One of my 3 trolling motor batteries is getting hot during charging.
Is it safe to say it’s shot?
Saturday I noticed a sulfur smell coming from my batteries and found it to be low on fluid and getting very hot. I disconnected it and let it cool before adding distilled water to fill it.
I switched the battery to a different charging bank and the same battery gets hot.
most likely it has two cells shorted together.
this can happen when a battery ages, sulfation causes swelling of the plates pushing them into other plates creating the short.
the sulfur smell is a dead give away of sulfation occurring.
depending on how well the battery is built,ie a cheap one,bridging that would support the plates and keep them apart if absent can allow the plates to contact each other during a rough ride whether it be on the water or on the road and create a short as well.
as you have seen with the low fluid level in the one cell,it can get hot enough to boil the acid out due to the shorting of the plates.
be extra careful removing/moving it as is it can explode when an internal short ignites the hydrogen gas in the cells.
I have scars on my face and hands to prove that.
I dont want you scared to death over it,just be careful with it while handling it.
Post a picture of it upside down so the distilled water can drain out. Wait 2 days and post a picture (it should be right side up by then) then refill and try to re-charge again. 
Sorry Gil, I couldn’t refrain myself. 
Post a picture of it upside down so the distilled water can drain out. Wait 2 days and post a picture (it should be right side u by then) then refill and try to re-charge again.
Sorry Gil, I couldn’t refrain myself.
let me guess,its pick on biggil week! dog pile !!
Do I hold the battery or the phone upside down?
It is one of 3 interstate deep cycle batteries.
So that probably means I need to replace all 3 in my 36v system.
Are agm batteries really worth the extra cost? Are the normally immune to this sort of problem?
Probably going with group 31 this time around.
agm’s are better by far IMO,but again,dont skimp because of price,there are some cheap ones of those too like anything.
make sure your charger can charge agm batteries.
Once you go AGM you will never go back. Best example is my motorcycle. Used to be you would have to replace the battery every 2 years. With AGM I’m over 5.
I compared going to AGM over my standard size 31 interstates. The cost difference was three times. My wet cell batteries last me about 3 years. In order for AGMs to be more cost effective, I would need to get over 9 years out of them. Didn’t make sense to me as interstates have treated me well through three boats.
#1706538
I compared going to AGM over my standard size 31 interstates. The cost difference was three times. My wet cell batteries last me about 3 years. In order for AGMs to be more cost effective, I would need to get over 9 years out of them. Didn’t make sense to me as interstates have treated me well through three boats.
X2!
<div class=”d4p-bbt-quote-title”>John Schultz wrote:</div>
#1706538
I compared going to AGM over my standard size 31 interstates. The cost difference was three times. My wet cell batteries last me about 3 years. In order for AGMs to be more cost effective, I would need to get over 9 years out of them. Didn’t make sense to me as interstates have treated me well through three boats.X2!
X3
Only I usually get 5 yrs out my batteries
No joke, I just got 10 years out of a standard sealed battery in my Kawasaki ATV. I have to agree with Joe, Chuck and John, it just isn’t worth it in my mind. I get about 5-6 years out of the interstate “seconds” batteries in my boat and I call that a win. I know many people who swear by AGM batteries, including my father (who has been a leader in the car battery recycling business for over 35 years). Maybe some day he’ll convince me to go AGM and I’ll see the light. Until then, Interstate seconds are what I use!
The biggest thing that kills deep cycle batteries is not charging them fully and not monitoring water levels. You keep on top of those, they will last 5 years with ease, yes, even the regular deep cycle non-AGM.
Recharge the battery as soon as you get to a power source. Not the next day or a week later when you finally remember it because your wife is riding you about going fishing and forgetting to get diapers for the kids.
I am curious to find out how long my batteries last. I bought all new in 14, and same year installed a Stealth DC onboard charger. My batteries are almost always fully charged because the big suzuki charges them when I run across the lake.
Based on my research, these are the advantages to AGM batteries over standard lead acid batteries.
– No maintenance.
– Usually rated for around 600 cycles from 50% charge. Results in longer life.
– Much slower decay rate.
– Typically longer and better warranties.
– Less outgassing. Less chance of explosive gases.
– More durable.
My failed battery is a group 27 Interstate deep cycle. Purchased new in 2014. Always charged with a Minnkota MK460 charger. I get better life on by far over the Wally World batteries I bought once.
This one may have failed because I failed to keep it full of water, old age or from an impact.
Either way, AGM batteries promise to solve those problems. If that happens and I get the expected 600 cycles, I’ll be ahead with less chance of premature failure.
I was planning to buy the Cabelas brand AGM batteries. If I do, it would take only 5 years to come out ahead if I only get 3 years out of my Interstates. Seems worthwhile to me.
I am curious to find out how long my batteries last. I bought all new in 14, and same year installed a Stealth DC onboard charger. My batteries are almost always fully charged because the big suzuki charges them when I run across the lake.
How many amps across how many banks for that charger?
I installed a Minnkota MK-3-DC in my boat and it only puts out 15A per bank. Not much charge for a short run.
<div class=”d4p-bbt-quote-title”>CaptainMusky wrote:</div>
I am curious to find out how long my batteries last. I bought all new in 14, and same year installed a Stealth DC onboard charger. My batteries are almost always fully charged because the big suzuki charges them when I run across the lake.How many amps across how many banks for that charger?
I installed a Minnkota MK-3-DC in my boat and it only puts out 15A per bank. Not much charge for a short run.
That’s a good question, but I don’t know the answer. It has been several years after I did all the research. I will have to dig through my emails with Danny at Stealth to see what he said. I know it varies based on the output of the alternator on your Outboard, but it isn’t outputting the exact amount the alternator does.
I have the digital gauge that he suggests and I can watch the voltage increase as it charges. Usually starts around 25 volts and then creeps up to 27.8 while running. Depending on how much use for the trolling motor, that may be a several mile long run.
I have a Minnkota MK-3-DC installed in my boat too. I think of it more as increased run time and increased battery life. The starting battery has to get to 13.5 volts first before it turns on and starts sharing electrons. And I use my starting battery for my electronics and pumps. I don’t expect it to recharge my batteries full. But every bit helps. In both categories.
I have a Minnkota MK-3-DC installed in my boat too. I think of it more as increased run time and increased battery life. The starting battery has to get to 13.5 volts first before it turns on and starts sharing electrons. And I use my starting battery for my electronics and pumps. I don’t expect it to recharge my batteries full. But every bit helps. In both categories.
I agree with that. That’s how I think it was advertised.
Unfortunately in my case it didn’t help. I do know I was having issues with my MK-460. I had one bank that was not charging. I finally figured out it was a loose fuse terminal. Part of the inline fuse was not making contact. I squeezed it together and it works now. Unfortunately One of my batteries had to suffer as a result.
I’m thinking he was looking at top of the line AGM batteries. When on sale a group 31 AGM can be had for around $200. Last year I did load up on the Northstar virgin pure lead AGM’s Cabelas sells. They were on sale and I got a huge Cabelas buck kickback. 4 year warranty. Northstar’s are concidered the best. My kid says that’s what the subwoofer guys use 
. I have never seen my 36 volt bank go below 50% in a day of fishing. I expect many years out of them.
Comparing top of the line agm batteries to bargain lead acid batteries is not an accurate comparison.
I compared interstate group 27 to the cabelas group 27 agm.
Interstate: $120
Cabelas AGM: $200
Less than twice the cost. Double the life and you’re ahead. Double the warranty, better durability, etc.
2x
Got a few lessons on AGM batteries over the past few days. Spoke to a few tournament anglers that used only Interstate batteries and switched over to interstate AGM for a while and had a very educational conversation with an employee at the Interstate batteries store.
My thought that you could expect double the life (in years) isn’t necessarily true. It’s all about the severity of the depth of discharge (dod). I think most people know and understand this but I never realized it was by far the single biggest factor for battery life.
If you severely discharge an AGM battery regularly, you might not see any improved life over a standard battery. I was also told that AGM batteries tend to have slightly lower reserve capacity.
If overall you can keep the dod to less than 50% and keep your batteries topped off, there’s no reason you shouldn’t expect 5+ years from any deep cycle battery.
So, the biggest piece of advice I got from the guy at the Interstate batteries store regarding battery select, get batteries with the biggest reserve capacity possible and you’ll maximize life.
It’s been said here every time a battery discussion comes up. Go big or you’ll be buying new batteries often.
Btw, I really appreciate all the advice. I ended up going with another group 27 from Interstate for a smoking deal. I would’ve gone with a used one but they didn’t have any. As soon as these are done, I’ll be going with larger batteries next time.
Anyone looking to buy batteries I very highly recommend Interstate Batteries in Coon Rapids. Great price and very knowledgeable. I will be going back for my next battery purchase.
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