Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-10-2013, 18:50   #1
Registered User
 
Nan26's Avatar

Join Date: Oct 2013
Location: Knoxville, TN
Boat: Pearson 26
Posts: 5
Solar wiring

I am currently wiring a 20 watt solar panel on my sailboat in order to charge my twin deep cycle batteries. When I first installed the solar panel I wired it to the positive, and negative of one battery, and assumed it would charge the other, as they are in parallel. When I visited my boat a few days later I measured the batteries and one battery had charged and the other had not. Do I need to wire the solar panel to the positive of one battery, and the negative of the other, or something other than that?


Please bear with me, as this is my first post
__________________

__________________
Nan26 is offline   Reply With Quote
Old 02-10-2013, 19:10   #2
Senior Cruiser
 
Blue Stocking's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: St. Georges, Bda
Boat: Rhodes Reliant 41ft
Posts: 4,117
Re: Solar wiring

Positive of one, negative of the other, everything else, size, condition, etc, being equal.
__________________

__________________
so many projects--so little time !!
Blue Stocking is offline   Reply With Quote
Old 02-10-2013, 19:24   #3
Registered User
 
jkindredpdx's Avatar

Join Date: May 2011
Location: Portland, OR, USA
Boat: Hallberg Rassy 35'
Posts: 1,047
Images: 5
Re: Solar wiring

Quote:
Originally Posted by Nan26 View Post
I am currently wiring a 20 watt solar panel on my sailboat in order to charge my twin deep cycle batteries. When I first installed the solar panel I wired it to the positive, and negative of one battery, and assumed it would charge the other, as they are in parallel. When I visited my boat a few days later I measured the batteries and one battery had charged and the other had not. Do I need to wire the solar panel to the positive of one battery, and the negative of the other, or something other than that?


Please bear with me, as this is my first post
that first post was nerve wracking for me, welcome to the club.

Do you have an A/B switch that's preventing charging of your second battery? I connected my Red to one battery + and black a ground. I'm not electric savvy, so I did buy "The 12volt Bible" used for a couple bucks. It's come in handy a couple times.

IMO. You should have a controller between the panel and the batteries or you can cook them. These guys are very nice and helpful over email or the phone and reasonably priced (I visited their warehouse and office too) Solar Panels from Wholesale Solar. I also wanted an isolator to avoid ruining the alternator on my engine and it allowed me to run wires to my two banks separately. Not sure I remember right but, 60watts panels, controller and isolator ran me about $150. Pretty sure the controller was less than $10.
__________________
http://www.sednahr35.blogspot.com/ Jim K.
jkindredpdx is offline   Reply With Quote
Old 02-10-2013, 20:05   #4
Registered User
 
Nan26's Avatar

Join Date: Oct 2013
Location: Knoxville, TN
Boat: Pearson 26
Posts: 5
jkindredpdx- I do have a battery switch, and a charge controller. I do not think that the battery switch Is affecting it because I can turn the batteries off and both charge equally when running the motor. I looked up the book you suggested, and I think I will buy that book to keep on the boat.
Thanks.
__________________
Nan26 is offline   Reply With Quote
Old 02-10-2013, 20:23   #5
Registered User
 
jkindredpdx's Avatar

Join Date: May 2011
Location: Portland, OR, USA
Boat: Hallberg Rassy 35'
Posts: 1,047
Images: 5
Re: Solar wiring

Quote:
Originally Posted by Nan26 View Post
jkindredpdx- I do have a battery switch, and a charge controller. I do not think that the battery switch Is affecting it because I can turn the batteries off and both charge equally when running the motor. I looked up the book you suggested, and I think I will buy that book to keep on the boat.
Thanks.
So like I said "I know nothing. . ." hopefully someone can answer this, but if you connect to one battery + and the other battery - aren't you over riding the A/B and making a connection between the two battery banks through the solar panel that would balance and/or drain both batteries? I connected mine that way before the isollator. One battery was 100% the other 50% and the next day found both batteries at 75% despite the A/B setting.
__________________
http://www.sednahr35.blogspot.com/ Jim K.
jkindredpdx is offline   Reply With Quote
Old 02-10-2013, 20:40   #6
Registered User

Join Date: Oct 2013
Location: maryland
Boat: columbia 36
Posts: 2
Re: Solar wiring

if the batterier are wired parrell to one another the negitive of one battery is allready the negitive of the other they are tied positive to positive and neg. to neg. it is possible that the condition of the batterys differ as internal resistance would cause one battey to charge at a different rate than the other using a controller is a must. follow the instructions.
__________________
therondor is offline   Reply With Quote
Old 02-10-2013, 22:04   #7
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,056
Re: Solar wiring

Nan, I'd suggest ordering one of the inexpensive basic 12v books and while you are waiting for it to come, use a pencil (both ends!) and pad to make a diagram of your electrical system. I'd bet there is something you aren't aware of, that disconnects the two batteries when the motor is off or the switch is off, otherwise two batteries hard-wired in parallel would have both been trickle charging.

You may simply have one bad battery, coincidentally, or some other simple and logical problem. But unless you explore the system and are 100% certain of where and how everything is hooked up--it will find a way to bite you, sooner or later.

One 20W panel probably (probably) can keep trickle charging two batteries with no harm and no extra components, as long as there is a diode in the panel so it doesn't drain them at night. If they are big batteries and a small charger, no controller etc. is needed, especially if they are conventional wet lead batteries and you can top up the electrolyte from time to time if needed.
__________________
hellosailor is offline   Reply With Quote
Old 02-10-2013, 22:26   #8
Registered User
 
CarinaPDX's Avatar

Join Date: Jan 2010
Location: Portland, Oregon, USA
Boat: 31' Cape George Cutter
Posts: 1,682
Re: Solar wiring

I recommend getting someone who understands these things to have a good look at your setup. Otherwise, do as Hellosailor recommends and diagram the system.

FWIW the negative grounds of both batteries should be tied together so the solar negative could be attached to either, or better at the common ground point. The alternator charges both batteries because it is probably not going through the selector switch but instead through either isolator diodes (most likely) or a battery combiner to both batteries. By attaching the solar positive to one battery positive you will not charge the other unless the switch is set to "both". The answer is to either use diodes to connect the solar positive to both batteries, or use a charge controller with outputs for both batteries. BTW an unregulated 20W panel is sufficient to destroy both batteries over a prolonged period of no load and bright sun so take care.

Greg
__________________
CarinaPDX is offline   Reply With Quote
Old 03-10-2013, 00:10   #9
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Solar wiring

Hi Nan26 welcome to the forum.

If the batteries were just wired in parrallel then wiring them as you have described would charge both batteries.

It is likely you have some sort of isolation device between the batteries to prevent them both going flat. The isolation devices are automatic and will conect the batteries together when charged by the alternator but automatically isolate them when the alternator is not running.
The two most common devices are:

1. A split diode
This acts as a one way valve
If you have this system the solar panel will only charge the battery it is connected to

2. A VSR (voltage sensitive relay)
This connects the batteries when the voltage is high
If you have this system the solar panel will charge both batteries, but on solar it will charge the one that it is connected to until it is almost full and only then connect the second battery.

The simplist way for you to charge both batteries better is to move the + wire that comes from the solar panel from the battery to the battery switch. (Don't forget a fuse a solar panel wire) If you have a battery switch labeled 1, 2 or both.
Selecting 1 will cause the solar to charge battery 1. 2 will cause the solar to charge battery 2. Both will charge both batteries, but you can also flatten both batteries if the switch is in this position and the drain is higher than the input.
__________________

__________________
noelex 77 is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:49.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.