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Solar Trickle Charger

May 24, 2010
18
Bristol 32 Buffalo
Just replaced my starting battery with a new, wet cell unit and decided to install a 4w Coleman solar trickle charger to keep the battery charged up. After 5 days on the solar charger at the mooring my battery was weak and had to jump it with an external charger to get the engine to start. Is it possible that the solar array is discharging my battery at night? Coleman says this particular unit doesn’t require a regulator. Do I need a better/larger solar panel to keep the battery charged up?
 
Oct 24, 2010
2,390
Hunter 30 Everett, WA
First off, 4 watts is tiny. It would take a long time to bring up your battery. In the dark, it may be draining a bit of current. You could install a small diode (such as a 1N4003) in series with it to make sure. If you need to replenish 20 amp hours, you will need at least 65 hours of direct bright sunshine plus some for inefficiency. Figure at least 2 weeks without a draw. (A really rough guesstimate to be sure)

Ken
 
Jan 19, 2010
9,953
Hunter 26 Charleston
Was your battery dead before you hooked up the solar panel? If not then something is really wrong. If it is hooked up backwards by accident, then it will certainly drain your battery. Do you have any other loads on your system? For instance a float switch on a bilge pump that occasionally switches on?
 
Oct 19, 2017
6,879
O'Day 19 Littleton, NH
Why does the solar panel not need a regulator? Does it read the back charge from the battery? Is there a regulator built into it? If so, how does it know what size battery it is charging? I'm showing my ignorance here, but don't regulators prevent over charging? I would think the battery dictates that. Or is it the battery that doesn't need a regulator?

- Will (Dragonfly)
 
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May 24, 2010
18
Bristol 32 Buffalo
Rgranger, the battery was new & fully charged when I hooked up the solar panel. The only thing that’s a load on the batteries is my automatic bilge pump, which rarely switches on. I’m really mystified why it’s draining, which is why I’m wondering if it’s the solar panel, which seems strange. I just returned from a two hour sail during which I ran the engine the whole time to charge the battery (I started it with jumper cables). I’ll be interested to find out if it holds the charge without the solar panel.
 
May 24, 2010
18
Bristol 32 Buffalo
Will Gilmore - don’t feel uninformed - I’m in the same boat! I’ve never had a solar panel but wanted to try one to keep my battery charged. The one I purchased (Coleman 4w) has an internal diode that supposedly keeps it from discharging the battery at night. My understanding is that an external regulator is required only for higher wattage panels.
 
Jun 24, 2014
80
Westsail 28 72 Long Beach , California
Oct 24, 2010
2,390
Hunter 30 Everett, WA
Why does the solar panel not need a regulator? Does it read the back charge from the battery? Is there a regulator built into it? If so, how does it know what size battery it is charging? I'm showing my ignorance here, but don't regulators prevent over charging? I would think the battery dictates that. Or is it the battery that doesn't need a regulator?

- Will (Dragonfly)
Some small panels don't produce enough current to damage a battery. The downside is they don't produce enough current for a practical charge.

Ken
 
Sep 27, 2008
155
Hunter 41 Longport,NJ
My system is strange - I have a dedicated starter battery for the genset, which is not connected to anything except an on-off switch. If I don;t use the genset, the battery eventually discharges. I was thinking to get a small solar trickle charger - rather than install one into the existing charger system system Of course - I detest drilling more holes for wires Any thoughts/recommendations ? It's a hunter 41
 

danm1

.
Oct 5, 2013
125
Hunter 34 Mamaroneck, NY
Jul 23, 2009
489
Beneteau 31 Oceanis Grand Lake, Oklahoma
Something obviously drained the battery. Get out a meter and find out whats draining the battery. Every solar panel should have a regulator but 4 watts is probably fine unless you live in a hot climate. A better solution would a slightly bigger panel and a regulator.
Find the current leak !
 

DArcy

.
Feb 11, 2017
1,197
Islander Freeport 36 Ottawa
On my last boat I had a 7 watt solar panel with no regulator and it did a great job of keeping the battery topped up. After 5 or 6 days away from the boat I'd come back to a fully charged battery. These small panels just cannot provide enough current to damage a group 27 battery and I got about 6 or 7 years out of store brand batteries with that setup.
Try measuring battery voltage with and without the panel connected in bright sunshine and with the panel in the dark. If it goes up with the panel connected in sunshine but down (relative to no solar panel connection) in the dark then the panel doesn't have a diode. Note that a 5 watt panel will not change the voltage very much so you will need an accurate DVM for this reading.
 
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Mar 6, 2008
681
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
Danm1, are you using a regulator aswell.
The 4watt solar panel may not produce high enough of voltage so that the regulator actually put out current.
 

danm1

.
Oct 5, 2013
125
Hunter 34 Mamaroneck, NY
Danm1, are you using a regulator aswell.
The 4watt solar panel may not produce high enough of voltage so that the regulator actually put out current.
No. I just used the panel hooked directly to the battery. It allegedly had some built in protection.
 
Jun 16, 2020
64
Hinckley Sou’wester 30 Falmouth ME
If I could open this discussion up again and apologies for my ignorance, but for weekend sailors like me looking for a relatively simple arrangement, do you mount solar panels permanently or can you have a more temporary arrangement where you lay out the panel after you moor? Similarly, are panels permanently connect to the batteries with some kind of switch or do you connect when you tie up? Perhaps the answer is “yes” depending on what I want to do……Can I assume the regulator circuit prevents reverse current flow when the engine is running?
 

BarryL

.
May 21, 2004
827
Jeanneau Sun Odyssey 409 Mt. Sinai, NY
Hey,

I installed this on my last boat:


It was very easy to install. I permanently mounted the controller, which was connected directly to the house batteries. The solar panel gets connected with a quick connect. When the boat was on a mooring I would connect the panel and lay it in the cockpit. When sailing I would disconnect it and stow in the aft cabin. The panel put out enough power to ensure charged batteries after a few days in the sun,

For my new boat I bough the same basic system, but a larger 90W panel.

Barry


If I could open this discussion up again and apologies for my ignorance, but for weekend sailors like me looking for a relatively simple arrangement, do you mount solar panels permanently or can you have a more temporary arrangement where you lay out the panel after you moor? Similarly, are panels permanently connect to the batteries with some kind of switch or do you connect when you tie up? Perhaps the answer is “yes” depending on what I want to do……Can I assume the regulator circuit prevents reverse current flow when the engine is running?
 
Jun 11, 2004
1,199
Oday 31 Redondo Beach
I permanently mounted the controller, which was connected directly to the house batteries. The solar panel gets connected with a quick connect. When the boat was on a mooring I would connect the panel and lay it in the cockpit. When sailing I would disconnect it and stow in the aft cabin. The panel put out enough power to ensure charged batteries after a few days in the sun,
I did the same thing except I don't even disconnect the panel when I go out. Just put it down below until I want to put it back up in the sun.
Been working fine for years.

Ther shouldn't be any problem with "reverse current flow".
 
Jan 4, 2013
249
Catalina 270 Rochester, NY
I purchased a Suner Power 30 Watt system to keep my battery charged.

You really need a controller to keep your battery from being over charged when it is full.
When I leave the boat I just set it on cockpit seat and feed the cable over the hatch boards (enough clearance to the hatch).
 
Dec 1, 2020
86
CAL 27 Illahee / Brownsville WA
I was thinking about what you are dealing with this spring. I got a basic 50watt panel and 10 amp controller from Home Depot for under $90 ( looks like I paid to much based on current pricing) and it's been working so far for me. Like Lake Ontario above,I lay it flat in the cockpit when at the mooring behind my house her in the NW, and it so far is holding my two AGM's at 13.7v. NY might be similar to WA state as to sun angle and sunny days. It's about 24" x 27" and fits below the cockpit seats when sailing.

I decided that all the discussion about charge rates, etc. was overkill for my needs. If I only get a few years from the AGM's so be it, but having a 100 or larger panel is to big for a small Cal 27.



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