Solar Battery Charger

T

thechadmiller

New member
Hi everybody. This subject seems too complicated and it kinda makes my head spin.

We are about to go do our SJI trip for 10-15 days out. Never done anything like that before and not sure how charged our house battery will stay since it doesn't seem like we'll be traveling too far every day.

We don't have much stuff to draw the battery down, a small GPS, an iPad, rechargeable speaker and the Wallas for cooking mostly at this time of year. We have a couple of solar lights that seem to be fine for our needs so we don't plan on using the LED hard-wired ones all that much.

Is it super dumb to buy something like this:
https://www.amazon.com/gp/product/B0046 ... CUC0&psc=1

Just something to have hanging out during the day when we are moored? We don't have shore power to charge when at a dock.

Feel free to just say "save your money" and spend more later on something better or "this should do the trick".

thanks.
Chad
 
First I would say that is expensive for a 20 watt solar panel. Second, with your power demands an hour of the engine a day should more than suffice--or 2 hurst's every other day.

I believe that you have a 2017 Honda 90, which has a 35 amp alternator. This should have at least 20 amps available to the battery

Do you have two batteries? Most of the time the boats come with the smaller group 24 batteries--but that should suffice. These days I carry one of the small jump start kits (Li ion battery)--these can also charge cell phones etc. (we just charge our phones from the 12 volt system in the boat.

Enjoy the trip!
 
Chad, What size battery(s) do you have? One or two, Marine/RV Deep Cycle? You may find that you move enough that you don't need that solar. Do you have any way to monitor your battery SOC (State of Charge). I use a simple volt meter that plugs into the Cig lighter. Works, easy and cheap, and I can know when I need to run the OB's. I have found that I only need about a half hour a day, for what I run: Phone charger, small Garmin GPS for anchor watch, HH VHF charger occasionally, and rarely the Wallas. I do use a CPAP at night, about 7.5 hours, (about 5 amps), which is my biggest draw.

I'm with Bob on this one. It seems expensive for what you are getting. Get a way to monitor your battery voltage, and then you can know what you need to do next.

Harvey
SleepyC:moon
 
When I need to charge the house battery I just run the motor for awhile. My Honda BF90 can put about 20 amps into the battery at about 1K rpm. When anchored out, I just run the motor for about 20-30 minutes at a time when needed to top up the battery. Usually just takes once in the morning and once in the evening. Depends on whether or not we are using the refrigerator or not.

Unless you need the VAC a generator puts out, the motor alternator will charge the battery(s) a lot better than a small portable generator.

I have a Honda 1000, but only carry it for times we plan on being anchored out and anticipate needing the air conditioner.
 
I use a 25 watt solar panel to float the truck's battery when it sits for several weeks. I would not ask any more of it, but it does that job well. As I remember, it cost ~$30 from e-bay, so $144 seems excessive.

That said, with your load and our previous experience in moving about in the SJI (San Juan Islands, I presume,) you should be fine, charging by running your motor.

Boris
 
Get a little monitor like this and see what your usage is on the SJI trip. You may have to run your motor while at anchor or maybe not. Then you can decide if a solar kit is worthwhile. https://www.amazon.com/LIHAN-Charger-Di ... way&sr=8-4

You pay a hefty premium for the convenience of a little kit. Plug and play is nice and you can move it to the best spot for solar gain. But you are paying at least double for the watts that you're getting over doing a setup yourself. What is usually missing in the convenient kit is the solar controller (as an example https://www.amazon.com/Controller-Batte ... way&sr=8-4). These little gadgets improve the efficiency of solar charging and tell you much more about your batteries.

The other problem with the little kits is that they work okay for keeping a battery topped off, but if you really drain a battery down (over night for instance), you will be sitting for a while waiting for a 20 watt solar panel to bring the battery back up enough to start an engine. Bigger is better (and faster).

Mark
 
That is a very expensive package and 20 watts won't do much. If you want a package, look on Amazon for at least 100 watts. Those packages usually come with a very cheap Chinese controller. Look for packages with Renogy products. Those are still Chinese, but Renogy is a big Amazon supplier and they probably aren't going to be selling junk.

You can also put one together yourself for about half the cost and it will include a quality controller.

I gave a talk on solar power at the recent Hontoon gathering. Here is a link to the Trawlerforum library section where you can download an article I passed out: http://www.trawlerforum.com/forums/down ... o=cat&id=2

In this library section it is titled "Solar Panels for Your Boat". In the same section there are two other articles that I wrote: "Sizing a Large Solar Panel System" which talks about the use of a battery monitor to understand your DC loads and "Designing and Installing a Large Solar Panel System" which goes into the mechanics of the installation.

The latter two articles are appropriate for a heavy DC user. Most of you can just install one or two 100 watt panels which should cover your needs.

One thing I learned in the Q&A afterwards at Hontoon is that Victron now has a line of inexpensive MPPT controllers with or without a bluetooth interface. A single 100 watt panel can be installed with their 15A controller which costs about $88 without bluetooth. You will need their 20A unit for two 100 watt panels which is about $157 with bluetooth.

Victron's new products and competitive pricing with PWM controllers makes it worth considering a MPPT controller even for small systems.

David
 
Thanks everybody. I ordered a cig lighter voltage monitor.
We have 2 batteries, both marine. Both Group 24 size?
The starter battery says cranking and 800CCA / 1000MCA,
the house is deep cycle and 550CCA / 690MCA / 140 RC.

Just been reading lots of summaries and... yeah. Math. But even if I'm just kinda right, our regular electronics won't pull too much. The main variable would be the Wallas.

Fingers crossed.
 
thechadmiller":1jth3l80 said:
Thanks everybody. I ordered a cig lighter voltage monitor.
We have 2 batteries, both marine. Both Group 24 size?
The starter battery says cranking and 800CCA / 1000MCA,
the house is deep cycle and 550CCA / 690MCA / 140 RC.

Just been reading lots of summaries and... yeah. Math. But even if I'm just kinda right, our regular electronics won't pull too much. The main variable would be the Wallas.

Fingers crossed.
Click to expand...

Not to put too much of a damper on the fun, but if those "deep cycle" batteries don't also give an amp hour spec, they are unlikely to be true deep cycle batteries and won't last as long.

I agree, your Wallas heater will be the power hog.

David
 
If the Wallas works like my Espar, it is the startup that uses the most electricity. The glow plug is +8 amps and can run for 15 minutes. Once going, it drops down to about .8 amps. Given the tiny amount of fuel my Espar uses, I do most of my temperature regulation at anchor by opening the windows instead of letting the thermostat cause the unit to cycle. Running the batteries down is more likely and a bigger problem than running out of diesel.

Batteries aren't an issue when running, of course, or at anchor overnight (because I don't run it once I'm in bed). I can see my battery minder from the v berth, so I can check the state of charge before I fire up the Espar in the morning (also from my v berth). So far, I've always had plenty of juice (with 2 24s).

Mark
 
We use a Mohoo 100W fold-able panel.
We run a small Engel freezer for cocktail ice and to freeze ice blocks for the Yeti. I wanted a portable panel so we could anchor in the shade and extend out to the sun. So far, so good. The only time we have run the batteries down was during a summer in the SJI with smoke filled skies.
 
knewlin":p8nb8g9i said:
We use a Mohoo 100W fold-able panel.
We run a small Engel freezer for cocktail ice and to freeze ice blocks for the Yeti. I wanted a portable panel so we could anchor in the shade and extend out to the sun. So far, so good. The only time we have run the batteries down was during a summer in the SJI with smoke filled skies.
Click to expand...

Thanks for this! What size Engel do you use and how long does it take to produce a block of ice. Do you think 200W should run the Engel and a few other things?
 
Most of the Engels (We have 3 as we keep downsizing our boats) run at about 2.5 amps per hour, they will freeze a little ice in a few hours if already cold. We love them to keep things frozen and out of the fridge.
You can put together a very simple to wire up, thin lightweight100 watt panel with a 15 amp MPPT controller from Amazon close to your price range that is probably about minimum to run your boat at anchor for a couple of days without your motor or a generator. Next time you change batteries if you can move up to at least group 27s, the 31s I have are probably the max on these boats without a lot of hassle. The new panels come with connectors that you can buy extensions for that with a fuse holder near the battery make it near plug and play. Don't be afraid to use marine grade crimp connectors, they are easy and almost bullet proof. I have found that our last 2 boats systems between 300 and 400 watts will run the whole boat basically for ever off the dock
Good luck!
 
We just ordered solar for our home in SW Fl. So bye bye Elec bills to FPL but now bills to the Solar company which will be the same . Part of the enticements was the 30% Federal tax credit but also it gives you an inverter to use when FPL goes out and also a 1800 watt solar generator .I'm looking into upgrading it so hopefully getting one that will run my RV AC unit 9200 BTU . I will keep you all up to date

See some of you at the Mississippi Gathering JIm
 
jennykatz":1iq02afi said:
We just ordered solar for our home in SW Fl. So bye bye Elec bills to FPL but now bills to the Solar company which will be the same . Part of the enticements was the 30% Federal tax credit but also it gives you an inverter to use when FPL goes out and also a 1800 watt solar generator .I'm looking into upgrading it so hopefully getting one that will run my RV AC unit 9200 BTU . I will keep you all up to date

See some of you at the Mississippi Gathering JIm
Click to expand...

It will take a LOT of solar panels to run your RV's AC unit. A 9,200 btu/hr unit pulls about 1,500 watts. And if you want to run it after the sun goes down, it will also take a LOT of batteries and even more solar panels to recharge them the next day. I doubt if your RV has enough roof area for all those panels.

David
 
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