Getting The Most Out Of Your Boat Batteries

[BobT]

It seems that battery life and performance questions are often at the top of our heads. We don't get the life out of them or the daily performance we expect from them. I believe that most of the time the problem isn't the batteries themselves but rather the habits or practices of we sportsmen and women.

Batteries can be fickle not unlike a spouse and like a marriage, the more we put into them and the better we treat them the more they'll respond for us and the better they'll perform. Ever notice how we have less trouble with the starting batteries than we do with our trolling motor batteries? Why is that? Well, I'd like to offer a few tidbits for getting the most out of our boat batteries.

• Batteries do not like to go hungry. Don't you get cranky when your stomach begins to growl? Batteries do not like to be at anything less than fully charged. I can't explain why but I do know this is an accepted fact. One of the reasons our starting batteries often seem to last longer than our trolling motor batteries is because they are not allowed to spend much time at below full charge. Once that outboard starts it immediately begins feeding and recharging the battery. Our trolling motor batteries on the other hand don't get this good treatment. We use them all day sometimes and then maybe put the charger back on them when we get home or the next day or some time later. In the mean time they are sitting around at less than full charge and they are not happy at all. It's like the difference between us getting three meals a day or one meal every other day.
• Batteries get weak when their blood level drops. Imagine how well you could perform if your blood level was lowered. The electrolyte in your batteries should be kept to the bottom of the fill tubes inside the battery. It is particularly important to keep those lead plates covered. Exposing them introduces contamination for one thing. The amount of electrolyte in your batteries is directly related to the batteries capacity to hold a charge so low electrolyte translates into low capacity. When that fluid gets lower, it is like replacing the battery with a smaller one.
• Heat is a battery's enemy. Exposure to heat reduces a battery's life and results is faster evaporation of the water in the electrolyte. Charging a battery invokes an electric current (amps) through the battery and this generates heat within the battery so over-charging is a bad thing even if you are only applying 12vdc. Batteries, even at full charge, will almost always represent some load on the charging system so they will continue to draw a charge and allow current to flow even after they are completely at full charge and this can get worse as the batteries age. I've had my electrolyte levels drop while having the battery connected to a trickle charger because the amount of current that flowed through the battery at full charge was enough to fool the charger into believing it was not at full charge. For this reason, I refuse to leave any charger connected indefinitely even when they claim to be maintenance chargers. 
• Batteries do not like to freeze. Now this is one that can be puzzling. The best way to store a battery is cold as long as it remains at full charge. The chemical reactions that take place in a battery to release the electrons and provide current is far more active at warm temperatures than cold. This is one reason why a starting battery has a harder time starting an engine in sub-zero temperatures. Along with the cold motor and stiff oils making it more difficult to start your car's engine, your battery is not capable of delivering the current being demanded by the starter. This is why battery heaters can be helpful. Warming the battery makes the chemical reaction increase and thereby increases the battery's ability to deliver output current.

So to sum this all up for long battery life and best performance.

• Maintain electrolyte levels. Check your electrolyte level regularly. I check mine monthly if not more. 
• Maintain battery charge. Recharge your batteries as soon as possible when your done using them. Use a moderate charging rate such as 15A to 20A charger. The best chargers are the "smart" chargers that use multiple stages such as many on-board chargers use, which is another topic in itself.
• Store your batteries properly. Yes, they will lose some charge sitting on a shelf. Make certain your electrolyte is topped off and then the battery is recharged to full state before storing. Keep the battery in a cool dry place such as your basement. Throughout the storage period check the electrolyte and connect a charger for a few hours to recharge any shelf loss. This only takes a few minutes but can add much more life to your batteries. If you store them where they are subject to below freezing temps as I do, keeping them charged becomes even more critical. I put a charger on mine for a few hours about every two to three weeks. Since I'm using an on-board "smart" charger just simply plug in my boat when I get home from work once in a while and then unplug it a couple hours later.
• Maintain good terminal connections. Avoid using the spring-loaded clamp on connectors but lean toward solid tight connections. Thoroughly clean your connections and the battery terminals before connecting the wires. Use dielectric grease on battery connections. It is inexpensive and easily found in most auto parts stores.  Not only does this improve conductivity by filling in the micro gaps due to the porous materials but it also helps reduce contamination of the connections. 

Hopefully this helps you obtain a much better relationship with your boat batteries. Happy fishing!

 

[delmuts]

Good info! A little care goes a LONG way! 

[Tom7227]

I bought one of those mini-chargers that pulses.  I think the idea is that it supposedly removes oxidation from the plates.  I leave these plugged in all winter.  Does anyone think they make a difference?  They never seem to move into the pulse mode despite the fact that the batteries are fully charged when I hook these jobberdos up.

[BobT]

I haven't looked into battery deoxidation so I can't comment on those. Maybe it's worth a little investigating. I wonder if maintaining proper electrolyte levels would inhibit oxidation by not exposing the plates to the atmosphere and thereby remove the benefit of these types of devices? 

[delcecchi]

I haven't looked into battery deoxidation so I can't comment on those. Maybe it's worth a little investigating. I wonder if maintaining proper electrolyte levels would inhibit oxidation by not exposing the plates to the atmosphere and thereby remove the benefit of these types of devices? 

Sulfation maybe?  Battery oxidation is new to me.  Sulfation is a  known problem for sure. 

[BobT]

What causes sulfation? 

[Pat K]

What causes sulfation? 

When a batteries charge is below 75-80% for an extended period, the minerals in the electrolite form deposits on the plates and decreases the battery performance. I think the deposits are mostly sulfur.  The chargers that "pulse" are supposed to break up the deposits.

Edited October 19, 2015 by Pat K

[BobT]

I think my onboard charger has a maintenance feature that is supposed to help with this. Cool.

[Tom7227]

I misspoke it is sulfication.

[h8go4s]

I misspoke it is sulfication.

You misspoke again. It's sulfation, not sulfication.