AA charger options for small 14w or 21w panel

[gracklemann]

I'm looking to have a portable system for charging AA Ni-Mh batteries and USB devices. I'm looking at one of the Anker portable panels, likely the 14w or 21w models.
For AA charging, the GoalZero Guide 10 looks almost perfect.. charges AA or AAA batteries, and it should handle non-continuous power from a small panel. As a bonus it can act as a booster pack as well.. The only thing that gives me pause on it is that it will only charge 4 batteries at a time.
EDIT: as in you have to have 4 batteries in it, no individual charging circuits.
Of course I could just carry extra NI-Mh batteries and wait until 4 are drained before charging.. and this might be the simplest solution, but..

I've seen other, "better" AA chargers that accept a 5v/3a USB input (the output from the Anker panels), but I don't know how well they'd function with non-continuous power.
I've searched quite a bit, but haven't seen any other options. Does anybody know of a AA charger that will work well off a 14 or 21w panel?
Or any other advice?

Thanks!

[PNjunction]

You are wise to avoid the GZ AA charger that only charges when there are FOUR batteries in circuit. That means unbalanced cells get totally overcharged, while the weaklings catch up. Even Sanyo / Eneloop has dropped their older chargers which used to charge in pairs to individual charging circuits. Should have done that YEARS ago, but I digress.

Aside from attaching say a Powerex / Maha MH-C9000 to a dc source like a battery and panel, is the Powerfilm AA charger. The one that handles 4 cells, not just two and a dinky usb port.

The 4-cell folding Powerfilm is actually VERY smart, even though it charges in pairs, and not individually. It knows how to deal with a non-stable source like the sun. Essentially, it will fast charge only up to about 80% SOC, and then walks it's way to the finish - slow, but not a trickle. That comes later. This avoids hammering the cells when the sun is variable. It was designed from the start to work in the sun, and isn't just a cheap thin-film slapped onto a dumb charger circuit.

It isn't the cheapest, and there are copycats around. If you value your AA nimh cells, and need a smart solar charger for it, then this is the way to go - because it does the right thing, albeit only in pairs.

[gracklemann]

Thanks for the rec PNJunction. The 4 battery Powerfilm unit does not appear to have a USB-device charge option. The 2-battery version does however, so it's possibly an option. The documentation on their products is pretty shoddy.. hard to tell much from the Amazon descriptions, and I can't find a company webpage.. Thanks again for the info.

[PNjunction]

Unless one absolutely needs AA charging, the Anker 14w (or 8w panel if you have the time), and one of their li-ion battery packs makes better sense in today's world. The "IQ" ports of the Anker help alleviate the need to find / make custom usb cables for the best power transfer.

BUT, if you do need AA charging, you can find info about it right here along with a pdf of the brochure. The brochure does not give full details, but more information is included in the actual owner's manual:

http://www.powerfilmsolar.com/products/?aa_battery_foldable_solar_panel&show=product&productID=271505&productCategoryIDs=6578

Note that I don't recommend the smaller AA/USB combo, since the power output from the usb port is pretty marginal these days, and being powered solely by two nimh AA's means that unless you are using a Startac flip-phone from the 90's, you won't make much of a dent in any modern devices.

Hence, the recommendation for the 4AA unit, whether you intend to charge just 2 or 4 AA's. Powerfilm is smart to know that unlike other common solar chargers, they don't do dv/dt EOC detection since passing clouds, shadows etc would restart the detection process multiple times, and if you miss a dv/dt detection, you can easily overcharge them. So they basically charge fast to 80%, and then walk it in a bit slower. Should intermittent sun occur, when the cells start charging again, the unit is smart enough not to hammer them with full current when they are already near full charge.

Tip: Once the charge led's stop blinking to signify a full charge, if you REALLY want to get a full charge, continue to do so for an additional hour or two as they are really only about 95% SOC. This is somewhat similar to how the Maha / Powerex 9000 charger deals with the end of charge too, although most consumers aren't aware of it as it is not published in the manual, but verified later by manufacturer's engineers.

The thing about Powerfilm is that they are the real deal. When one wants to move beyond backyard / picnic table weekend fun, but get serious about portable solar ops, then you move beyond the toys. And you won't be paying toy prices either, as part of their acceptance testing is to put bullets through them for the military.

[gracklemann]

So looking at the options (I can find) and PNJunction's advice.. likely one of the Anker panels with "IQ" technology would be best for USB devices.
The Powerfilm 4aa charger best for just AA/AAA battery charging.

So I'm looking (currently) at two options to satisfy both:
1) Anker 15w panel (for USB) - $45
+ Powerfilm 4aa panel/kit for AA/AAA - $90
= $135 total

OR
2) Anker 15w panel for USB - $45
goal zero guide 10 battery pack only for AA/AAA (charged off the Anker panel via USB) - $50
= $95 total

The GZ battery pack has the disadvantage that it has to charge 4 batteries at the same time, the Powerfilm can charge in pairs. The Powerfilm, probably, has better protection for the batteries..
The GZ specs state that is has overcharge/undercharge protection, but difficult to say how "good" it is. It is made to work from their 10w solar panel.. Possible they are assuming that with 10w it would be harder to fry the batteries? If that is the case, then paired with a 15w (or 21w) Anker panel would this "protection" be negated somewhat?

Again, thanks for the info PNJunction. It's been helpful.

[PNjunction]

Yes, the GZ has to charge in "quads".

Oh, it will take less, but the cells burn up. I know - I've been through 3 iterations of them, starting when there was no addendum or warning.

The Anker 14 watt panel only has a 5v output that terminates into a usb jack. This usb output port has some smarts ("IQ") about the best possible internal configuration. In the old days, you used to have to build / find your own "charge only" cables and the like for best performance. There is no 12v output.

Thus the Anker does not make a proper panel for a GZ battery charger.

The GZ's use common coaxial interconnects, and the dc power leads themselves are carried across coaxial cable, and not standard 2-wire cabling as we know it. For custom setups, you'll need to be wiring up your own stuff with coaxial dc connectors to fit the GZ products. These dimensions change depending upon model.

So yes, stick to an Anker panel, along with their high-quality battery packs for charging cellphones and other usb driven devices. Build quality, engineering, and often overlooked - their internal cell quality is very very good. Lesser products may tend to throw in cheap trashy cells - but the consumer is unaware.

For AA, then the Powerfilm 4AA is your best bet in the portable category. Or, like I say if you really want to go over the top, you carry around a medium sized lead-acid AGM, 50 watt panel, and use a Maha / Powerex MH-C9000, which can run from dc. The large agm battery serves as the stable power source. Not quite as portable.

For backyard / picnic fun, I have a few GZ folding Nomad panels myself. But when it becomes time to get serious, then the Powerfilm stuff comes with me - and not just the AA charger but the larger folding / rolling panels along with charge controllers, batteries, etc.

[Shadow Catcher]

The Maha 12v DC or 120V AC will cahrge 1, 2, 3 or 4 batteries at a time. I have one of the big ones am am pleased with it.

[jakesz28]

I have looked for other AA/AAA chargers that I could use with my 16W AllPowers fold-able panel. But I have not found anything yet. I was even considering using the solar to charger a ankler battery pack and than using the battery pack for a stable usb voltage to charge the AA/AAA batteries.

[PNjunction]

Avoid too many kludges - agm > anker > AA is just too inefficient.

I also forgot how smart the Powerfilm 4AA charger is when it comes to depleted batteries!

If it detects batteries that are fully discharged (those below 1v), instead of just hammering them, it knows to do a soft-start to *gently* bring them back to normal operating voltages before allowing for full current to pass. If you don't do this, then you can make what is a severely discharged, but otherwise good cell (if you get to them in time), go high-resistance, or just plain damage them.

Ironically, this is similar to how you treat LiFePo4 too when discharged too far, but that's another thread.

So the Powerfilm protects highly discharged batteries at the low end, knows how to deal with an unstable source from the sun like passing clouds, shadows and whatnot, and generally shows that these guys just didn't slap together some crap for the camping crowd. Some real solar engineering and knowledge of how to treat AA's went into it.