The Ultimate Power Source ™


Posted: Jul 14, 2011

Marine Battery Maintenance

I recently spent a few days at one of my favorite places on earth, Camp Anokijig. Anokijig is a summer camp in Wisconsin, where I spent many weeks as a summer camper, staff member and now, a volunteer. Over the years, Johnson Controls and OPTIMA Batteries have also taken an interest in Anokijig and even sent volunteers up to help out with work around the camp property.

On my most-recent visit, I was had intended on taking out one of the pontoon boats, to photograph campers on the water, doing all sorts of things from sailing to fishing. Unfortunately, the battery on the pontoon boat would not turn over the engine and it was one of our batteries! However, the reason it wouldn't start the engine, is because it had beendeeply-discharged.

This is not an unusual occurrence for any battery and is in fact, fairly common in marine applications.When I subsequently checked the voltage in the other boats, I found three other batteries discharged below 12 volts, which means these batteries were more than 50% discharged, some as much as 90% discharged. The scenario surrounding this battery (and the others) actually paints a fairly clear picture of how marine batteries can become deeply-discharged. Camp Anokijig sits on Little Elkhart Lake, which is only about 60 acres in size. Additionally, whenthey send 50 campers out on the water in paddleboats, rowboats, canoes, kayaks and other sorts of boats, the lake does tend to get a bit crowded. As a result, when this pontoon boat (or any of the other motorized boats in Anokijig's fleet) head out on the water, they usually do so at a pace barely above idle.

None of these boats have significant electrical accessories, which could slowly discharge their batteries, but they do often end up being started, driven short distances, stopped and started again. This type of use will slowly discharge any battery, as the alternator never ends up having enough time to replace the energy used to start the boat, resulting in a net voltage loss each time the boat is used. Eventually, (depending on the size of the battery and cranking demands of the engine) the battery will get discharged to the point, where it won't be able to start a boat.

What is the solution? Ideally, a boat would see regular use, with the engine operated at speeds and fora length of timesufficient enough to maintaina proper chargein the battery. On this particular lake and in many other applications, that simply may not be possible. While a quick disconnect on an automotive battery cable can prevent a parasitic draw in automotive applications, that really isn't the issue here. The real problem is getting voltage back into the batteries and keeping them as close to fully-charged as possible.

For Camp Anokijig, the most-viable option is periodic charging of the batteries in their fleet. Multimeters can be had at most auto parts stores for less than $20 and should be a part of any battery maintenance program. Multimeters provide an easy way to check battery voltage, not to mention saving thehassle of lugging a 45-pound battery from a boatto a charger, only to find out the battery doesn't need charging. When batteries get close to 12.4 volts, it's time to charge them back up. Our deep-cycle BlueTop batteries will see a full state of charge at about 13.0-13.2 volts.

While some folks may opt for solar chargers that stay on the boat, there are a couple of concerns with these units. As with any charger, it is a good idea to make sure the charge is regulated. Even though a solar charger may only be the equivalent of filling a bucket of water with an eye dropper, eventually that bucket will fill up and you'll want to make sure any charger you use doesn't over-charge the battery. You'll also want to make sure your solar charger is capable of generatingenough energy tomaintain your battery. If the boat is stored in an area that doesn't see much sunlight or the panel is too small for the battery, this might not be option.

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