Dual Battery Solar Charging System??

[Euphoria2011]

I am considering installing an inexpensive Solar charging system on my oday 28. I do not keep shore power connected during the week ($6 per day) so I thought as my next project I might install the Morningstar’s SunSaver Duo 25 amp dual battery Charging system (http://www.morningstarcorp.com/en/sun-saver-duo) with a 50 or 80 Watt solar panel (ebay @ $100) input to keep the 2 Interstate SRM-27B batteries freshened up for the weekend.

I called and spoke to the tech support and they suggested that I could go as much as a 280 watt panel but I wanted to keep this project under $300 so a lower watt panel would be fine.

What do you guys think??? Would you do it?

 

[SailingCal21]

That's exactly the configuration that I have on Karma. Works great for me. I have shore power available, but choose to keep it disconnected whilst I'm not at the boat. My house bank consist of 2 6V 220AH Trojans the starter battery is a 100 AH deep cycle battery.

 

[Stu Jackson]

Why do you think you need to keep your reserve bank charged during the week? It only takes a few amp hours to start your engine, and motoring should replenish it. You could save some $$ by just buying a simpler one bank controller for your house bank.

Without knowing your banks sizes and how you're wired, and your boat use and energy budget, it's hard to say.

Good idea to stay unplugged when you're not there though.

 

[Euphoria2011]

Yes, i only have two group 27 batteries and i mainly use battery 1 as the starting battery and battery 2 for cabin load stuff while at anchor.
These two batteries are 90 amp hour batteries i think.

 

[tcwaltz]

I've posted about the solar set up on my Oday 28 before and it's pretty extensive. I only use shore power for my AC and to run tools when I'm working on the boat. I have a 230w @ 24v solar panel thst connects to a BZ MPPT charge controller. My house bank consists of 4 Trojan T105 6v batteries and a group 38 engine start battery. I have a pathfinder and battery switch installed as well. My lighting is about 95% LED now. My wife and I spent a week on the hook and never had power problems. On solar I never saw voltages below 12.6v after a full night of usage. We did run the engine periodically but that was to heat water for a shower

VHF and fm radio was on during the day as well as refrigeration and some lighting. Led anchor light at night as well as everything else running during the evening and power was great.

One thing I will say is the batteries seem more stable not being on the charger because they discharge at night and charge during the day. I have water miser caps on my batteries and have only had to add a little water once in the last year. I attribute thst to not boiling it out with an electric charger.

 

[Euphoria2011]

Yes, so I was planning to get a 50 Watt "hard frame" type panel and make a semi-permanat mount pole from the stern rail or something like that but i then began to wonder where would I store this dang thing, so now --I am thinking maybe a 25 Watt semi-flexible panel so I can just slip it under a cabin cushion when we go out.

So do you think a 25 watt panel would be enough juice to keep the batteries top charged much less then a 50 watt-er?

Here are some shots of the two panels, the long one is the flex 25 watt

 

[tcwaltz]

I'd get into the 80 watt range. You need to look at charging amps. I originally has a 135 watt panel onboard. It was great for topping batteries and the like but didn't give me all day staying power on the hook. What I have now is peak 8.7amps @24v...the charge controller converts to 12v which would give me peak 17ish amps. I've never needed more than 11 amps of power from the solar

 

[Richard19068]

Yes, so I was planning to get a 50 Watt "hard frame" type panel and make a semi-permanat mount pole from the stern rail or something like that but i then began to wonder where would I store this dang thing, so now --I am thinking maybe a 25 Watt semi-flexible panel so I can just slip it under a cabin cushion when we go out.

So do you think a 25 watt panel would be enough juice to keep the batteries top charged much less then a 50 watt-er?

Here are some shots of the two panels, the long one is the flex 25 watt

If all you want is to keep the batteries "freshened up for the weekend" as you said in the original post then 25 watts is plenty.

 

[Euphoria2011]

25 watts x 5 sunlight hrs = 125 watts per day.

125 watts/12 volts = 10.4 amps per day.

10.4 divided by 2 because of two batteries?

means each battery would get a spoonful of 5 tasty amps each sunny day

am I thinking right?

 

[tcwaltz]

What is the peak charging amps of the 25 watt panel. What kind of loads do you have on your batteries? Are you running refrigeration? I'm if the mind that if you are to the trouble to do solar then make it useful.

 

[Euphoria2011]

No loads, boat just sitting at the dock during the week

 

[Euphoria2011]

$210.00 Solar Project update

OK, so it looks like my solar project is working, (total project costs was $210)... its been one week of being spoon fed from the new solar system, weather was a mix of sun and clouds, and both batteries, which are usually sitting at around 12.6 Volts after sitting idle all week, were both 13.3 volts.

 

[SailingCal21]

Looks like a job well done to me.

 

[Richard19068]

OK, so it looks like my solar project is working, (total project costs was $210)... its been one week of being spoon fed from the new solar system, weather was a mix of sun and clouds, and both batteries, which are usually sitting at around 12.6 Volts after sitting idle all week, were both 13.3 volts.

What kind of solar panel is that and where did you get it?

Thanks

 

[Euphoria2011]

Its a 25 Watt Semi-Flexible High-Efficiency 12V Solar Panel bougt from ebay seller discountsolar.