battery

[Craig Weis]

"I will request any (basic, not too techy) knowledge about a solar panel trickle down that maintains charge"

The solar panel over the fwd hatch on my CP-19 came from AutoZone. It's the second one, as a guest on board stepped on it and broke the glass. It still charged OK even when filled up with rain and condensation. He replaced it. It's no bigger then the hatch and goes up and down with the hatch. It sits up on four screwed on cane tips that are 3-M 5200 glued to the hatch for cooling air under neath it. The cell is diode protected so their is no back feed from battery to cell. Wires run under the hatch and down the compression post, through the storage compartment, through the quarter birth bulkhead and under the cushion to the battery in it's strapped down box.

Don't expect too much charge. On a sunny day, the meter shows 16 to 18 volts DC at about 300 milliamp going to the battery. That's just enough to boil the water out of a good battery in a season in Wisconsin. About 7 months. Remember the cell is working even when no one is on board so check the water even if it's a maintainers free battery.

You'll not have enough generated power from a cell to carelessly use say a chart plotter and depth gauge, radio, and stereo/CD/ and lights at night on a Friday evening, all day Saturday, and a Sunday return to home port cruise. I can use just the Raymarine ST-40 when I'm sailing for three days. And short bursts of use for the other stuff.
I sail with a 1000 amp cold cranking deep cell battery. I did boil the water out of my first 1000 CCA battery a few years ago. Turned it into a jelly like inside and dead shorted out one of the 6 cells, She made 10 volts when I traded it in.

skip.

 

[Bob Condon]

I am not sure that it would be worth putting a solar panel
when you are using an electric motor to power your boat.

If I could not recharge the battery via land power, I would consider one of the
coleman 1000W small generators, and mount a perminent charger onboard so that
when you are sailing, or just working around the boat, you could recharge.

EVERYTHING I read would tell me NOT to use the 12V off the coleman but instead use a real
battery recharger. The 12V is very dirty and unregulated which will not make your battery
happy.

My cape Dory could use a solar panel  for the house battery. The engine would be started
by the engine battery and allowed to charge. I would add the house battery to
recieve a charge when necessary.

The one issue I have with this boat is that it takes a lot of power to start the diesel engine
but for the 20 minutes you need to motor to the harbor entrance, the little 35W generator has no
where near replace what it needed to start.

I bring a power battery pack (like you would use for the car), recharge that and use that to start the engine
at times...

Also, friends on a Pearson 28, tell me to purchase a solar panel regulator($30) to protect your battery because it will manage
the power, make sure it is within proper voltage range and not allow to overcharge your battery...

[Joseph]

I have no experience with powering electric motors. I view the motor auxilliary in a sailboat more as an emergency device and am biased towards petrol-powered machines.

However, in regards to housekeeping batteries, for almost a decade I have charged the batteries in my sailboat with a flexible Uni-Solar pannel USF-11, 10.3 Watt  (http://www.solarwares.com/). After all these years mine is still going strong. However, I understand that Uni-solar no longer makes them.

I always used it with 75 Amp-hour marine deep-cycle wet cell batteries and never needed a charge regulator. This is what West Marine has to say about using charge regulators with solar panels: "As a general rule panels that produce less than 1.5% of a battery's rated capacity in amp hours do not require regulation. This means that a 1.5 amp panel is the largest you should use without a regulator on a 100-amp-hour battery."

The USF-11 max output is 10.3 W and 24 V. Since W = A*V, then A = W/V = 10.3/24 = 0.43 A, which is less than 1.125 A (i.e., 1.5% of the 75 Ah capacity of the batteries I use). Hence, no need for a charge regulator.

My rough estimate was that during an average day of solar light the panel would be able to replenish some 3-4 Amps and if during a cruise I could keep my daily (and nightly) demands below that value, I would never have to charge the batteries in any other way... and so far it seems to have worked.

However, this would clearly not work for powering an electric motor that would deplete a fully charged 75 Ah battery in an hour and a half...

Hope this is useful.

J.

[kahpho]

I would second Bob's advice to use a charger controller with a solar charger. It will protect your battery. A 12 volt wet cell battery generally should have 13.7 volts from the charger. More then that will cook the battery (for other battery chemistry's follow the manufactures recommendations). The controller will take care of that and remove charge when the battery is fully topped up. They usually have a blocking diode built in to prevent battery charge from back flowing to the panel during dark hours too.

Some of the cheaper ones I've seen will allow one charge cycle per day. That is if the battery gets topped up and the controller stops the charge cycle then no more charge until the next day. Usually that's not a problem for just keeping a float charge. Some will allow additional charge cycles if the the battery voltage drops a certain amount, indicating a drop in charge. For those who want all the whistles and bells there are all sorts of available features, meters, adjustable set points, % full indication in both charge and discharge cycles and on and on. You'll pay extra for those and they aren't really needed.

Prices start about $20 and go up to "oh wow". For a small system just get a cheap one. It's good insurance for your battery.


mel

[Shawn]

You can get a Solar charge controller for $28 at:

http://www.emarineinc.com/products/charge_controllers/controllers.html

Look at the Sun Guard 4.5.

I use the SunSaver 10  on my setup with a Kyocera KCM40 panel.

Shawn

[Craig Weis]

Bob Condon says, "Also, friends on a Pearson 28, tell me to purchase a solar panel regulator($30) to protect your battery because it will manage the power, make sure it is within proper voltage range and not allow to overcharge your battery..."

Wait a second!  A $30 dollar cell...hummmmmm, I don't think it will protect the battery. I'm thinking it will not effect the battery at all. And I'm thinking it's like "peeing in the ocean to make it overflow, ain't going to happen." Good thought though. Every amp 'in' helps prolong the 'take out' factor.

I lie to myself and tell me that my solar cell is doing good, when actually it can't hurt as long as I monitor the water level of the 6 cells. Every few weeks I do hook up a 6/2 amp trickle battery charger and give her a good cooking dock side. Nice and slow.

Once the voltage drops the Raymarine ST-40 Bi Data instrument goes heywire. This unit does have a three brightness internal backlit screen that one had better remember to turn off when sailing during the day. I only use the Raymarine 435i chartplotter to adjust the dead reckoning course when sailing to Green Island and points 'Nort' when doing a three day sail. The handy feature is...'Here is the boat. And here is a line on the scope that indicates the direction were sailing' and I put that line through Green Island then note the compass lie and follow that compass line. And power down the chartplotter asap. Really works well when I can't see the island do to crud or tall waves.

Joseph says, "1.5% of a battery's rated capacity in amp hours" don't require much attention.  So 10.3 watts, and 0.43 amps at 24 volts. The watts aren't as important as the amps, because amps are what you use with electric consumables on board. And amps are what boil the battery. And says, "My rough estimate was that during an average day of solar light the panel would be able to replenish some 3-4 Amps."
That is a hell of a long ways away from 300 milliamps. Even 0.43 amps is a long way from 300 milliamps. The 300 milliamps is the draw on my reciever in my R/C aeroplanes!

Additionally I might add if you sailors are using the flexible matt type solar cells that lays over the fiberglass and core construction used on some boats [not Com-Pacs] these can 'seal-in' the sun's heat and actually bubble up the cabin top on certain types of 'above water laminates'. Usually when the matt is removed or has air circulating under the cell the laminate will lat back down. It happened on my dockmate's 28 foot Sovereign. Just a though.

skip. Every lamp/bulb on the boat is an LED

[Salty19]

Skip, if I may make a suggestion to buy a charge controller and mount between the solar cell and + terminal. This should avoid overcharging and instead reduce voltage to float charge the battery once it's near capacity.   They also control reverse current flow during the night.

Right now you are putting too high of a voltage on the battery (solar chargers are often around 17 volts).
That will boil and destroy the battery, even at low amperage charge rates.  Granted at 300milliamps, it's a slow kill and probably just reducing the maximum capacity rather than boiling the acid (tough to say for sure).

A healthy battery can take about 14.7 volts max (varies on the battery) which is typical of a strong alternators' max output (often alternators will put out less--more like 13.7--14.4 volts).  As the battery becomes charged, the required voltage to keep charging  is reduced (this depends on charge rate, temperature, battery type, battery age, sulfation state). Hence why they are called float chargers--they reduce the voltage based on the condition of the battery..at least the conditions that the charger is intelligent enough to know).

What do you see a max battery volts when using solar charging right now (Or rather last summer when the sun was high)?
Remember that 12.7 is fully charged...

[Bob Condon]

Skip,

Sorry Skip but I find your questioning about regulators a bit comical. They work and protect batteries
and just because Comfort and Joy does not have one, does not mean they are
not a good idea.

I look at this as a business problem too. Regulator: $30 and you buy once. Good Deep Cell battery: $90 - 145.
No regulator means that you could buy a battery each year if you screw up....


Thanks
Bob

[Craig Weis]

Yes as I said this is all Greek to me. I had no idea nor knew a voltage regulator could be used in conjunction with a solar cell that puts out about 17 to 19 volts.

So what do I ask for and where do I ask for one?
skip.

[Shawn]

Skip,

See my post a little bit further up. If you want to be able to adjust the charge voltage for the battery type you need the 6 amp version or above. These are full PWM charge controllers, not just simple diverters.

Shawn

[Joseph]

Don Casey says...

Installing a solar pannel to maintain batteries

http://www.boatus.com/boattech/casey/30.htm

J.

[curtisv]

Skip,

You want a charge controller.  For a small panel that is giving you only 300 mA, almost any charger will do and they are cheap.  Boiling a batter is not cheap.

I had a small panel on a wet cell with no charge controller.  Left it for about two weeks when I thought it was disconnected.  Cooked a lot of water out ofthe battery.  I could add the water back but it never held much of a charge after that.  I had to replace it.

Put a separate fuse on either side of the battery, the charging side and the load side.  Fuses should be physically very close to battery positive.

Curtis

Here is a picture.  Pardon the amatuer art - I'm not a graphic designer and this was hand drawn.

[Craig Weis]

Thanx Curtisv, your the tops.
Well over to Radio Shack.

skip.

[Salty19]

Don's article leaves a lot to be desired, IMHO.   Seems atypical of his work.

Curtis..very nice diagram.  That's how I would install everything as well with one exception.  Put an appropriate size diode in between the controller and fuse to eliminate any chance of backfeeding power into the controller or panel.  With that said, most of the controllers have such a diode in their circuity so the additional diode is not needed.  Specifications to check on the controller is the ability to eliminate (not reduce) backfeeding.

Using Curtis' diagram, if your outboard has an alternator on it, connect it to the CONTROLLER, not the battery, the same way as the solar panel.  However if you have a modern current sensing landbased charger, you can bypass the controller.  Some controllers can accept multiple connections, so buy one for your future intended configuration.

[Shawn]

"Using Curtis' diagram, if your outboard has an alternator on it, connect it to the CONTROLLER, not the battery, the same way as the solar panel. "

Most of the cheaper solar regulators are not rated for an alternator input on them. The manufacturers specifically recommend against using them in that capacity.

Shawn