I'll Buy
Liam - if you are ever down this neck of the woods - I'll buy (nothing fancy - on the cheap)!
Liam - if you are ever down this neck of the woods - I'll buy (nothing fancy - on the cheap)!
Solar Pannels
- Thread starter Tony23670
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The math
2 solar panels at 4 watts each = 8 watts. Conventional wisdom says to only count on 1/2 of the rating. That gives us 4 watts per hour. If you have 8 hours of direct sunlight...absolutely no shade then you will have 'collected' the equiv. of 32 watts. Assuming zero losses for electrical resistance of wires we still have less than 3 amps per day total at 12 volts. Most anchor lights draw approx 1 or more amps per hour. the 3 nav lights will draw 3 amps in one hour. With what little you are gaining, it doesnt seem like its worth the effort. Money is much better spent on an additional battery. BTW, power (watts) = volts X amps, or more specifically, in your particular interest amps = watts / 12 volts IMHO Tony B
2 solar panels at 4 watts each = 8 watts. Conventional wisdom says to only count on 1/2 of the rating. That gives us 4 watts per hour. If you have 8 hours of direct sunlight...absolutely no shade then you will have 'collected' the equiv. of 32 watts. Assuming zero losses for electrical resistance of wires we still have less than 3 amps per day total at 12 volts. Most anchor lights draw approx 1 or more amps per hour. the 3 nav lights will draw 3 amps in one hour. With what little you are gaining, it doesnt seem like its worth the effort. Money is much better spent on an additional battery. BTW, power (watts) = volts X amps, or more specifically, in your particular interest amps = watts / 12 volts IMHO Tony B
I can add my 2 cents worth here. For an anchor
light I use a kerosine lantern. For general cabin light I use a kero lantern. For reading I use an incandesent electric. LED nav lights will save a lot of battery power. I may decide to go with LED reading lights but I don't need to. Kerosine nav lights are legal and can burn all night on 12 ounces of fuel for all three.
light I use a kerosine lantern. For general cabin light I use a kero lantern. For reading I use an incandesent electric. LED nav lights will save a lot of battery power. I may decide to go with LED reading lights but I don't need to. Kerosine nav lights are legal and can burn all night on 12 ounces of fuel for all three.
Since we are talking solar panels, Tony B has the facts.
A watt is a measure of power. Voltage times amperage equals power (watts) VxI=P. Most batteries are rated say 80 to 100 amp hours. You really shouldn't use more than 50% of a batteries potential before recharging to a full charge. So, if your battery is an 80 amp hour battery, you should only figure that battery for about 40 amps. It also matters how fast you pull those amps out of that battery. Batteries are rated at a given ampere draw. The faster the draw the lower the amp hours. Back to the solar panel....so we used the battery this weekend and drew 40 amps. We have 40 amps to put back in. say we have 40 hours of sun. To recharge that battery, we would need ( ideally, life is more complicated)) to put back into the battery, 40 amps in those 40 hours. That would be 1 amp/ hour. At 12 volts, you need a 12 watt (1 amp x 12 volts = 12 watts) panel minimum. I can blow 40 amps over night with out a refrig! r.w.landau
A watt is a measure of power. Voltage times amperage equals power (watts) VxI=P. Most batteries are rated say 80 to 100 amp hours. You really shouldn't use more than 50% of a batteries potential before recharging to a full charge. So, if your battery is an 80 amp hour battery, you should only figure that battery for about 40 amps. It also matters how fast you pull those amps out of that battery. Batteries are rated at a given ampere draw. The faster the draw the lower the amp hours. Back to the solar panel....so we used the battery this weekend and drew 40 amps. We have 40 amps to put back in. say we have 40 hours of sun. To recharge that battery, we would need ( ideally, life is more complicated)) to put back into the battery, 40 amps in those 40 hours. That would be 1 amp/ hour. At 12 volts, you need a 12 watt (1 amp x 12 volts = 12 watts) panel minimum. I can blow 40 amps over night with out a refrig! r.w.landau
Forgot the overcharge protector. For $25 to $50 you can install an overcharge pr
That will keep the batteries from frying if you miss a weekend. r.w.landau
That will keep the batteries from frying if you miss a weekend. r.w.landau
r.w.'s right
Here's a link to an energy budget form (among the thousands posted on the web). Click on the "Energy Budget Sample.PDF" file in the first post of the thread and either open or save. The stereo load isn't included in the sums. It's more like 1.0 A, not 3.5 - depends on your rig. You can spend $100s on an energy monitor as discussed in the rest of the posts, but you can also do the math in your head!
Here's a link to an energy budget form (among the thousands posted on the web). Click on the "Energy Budget Sample.PDF" file in the first post of the thread and either open or save. The stereo load isn't included in the sums. It's more like 1.0 A, not 3.5 - depends on your rig. You can spend $100s on an energy monitor as discussed in the rest of the posts, but you can also do the math in your head!
Other Options
On a small boat, the best option is still an extra battery. I always buy a deep cycle battery for my vehicles. When Im taking a trip, even for just a few days, I take the battery out of my vehicle and put it on the boat and dont hook it up. I keep it as a spare in case i run all of my batteries dead, I still have a starting battery. When I had my Catalina 25 and my MacGregor 25, i did the same thing but didnt need a starting battery. I never did run my batteries completely down even after a week, but if I did, I figured that I can always get a boost in the parking lot to start my vehicle. The other option is energy conservation. I replaced all of my incandecsent lights with fluorescent lights. Even the 12 volt lights. A 15 Watt (1 1/4 Amp on a 12 volt system) will give as much light as a standard 60 Watt incandescent light. The beauty of using 12 Volt incandescent, is that you can change out all of your lights with normal 110 volt light fixtures which cost next to nothing. You just have to mark the 12V and the 110 volt so as not to get them mixed up since they both have the same base. Tony B
On a small boat, the best option is still an extra battery. I always buy a deep cycle battery for my vehicles. When Im taking a trip, even for just a few days, I take the battery out of my vehicle and put it on the boat and dont hook it up. I keep it as a spare in case i run all of my batteries dead, I still have a starting battery. When I had my Catalina 25 and my MacGregor 25, i did the same thing but didnt need a starting battery. I never did run my batteries completely down even after a week, but if I did, I figured that I can always get a boost in the parking lot to start my vehicle. The other option is energy conservation. I replaced all of my incandecsent lights with fluorescent lights. Even the 12 volt lights. A 15 Watt (1 1/4 Amp on a 12 volt system) will give as much light as a standard 60 Watt incandescent light. The beauty of using 12 Volt incandescent, is that you can change out all of your lights with normal 110 volt light fixtures which cost next to nothing. You just have to mark the 12V and the 110 volt so as not to get them mixed up since they both have the same base. Tony B
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