Solar Trickle Charger

LakeOntario270

LakeOntario270

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Jan 4, 2013
287
Catalina 270 Rochester, NY
Because of flooding on Lake Ontario I have lost my dockside power. To be able to charge my starting battery I purchased a 30W solar panel with a controller. I plan to clip onto the wires from my normal AC charger that run to the battery (they are easily accessible).
Once I have my dockside power back later this summer can I make a permanent connection to the battery? This means I would have the alternator, AC charger, and solar charger all connected in parallel.
 
D

dlochner

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Jan 11, 2014
13,114
Sabre 362 113 Fair Haven, NY
Yes, but....

There is a limit to how many connections can be on the battery post. Four current drawing connections is the limit. Temp sensors don't count. You could run out of battery post.

Everything coming off the battery post needs to be fused within 7 inches of the battery.
 
SirMichael

SirMichael

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Jun 1, 2016
162
Hunter 28.5 Lake City, MN
You will want to check your battery voltages once you have the solar panel connected up. I am not sure if a 30 W solar panel will be enough to run the battery charger. The battery voltage should be roughly 13.4 V DC once you have your solar panel connected up to the AC charger.

Another thought would be to try to find a different DC battery charger that would run off of a voltage, probably a little higher than 15 V. I’m not sure what your solar panels put out for voltage.

Mike
 
Captain Larry-DH

Captain Larry-DH

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Jun 14, 2010
2,381
Robertson & Caine 2017 Leopard 40 CT
SirMichael said:
You will want to check your battery voltages once you have the solar panel connected up. I am not sure if a 30 W solar panel will be enough to run the battery charger. The battery voltage should be roughly 13.4 V DC once you have your solar panel connected up to the AC charger.

Another thought would be to try to find a different DC battery charger that would run off of a voltage, probably a little higher than 15 V. I’m not sure what your solar panels put out for voltage.

Mike
Click to expand
Mike -- Solar panels are connected to a solar charge regulator, that in-turn is connect to the battery bank. It is not connected to the AC charger. (However, the output of the AC charger is also connected to the battery bank, so both devices are connected in parallel on their outputs to the battery).
The solar regulator prevents overcharging, and optimizes the charge current based on the battery banks charge acceptance level. (The better ones are also temperature compensated.)
 
D

dlochner

.
Jan 11, 2014
13,114
Sabre 362 113 Fair Haven, NY
SirMichael said:
You will want to check your battery voltages once you have the solar panel connected up. I am not sure if a 30 W solar panel will be enough to run the battery charger. The battery voltage should be roughly 13.4 V DC once you have your solar panel connected up to the AC charger.

Another thought would be to try to find a different DC battery charger that would run off of a voltage, probably a little higher than 15 V. I’m not sure what your solar panels put out for voltage.

Mike
Click to expand
Captain Larry-DH said:
Mike -- Solar panels are connected to a solar charge regulator, that in-turn is connect to the battery bank. It is not connected to the AC charger. (However, the output of the AC charger is also connected to the battery bank, so both devices are connected in parallel on their outputs to the battery).
The solar regulator prevents overcharging, and optimizes the charge current based on the battery banks charge acceptance level. (The better ones are also temperature compensated.)
Click to expand
As I understand the original post, basically, he plans on using the battery charger cables as an extension cord to reach the batteries until the water recedes on the lake and he can use shore power again at which point he'll connect the solar panel to the batteries correctly, i.e., to the battery posts or to positive and negative busses. He does have a controller to regulate the voltage.

A 30 watt panel properly controlled will have a maximum out put of about 2 amps at 14v in full sunlight. That's enough keep the batteries topped off, but not enough to recharge a partially discharged battery, unless there is a lot of sun with the panel properly positioned to maximize the solar energy for a good many days. In upstate NY this spring, those conditions aren't happening! He'll get about 8-10 amp hours a day out of a 30 watt panel if he has a decent MPPT controller and the weather cooperates.

I don't think the OP intends to run the AC charger off a small DC solar panel.
 
LakeOntario270

LakeOntario270

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Jan 4, 2013
287
Catalina 270 Rochester, NY
Just came today. Hooked it up to my battery just as it stated to rain. Panel still putting out 260ma.
Solar1.jpg
Solar2.jpg
 
NotCook

NotCook

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Dec 29, 2008
806
Treworgy 65' LOA Custom Steel Pilothouse Staysail Ketch St. Croix, Virgin Islands
That looks pretty big for only 30 watts. Not much smaller than a 100W panel. Glad to see you were planning to use a charge controller, as a panel will such the juice out of the battery once the sun goes down without a charge controller or blocking diode.

For what it is worth, I was going to invent Lunar Panels, but it seems that solar panels will do the same thing. For example, our 7.4 kW array on our home actually puts out current during a full moon. We actually measured 3 watts output on a clear full moon night. If that scales, one could get 30 watts for trickle charging out of a 74 kW array - that would be about a mere 240 300 watt panels. Just sayin.
 
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Likes: Captain Larry-DH
NotCook

NotCook

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Dec 29, 2008
806
Treworgy 65' LOA Custom Steel Pilothouse Staysail Ketch St. Croix, Virgin Islands
dlochner said:
No need for a Bimini, dodger, or awnings with that array! Of course, it might present problems is you tried to sail that boat.
Click to expand
Maybe there's a new idea for sails - flexible solar panels. Reefing might be a challenge, though.
 
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