes on charge as soon as I get done with the boat and stays on charge till next outing. I have a “Guest” two bank onboard charger.

[Terry]

I believe it only hurts them if you leave them uncharged for a long time when they are under 50%
I have ran them all but dead , charged them when I got home and they lasted 7 years 

[AKRISONER]

5 hours ago, Rattletrap2 said:

It wasn’t until a couple of years ago that I learned you can damage a lead acid deep cycle battery by discharging below 50 %!! I have had trolling motor and RV batteries for like 35 years, but somehow missed this point! DOH!! So your 90 amp hour battery is really only good for 45 amp hours. I am very careful about this now! Especially with the RV!!

I use my electric bow mount probably way more than the gas engine, but do not run the battery down. It goes on charge as soon as I get done with the boat and stays on charge till next outing. I have a “Guest” two bank onboard charger.

This is the number one reason to splurge and go AGM 

 

they handle deep discharge much better. For guy that like to put long days in especially in bad weather, there’s an expectation of deep discharge on the batteries. 
 

you should always plug the boat back in ASAP