Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 04-11-2018, 22:00   #1
Registered User

Join Date: Jun 2018
Posts: 34
charging both batteries A+B using solar

I'm just about to install solar to my 25' Compass 750 and not sure how to set it up to charge both batteries (or if you can do this at all). I have two x 100ah 12v sealed batteries set up with isolating switch to offer battery 1, battery 2 or both batteries.

I just ordered this: 100 Watt 12V Solar Panels Kit + 20A Charge Controller for Off-Grid 12 Volt Battery System


As far as I understand I can only apply the charge to one of the batteries without setting up a similar isolating switch to swap between either battery, but can't charge both batteries at the same time

Is this correct?
__________________

OZ-Sailor is offline   Reply With Quote
Old 04-11-2018, 22:14   #2
Registered User

Join Date: Jan 2017
Posts: 12,578
Re: charging both batteries A+B using solar

No.

While they are paralleled, they act like a single 200AH bank.

Not quite optimal with a switch in between, or if they are at different temperatures. But NBD.

More to the point are both the same model batt?

You could use a manual switch to combine for charging purposes, but a VSR / ACR would be better.

What is the reason for your split design?
__________________

john61ct is offline   Reply With Quote
Old 04-11-2018, 22:25   #3
Registered User

Join Date: Jun 2018
Location: Kemah, TX
Boat: 1979 Cape Dory 30 Cutter
Posts: 138
Re: charging both batteries A+B using solar

If you connect the charge controller to one battery and turn the isolating switch to both you will charge both batteries. If you turn it to A or B you will only charge the battery that the charge controller is connected to.
If one battery is house and one battery is start I would connect the charge controller to the house battery.
J.Kitchens is offline   Reply With Quote
Old 04-11-2018, 22:25   #4
Registered User

Join Date: May 2010
Location: Sydney Australia
Boat: Fisher pilothouse sloop 32'
Posts: 1,494
Re: charging both batteries A+B using solar

Quote:
Originally Posted by john61ct View Post
No.

While they are paralleled, they act like a single 200AH bank.

Not quite optimal with a switch in between, or if they are at different temperatures. But NBD.

More to the point are both the same model batt?

You could use a manual switch to combine for charging purposes, but a VSR / ACR would be better.

What is the reason for your split design?
Or you could get a charge controller that will charge two banks independently.
__________________
Rob aka Uncle Bob Sydney Australia.

Life is 10% the cards you are dealt, 90% how you play em
Uncle Bob is offline   Reply With Quote
Old 04-11-2018, 22:32   #5
Registered User

Join Date: Jan 2017
Posts: 12,578
Re: charging both batteries A+B using solar

Please link to such a one, other than the Morningstar SunSaver Duo POS.

If that feature were actually required, which here it is not,

then a DCDC charger would deliver it more reliably and offer multiple other uses and lots more flexibility.
john61ct is offline   Reply With Quote
Old 04-11-2018, 22:34   #6
Registered User

Join Date: Jan 2017
Posts: 12,578
Re: charging both batteries A+B using solar

Quote:
Originally Posted by J.Kitchens View Post
If one battery is house and one battery is start I would connect the charge controller to the house battery.
Yes, or whichever you use more frequently for deep cycling.
john61ct is offline   Reply With Quote
Old 04-11-2018, 22:39   #7
Registered User

Join Date: Jun 2018
Location: Kemah, TX
Boat: 1979 Cape Dory 30 Cutter
Posts: 138
Re: charging both batteries A+B using solar

Or you could connect the charge controller to the Output terminal of the switch and then have the option of A B Both or None.
J.Kitchens is offline   Reply With Quote
Old 04-11-2018, 23:20   #8
Registered User

Join Date: Dec 2010
Location: W Carib
Boat: Wildcat 35, Hobie 33
Posts: 11,387
Re: charging both batteries A+B using solar

Quote:
Originally Posted by J.Kitchens View Post
Or you could connect the charge controller to the Output terminal of the switch and then have the option of A B Both or None.
None (off) = bad for most controllers...similar to throwing it to off with alternator spinning.
belizesailor is offline   Reply With Quote
Old 05-11-2018, 05:09   #9
Registered User

Join Date: Jan 2017
Posts: 12,578
Re: charging both batteries A+B using solar

Plus the output wires should have a chance of accurately detecting batt voltage on one bank.
john61ct is offline   Reply With Quote
Old 05-11-2018, 09:53   #10
Registered User
 
mvmojo's Avatar

Join Date: Mar 2018
Location: www.mvmojo.com
Boat: Robt Beebe Passagemaker 49-10 in steel
Posts: 217
Re: charging both batteries A+B using solar

Quote:
Originally Posted by J.Kitchens View Post
Or you could connect the charge controller to the Output terminal of the switch and then have the option of A B Both or None.
Quote:
Originally Posted by belizesailor View Post
None (off) = bad for most controllers...similar to throwing it to off with alternator spinning.
There's nothing wrong with connecting to the "output" of the A - B - BOTH - OFF switch, but best practice would be to also put an on/off switch from the panels to the charge controller. If you want to disconnect the batteries, switch the panels off first so they are not feeding the charge controller. Then switch off the battery switch. When turning things back on, switch on the battery switch first, then switch on the panels. The reason for this is that most charge controllers are powered by the batteries rather than the panels. Turning on the controller first allows it to boot it's software, configure itself, and get ready to control the input from the panels. You want to have the charge controller powered up before you switch on the feed from the panels. Likewise, you want to have the charge controller powered on when you switch the panels off to allow an orderly shutdown of charge regulation. To do this, you switch the panels off before switching off power to the controller. Rule of thumb: Power from your batteries to your charge controller is First On, Last Off.
mvmojo is offline   Reply With Quote
Old 05-11-2018, 10:23   #11
Registered User

Join Date: Jan 2011
Location: Holland, Michigan
Boat: Catalina 30
Posts: 191
Re: charging both batteries A+B using solar

Here's what I do when I put the boat up for the winter.... I have a small solar bank ( 15 w) and I use it to keep both house and starter battery charged. My plus side is connected to both batteries... so I have them in parallel. I run the solar directly to the batteries, and don't use any of the boat wiring. This is really simple... but it works. You don't need too much amperage. A 100 panel is way overkill. You had better have a good controller in between the battery and the solar panel, or you will overcharge the batteries.
carlheintz is offline   Reply With Quote
Old 05-11-2018, 12:00   #12
Registered User

Join Date: Mar 2015
Location: New Zealand
Boat: Moana 33
Posts: 1,092
Re: charging both batteries A+B using solar

Interesting thread with very useful info, thanks. One option not yet mentioned is the Votronic range of controllers (from Germany, there may be other makes) that charge the house bank while also trickle-charging the start battery. Simple to install and I've had no problems since installing about a year ago.
NevisDog is offline   Reply With Quote
Old 05-11-2018, 12:00   #13
Registered User

Join Date: Feb 2013
Location: New City, New York
Boat: Oday 25
Posts: 158
Re: charging both batteries A+B using solar

I do what carlheinz does. Both of my 2 group 24's are connected to a 50 watt panel with a simple controller with the master on both, all winter. Keeps everything charged. I do the same when I leave the boat on the mooring during the summer. So far the batteries are fine for the last 5 years.
ebsail is offline   Reply With Quote
Old 05-11-2018, 12:33   #14
Registered User

Join Date: Jun 2018
Location: Kemah, TX
Boat: 1979 Cape Dory 30 Cutter
Posts: 138
Re: charging both batteries A+B using solar

Quote:
Originally Posted by belizesailor View Post
None (off) = bad for most controllers...similar to throwing it to off with alternator spinning.
I have personally checked this on numerous (not all) charge controllers with no ill effect. I know for a fact it will ruin an alternator but an alternator is a completely different beast than a charge controller.
J.Kitchens is offline   Reply With Quote
Old 05-11-2018, 13:58   #15
Registered User

Join Date: Aug 2011
Location: Everett, Washington
Boat: Yorktown 33
Posts: 18
Re: charging both batteries A+B using solar

Can you leave your solar charge controller connected while the engine is running the alternator?
__________________

joehixon is offline   Reply With Quote
Reply

Tags
charging, solar

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Solar charging with A/C charging CapnCrunch Electrical: Batteries, Generators & Solar 14 01-07-2018 10:07
Solar charging while also charging via shore power? Jarel Design Electrical: Batteries, Generators & Solar 13 10-06-2017 08:50
Crew Available: Pracical degree qualified engineer and professional cook couple, both mid 40s. Both squirty34 Crew Archives 0 17-11-2015 14:34
Charging Engine for Both ac and dc bobfnbw Electrical: Batteries, Generators & Solar 2 09-03-2010 22:26

Advertise Here


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:08.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×

ShowCase vBulletin Plugins by Drive Thru Online, Inc.