West also carries a 6W and a 18W version of the panel. You might squeak by witht the 6W version provided your batteries are not significantly over 100Amps AND your boat is reasonable water tight. You can connect to just one battery if you have a combiner switch that you can place on "both". The 6W panel can't generate enough voltage to harm your batteries but the larger panel would need a charge controller.
12-10-2006 09:57 AM
Well, it's a good question. The answer is a definite, "maybe".
Lots of factors in play here.
Type of battery: flooded batteries have a self-discharge rate of 2-10% per week, while AGMs and gelled batteries are more like 1-5% per month. An older flooded battery might lose as much as 1% per day.
The model you're looking at is rated at 2 watts, or approximately 135 milliamps @ 15V. That's a peak rating, when the sun is shining directly on the solar panel.
How much sunlight do you have in your area? Are you in the north? The south?
Let's say you live in the mid-Atlantic region where you might expect 4-5 hours of good sunlight per day. 5 hours x 135 ma = 675 ma or about 2/3 of an amp-hour. If you have, say, a 100AH flooded battery, it might lose as little as .285 AH per day or as much as 1.4 AH per day through self-discharge, in which case your little solar panel would be hard-pressed to keep up even with self-discharge. This doesn't count an additional LOAD on the battery, like if your bilge pump runs.
I'd say the panel is probably undersized for your purpose.
Whatever you do, be sure that the panel you get has a regulator of some sort to avoid OVERCHARGING and damaging your battery.
12-10-2006 08:15 AM
Solar Trickle Chargers
I’m keeping my Catalina 25 in the water this winter with the proper bubble wrap. I would like to keep the batteries in the boat so the bilge pump can stay operational in case of an emergency. I was looking at the “2W Battery Saver SE - Solar Trickle Charger” which is available at West Marine for only $35.00. Will this satisfy my needs of keeping my two batteries fully charged during the winter months? Logistically, will I be able to connect the panel to both batteries or will I need to choose 1 and bring the other home for basement storage and charge.
Your thoughts and recommendations are greatly appreciated!