Battery question - solar charger

A forum for discussing boat or trailer repairs or modifications that you have made or are considering.

Moderators: Catigale, Paul S, Heath_Mod, beene, Hamin' X, kmclemore, tangentair

rszobel
Engineer
Posts: 136
Joined: Mon Jul 09, 2012 7:16 am
Sailboat: MacGregor 26X
Location: Haymarket VA

Battery question - solar charger

Post by rszobel » Sun May 12, 2013 8:43 pm

I have a couple of solar panels set up on my :macx: by previous owner but only a single battery. I want to get a second battery and set it up as a house battery and use original for engine only. My question is this .... Can I set up the solar panels to charge both batteries at the same time ? If so how do I do this?

Tere is a controller that works with the solar panels as well.

User avatar
Divecoz
Admiral
Posts: 3789
Joined: Sat Oct 16, 2004 4:54 pm
Sailboat: MacGregor 26M
Location: PORT CHARLOTTE FLORIDA 05 M Mercury 50 H.P. Big Foot Bill at Boats 4 Sail is my Hero

Re: Battery question - solar charger

Post by Divecoz » Sun May 12, 2013 9:04 pm

WE can guess and assume but it would be helpful to know what you have.. wattage of collectors, brand and model of controller etc etc ..BTW you really do want batteries of the same age size type and even manufacturer .. do you as well have a battery combiner?
rszobel wrote:I have a couple of solar panels set up on my :macx: by previous owner but only a single battery. I want to get a second battery and set it up as a house battery and use original for engine only. My question is this .... Can I set up the solar panels to charge both batteries at the same time ? If so how do I do this?

There is a controller that works with the solar panels as well.

Paul S
Site Admin
Posts: 1674
Joined: Tue Jan 06, 2004 1:50 pm
Sailboat: Other
Location: Boston, MA
Contact:

Re: Battery question - solar charger

Post by Paul S » Sun May 12, 2013 9:31 pm

rszobel wrote:I have a couple of solar panels set up on my :macx: by previous owner but only a single battery. I want to get a second battery and set it up as a house battery and use original for engine only. My question is this .... Can I set up the solar panels to charge both batteries at the same time ? If so how do I do this?

Tere is a controller that works with the solar panels as well.
voltage sensing relay? once the first battery is charged, it will automatically combine the 2 and charge the second. Once the charging goes away, the batteries separate.

There may be other ways to do it, but this is simple and effective.

That is how I do it on my mac. I charge (via engine, or battery charger) starting battery only, then once the voltage gets up there.. it will combine them, then they separate once the charging is taken away. I can't imagine the charging source matters - engine, charger, solar, etc.

User avatar
RussMT
Admiral
Posts: 5527
Joined: Thu Oct 11, 2007 2:01 pm
Sailboat: MacGregor 26M
Location: Bozeman, Montana "Luna Azul" 2008 M 70hp Suzi

Re: Battery question - solar charger

Post by RussMT » Sun May 12, 2013 10:03 pm

What Paul said. That's exactly how mine is setup. My combiner will combine both when either batt is being charged. My solar panel is connected to house and will charge both when charging. Motor is on its own batt and will charge via combiner the house batt. Both are separate and isolated when not being chaged.

User avatar
Rick Westlake
Captain
Posts: 778
Joined: Wed Aug 22, 2007 6:05 pm
Sailboat: MacGregor 26X
Location: Casa Rio Marina, Mayo, MD; MacGregor 26X, "Bossa Nova" - Bristol 29.9 "Halcyon"
Contact:

Re: Battery question - solar charger

Post by Rick Westlake » Mon May 13, 2013 8:27 am

I set my solar-charging system up with a dual-output charging controller, a Chinese knock-off of the Morningstar SunSaver Duo.

(I put the Morningstar SunSaver Duo on my trade-up boat, my Bristol 29.9 - the one I found included a battery meter. Worth considering.)

User avatar
Bobglas
Engineer
Posts: 142
Joined: Sat May 12, 2012 3:00 pm
Sailboat: MacGregor 26M
Location: Jefferson, NY

Re: Battery question - solar charger

Post by Bobglas » Mon May 13, 2013 2:14 pm

Two batteries Perko switch, controller hooked up to the switch, I charge house, or starter or both by using the Perko switch. :macm:

User avatar
Sea Wind
First Officer
Posts: 402
Joined: Mon Mar 28, 2011 11:45 am
Sailboat: MacGregor 26X
Location: Mayo, MD Suzuki DF90hp

Re: Battery question - solar charger

Post by Sea Wind » Mon May 13, 2013 2:22 pm

Two batteries Perko switch, controller hooked up to the switch, I charge house, or starter or both by using the Perko switch.
I have the same setup

bartmac
Captain
Posts: 722
Joined: Sun Apr 18, 2010 7:11 pm
Location: North Coast NSW Aust

Re: Battery question - solar charger

Post by bartmac » Mon May 13, 2013 5:44 pm

have a couple of solar panels set up on my :macx: by previous owner but only a single battery. I want to get a second battery and set it up as a house battery and use original for engine only. My question is this .... Can I set up the solar panels to charge both batteries at the same time ? If so how do I do this?
You need to consider a number of things....firstly charging 2 or more batteries off one source is not a long term solution ie unless all batteries are exactly the same the controller will "see" an average of the combined voltage ie 12.4 + 12.7=12.5 so will charge as though both batteries are 12.5....probably over charging one and undercharging the other. A voltage sensitive relay will do the same...as the relay opens the combined voltage is what the controller or the motor regulator will see and adjust accordingly.... BUT will guard against a flat starting battery. All of this is further complicated by if the second battery is a different construction ie to make it deep cycle....AGM or Gel....which if charged like a wet lead cell battery will certainly shorten the life of those batteries.....they don't like the higher voltages and should not be "gassed". One solution we have is to have all charging into start battery (and controller set for that battery type)....and then a voltage sensitive relay into a DC-DC charger (set for the house battery type)
Complicated but new batteries are also expensive. We learnt from service vehicles we run....24v but 2 x 12v batteries....we were forever replacing batteries until we realised the use of one battery for 12V loads was causing that battery to be undercharged and the other to cook ie overcharge.
I guess our 2 x 184Ah Geltech batteries at 700-800$ each is another reason to be carefull...in both our camper and Mac we have volt meters and temperature gauges near the biggest load ie refrigeration......the 2 meters combined give us a good idea whats going on....have taught my wife to be aware of temp rising and/or voltage lowering....most of our other loads on board are either intermittent or small so don't really pose a load problem

Boblee
Admiral
Posts: 1701
Joined: Thu Aug 10, 2006 7:08 am
Location: Berrigan, Riverina Australia boatless at present

Re: Battery question - solar charger

Post by Boblee » Mon May 13, 2013 5:56 pm

Very good summation Bartmac, mind you I just have all batteries hooked together with the option of using the perko switch and it works ok with the original start battery still going strong after 7-8 yrs despite being flattened several times but they are all the same type.

bartmac
Captain
Posts: 722
Joined: Sun Apr 18, 2010 7:11 pm
Location: North Coast NSW Aust

Re: Battery question - solar charger

Post by bartmac » Mon May 13, 2013 6:35 pm

A manual switch will only work if the construction/chemistry of the batteries in question are the same...the controller will see the switched on battery and charge it accordingly.............old-timers disease however has set in and I'm looking to idiot proof all systems...This weekend I actually replaced our manual truck switch with a voltage sensitive one which controls our truck to camper and truck to Mac 12v DC-DC charging circuit........even though we have a large voltmeter which lights up when circuit is ON....it has been forgotten :( ......no damage as our camper or Mac voltmeter would be alerting us...ie higher than expected voltage especially at night....no solar input and thus would expect voltages in the 12.4-12.7 range...with charger going its going to be 13.6-13.8V

Paul S
Site Admin
Posts: 1674
Joined: Tue Jan 06, 2004 1:50 pm
Sailboat: Other
Location: Boston, MA
Contact:

Re: Battery question - solar charger

Post by Paul S » Mon May 13, 2013 7:25 pm

if the batteries are the same use a VSR

if the batteries are different - a voltage follower like Balmar duo charge is a great solution - charge the large house battery and trickle charge the smaller starting battery.

have a manual switch on our big boat... hate it.. way too many times not switching it to charge the proper battery. the duo charge takes the human factor out of the situation.

I prefer the 3 switch + VSR for the mac (2 same batteries).

both solutions takes the human factor out of the situation.

bartmac
Captain
Posts: 722
Joined: Sun Apr 18, 2010 7:11 pm
Location: North Coast NSW Aust

Re: Battery question - solar charger

Post by bartmac » Mon May 13, 2013 7:36 pm

One of the problems with battery systems is that most people rely on voltage as some sort of measure as to how well their system is performing......no good...voltage is NOT the measure...amperage is the usage measurement or more correctly Amp hours.....We live in an area where there's a "hippie" element...living on low voltage,solar etc etc...the majority are kidding themselves as to how good their 12v systems are and when the sun doesn't shine it fairly quickly shows the use of automotive batteries in a house system just doesn't work properly....Macs are not a house but if you want a reliable system which will work for more than a weekend it will need $$$ and time or you need to get rid of the load sapping things on your Mac....ie the fridge...most other stuff will be fine

User avatar
Sea Wind
First Officer
Posts: 402
Joined: Mon Mar 28, 2011 11:45 am
Sailboat: MacGregor 26X
Location: Mayo, MD Suzuki DF90hp

Re: Battery question - solar charger

Post by Sea Wind » Mon May 13, 2013 7:45 pm

You need to consider a number of things....firstly charging 2 or more batteries off one source is not a long term solution ie unless all batteries are exactly the same the controller will "see" an average of the combined voltage ie 12.4 + 12.7=12.5 so will charge as though both batteries are 12.5....probably over charging one and undercharging the other. A voltage sensitive relay will do the same...as the relay opens the combined voltage is what the controller or the motor regulator will see and adjust accordingly.... BUT will guard against a flat starting battery. All of this is further complicated by if the second battery is a different construction ie to make it deep cycle....AGM or Gel....which if charged like a wet lead cell battery will certainly shorten the life of those batteries.....they don't like the higher voltages and should not be "gassed". One solution we have is to have all charging into start battery (and controller set for that battery type)....and then a voltage sensitive relay into a DC-DC charger (set for the house battery type)
Complicated but new batteries are also expensive. We learnt from service vehicles we run....24v but 2 x 12v batteries....we were forever replacing batteries until we realised the use of one battery for 12V loads was causing that battery to be undercharged and the other to cook ie overcharge.
I guess our 2 x 184Ah Geltech batteries at 700-800$ each is another reason to be carefull...in both our camper and Mac we have volt meters and temperature gauges near the biggest load ie refrigeration......the 2 meters combined give us a good idea whats going on....have taught my wife to be aware of temp rising and/or voltage lowering....most of our other loads on board are either intermittent or small so don't really pose a load problem
Isn't this only true if using a combiner or charging in "both"? Even if you have different batteries and you only choose 1 or 2 on a manual switch then the controller would know what to do, right?

bartmac
Captain
Posts: 722
Joined: Sun Apr 18, 2010 7:11 pm
Location: North Coast NSW Aust

Re: Battery question - solar charger

Post by bartmac » Mon May 13, 2013 7:57 pm

The controller I have is programmable for battery type...ie bulk , absorption, and float voltages...that only works if all batteries you charge are of that type...start mixing types and you need something more sophisticated

User avatar
Obelix
Captain
Posts: 524
Joined: Wed Feb 13, 2008 3:20 pm
Sailboat: MacGregor 26M
Location: Port Richey, FL, 26M 2008 "New Love" - 60hp E-Tec

Re: Battery question - solar charger

Post by Obelix » Mon May 13, 2013 8:08 pm

You need to consider a number of things....firstly charging 2 or more batteries off one source is not a long term solution ie unless all batteries are exactly the same the controller will "see" an average of the combined voltage ie 12.4 + 12.7=12.5 so will charge as though both batteries are 12.5....probably over charging one and undercharging the other.
If two batteries are connected directly in parallel, they would not have dissimilar voltages and the charger would therefor act as if there is only one battery. I somehow don't see how there could be an averaging of voltages by the charger.

Obelix

Post Reply