Battery and charging question

Question:

When I bought my boat several years ago it had a lawn mower battery in it as well as a trashed deep cycle.  The lawn mower battery worked well for several years day sailing and would run the anchor light or running for day trips and overnight. I would take another battery to run the cabin lights if overnighting. The lawn mower battery weighs nothing and charges fast at home. Personally I am like you considering a dedicated battery and have already decided on eventually installing a regulated solar system. Hopefully next year. – Hide quoted text — Show quoted text – I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option? The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator? I would appreciate any constructive comments or suggestions about any of this. Pete Before you buy.

– 22′ Southcoast Eclipse   Florida Panhandle  ***  Type 2 as of 12/98 http://mrwayne.webprovider.com/index.htm Before you buy.

Response:

Since I usually run the motor for only a few minutes, just to get out of the marina, I guess the alternator isn’t worth the cost.  I do sometimes run the motor for longer periods but this is not that frequently. You mentioned the Davis Mega Light, That sounds like a good idea that would keep my battery usage way down, probably even to the point where a 10 watt solar panel would keep it up to snuff most of the time.  I have a second 33 AH battery that I can keep charged at home and take along on those ocasions where I think I might need more battery. How does Davis manage such low power consumption and why doesn’t someone use the same technology for running lights? I see in all of the catalogs for solar panels that they don’t use any controller with panels smaller than 15 watts.  They are talking about larger batteries though.  Will a 10 watt panel overcharge a 33 AH battery if left for weeks without any usage?  If so will the charge controllers designed for 15 watt and larger panels work with a smaller panel? Pete Before you buy.

Response:

I had a charging coil in my suzuki 3.5.  It was enough to keep the batt up for what I needed.  Your consumption may vary.  A solar cell would probably keep you up  all night, if you need to.  I used an hurricane lamp clipped on to a bowline knot loop in the topping lift for an anchor light, which is only required if you anchor in uncharted anchorages. As I did not use the engine much, an anchor light would just about kill the batt overnight. Terry K – Hide quoted text — Show quoted text – I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option? The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator? I would appreciate any constructive comments or suggestions about any of this. Pete Before you buy.

Response:

Pete The Mega Light (now DAVIS) uses a combination of not new technologies.  I too wondered why they seemed to be so efficient.  The answer is obvious. In the first place they are simply not real bright.  Of course compared to a moonless night at sea or in some tropical anchorage they’re plenty bright. Looking to pick out your yacht from a whole bunch in a busy, well lit anchorage…good luck. However perhaps the a green, strobed version might make them distinctive (if not bright). Technically, The last time I looked, they used regular "grain-of-wheat’ lamps housed in a reasonably efficient lens package. Absolutely Fantastic for lighting up the cockpit so you’ll not stub your toe, or so you can find the combination to the lock….but NEVER for navigation. In lighting you can use more efficient technologies, proper electrical supply & controls as well as mechanical means such as lenses….but there’s absolutely no free lunch. skennedy Sinewave Marine Electric ABYC Certified Tech’s.

– Hide quoted text — Show quoted text – You mentioned the Davis Mega Light, That sounds like a good idea that would keep my battery usage way down, probably even to the point where a 10 watt solar panel would keep it up to snuff most of the time.  I have a second 33 AH battery that I can keep charged at home and take along on those ocasions where I think I might need more battery. How does Davis manage such low power consumption and why doesn’t someone use the same technology for running lights?

Response:

I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  

  Sounds like an expensive battery.  The small, "24 series" deep cycle batteries should cost around $50 and will provide 85 amp-hours of capacity.   Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time.

 Okay, so you already have these batteries.  How old are they?    I would think that carrying the battery back and forth will get old quick.  You will be much better off with a permanent installation and charging system. 2. Using a solar panel.

  If you don’t have dock power available, then this is your best bet. You probably don’t want more than a 5 watt panel unless you are also going to get a charge controller (voltage regulator).  As long as you have all week to recharge the battery, a small panel should work just fine. 3. Getting an alternator for the 4 HP Mercury outboard.

  If you were going to be buying a new motor, then I might go this route.  I would not advise upgrading an old motor.  I suspect that you would not get enough run time to make a significant difference in your battery charge anyway. The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator?

 They are usually additional coils added under the flywheel with a rectifier box located off the motor someplace.  Installation on an existing motor could be a real pain.  They often have no voltage regulation, which can be a real problem for small gel cells.   Rod McInnis

Response:

Why not find a small penal (5W or so), hook to both batteries.  If after a while you find that 5W., isn’t doing the job add  another 5W. penal.   Mike – Hide quoted text — Show quoted text -Brand new.  I got them for free from a friend who maintains UPS units.  I would think that carrying the battery back and forth will get old quick.  You will be much better off with a permanent installation and charging system. Yep. 2. Using a solar panel.   If you don’t have dock power available, then this is your best bet. You probably don’t want more than a 5 watt panel unless you are also going to get a charge controller (voltage regulator).  As long as you have all week to recharge the battery, a small panel should work just fine. I usually sail a few times a week, but I don’t use lights most of the time, so that would probably be OK.  For those few times when it wouldn’t, I could take the second battery along. 3. Getting an alternator for the 4 HP Mercury outboard.   If you were going to be buying a new motor, then I might go this route.  I would not advise upgrading an old motor.  I suspect that you would not get enough run time to make a significant difference in your battery charge anyway. I have pretty much ruled the alternator option out. I am thinking about the solar panel, but I guess I do have one other option.  I could get a different slip that has shore power.  There are a few at the marina that are only about $100 more per year.  They have some other advantages as well such as running water. Pete

Response:

Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time.  Okay, so you already have these batteries.  How old are they?

Brand new.  I got them for free from a friend who maintains UPS units.  I would think that carrying the battery back and forth will get old quick.  You will be much better off with a permanent installation and charging system.

Yep. 2. Using a solar panel.   If you don’t have dock power available, then this is your best bet. You probably don’t want more than a 5 watt panel unless you are also going to get a charge controller (voltage regulator).  As long as you have all week to recharge the battery, a small panel should work just fine.

I usually sail a few times a week, but I don’t use lights most of the time, so that would probably be OK.  For those few times when it wouldn’t, I could take the second battery along. 3. Getting an alternator for the 4 HP Mercury outboard.   If you were going to be buying a new motor, then I might go this route.  I would not advise upgrading an old motor.  I suspect that you would not get enough run time to make a significant difference in your battery charge anyway.

I have pretty much ruled the alternator option out. I am thinking about the solar panel, but I guess I do have one other option.  I could get a different slip that has shore power.  There are a few at the marina that are only about $100 more per year.  They have some other advantages as well such as running water. Pete Before you buy.

Response:

If I understand correctly, you want to ensure that the battery is charged when you go to the boat for a daysail- for this a solar cell is perfect, preferably with a regulator, 10 watts is fine from my experience. A single overnight stay would be possible on your battery. The outboard alternator is close to useless- I had a 9.9hp 4 stroke with a 6 amp alternator and it made very little difference even running it much more than I liked. Charging at home would also be good but it is one more job to do before you go sailing which is why I recommend the solar option.

– Hide quoted text — Show quoted text – I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option? The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator? I would appreciate any constructive comments or suggestions about any of this. Pete Before you buy.

Response:

The worth of the alternator on your outboard is dependant on how much you motor. It you are only motoring for 30 minutes a day or so (about the length of time I use my motor, if that), then it is not going to do you a whole lot of good. What is the maximum length of time you are going to be out on your boat?  If you aren’t planning on going overnight, then the 33 amp battery should be plenty. It is a convenient size (I am assuming group U-1), and will not signifcantly affect your sailing ability. Figure out your power usage: navigation lights: 0.8amp ea x 2 = 1.6 amps x 2 hours per day= 3.2 amp-hours gps: 0.4 amps x 10 hours per day = 4.0 amp-hours anchor light: 1.3 amps x 8 hours= 10.4 amp-hours radio? are you going to plug it into a charger or something? Total: 17.6 amp-hours.  Results may vary depending on the time involved and the wattage of your  lights. Using a davis anchor light (0.074 amps x 8 hours= 0.6 amp-hours) would go a long way toward reducing this load. You generally don’t want to drain a deep cycle battery below 50% charge (33 amps-hours/2=16.5 amps). (33 amp-hours is the amount the battery will produce over 20 hours of discharge that leaves the battery essentially drained, with a constant discharge rate of 33/20=1.6 amps).  This pretty much what you would get for an overnighter.  Seems like you wouldn’t need a charging system if this is all you intend. If you decide to get a solar charger, note that the solar panel will put out a total amount of power equal to 4-5 times it’s rating (depending on climate and time of year).  So a 10 watt panel will produce a maximum of 4 amp-hours in a day.  That is not going to go very far.

– Hide quoted text — Show quoted text – I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option? The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator? I would appreciate any constructive comments or suggestions about any of this. Pete Before you buy.

Response:

[[ This message was both posted and mailed: see    the "To," "Cc," and "Newsgroups" headers for details. ]] I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option?

I have a 10 watt Unisolar panel,   it keeps an 8-D house battery fully charged, no muss, no fuss. craig poole

Response:

- Hide quoted text — Show quoted text – I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option? The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator? I would appreciate any constructive comments or suggestions about any of this. Pete

It’s not going to hurt to add the alternator option, but I doubt you’ll get good results.   First, 4 amps (max, in reality less) isn’t going to keep up with your lights if you do anything at night.   Second, you’ll probably need to add some regulation to keep from damaging the gel battery if you motor for long periods of time.  I don’t believe the outboard will be well regulated. (Someone else more familiar may have better information here.) The solar panel will probably be a good choice, but if you have a gel battery, again,  you need to take care that it is reguated properly. Gels aren’t very forgiving of overcharge. Also, if you plan to anchor out or spend much time at night, your 33 ah battery probably isn’t big enough. Gene Gruender Rainbow Chaser

Response:

I would buy a small gell sell for a daysailor since they can be submersed plus acid will not leak when you capsize. "Trains are a winter sport"

Response:

I would buy a small gell sell for a daysailor since they can be submersed plus acid will not leak when you capsize.

The 12 V, 33 AH battery that I mentioned is a gel cell.  Small is a relative term.  I guess that 33 AH might be a little on the large size for a daysailer, but I don’t think it is too big.  Comments? Pete Before you buy.

Response:

I have a small daysailer and want to add a battery for lights, gps (M315), radio (handheld), etc.  The battery I plan to use is a deep cycle 12 V, 33 AH battery, originally intended to be used in an UPS unit.  I have a few questions regarding this installation. Charging options that come to mind are: 1. Charging at home and carrying back and forth to boat.  I actually have two batteries so one could be on trickle chare all of the time. 2. Using a solar panel. 3. Getting an alternator for the 4 HP Mercury outboard. Does anyone care to comment on the solar panel option? The Mercury outboard has an optional alternator listed as a feature. The web page says, "Alternator: Optional 4 amp (50 watt)".  Anyone know anything about this unit?  User installable?  Cost?  Does it work well?  Is it just a coil to be added to the magneto or really an alternator? I would appreciate any constructive comments or suggestions about any of this. Pete Before you buy.

Response:

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