Solar Charger for AA Batteries

Re: Solar Charger for AA Batteries

Photowhit wrote: »

yes a tricky search, since everything around here has solar and batteries and 'aa' is too short a string.

"The" is a common word and has been omitted from the search. "Who" is a common word and has been omitted from the search.
No search criteria specified.

Not a real search, btw...

Re: Solar Charger for AA Batteries

steven,
the charger i have was in one of the links coot linked to, but you may have overlooked it.
http://www.gnbatteries.us/servlet/the-265/IC-dsh-U6S1234-dsh-LED%2C-hitech-charger%2C-aa/Detail
it does aaa, aa, c, and d size up to 6 batteries and each charges singly. that means each battery you put in there is charged by itself and not in series with another battery like many other types. that allows odd battery numbers to be charged such as 1, 3, or 5. it also switches to float mode after charging.8) only complaint is you have to be careful with the small connector into the charger as the wire is heavier than the connector can take if carefree with it.

i love this charger and use it allot and i've had it for years. i may buy another if i think of it as you never know.

ps-this site may give you more info on it than the one i previously listed.
http://www.batterymart.com/p-ic-u6s1234-led-universal-consumer-battery-charger.html

pss-sorry as you can't do a 19vdc battery pack readilly from this charger so if you want to use that you will need to do something fancy like dc to dc conversion into a special charger, maybe?

Re: Solar Charger for AA Batteries

I think you'll be happy with the PowerFilm for AA's at least. Just remember to allow for an additional hour or so after the full charge signal is lit, since that is really only about 80-85% charged. Usable for most people at that point, however it may be a reason for some poor reviews for those that take time to measure voltages / analyze it.

Note that instead of outright rejecting cells with high-impedance (old stock, deeply dishcharged, abused etc), it will at least attempt to bring up the voltage by trickling at first before heading into a fast charge. So it has some smarts.

Do yourself a favor and use quality cells from the start. Some reviews reveal that they are trying to revive drugstore-quality cells from the 1990's, mismatched cells from kids toys etc and want to keep them alive well beyond their normal lifespan - even if they have ridiculously low capacity even after being revived. While there are a variety of good cells out there, the standard seems to be Sanyo Eneloops as the enthusiasts reference.

Re: Solar Charger for AA Batteries

My advice is to avoid anything marketed as a "solar battery charger". Instead, get a good charger that can be powered directly from 12 VDC. This one is excellent because it tells you how much energy went into charging each battery, allowing for all kinds of metrics and analysis. This one is not good because it requires more than 12v to run.

Once you get a battery charger that can be powered by 12v, it's a simple matter to add solar to the mix, because so many PV systems are designed around 12v. With a 10 watt panel, you wouldn't even need a charge controller. Just get a small 12v battery (7AH should be fine). Battery stays indoors and out of the sun/heat/cold/rain. Panel goes outside. Panel charges 12v battery. 12v battery charges all your other batteries.

This is a robust and flexible system that will outlast all the "solar battery charger" junk. Batteries can be charged at night because they're being charged from the 12v battery and not directly from the sun. That same charger can be powered via VAC with a power brick. Or from your car battery. The 12v battery can be used to power other things--not just the battery charger. All the parts can be replaced/upgraded as needed. The only disadvantage is cost (but you get what you pay for), and while it's portable, it's certainly not for backpacking.

Re: Solar Charger for AA Batteries

Sparkletron wrote: »

My advice is to avoid anything marketed as a "solar battery charger". Instead, get a good charger that can be powered directly from 12 VDC. This one is excellent because it tells you how much energy went into charging each battery, allowing for all kinds of metrics and analysis. This one is not good because it requires more than 12v to run.

The PowerFilm is certainly not junk, and is the only solar charger that takes into account the fact that you might have shadows or passing clouds. Ordinary chargers, albeit excellent ones like the Maha 9000 linked to, will reset or get confused under deep shadow or passing cloud. This leads to a reset back to default charging currents, resets timers, etc - and worst of all subjects already charged batteries to multiple instances of delta-v detection at 1000mah initial current when it is not necessary.

I use one of these myself, but only off-the-solar-grid so to speak, by merely charging a larger agm and bringing that back in at night for a two-step process where there is no chance of cloud/shadow reset. Still, one must account for the fact that cells are exothermic during charge, and both charger and battery are in direct sunlight - although you can shade the batteries with the extra flap - but when it is 100 degrees ambient in the Nevada desert, it is not the best idea. Most junk solar chargers are either useless slow-roasters, or will quickly expire at 85 degrees.

Quick note about the 9000 not commonly known - the VERY first voltage you get when you insert the cells is actually an impedance check. The 9000 will kick out cells with an impedance higher than about 2.2. You can gauge the health of the batteries when the data is presented once, and only once during insertion. (after this one-time reading, the true cell voltage will be displayed thereafter.

1.6 = very health new cell, full capacity available
1.8 = middle aged - electrolyte drying, capacity decreasing
2.0 = old aged - cell has met it's EOL, dry electrolyte, or you just picked up a pack of shelf-queens from the supermarket 5 years old or worse. More resistor than battery.

This is not something mentioned in the 9000 manual, but if you are buying new batteries and keeping track, write these values down when you get new cells for reference.

The Powerfilm does it right by taking the SOC up to 85% or so quickly, and then trickling in the rest after an hour beyond the normal indication for a finished charge. Many don't know about this. That way, passing clouds don't confuse the charger, or subject the charged cells to repetetive delta-v EOC detection. On a similar note, the Maha 9000 will also dump in 120mah total in two extra hours of charging before going to a true 10ma trickle. This is part of a conservative / safety measure on Maha's part after delta-v detection to ensure the cells are truly charged fully. Others might have delta-v's that are delayed, and risk missing the trigger.

I would keep a careful eye on using AA-AAA adapters in the powerfilm. While eneloops can be safely charged at 1C, the AAA's will charge up very quickly, and being exothermic, it would be a good idea to keep an eye on them, or not charge them on top of dry grass etc. Common sense stuff. I don't do AAA, so you are on your own there.

Re: Solar Charger for AA Batteries

My philosophy is to realize that 'where you are now is not where you will be in the future' and when you design for what you think you need now you are setting up a problem down the line. I use our Maha at home and it goes with us in the teardrop, it is powered there by the Morningstar inverter fed by the 185W solar panel into a Sunsaver.
The anticipated needs morphed and additional loads have been added. XM radio, 3G hotspot, chargers for camera battery, chargers for cell and iPad and laptop... My advice think bigger than what you think you need!

Re: Solar Charger for AA Batteries

PNjunction wrote: »

Seriously, how robust and flexible does one need to be to charge 4 AA's?

Hard to say without knowing all the facts. Does your life depend on it? Then I would hope you'd choose the most flexible and robust system you can afford. Also, the OP expressed a desire to charge more than just AAs. My suggestion is FLEXIBLE enough to accommodate other chargers and charging at night while the OP is asleep. I can't imagine a more efficient way of charging. Charging during the day... deprives the OP of the use of those batteries when they may be needed most.

Before this tussle turns into hundreds of posts, let me just say that you offered a good solution and I offered one as well. Your suggestion has merits as does mine. I think the OP has enough information to make an informed choice, or to post if more info is needed.

Re: Solar Charger for AA Batteries

let's revisit this as more inline with steve's original plan. with that energizer xp18000 the big problem he would have is charging that from solar. small controllers would only bring it to about 24v and we don't know how critical the input voltage of 19v is. if it is like many ac adapters then this may be at 24vdc, but if critical then some further efforts would be needed to bring the voltage inline and a possibilty could even be a high current linear regulator ic arrangement to accommodate it. of course one could also place up to 10 diodes in series rated for at least 3.5a to drop the voltage on a pwm or linear type regulator or cc. (not a common current value, but 6a is)

the other problem would be the pvs to charge the xp as it would need a higher vmp to operate a proper charge. maybe 2 of the 12v pvs or one of the 60 cell pvs. it would require at least 3.5a and does mean not very portable to charge this main xp hub for recharging the other devices. if cost is not as important then you could use an mppt cc to down convert the voltage from the higher voltage pvs, but getting to the target voltage of 19v may not be so easy to do as i'm not sure off hand what mppt ccs may accommodate this odd voltage. the diode arrangement is not advisable to use with the mppt cc, but i believe it would be fine with pwm ccs.

i think steve would like options to charge this xp18000 rather than the other obvious routes we would choose, but this is proving to be just as difficult. unless you get somebody to come up with a special regulation circuit aimed at this odd voltage straight from the pvs then the other methods we invoked start to seem more viable.

imo, 2.2w isn't really viable when talking of many batteries that need charged, many of which can be large in capacity. also the charge time window will be small even for a sunny day.