Solar charging options

Mar 2, 2018
176
Catalina Wing Keel San Diego
Sorry if this subject has been covered.
I'm looking for suggestion for keeping my 22 battery top off while on a week long sailing trip.I have to admit my total lack of understanding my electrical system or better yet what my batteries needed to charge it fully.
It seems a 12v AGM battery needs 10-15amps to keep it charge up. My 13w solar panel was only putting out 1.08a which wasn't doing anything. Now my 3+ year old battery is headed down and won't charge up to more than 12v .
I looked into what it would take to keep it charged up with a solar panel and it looks like at least a 150w panel =12.5a. The folding ones I see are pretty big for a 22.

So what is everyone else using

Thanks Roderick
 
Oct 10, 2013
127
Catalina 22 Minneapolis
I think the controller you use is at least as important as the solar panels.

I use a 50-watt panel and a Genasun charge controller. I spent more on the controller than on the panel.

I use an electric trolling motor instead of a gas outboard, so I'm reliant on electricity.

The 50-watt panel is more than enough when I'm day sailing three times a week.

It doesn't keep up when I'm camping out on the boat. Between playing music, charging phones, and running the lights at night I'm using just a little more than what the panel puts out. But I only stay on the boat for two days, so I have plenty of reserve battery, and after a couple days away from the boat the battery is back to full again.

If you want to be out for a week and plan on using a moderate amount of electricity you might want a 100-watt panel.
 
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AaronD

.
Aug 10, 2014
538
Catalina 22 9874 Newberg, OR / Olympia, WA
I think the controller you use is at least as important as the solar panels.

I use a 50-watt panel and a Genasun charge controller. I spent more on the controller than on the panel.

I use an electric trolling motor instead of a gas outboard, so I'm reliant on electricity.

The 50-watt panel is more than enough when I'm day sailing three times a week.

It doesn't keep up when I'm camping out on the boat. Between playing music, charging phones, and running the lights at night I'm using just a little more than what the panel puts out. But I only stay on the boat for two days, so I have plenty of reserve battery, and after a couple days away from the boat the battery is back to full again.

If you want to be out for a week and plan on using a moderate amount of electricity you might want a 100-watt panel.
Sorry if this subject has been covered.
I'm looking for suggestion for keeping my 22 battery top off while on a week long sailing trip.I have to admit my total lack of understanding my electrical system or better yet what my batteries needed to charge it fully.
It seems a 12v AGM battery needs 10-15amps to keep it charge up. My 13w solar panel was only putting out 1.08a which wasn't doing anything. Now my 3+ year old battery is headed down and won't charge up to more than 12v .
I looked into what it would take to keep it charged up with a solar panel and it looks like at least a 150w panel =12.5a. The folding ones I see are pretty big for a 22.

So what is everyone else using

Thanks Roderick
First, don't confuse watts / amps from the panel (instantaneous) with watt-hours / amp-hours to or from a battery. The first is measured at a single point in time, the latter is a total amount of power delivered to a battery (or delivered by a battery to your electrical devices). I.e., you care about maximum power delivery _and_ about how many hours your panel can provide that power for. Your battery will be rated in amp-hours - e.g. a group-31 AGM might be 105 Ah. At 12.6v that's 12.6 * 105 ~= 1300 watt-hours. You don't want to drain a lead-acid battery below about 50%, so that's ~52 Ah / 650 wh of usable capacity (but measure conservatively, because battery capacity decreases over time, and you don't want to

Recommendation: First, try to compute your power budget. That sounds complicated, but it's really pretty easy - look up the power draw of the devices you run and estimate how many hours you'll be using each device for. Some are probably on 24/7 (e.g a battery monitor or a CO detector). Some will be on for only a few hours per day (VHF, cabin lights, perhaps).

Our power budget while cruising comes in at ~370 watt-hours (~30 amp-hours). That includes VHF (for 9 hours) cabin lights, charging phones, the 2 iPads that we use for navigation and/or entertainment, anchor light, etc. (I can share that spreadsheet if it'll be helpful).

To power that, we use 2 50-watt panels. I can't quite swing the great Solbian panels recommended by @Maine Sail, so I use 2 cheap ones - if one breaks, I still have 1/2 my power for the rest of the cruise (and they're only ~$100 to replace). We use a Rogue 20A controller, which isn't available anymore. You might look at the Victron (https://shop.marinehowto.com/products/victron-75-15-mppt-controller). I really like the remote display on my Rogue, but the Victron's price is very reasonable.

I've heard that a good rule of thumb is to estimate that you'll get ~5 hours per day of your panel's maximum power, spread over ~12 daylight hours. So a 50w panel might deliver ~250 watt-hours. In reality, it will be much less than 50w in the morning and evening, and only come close to peak output (if you're lucky) around mid-day. Here in the cloudy PNW, I estimate 3.5 hours.

I find that our solar system gets behind a little if we're out sailing for a few days straight - I usually only put the panels out when we have the bimini up, and the sails often shade the panels. We catch back up if and when we spend a day or two at a dock. As you'd expect, we also get behind on rainy days. So it's good to have enough battery and panel capacity to handle clouds or rain. We've gone out for up to 2 weeks at a time, and I don't think we've every drained our batteries by more than ~40 Amp-hours (~20%). We caught back up when the sun came out.

AGM's are pretty sensitive to charging voltages. So when you look for a charge controller, be sure to get one that you can configure to match the voltages your batteries expect (your battery manufacturer will have a manual for the battery listing all those voltages). I made the mistake of buying a standard controller, and then found I had to replace it with a more configurable model to avoid frying my AGMs.

Protip: Look at some of @Maine Sail's articles over at his subforum, and at marinehowto.com. You'll learn more than you ever thought there was to know about batteries and solar.
 
Feb 26, 2004
21,959
Catalina 34 224 Maple Bay, BC, Canada
Roderick,

The first thing you need to do is an energy budget. If you sail one day a week and use a small panel to recharge your battery, it could work. If you sail multiple days, it's a different answer. And the size of you battery bank can make all the difference.

None of us was born an electrician, nor did we "come with" solar knowledge. We all read a lot and learned.

What you take out has to be returned. There are "shortcuts" from the wattage of the panels to the ah per day they can contribute. That's simple math, though.

You could start here:

The All-Important Energy Budget:
Energy Budget

IMPORTANT BASICS What are amps & amp hours (thanks to StuM from CF.com)

Amps v Amp hours v Amps/Hr - Cruisers & Sailing Forums

These come from:

Electrical Systems 101 Electrical Systems 101

This is another good resource: Marine How To - DIY for Boaters

I, personally, would question the use of an AGM battery in a C22. They require many things, and if you poke around in the Elec 101 you'll find a few discussions about their limitations.

I had a C22 for 5 years and a C25 for 13 years. I know small boat systems. There's not too much to them. Charlie Wing's book is very good for something to get you started.

If you want to stay out longer, you need both more batteries for a larger "bank" and/or more solar. How to balance that is the trick we've all learned. And in many cases, our decisions are different, i.e., marina hopping or anchoring out create drastically different requirements and answers.

Good luck.
 
May 24, 2004
6,799
CC 30 South Florida
We take long trips on our trailerable 22' and we keep the batteries (2 group 24, deep cycle, Wet cells) charged by spending at least every other night in a transient slip. (We go for the hot showers and restaurants but stay for the use of shorepower) First take your battery to an auto parts store and have it tested; it is very possible that after 3 1/2 years of questionable cycling that its capacity to store charge may be significantly hampered. It is imperative that the battery be in good health prior to deciding on the best recharging option.
 
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greg_m

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May 23, 2017
692
Catalina Jaguar 22 Simons Town
Electric is not cheap to start with. So I tend to agree with a previous comment on the charger/controller quality. At the outset I would recommend a higher rated charger/controller than what your budget (electrical and financial budget!) dictates. Space to grow into if you will. Also I would not go with wet lead acid batteries as the house batteries as inevitably there are high power consumption days and low solar energy days that coincide and the poor battery takes a knock... the wet cells never fully recover from a very low level discharge. Don't care how fancy the charger is!

Also, of course, one should look at lifestyle "needs" versus "wants". A 22 is a basic camping boat... be realistic and "rustic" about the trips.

Take a look at the stars instead of staring into a cellphone screen!
 
Sep 30, 2013
3,292
1988 Catalina 22 central Florida
We have two 30-watt Renogy panels mounted on the pushpit. They can be rotated up and down to point closer to the sun. Coupled with a Victron MPPT controller, they keep our single battery (Trojan 24TMX, flooded) charged indefinitely while sailing. And we are power hogs: 7" chartplotter, autotiller, VHF, nav lights, two phones, a tablet, two vapes and a bluetooth speaker. Even on cloudy days we rarely get below an 75% state of charge.

I respectfully disagree with @greg_m on the wet-cell issue. Flooded batteries are less finicky about the way they are charged than AGM, gel, or lithium, and they provide a higher Ah capacity in a given weight and footprint. Not to mention cost! If they get discharged so far as to damage them, that's a charging problem, not a battery problem. Some good reading on the subject: AGM Batteries - Making The Choice





 
May 23, 2016
1,014
Catalina 22 #12502 BSC
Gene, great post and even greater link to Maine's discussion. Lots to unpack there as I am clueless on the subject...I'll take your advice and platform when we go solar someday...thx for this!
 
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Feb 25, 2018
23
Sabre 30 Long Island
Hi Gene,
Nice Solar Setup. I am also planning to install some solar panels onto my pushpit rails and to use a Victron controller.
May I ask what hardware you are using for your rail mounts, they look to be adjustable ?


Thanks
 

AaronD

.
Aug 10, 2014
538
Catalina 22 9874 Newberg, OR / Olympia, WA
Here's more on AGMs. Gene is right.

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries

Additional Observations on the Limits of AGMs Electrical Systems 101
:plus: to @Gene Neill and @Stu Jackson (from an AGM owner) about the commitment of AGMs, in initial battery cost and care (particularly a smart charger programmed to the right voltages).

So, if they're more expensive and more finicky, why do I have AGMs? One big advantage of AGMs is that they can accept higher amperage in the bulk charge phase. But that's clearly not applicable to a C22 charging from solar. This might have changed in the 5+ years since I bought mine (and I might have been wrong then), but the compelling advantages to me were:
1) They're sealed and won't offgas into the cabin area where we're living (well, mostly sealed - they do have an overpressure vent, but that shouldn't ever vent under normal usage)
2) If they ever were to crack (in a knockdown or trailering mishap), they won't leak electrolyte (it's absorbed in the glass mats and not sloshing around loose)

I'm not sure those reasons should have been compelling, but that's what I was thinking about when I bought them.
 
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Sep 30, 2013
3,292
1988 Catalina 22 central Florida
Hi Gene,
Nice Solar Setup. I am also planning to install some solar panels onto my pushpit rails and to use a Victron controller.
May I ask what hardware you are using for your rail mounts, they look to be adjustable ?


Thanks
Thanks! Those are Sea Dog Rail Clamps. They've done very well so far. We LOVE this system. A few more pics/video here.
 
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greg_m

.
May 23, 2017
692
Catalina Jaguar 22 Simons Town
Hi all... no offence taken whatsoever on different points of view... it's how we share, learn and grow! Living in a country where the electrical supply from the grid is not guaranteed and most households are experimenting with off grid survival we have an abundance of views and solutions for off grid power... but what was above mentioned is it's all about the best bang for YOUR buck.

Batteries have come a long way in terms of construction and reliability... even ones of Chinese origin's! ;)

My experience on safari in Africa is what leads me in terms of batteries. Heavy duty flooded (FLA) lead acid battery for starting the big off road vehicle diesel and on a completely separate system the "top of the range charger/controller" for the domestic use battery.... which was a fairly expensive AGM. Out in the desert with no civilization around for three days walking over dunes in hot scorching sunlight you definitely don't want the battery used to start the engine fail! The AGM was regularly run down completely flat keeping the Engel -40 fridge/freezer going (need cold beers) and charged when running the engine.

Anyways... both batteries did the job and then both batteries died after several years of aggressive use... I don't do the safari thing anymore so I never replaced the AGM. I continue to purchase a slightly over rated (over sized in terms of Ah) FLA of cheaper cost for my stater battery.

On the boat... I use a 12V gel cell purchased for a motor cycle outlet, the cheapest solar controller that had an auxilary output for lights and a USB port and a small 50W panel! I don't sail very far from a marina on False bay so shore power/going home is not an issue.

My recommendation was on the charger... get the best/highest rated you can afford. It will look after batteries well. :)

Edit: 21/11/2019... thought I would add some photos from a particular safari... 10 days in the Namib (Naukluft) desert, West coast Afrca, Namibia. Yes we had to go over the big dunes! My vehicle was a 2002 Jeep Grand Cherokee 2.7 CRD. Fantastic safari vehicle :)
 

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Mar 2, 2018
176
Catalina Wing Keel San Diego
Wow so much information to take in! I can't believe all the help here , Thank you.
I have to start off with the low voltage on the battery may have been caused by thinking I had charged up the battery at home before the trip. I had it all plugged in but may have not noticed the breaker to the charger was switched off ,OOhps.
Once back home it's been charging for a few days now and is back up to 13v !!
My energy needs on my boat are very low. We have LEDs on everything, use headlamps & Luci LEDs lamps. Phones and Kendles are all charged on battery banks that are precharged and rechargeable .
We may have an autopilot running for part of the day @ 5a per day or .7 amph
VHF radio 2.0amp /.5 amph
Depthsounder when anchoring .2amph
Total at the most is 8.5amps per day which would be very high.
My feeling is even though I only have a 13w solar panel if I have it out in the sun and I'm running my autopilot it's going to be a wash. In the last 3 years we have always been able to keep the battery up at 12.5 all week.
So with no budget for anything extra at the moment I'm going to keep with what I am doing.
As for the AGM battery discussion the only reason I have one is it came with the boat...
Gene Neill I like your set up !

Thanks Everyone
 

greg_m

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May 23, 2017
692
Catalina Jaguar 22 Simons Town
Hi Guys... just a follow up on charging and battery voltage... From experience and what we teach at the maritime training school for the marine engineers sailing on large cargo vessels with batteries as the emergency source of DC... ;)

A battery measured with a voltmeter and disconnected from any electrical system... at "12.something" volts its flat/partial charge = discharged. It should actually ready in the 13.2 to 13.8 volts range to say that its actually charged.

The charging circuit needs to supply voltage in excess of what the battery voltage is to actually charge. So the charging circuit should produce voltage in the region of 13.2 to 14.4 volts.

So, if the solar panel/charger only provides 12.5 volts then the battery will never get fully charged.
 
Oct 10, 2013
127
Catalina 22 Minneapolis
That's why you need to have a proper charge controller. It should provide a high voltage for the initial bulk charge, then a lower voltage for absorption charge (to get that last bit), then still a lower float voltage to keep the battery charged without overcharging it.

These voltages depend on what kind of battery you have (flooded or AGM) so most good controllers can be configured for different batteries.

UNDERSTANDING BATTERY CHARGING STAGES
 

greg_m

.
May 23, 2017
692
Catalina Jaguar 22 Simons Town
We have two 30-watt Renogy panels mounted on the pushpit. They can be rotated up and down to point closer to the sun. Coupled with a Victron MPPT controller, they keep our single battery (Trojan 24TMX, flooded) charged indefinitely while sailing. And we are power hogs: 7" chartplotter, autotiller, VHF, nav lights, two phones, a tablet, two vapes and a bluetooth speaker. Even on cloudy days we rarely get below an 75% state of charge.

I respectfully disagree with @greg_m on the wet-cell issue. Flooded batteries are less finicky about the way they are charged than AGM, gel, or lithium, and they provide a higher Ah capacity in a given weight and footprint. Not to mention cost! If they get discharged so far as to damage them, that's a charging problem, not a battery problem. Some good reading on the subject: AGM Batteries - Making The Choice





On another point = I dig that tiller!!!
 
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Sep 30, 2013
3,292
1988 Catalina 22 central Florida
That's why you need to have a proper charge controller. It should provide a high voltage for the initial bulk charge, then a lower voltage for absorption charge (to get that last bit), then still a lower float voltage to keep the battery charged without overcharging it.

These voltages depend on what kind of battery you have (flooded or AGM) so most good controllers can be configured for different batteries.

UNDERSTANDING BATTERY CHARGING STAGES
Good point!

I'm a firm believer in the value of an MPPT controller vs. the cheaper PWM. There's no sense in going to the trouble and expense of installing a solar array, only to leave 10-40% of your available amp hours on the table, just to save fifty bucks or so.

Victron's app is also very cool. It is used to program the controller initially, and after that, Bluetooth lets you check your battery's state of charge, solar output, charging history, etc, right on your smartphone. No multimeter needed! And all this is so simple, even a techno-idiot like me can do it. :thumbup:
 

walt

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Jun 1, 2007
3,454
Macgregor 26S Hobie TI Ridgway Colorado
Cant remember what type of solar panel you already own.. but does it already have some type of charge control regulator built in? If so, you dont want a second charge controller in line. If you are starting over and are going to buy both a panel and controller, I will second or third or whatever.. the Victron 75/15 is a great choice. Ive been using this same one for a bunch of years.. never a glitch. Mine is an older model without the BT to smart phone interface.. I think that would be nice to have.

Quick look at what you currently have which lets say is a 15 amp hour daily use and a 13 watt solar panel. A rule of thumb I saw one time which Ive come to like is that the daily amp hours from a solar panel will range from .2 to .5 times the rated watts. This is a unit-less conversion.. but it says that your 13 watt panel will provide between .2*13 = 2.6 amp hours to .5*13 = 6.5 amp hours per day. That is a big range of output.. but thats what happens with solar. One day you get good sun all day and no shading.. you get the high end of that. Next day has fog in the morning, you might get on the low end of that. If the panel gets even a little bit of shading, you can even cut those numbers by up to 50%. Pointing the panel and MPPT vs PWM vary this rule a little.. but I think its still a fair ballpark estimation to use.

This says that your 13 watt panel is not enough. But.. you have a battery that by itself can provide everything you need for a bunch of days. Lets say you have an 80 amp hour capacity battery giving you generally 40 amp hours of use-able capacity. With no solar and 10 amp hours daily use, you can go for 4 days. Now add in the 13 watt panel and lets say its giving an average of 4.5 amp hours per day. You are using the same 10 amp hours per day but with the solar input, you are actually only drawing 10 - 4.5 = 5.5 amp hours per day from the battery. Now you can go 40/5.5 = 7.2 days before the battery gets too low.

So... I think even with your 13 watt panel.. you are sort of OK for nearly a week trip with some power conservation.. as long as it gets no shading. I think you would be in pretty good power luxury if you changed that out to a 30 watt panel mounted where it gets no shading (so it has to hang off the back somewhere) and that Victron MPPT controller. You would probably be happy with the Genasun MPPT controller also mentioned by someone else.

FYI, I have taken S. Cal week long trips where I have tried 10 W, 20W, 30W solar panels all with no shading and always with the nice sunshine you get. My outboard also sort of contributes to the battery charging (how much I dont know). I thought 10 watt was too little. 20 W was mostly adequate but I had to be a little careful with power use. 30 W was fairly comfortable. 40 watt.. you will be in power luxury. This all assumes no or very little shading on the panel. If you mount the panel in a bad spot (like under the boom) expect the power out to be even considerably less than half of what you get with mounting a good spot (like where Gene has his mounted out to the rear where the rig generally wont cause much shading).

I also measure everything with a battery monitor so I can check amp hours deficit into the battery each day as well as current and voltage.
 
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