Best type of battery for a 22' daysailor with 8hp,electric start; deep cycle, good car battery with a lot of amps, dual purpose, if there is such ..... motor running charges the battery; can I hook up two together for longer service; any comments would be helpful. Getting ready for my 2nd season of sailing...
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type/size
depends on what the current demand is as well as the capacity to recharge it. The only info you provided is that you have very little charging capability so a large bank will always be under-charged thereby reducing it's useful life.
depends on what the current demand is as well as the capacity to recharge it. The only info you provided is that you have very little charging capability so a large bank will always be under-charged thereby reducing it's useful life.
Based on the information you provided
a single group 27 or 31 deep-cycle might satisfy your needs. Don't use a typical car battery as they can't handle deep discharges. A good deep-cycle should start your outboard just fine. If you want to trade no maintenance for some $$, an AGM or Gel works well if you have a good 3-stage onboard charger. Your motor won't charge your battery much except for when you run a good distance via motor at 1/2 throttle or better (most outboards are rated at ~ 6 amps at 75% throttle). You can parallel two batteries to double your capacity. Tie + to + and - to - then run your outboard alternator output to them and your DC panel connection. It is best if you have a switch to disconnect house loads but if you're only a daysailor, may not be necessary. Hope this helps.
a single group 27 or 31 deep-cycle might satisfy your needs. Don't use a typical car battery as they can't handle deep discharges. A good deep-cycle should start your outboard just fine. If you want to trade no maintenance for some $$, an AGM or Gel works well if you have a good 3-stage onboard charger. Your motor won't charge your battery much except for when you run a good distance via motor at 1/2 throttle or better (most outboards are rated at ~ 6 amps at 75% throttle). You can parallel two batteries to double your capacity. Tie + to + and - to - then run your outboard alternator output to them and your DC panel connection. It is best if you have a switch to disconnect house loads but if you're only a daysailor, may not be necessary. Hope this helps.
You'll be lucky to get
a max of a 3 amp charge with an outboard motor. If you are at a dock I'd suggest a shore powered charging system & if you're at a mooring a solar panel. An outboard motors alternator will be lucky to keep up with use and at most be a break even but will have a very tough time topping up the battery. Yes you want a deep cycle and any group 31 or 27 deep cycle can start your engine.
a max of a 3 amp charge with an outboard motor. If you are at a dock I'd suggest a shore powered charging system & if you're at a mooring a solar panel. An outboard motors alternator will be lucky to keep up with use and at most be a break even but will have a very tough time topping up the battery. Yes you want a deep cycle and any group 31 or 27 deep cycle can start your engine.
Optima makes a combo battery
Optima has a great marine AGM battery that they rate as a combination starting and deep cycle battery. They call it a "Dual Purpose" battery. It's plenty good for starting and tilting our Honda 9.9. The beauty of AGM is that it can't spill like a flooded cell can.
Optima has a great marine AGM battery that they rate as a combination starting and deep cycle battery. They call it a "Dual Purpose" battery. It's plenty good for starting and tilting our Honda 9.9. The beauty of AGM is that it can't spill like a flooded cell can.
For a daysailer a good "dual purpose "
like kd4ao recommends. The alternator on your outboard will not be able to keep it charged so a battery charger will be necessary. If left alone a partially discharged battery will sulfate itself and fail prematurely. Walmart sells a three stage Vector charger for about $14 that will work like a champ provided you are near a power source.
like kd4ao recommends. The alternator on your outboard will not be able to keep it charged so a battery charger will be necessary. If left alone a partially discharged battery will sulfate itself and fail prematurely. Walmart sells a three stage Vector charger for about $14 that will work like a champ provided you are near a power source.
Daysailor electrical requirments
I'm making the assumption that you don't anchor overnight in your day sailor. Things you probably have as electrical power consumers: stereo, nav lights, engine starter, nav/wind instruments, bilge pump With those as loads you are looking at an amp-hour consumption of: stereo on for 12 hours @ 2 amps = 24 AH nav lights on for 3 hours @ 4 amps = 12 AH engine starter on at 3/3600 hours (3 seconds) @ 30 amps = 0.025 AH mav/wind instruments on for 12 hours @ 1 amp = 12 AH bilge pump on for 10 seconds an hour for 12 hours at 6 amps = 12*10/3600 * 6 = 0.2 AH for a total for 12 hours of 24+12+0.025+12+0.2=19.4 AH every 12 hours of sailing. This is pretty conservative as you would not normally have the mav lights on on a day sailor but the AH used is still pretty small Any battery that can put out the required max amps for the starter and has more than 40 AH would work. 40 AH because you don't want to draw the battery down below 50% discharged. This is well within the range of the smallest marine battery you can buy (group 24) and you certainly don't need 2 of them. If you have other loads just add them to the total but I think you should be just fine with a group 24. It will also be easier for your motor to recharge a smaller battery and keep it "topped off"
I'm making the assumption that you don't anchor overnight in your day sailor. Things you probably have as electrical power consumers: stereo, nav lights, engine starter, nav/wind instruments, bilge pump With those as loads you are looking at an amp-hour consumption of: stereo on for 12 hours @ 2 amps = 24 AH nav lights on for 3 hours @ 4 amps = 12 AH engine starter on at 3/3600 hours (3 seconds) @ 30 amps = 0.025 AH mav/wind instruments on for 12 hours @ 1 amp = 12 AH bilge pump on for 10 seconds an hour for 12 hours at 6 amps = 12*10/3600 * 6 = 0.2 AH for a total for 12 hours of 24+12+0.025+12+0.2=19.4 AH every 12 hours of sailing. This is pretty conservative as you would not normally have the mav lights on on a day sailor but the AH used is still pretty small Any battery that can put out the required max amps for the starter and has more than 40 AH would work. 40 AH because you don't want to draw the battery down below 50% discharged. This is well within the range of the smallest marine battery you can buy (group 24) and you certainly don't need 2 of them. If you have other loads just add them to the total but I think you should be just fine with a group 24. It will also be easier for your motor to recharge a smaller battery and keep it "topped off"
Batteries & Such
Just run down to Wally World, and pick up one of their Max, marine batts. Rated 105 or 115 AH, forget which. 105 AH should take care of all your electrical needs for several days, certainly for a weekend. If you want to spring for the bucks, you can get a Gel Cell, or an AGM which has less capacity and costs twice as much or maybe more. Plus the gell cells and AGM's need a specialized charger, read that as more bucks. But for a day sailor, why spend that kind of money. That little kicker just won't do the job of recharging so you will need a charger or a solar panel. But for a regular wet cell deep cycle battery, an el cheapo charger will do the trick.
Just run down to Wally World, and pick up one of their Max, marine batts. Rated 105 or 115 AH, forget which. 105 AH should take care of all your electrical needs for several days, certainly for a weekend. If you want to spring for the bucks, you can get a Gel Cell, or an AGM which has less capacity and costs twice as much or maybe more. Plus the gell cells and AGM's need a specialized charger, read that as more bucks. But for a day sailor, why spend that kind of money. That little kicker just won't do the job of recharging so you will need a charger or a solar panel. But for a regular wet cell deep cycle battery, an el cheapo charger will do the trick.
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