Wow…so it seems that what happened to me in the first post is simply my accessories draining the starter in 3-4 hours? Or could it be that the water in my battery has been “boiled” off by being connected to the MinnKota onboard charger?
I just hope that it is not a short tho’
Your battery should never read less than 12 volts even when fully drained(discharged) if it reads less than 12 volts, it has a bad cell or is shot and should be tested with a battery hygrometer. GPS units really drain todays batteries. Your charger shouldnt boil off any water but check to make sure your full.
Not sure about the wire size (it was my dad that did this, not me). The ends were the type that look like washers and attach with the wing nuts to the drained starter battery.
He has a 60 horse Yamaha that he was cranking over.
OK…I did some checks today with a multimeter set at 10V DC. So my battery at full charge is more than 10V. I checked for shorts by touching the black to the aluminium and it barely moved. So I assumed that there is no short.
However, I did check the water and it looked quite dry in there. I am not sure how much water there should be in the cell, but I could not see any water level. It is a Trojan battery that is less than one year old. So I am going to get some distilled water and top it up. I wonder who sells distilled water tho’. I guess, I will go to a gas station. Thanks.
Quote:
Since the early ’90’s when graps/GPS units became the norm, and boats added second livewells, and electric motors became good enough to become primary fishing motors no matter what the conditions are, dead starting batteries also became the norm. It started to become common to have to jump the starting batteries from the trolling motor power source to get home.
So……for the past ten or more years, I have NOT put a “starting” battery in any of my boats. I use the SAME size/style battery for my starting battery as I do for the bowmount. That being a 27 or 31 series regular deep cyle battery. Since doing so, I have NOT ever had an issue with my “starting” battery. After 6-7 hours of NOT using the big engine, having at least two if not three graph/GPS units running continuously along with both livewells on full time, NO problems. In those situations or even lesser use, a “normal”,healthy starting battery would have been too dead to run the big engine.
My advice to ALL…use a regular deep cycle trolling motor battery for the starting battery too. (not some combo deal(starter/deep cycle) either. A regular 27 or 31 size deep cycle.
Steve Fellegy
#49
OK…I just realized that my starter motor battery is a large deep cycle trojan. Yeah…it was dry as a bone. Probably explains why I had the incident now.
There are basically a few issues here :
1. My ignorance – I have been spoilt by maintainence free batteries and thus have not gotten into the habit of checking the water level in the battery for the last few years. I assumed that the Trojan was maintainence free. Plus the fact that I had Minnkota on-board chargers which are supposed to “maintain” your batteries after charging them, I have basically left them all alone.
2. So now, how regularly am I supposed to check my batteries from now? After filling up with the distilled water, a couple of my cells had water that contained some muck and particles. Does this mean that this battery needs to be replaced now? Also, after filling up, I connected it back to my charger and my charger now acts wierd. It shows that the battery is full but the charging light is also on at the same time and it is buzzing away. So I have disconnected it.
3. What exactly does the onboard charger do to maintain my battery? Does it just prevent the water from freezing over? If so, then how did I lose so much water in a space of 6-7 months?
I run a battery tender on my main battery. So when I plug in my trolling motor batteries, the main battery also gets some attention. I think the tender was $25 at the local parts shop.
I have started to look at the wiring in my boat, I have wires hooked up to all 3 batteries (main and 2 for trolley), and I’m not sure what they run. Spaghetti mess. I’ll have to put that on my list of things to do.
Just a suggestion.
Jami
Hi, Please dont waste your money on the so called maintance free battery, they still use water the same as a regular battery the only difference is you cannot fill them 
. I have been working with DC power plants(batteries) for better than 15 yrs. when batteries are exercised, charging/discharging the will use water plain and simple. i would suggest checking your battery water level a couple times during the summer, add distilled water as needed then charge them up.
you can get distilled water and any grocery store, walmart or any of those style stores for under a buck a gallon or you could be like the company i work for and pay about 6 bucks a gallon 
CA
I noticed I missed part of your post 
so you filled the batteries with distilled water and hooked your charger up and the charger is acting weird. sounds like its buzzing which would suggest its putting out its max charge. what is the dial reading on it. that should show you how many amps your battery is taking. when it is fully charged it should read 0. if it is bouncing around say between 0-5 and isnt stable, I would assume your battery is toast.
your onboard charger is a trickle charger which means it just puts a little charge into your batteries, and over the winter will keep the battery from freezing because of the chemical process. I would suggest getting new ones, regular not the maintance free, and check the water level every couple months fill as needed and before winter storage. Just doing this little bit, I always get about 8-9 yrs out of my truck battery and about 5 yrs out of my boats.
Hope this helps, any questions send me a PM
CA
CA,
I’ve always been under the impression that when you see your charger reading jumping around or moving, this indicates that your battery is not accepting the charge from the charger. Is that statement true? Every battery I’ve thrown out has done that. Do you happen to know the physics behind it?
Indeed sir I do. Your 12 volt battery has 6 cells in it, each of those cells should be 2.2 volts. When a battery goes dead what generally is the cause is from the sediment caused from the chemical action that is constantly going on in a battery. Between the plates in the battery is where the “magic” happens when you charge it/discharge it this causes small crystals to form on the battery plates, in time they fall off and little pieces of the plates and that is the sediment in the bottom of the battery. Over time that will reach a certain point where it shorts the plates in a cell/cells. Now your battery is no longer a 12 volt battery, but a 10 volt battery instead. Your 12 volt battery charger cannot charge that because the charger detects the short and stops, that is why it attempts to charge then stops and keeps doing that routine. Or at least that is what I recall from the school I look long ago and far away. I hope this didn’t put you to sleep 
CA
The alternator on some of the older motors, for example my 88HP Johnson SPL (now traded), was simply not strong enough to keep everything charged, although my trolling motor runs off a seperate battery. You probably have a newer motor, but if not, perhaps the problem is an alternator which cannot handle everything you run.
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