Solar Power Charging

[captainron19]

Was thinking of possibly getting one of those DC Solar Charging panels. Any thoughts on them? My current configuration is 2 batteries to a switch (wiring setup diagram below) Since I have 2 batteries would I need 2 of the solar panel charging units or would one suffice? And if one..... how would I go about hooking it up?

 

[Silvertip]

Re: Solar Power Charging

1) Your bilge pump should be wired to the largest of the two batteries and NOT the COM terminal. Why? With the switch in the OFF position the bilge pump won't run.

2) Solar panels a) a theft target for thieves, b) generally way to low little output to charge ONE battery much less two. c) to get one that would actually CHARGE and not just MAINTAIN, it would need to be nearly the size of your boat.

3) Depends on where your boat sits when not in use and how long it sits. The longer the boat sits the more realistic a solar panel becomes but size (Watt output) does matter. Most of the two foot square panels are in 15 watt (about 1.3 amp) range which is nothing more than a maintainer to keep ONE battery topped off between uses. If the boat has a high power stereo this type of unit will simply not recharge a deeply discharged battery. Just because a panel outputs 12 volts does not make it a charger. The manufacturers would like you to believe it does. You need a minimum of 4 - 5 amps output to qualify as a charger. Those are big panels and they get pricey. Since they don't work at night, they are equally worthless for camping where shore power is not available.
This is probably not what you want to hear but analyze what the panel must do and what output you NEED to do that job.

If you do end up with a panel, wire the negative to the same negative (either battery) as the other grounds. Wire the POSITIVE to the COM terminal and set the switch to BOTH, BAT 1, or BAT 2 depending on what which battery or batteries need charging. Same as when running the engine. Your the electrical traffic cop -- tell the juice where to go.

 

[captainron19]

Re: Solar Power Charging

The boat sits dry in my yard when not in use. The only thing I was looking for as far as charging was to allow me to have the ability of having a few electronics on when in the water and engines are not running... vh radio and am/fm radio so as not to drain down my battery.

As far as the bilge pump goes.... since the boat does not sit in the water I have left it on a switch at console.... current bilge pump does not have a float switch (either on or off) Thats how it was when I purchased the boat but I plan on replacing it with a bilge pump with a float switch and keep it hot all of the time

 

[UncleWillie]

Re: Solar Power Charging

.... The only thing I was looking for as far as charging was to allow me to have the ability of having a few electronics on when in the water and engines are not running... VHF radio and am/fm radio so as not to drain down my battery...

So you ar NOT looking to charge the battery, you are looking for a second power source to place in parallel with the battery.

A VHF radio on receive that occasionally breaks squelch and a music radio played at a low conversational level will need at least one AMP (12watts) maybe a little more.
The panel only delivers the advertised output in Full, Blue Sky, Sunlight with the panel tilted and pointed directly at the Sun.
You are in New Jersey not Arizona, so at least 30 watts bare minimum will keep up with the load, or at least extend the battery capacity significantly.

A group 27 battery has about 100 amp-hours of capacity. So the battery alone will run your two radios for at least 2 days days and nights continuously; possible up to 4 days.

The Solar Panel will add another 6 hour per day if you get full Sun every day.
So the 4 day battery could be extended to possibly 5 days with the help of the panel.

An ECONOMY SOLAR PANEL KIT can be had for ~$200 or the price of 2 Economy Batteries.
The panels take up a square yard and will need to be stowed when under way.

But the good news is ...... Well, why did we think this was a good idea again?

If you do not plan on being anchored for days on end or at least run the engine for an hour a day;
The battery you already have will be just fine.
A better and less expensive option would be to separate your batteries with an ACR and operate the engine off of one battery and everything else off the other.

 

[Silvertip]

Re: Solar Power Charging

He has a dual battery switch which is why the solar panel is such a waste.

 

[jhebert]

Re: Solar Power Charging

Typically you cannot directly connect the output of a photo-voltaic panel to a 12-Volt lead-acid storage battery. Typically an intermediate device is placed between the photo-voltaic panel and the storage battery. This device is called a charge controller. People who operate recreational vehicles (RV's) and who stay in remote places instead of KOA campgrounds are probably much more experienced at generating their own electricity with solar power than boaters. I would look for advice from those off-grid RV-er's.

Here is an example of a highly efficient charge controller:

Morningstar Corporation ? SunSaver MPPT

Here is a very informative blog created by a gentleman that is an off-grid RV-er and a good engineer. He talks about various methods of generating electricity from photo-voltaic panels and efficiently using it to produce stored electricity in lead-acid batteries. I have found this blog to be very informative. Its author has first-hand information to offer, based on his experience, and he brings an engineer's analysis to the problems. I highly recommend reading this:

HandyBob's Blog ? Making off grid RV electrical systems work

As a solution for providing power on a boat, I don't think photo-voltaic panels are a good method. Many drawbacks have been mentioned by others. In general, the size and cost of the photo-voltaic panels needed to deliver any sort of reasonable electrical energy make them unworkable on a small boat.

 

[Silvertip]

Re: Solar Power Charging

A charge controller is not needed on low output panels because they simply cannot fully charge a battery.

 

[captainron19]

Re: Solar Power Charging

If you do not plan on being anchored for days on end or at least run the engine for an hour a day;
The battery you already have will be just fine.
A better and less expensive option would be to separate your batteries with an ACR and operate the engine off of one battery and everything else off the other.

Thanks for the replies guys very helpful.

I see you mentioned about separating my batteries with an ACR....what exactly is that? (this is my first year with boat) - would appreciate any comments based on my wiring diagram above on the way I operate right now. Right now, I just put the switch to "both" to start and run the boat and when I am sitting with the engine off I simply turn the switch to off. So if I want to run the radio while sitting my plan would be to switch my battery switch to the non-starting battery. I have also heard of some input from other people that based on my wiring configuration with my switch i should not start the engine in the "both" position but instead use the switch in the starting battery position only but if I do that and run with the switch in that position the other battery will not be charging correct?

 

[UncleWillie]

Re: Solar Power Charging

An Automatic Charging Relay (ACR) will connect the two batteries together if Either one of them is receiving a charge.
It closes when either battery is above 13 or so volts, and opens when they go below 13 or so volts.
Install and rewire as shown



Switch stays in position #1 (Port) to start the engine.
Relay closes and both batteries charge.
Shut down engine. Relay opens.
Radios run only off of Battery #2 (Strbd)
Battery #1 is reserved for restarting.
Engine can be started from #2 or Both if needed by switching.

Using the 4 terminal switch that comes with the Add-A-Battery Kit adds the ability to turn OFF both Batteries.

It will do what you are now doing manually, but without all the thinking and possibilities of forgetting to switch.

 

[captainron19]

Re: Solar Power Charging

Thanks for the reply and diagram UncleWillie

I assume I chould just take 2 wires from the ACR and connect them to the #1 and #2 posts in my switch? Do you recommend any specific brand or model?

I noticed you stated to start in pos 1 to start battery so it will draw from the correct battery but if I do that and run the boat with the switch in that position then battery 2 will not receive any charge correct? I assume not wise to switch the battery positions while the engine is running. My original thought was to keep switch in "both" position for starting and running the boat then when i am sitting and just want to have my radio on switch to pos #2

 

[UncleWillie]

Re: Solar Power Charging

Thanks for the reply and diagram UncleWillie

I noticed you stated to start in pos 1 to start battery so it will draw from the correct battery but if I do that and run the boat with the switch in that position then battery 2 will not receive any charge correct? I assume not wise to switch the battery positions while the engine is running. My original thought was to keep switch in "both" position for starting and running the boat then when i am sitting and just want to have my radio on switch to pos #2

NO!
Switch stays in #1.
Boat starts from battery #1
With engine running and battery charging, The ACR Connects Battery #2 to the First and BOTH Charge!

When you Stop, The batteries stop charging and the voltage drops below 13 volts,
The ACR Opens and separates the Batteries.
The Radios draw ONLY from Batt #2. NO Switching required! That is the whole point of the ACR!

The ACR Eliminates the need to ever switch anything other than to OFF at the end of the day if desired.

-----------------------------
With your Current wiring, YES! Start in #1, #2, or BOTH, your choice.
Run in Both to charge both Batteries.
Select #2 when stopped to save #1 for the restart.
Then switch back to both while running.

The ACR does all of this for you automatically. No thinking, No messing up!

You can move the switch while the the engine is running but DO NOT turn it to the OFF Position even for a split second.
Disconnecting the batteries from a running alternator will cause the voltage regulator to de-regulate possibly frying the ignition.
You can switch #1 >>> BOTH >>> #2 but NEVER! #1 >>> OFF >>> #2.