solar AA battery charging

[cckw]

I am new to solar and know the low end questions from newbies can be annoying to the rest of you, but I hope you won't just roll your eyes and hit the back button. I have several questions:

First off, If I am buying a small solar panel online, are they all similar? or do I need to know things in order to get a good one? etc?

part #2...

I want to do a basic AA battery charging system. The AA charger is a smart charger that monitors charge and stops when charge is complete, so that the NiMh AA's do not get overcharged which they don't tolerate very well.

the charger I would use has a 12v input I have 2 different models that do this, Maha C-9000 and Duracell CEF-23 Maha has a max draw of 2amp, but that is if using max charge rate on all 4 channels. The Duracell CEF-23 has a max draw around 500mA.

My thought is to get a small solar panel and a 12v battery like used in a computer UPS. 12v 26Ah. or similar. then to the charger. The charger requires a stable 12v to work right, so having the battery in the circuit will stabilize that, right? Or do I need some additional regulation?

what wattage would I want in a solar panel? I'm near Omaha NE. usage would be to charge AA batteries for flashlights when power is out for days.

[Sunking]

[QUOTE=cckw;42699]My thought is to get a small solar panel and a 12v battery like used in a computer UPS. 12v 26Ah. or similar. then to the charger. The charger requires a stable 12v to work right, so having the battery in the circuit will stabilize that, right? Or do I need some additional regulation? Yes you would need a charge controller between the solar panel and battery so you do not cook you 12 volt battery.

what wattage would I want in a solar panel? I'm near Omaha NE. usage would be to charge AA batteries for flashlights when power is out for days.

Based on a 12 volt 26 AH battery you would want about 30 to 40 watt panel, and a 5 amp charge controller. 5 amp CC is about as small as they make them.

FWIW a 12 volt 26 AH battery is way overkill to charge AA batteries with.

[cckw]

The charge controller is too protect the larger battery? My thought, was the larger battery in the circuit would function as a charge controller to the AA charger.



A continuing though: in charging tool batteries (NiCad) do you charge a 12v batt with 12v, 18 with 18, etc? or is a higher charge rate a higher voltage?

[Mike90250]

Well, you need a smallish (10- 30 ah ) 12V battery to "stabilize" the voltage. Otherwise, every time you have a cloud pass, the panel will shut down, and the AA charger will reboot, maybe. Or lock up. Or go nuts. Or recover just fine.

But it's a pain, and I would always worry, so a 20-30w panel, small 12V sealed (AGM , not a GEL) battery, and a cigar lighter, socket.

I use the Maha C401 aa/aaa Charger

[noone]

Solar aa charging

Hi

I just leave a 5 watt panel in my window and plug a 2/4 AA charger into it directly.


It works fine.
I use it for AA cameras, radio, lights and have not had to plug a mains charger in for months.

[Modern Outpost]

Yes, but less is needed

You are correct on all points... solar panel into an SLA storage battery (so you aren't at the mercy of the sun all the time), then into your AA charger. Using the SLA battery will also allow your chargers to operate at full power when you want them to.
So, the issue comes down to choosing a panel to offset your AA charging demands.
If you are wanting to charge 4x AA's per day, from completely dead (never a good idea to 0% a battery), then you would need to offset approx 16 Watt-Hours of power (the capacity of 4 AA's plus a bit for charger waste). You could do this with a 5 Watt solar panel during summer months.
If you only need 2x AA's per day, then perhaps a $29 2-Watt 12V trickle charge panel would keep up.
The SLA storage battery you choose doesn't need to be very big... a 7.5AHr/12V stand-by battery would work fine. You can get these at places like Radio Shack.
Charge Controller? Probably a good idea if you are going to use the 5W panel with a small SLA battery, but you might not want the extra expense or wiring headache for the 2W panel which would take a long time to damage a battery. Your call. If you do, get a very basic charge controller in the 2-5A range.
Hope that helps!

[cckw]

So does it matter the brand of charge controller and solar panel? how do I find good ones? other related advice?

[Modern Outpost]

So does it matter the brand of charge controller and solar panel? how do I find good ones? other related advice?

For portable applications, I like the PowerFilm line of solar panels. Excellent in all light conditions. And if used with a 7.5 AHr SLA battery or larger, a 5 Watt PowerFilm would likely not need a charge controller due to its 15.4v nominal operating voltage. But if you want to not worry about overcharging, use the 4Amp charge controller promoted by PowerFilm (item# RA-9).

If you want to use a trickle charger in the 2W range, I can personally recommend the Brunton SolarFlat 2. Many automotive shops offer similar panels, but they are not built to the same quality standard as the Brunton. I wouldn't bother with a charge controller on the 2W panel. Brunton also makes a SolarFlat 5 rigid panel.

I hope this helps.

[Bratan]

Take a look at Goal Zero "Guide 10 Plus" charging system. You can find one online for around 100$, it's seems very durable. Comes with 7 Watt foldable panel (each is 3.5 W monocrystalline cell) and I think they are semi-flexible. And 4 AA charger (w/ batteries) included as well. It has USB and 12 Volt cigarette lighter adapter socket. Manual says it should take 3 hours to recharge in good sun. I only had it for a week, and yet to take it outside but on my window it seems to charge big 12 Volt LED light in a day or so. It charges my iPad 2 (from battery pack only), but I didn't test it completely (just plugged in once)Whole thing folds and very portable (seems durable too).
Just watch out for original Guide 10 kit, it has issue with electronics (melts) and battery pack won't charge iPad or other tablets.
And no I don't work for Goal Zero, but I really like their design. I'm trying to make similar one only on a bigger scale.

[Sunking]

Try Walmart. They sell a 20 pack of AA DuraCells of 10 bucks and will last for a couple of years.. Lot less expensive and you can put it in your pocket.

[cckw]

I'm not necessarily looking for flexible panels. Although, I did bookmark the two mentioned. what brand or type of rigid panels should I buy or avoid as a general rule of thumb? Or do we try to not name names?

[Mike90250]

Amo-Poly.jpg

Avoid amphorus panels, they are less efficient, and loose power over time.

[PNjunction]

...I use the Maha C401 aa/aaa Charger...

I'm quite a bit late to this party, but have used many Maha chargers, and would seriously consider upgrading from the C401 to another Maha with a more modern pulse. I also just use a larger AGM, and then run my AA chargers from that.

That 401 charger uses a much older algorithm which REALLY cooks the batteries beyond the normal exothermal heating. Newer models even come without the hinged door. And, with today's capacities, the low current setting of only 300ma is way under Maha's recommended 0.5C for accurate delta-v detection so missed delta-v's are a higher risk on the slow setting especially. It's one thing to get hot, and another to practically burn your hand.

Something like the MH-C9000 works great on DC. Yeah, it has all the analyzer features (which I use quite often), but you can just run it simply plug n play if you want. Or, if you want to run from an inverter, the C801D or C800S do fine too with more modern waveforms. I only run pure sine wave inverters, so I haven't tried them on msw types. The Maha Faq shows the recommended settings for today's capacities.

[Mike90250]

I'm quite a bit late to this party, but have used many Maha chargers, and would seriously consider upgrading from the C401 to another Maha with a more modern pulse. I also just use a larger AGM, and then run my AA chargers from that.

That 401 charger uses a much older algorithm which REALLY cooks the batteries beyond the normal exothermal heating. Newer models even come without the hinged door. And, with today's capacities, the low current setting of only 300ma is way under Maha's recommended 0.5C for accurate delta-v detection so missed delta-v's are a higher risk on the slow setting especially. It's one thing to get hot, and another to practically burn your hand.

Something like the MH-C9000 works great on DC. Yeah, it has all the analyzer features (which I use quite often), but you can just run it simply plug n play if you want. Or, if you want to run from an inverter, the C801D or C800S do fine too with more modern waveforms. I only run pure sine wave inverters, so I haven't tried them on msw types. The Maha Faq shows the recommended settings for today's capacities.

Thanks for the update. As I already have 2 of the 401's and their AC & DC cords, I'll look at the newer one when I have to replace one. Mike

[Jeffw1]

I don’t know if this will help but I agree that Maha is a darn good charger for AA/AAA.

I went fully to rechargeable years ago as I was sick to death of the constant purchase of AA for the kids: Gameboys and other gizmos so replaced everything! remote controls, clocks, toys everything back then. If I recall about £300+

The chargers I picked were the cheap and nasty ones (4 cells) and all never performed as rated and killed a lot of batteries, which I had to replace.

So I finally bought a LaCrosse (it had some good reviews) but died after a weeks use, and the SOB I bought it off ignored my e-mail and so did the company (I lost and so did they as I wouldn’t touch him or that company again) So I researched again and came to the Maha and Ansmann so bought the Ansmann for when I’m out and about and the Maha for the house. (Both have been perfect)

I settled for the 8 cell Maha MH-C800S and what a charger…There’s only two buttons – Left is cycle, discharge, charge etc which takes about 24 hours, or hold the right and do a soft charge which I always do instead of the default which is fast.

There’s a newer model that does 8 C and D cells as well as AA and AAA (I was thinking about it but don’t use anyway, so couldn’t see the point.)

I’m aware the C9000 allows for setting charge parameters etc., but I opted for the LaCrosse which died on me.

I bought my last lot about 5 years ago (batteries) and still have a good few of the originals ticking along nicely. I can’t recommend the Mahas or Ansmann chargers enough.

Have I lost or made money? I’ve spent maybe £5-£600 in total on chargers and AA/AAA’s but prior I was paying about £8+ per week albeit the kids are older now and moved on to newer toys so my costs decreased…I’ve still reckon I’ve saved over £1k (I’m kind’a bringing it down as they got older.)

So yep, the Maha MH-C800S if you wish to upgrade, you can’t go wrong Mike.