smart solar battery charger

mattbatson · December 2010

Beginner here...

so here is what I'm looking for...

I want a solar charger that I can use to charge 12 volt car batteries, 6 volt batteries, even connect to my eneloop battery charger so I can charge my AA's.

I want it to be a smart charger, one that can condition, refresh, etc...

It needs to be portable. I need to be able to move it to the tool shed where the riding mower sits so I can charge the battery, or the driveway for the sports car that only gets driven once a week or so, etc...

I dont want to have to buy twice after making a bad purchase the first time, which is why I'm asking on here. I dont mind paying more for quality either.

thx

BB. · December 2010

Re: smart solar battery charger

Hmmm... Wide range of needs.

Would a "central" solar array + storage battery as the energy source--then plugging in the other items to charge as needed (day or night, good weather or bad) going to work for you?

Or is this a minimalist thing and you want 1 portable solar panel of some sort and a small/portable/flexible charger that can be taken on hikes/etc. for on the spot recharging?

In general, I think a central power station (solar panel + charge controller + battery bank) that can supply power to (either 12 VDC or 120 VAC) day or night is a better solution for a fixed installation.

Portable solutions--solar panels are big/heavy/and don't really generate much power. For short term camping--picking devices with long battery life and common cells (AA, or lithium AA/C123A/etc.) type cells and skipping the solar panel may be a better solution (portable system pretty much requires the system to be fixed during daylight to recharge your batteries--may limit your ability to travel if you need 1-2 days for a small array to recharge your batteries.

Anyway--your needs?

-Bill

hillbilly · December 2010

Re: smart solar battery charger

Depends a bit on how much charging you would want to do with it on a daily/weekly/monthly level too. I did make up a pretty small portable power station for a month long river trip that worked ok for very small loads; used to recharge a few ipods, and some camera batteries mostly. Sounds like you're looking for a lot more than that, you could check out the portable back up power system that xantrex makes (I've had no personal experience with it).
My setup was 3 10watt panels connected in parallel to a 12v mppt charger that I already had, charging a 35ah sealed agm battery. The whole kit fit nicely into a single waterproof ammunition can which was portable but not exactly lightweight (the can itself weighed about 7lbs as I recall, and the battery and panels with padding and all made for about a 50lb box). I could run off the battery for a few days with limited or no charging (if needed), and I knew that I would have a few opportunities every few days to leave the array out in the sun all day to fully charge the battery back up.
Getting much energy out of any portable system is likely to be a bit unwieldy and not exactly the cheapest, but for smaller loads I'd say that it's fairly doable (I could have gone with a smaller battery and less PV if I had known that I'd have sufficient recharging opportunities). Not sure if this is helpful or relevant, hope it gives you some ideas to run with.

BB. · December 2010

Re: smart solar battery charger

And there is the whole alternative rechargeable battery idea (light weight, lots of power):

Lithium Iron Phosphate Batteries; LFP; LiFePO4 discussions

-Bill

mike95490 · December 2010

Re: smart solar battery charger

I don't know of any solar 6V chargers that are worth anything.

I do like the Maha C401FS 4 channel AA & AAA charger that has a 12V input, and has fast and slow rate charging. Slow rate is preferred for the enloop batteries.

Morningstar has several 12V solar charge controllers that will properly charge a 12V battery. You would have to pair that up with sufficient solar PV panels. (200 - 600W)

Ralph Day · December 2010

Re: smart solar battery charger

I did make up a pretty small portable power station for a month long river trip that worked ok for very small loads;

Yikes! Ipods on a river trip? Back in the olden days (when I used to canoe trip) we weren't even allowed to take a watch. Like Forrest Gump...when we got hungry, we ate, etc etc.

Ralph

mattbatson · December 2010

Re: smart solar battery charger

BB. wrote: »

Hmmm... Wide range of needs.

Would a "central" solar array + storage battery as the energy source--then plugging in the other items to charge as needed (day or night, good weather or bad) going to work for you?

Or is this a minimalist thing and you want 1 portable solar panel of some sort and a small/portable/flexible charger that can be taken on hikes/etc. for on the spot recharging?

In general, I think a central power station (solar panel + charge controller + battery bank) that can supply power to (either 12 VDC or 120 VAC) day or night is a better solution for a fixed installation.

Portable solutions--solar panels are big/heavy/and don't really generate much power. For short term camping--picking devices with long battery life and common cells (AA, or lithium AA/C123A/etc.) type cells and skipping the solar panel may be a better solution (portable system pretty much requires the system to be fixed during daylight to recharge your batteries--may limit your ability to travel if you need 1-2 days for a small array to recharge your batteries.

Anyway--your needs?

-Bill

Hey Bill,

Okay, I dont need it for backpacking or camping. I guess if I think about it, it doesnt have to be THAT portable. I can disconnect the mowers battery and take it to the charging station, for instance.

Ok, so a central charging station would work fine.

mattbatson · December 2010

Re: smart solar battery charger

Okay, from reading the responses so far, I will say that it does indeed sound like I should get a panel in the 200 to 400 watt range.

That is fine, I can do this. I'll probably just build a stand for the panel(s) out in the yard and then just run the wires back to the garage where the charger or inverter or whatever else it is I would need, would be stationed.

If anyone could give me a rundown on required stuff I would need or specifics on exactly what YOU would buy. Brands you trust, stuff like that.

For instance,
"if I were you, I would buy X panel (or any of these brands of panels), wire would be x gauge back to the charger or inverter (I'm a beginner at this stuff:D), wired to x charger"

that sort of thing...

I would really appreciate it.

thx

mike95490 · December 2010

Re: smart solar battery charger

2, 150W - 200w PV, wired in series, can use long cord to site in yard
MS Sunsaver MPPT 15A
or
2, 150W - 200w PV, wired in parallel, orient one at 160deg, one at 200deg for "wider" charge profile. Needs heavy gauge wire, shorter length
MS 20A PWM charge controller (several types in the $90 range, with timers or other goodies)

Maha C401 aa/aaa Charger w/ car cord

optional: SureSine 300W inverter to power a 6V flooded battery charger.

BB. · December 2010

Re: smart solar battery charger

Remember a solar panel is a (usually) large single weight (~1/8") piece of tempered glass in a metal frame.

Normally, you want the panel fixed mounted (roof or ground mount) way from golf balls, baseballs, rocks from lawn mowers, etc... Do not lean the panel against the wall or put free standing legs on it... A gust of wind (or act of kid)--and you end up with $500+ piece of modern art (shattered tempered glass).

A good place to start--take a look at this thread:

Information and links on a bunch of common solar questions:

Here is a nice thread with video from Keven in Calgary Canada that shows designing and installing solar PV in a small RV trailer.

Emergency Power

Basically a very long thread that starts from the beginning with a few vague requirements through design and assembly for a "portable" solar RE off-grid power box.

And here is another example by Mike90045 called the Solar Monolith:

We can talk about brand and details too--but want to make sure we understand your loads...

You can start with an end point (XXX watts of solar panels, or XXX Amp*Hour XX volt battery bank) etc... And we can fit rules of thumb to give you a range of panels/batteries that meet your requirements.

Or we can start with your loads, and fit the panels/controllers/batteries/inverters to support those.

Once we know the actual size of array/battery/inverter/etc... Then we can talk about exact components... For the most part, solar systems are not easy to grow later (cost effectively)... If you get outside a 1:2 expansion range--you almost always need new major components (and $$$) (charge controller, battery bank, AC inverter, etc.) to meet the new requirements.

Because we are all kind of cheapskates here :roll:, we kind of harp on 1) Conservation 2) use less power by turning things off 3) pick devices that don't waste power (or conservation, conservation, conservation). Then understanding your loads--and finally design a system that meets those needs.

For starter/educational systems--frequently we do start with 200 watts of panels, what support hardware would work. So--either works for us.

-Bill "I type too much" B.

mattbatson · December 2010

Re: smart solar battery charger

mike90045 wrote: »

2, 150W - 200w PV, wired in series, can use long cord to site in yard
MS Sunsaver MPPT 15A
or
2, 150W - 200w PV, wired in parallel, orient one at 160deg, one at 200deg for "wider" charge profile. Needs heavy gauge wire, shorter length
MS 20A PWM charge controller (several types in the $90 range, with timers or other goodies)

Maha C401 aa/aaa Charger w/ car cord

optional: SureSine 300W inverter to power a 6V flooded battery charger.

Thanks, I'm getting a clearer picture of what I need. Hopefully when I buy components there will be some schematic/wiring diagrams.

on the maha charger...I did buy this http://www.amazon.com/Sanyo-Eneloop-Pre-Charged-Rechargable-Batteries/dp/B000IV0REA/ref=sr_1_2?s=electronics&ie=UTF8&qid=1292453616&sr=1-2 when I purchased my eneloop batteries.

Do you think it is worth it to buy the maha also? Is it significantly better than the eneloop charger you think?

mattbatson · December 2010

Re: smart solar battery charger

BB. wrote: »

Remember a solar panel is a (usually) large single weight (~1/8") piece of tempered glass in a metal frame.

Normally, you want the panel fixed mounted (roof or ground mount) way from golf balls, baseballs, rocks from lawn mowers, etc... Do not lean the panel against the wall or put free standing legs on it... A gust of wind (or act of kid)--and you end up with $500+ piece of modern art (shattered tempered glass).

A good place to start--take a look at this thread:

Information and links on a bunch of common solar questions:

We can talk about brand and details too--but want to make sure we understand your loads...

You can start with an end point (XXX watts of solar panels, or XXX Amp*Hour XX volt battery bank) etc... And we can fit rules of thumb to give you a range of panels/batteries that meet your requirements.

Or we can start with your loads, and fit the panels/controllers/batteries/inverters to support those.

Once we know the actual size of array/battery/inverter/etc... Then we can talk about exact components... For the most part, solar systems are not easy to grow later (cost effectively)... If you get outside a 1:2 expansion range--you almost always need new major components (and $$$) (charge controller, battery bank, AC inverter, etc.) to meet the new requirements.

Because we are all kind of cheapskates here :roll:, we kind of harp on 1) Conservation 2) use less power by turning things off 3) pick devices that don't waste power (or conservation, conservation, conservation). Then understanding your loads--and finally design a system that meets those needs.

For starter/educational systems--frequently we do start with 200 watts of panels, what support hardware would work. So--either works for us.

-Bill "I type too much" B.

thanks so much bill.

I like that portable solar arrangement. I was thinking of building something like that based off a movers dolly.

I have read enough on here to know that you always calculate your loads first before choosing a system. And that conservation is much easier and cheaper than a bigger system.

Now, in my case, the biggest thing I will be charging will be a normal everyday car battery. And i dont care if it charges in a day or two. I'm just looking to keep it in good condition for when it sits for a couple of weeks or so. Same with the mower battery, which can sit for over a month at at time.

I got tired of buying new batteries every year for my sports car and mower and decided to look for a solution.

I figured that if I built a system like this, that it could also charge other batteries too (like the AA's I use in just about everything)

I've also read enough to know that it is most cost effective to build something to the correct size the first time, as it is hard to expand without spending money.

So, I plan to err on the large size. Because the solar panels will not be used for anything I really depend on, I figure I have more flexibility.

Those links you posted are great by the way.

mike95490 · December 2010

Re: smart solar battery charger

mattbatson wrote: »

Do you think it is worth it to buy the maha also? Is it significantly better than the eneloop charger you think?

In the 2nd photo of the "Monolith", you can see the Maha charger in the back, behind the other stuff.
I like it because it has 4 channels of charging, the Sanyo has 2, which means it can only charge pairs of batteries. Too bad if your gadget takes 3 AA.

Also, not visible in the monolith, are the batteries, under the shelf, at the very bottom. gives it great ballast! (2 COSTCO deep cycle batteries)

Now linked to my facebook page, which is open access to this album:
http://www.facebook.com/album.php?aid=2074858&id=1196643274&l=7e66e96c3c

mattbatson · December 2010

Re: smart solar battery charger

mike90045 wrote: »

In the 2nd photo of the "Monolith", you can see the Maha charger in the back, behind the other stuff.
I like it because it has 4 channels of charging, the Sanyo has 2, which means it can only charge pairs of batteries. Too bad if your gadget takes 3 AA.

Also, not visible in the monolith, are the batteries, under the shelf, at the very bottom. gives it great ballast! (2 COSTCO deep cycle batteries)

My monolith would be the same, except it wouldnt have to carry any batteries. I wouldnt be using it as a power station, only as a charging station for my various battery's.

I'm looking at 150-200 watt panels right now. Any I should stay away from? Recommendations?

BB. · December 2010

Re: smart solar battery charger

Keep with crystalline solar panels. Will be physically smaller than thin film.

I would still suggest that a storage battery in the base. It is very handy for emergency use at night and on cloudy days.

-Bill

hillbilly · December 2010

Re: smart solar battery charger

I absolutely agree about having a storage battery in the system, otherwise you'll likely find that you'll have a very limited amount of power for a short window of time. With the storage battery, you can in theory use more power than your PV can produce in a day... as long as you will have a few days afterwards to allow the PV to fully recharge your storage battery.

Think of it as a sort of energy savings account; you put a few watt-hours away each day, with the potential to pull a more signifigant amount of energy out of it when needed. The key to this is a good understanding of how much power you'll need, for how long, and how often... then you need to figure out how much PV it would take to recharge the battery back up in a reasonable time frame.

niel · December 2010

Re: smart solar battery charger

some chargers given enough pv to power them can quick charge the batteries can negate the need for a larger battery to keep things going past sunset. the thing to watch is that the input voltage to the charger will not be exceeded by the pv voc so some regulation may be needed and of course those regulators are often charge controllers that often need a battery connected to operate properly.

mike95490 · December 2010

Re: smart solar battery charger

- heres a pictorial of my Monolith construction:
http://tinyurl.com/SolarMonolithConst
you can use batteries, or not.

smart solar battery charger

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