PowerFilm AA solar charger review & UK test....

[Martyn]

Part 1:

Product: PowerFilm AA battery solar charger.
Dimensions: Folded: 140mm x 80mm x 33mm, Open: 790mm x 80mm.
Weight: Without batteries: 123g, With 4 Eneloops: 227g
Power: 2.2W
Volts: 3.6V
Current: 0.6A
Website: http://www.powerfilmsolar.com/

A lot of people seem drawn to solar chargers for various bits of kit. We all seem to be ever more dependant on electronics in our lives, understandably so. Devices like GPS systems, smart phones, notebooks, torches, radios etc. make our lives much easier and more pleasurable. It's understandable that we want to use these things when out and about, camping, hiking, holidaying or whatever. The big problem is that they run on electricity and the absence of a convenient power socket in the nearest tree, can make that problematic. Solar chargers are an obvious solution and very many products sport small solar cells for this purpose. However, these solar driven items such as radios and torches are often underpowered and really only work to any level, in areas that reliably get many hours of good quality sunshine each day. Even then the small panels on these items are often pitiful and only really serve as a top up charger. In the UK where some areas can have 200 days a year of rain, such things are all but useless. Even a high quality solar panel will have it's output reduced to 30% efficiency on an overcast day, meaning the small panels on many of these things never generate enough voltage to work at all in our weather.

However, there are a couple of options which attempt to tackle this issue with more gusto. The PowerFilm AA battery charger is one. It takes the approach of charging AA batteries, which you can then use to power your kit. This is obviously beneficial as you can run anything, so long as it normally runs on AA batteries. Even kit like smart-phones, which are typically charged via USB, can still be charged using a cheap AA battery to USB adapter. There is still the issue of efficiency though. Solar panels do work in the UK, but because of the reduced efficiency, they need to be 3 or 4 times larger than their counterparts in sunny countries, to generate the same output.

So the $64,000 dollar question, is will the powerfilm AA charger work in typical British weather?

Before we go any further, I should say there are two versions of the PowerFilm charger. One version that charges 2 or 4 batteries, has 6 panels and puts out 2.2 watts (3.6V @ 0.6A) and the other charges 2 batteries but also has a built in USB charger, however it only has 4 panels and puts out 1.5 watts. I'm actually quite sceptical that either of these chargers will work terribly well, but I am extremely sceptical that the 2xAA/4 panel/USB version will work at all. I could be wrong about that, but there just doesn't seem enough solar panel real estate to do the job. With that in mind, I opted for the 4xAA/6 panel charger. I rationalised that even if the panel wont charge 4 AA batteries in 7 hours in the UK, at least it should be able to put a reasonable charge into 2 batteries, even if running at 30% efficiency on an overcast day. We shall see.

This is what the manual says about charging times and panel performance. You can see how the various lighting conditions, cloud cover and angle of sun to panel significantly effect the performance of the charger. In anything other than direct, bright sunlight that is perfectly at 90 degrees to the panel, the performance of the charger will be greatly reduced.



This is what the makers say about estimated charging times, obviously in ideal charging conditions...



The chargers are quite expensive in the UK, but significantly cheaper direct from the US. Mine arrived in the post yesterday. I lost no time in partnering it with a 4XAA USB adapter. This is how I have is set up for carry...



It's a very small package and very lightweight. Here with a UKPK for scale...



The elastic strap holding it all together doesn't come with the charger and is actually the wrist strap from a pair of Hatch CQB gloves which I discarded because I didn't like them. I saved them though, thinking the elasticated Velcro strap may come in handy for something.

The cheap, Chinese AA to USB battery adapter is a pretty lucky fit. Separated...



The battery compartment is on the reverse side from the solar panels and is really two compartments - 2 charging circuits side by side, here loaded with four Sanyo Eneloop batteries...



On the other side of the folding panel, we have the six solar panels and the back of the charger PCB. The PCB is printed with some simple operating instructions and is embedded with 2 LED's which blink in different sequences to indicate the status of the charger and batteries...





So, in Californian sunlight with the panel continually orientated towards the sun, we can expect four Sanyo Eneloops to charge to full from empty in around 7 hours. But what about Staffordshire on a rainy overcast day?

To test this there are various bits of electronics we could employ, light meters, volt meters and wotnot, but they are still a bit hit and miss. I have a battery tester, but it only really measures the voltage so is only any good for telling me if a battery is flat. Not much good for telling me how much juice is in a partially charged Eneloop. So I've constructed a simple real world test. Firstly, I fully discharged four batteries - I did this last night by running them in a 4 Sevens Quark on full power until they died. Each pair gave me about an hour of 200 lumens before they gave out, which is to be expected. I loaded up the PowerFilm charger with 4 batteries and put it on a south facing bedroom windowsill at at 45 degree angle to the sun at about 10:00am this morning. The weather was horrible at the time, very overcast, raining and no sign of sunshine, though it's brightened up now. Still not exactly bright sunshine but enough light to cast shadows through the window. It's very variable and probably typical of the kind of weather you can expect on any day between April to October. I'll leave the charger on the windowsill till 5pm tonight, which will give it the full 7 hours recommended for 4 empty batteries.

To see how much charge is put into the batteries, I decided to use my iphone 4 paired with the 4xAA USB adapter. This represents a pretty good real world test I think. The iphone is notoriously picky about charging and using this kit in this way is probably how I would use it in real life.

I discharged my iphone by running the TomTom app, which eats the battery alive - it'll take a full phone battery down to empty in a couple of hours. It's running now and the battery is currently down to 24%. When it gets to 5% or less, I'll stop the app and turn the phone off. At 5pm tonight, I'll take the batteries out of the PowerFilm charger and put them into the USB adapter and attempt to charge the iphone. I'll be able to tell if the batteries are charging the phone and at what % they stop charging. How many charges will I get? I have no idea. I'm sceptical it'll do much to be honest. I can see the lights blinking to say the panel is putting charge into the batteries, but how much in this weather? I guess we'll have to wait till 17:00 hrs when we'll find out if this....



...is a must have piece of Gucci kit, or an expensive paperweight.

Thanks for reading.

[Martyn]

Part 2:

Results time. OK, I messed about with my iphone untill the charge was at 9%. I originally dropped it to 4%, but then the phone wouldn't turn on and I wanted the charge indicator for the pics, so I juiced it up to 9% for the starting point.



For most of the day it was very overcast, several rain showers from light to heavy, some periods of black cloud, some sunshine poking through around lunchtime and a bit more from about 3pm onwards. The UV index varied from -1 to +2 at my postcode, according to several websites. Basically low and typically British.

I took the Powerfilm down at exactly 5pm and removed the batteries, put them in the cheap, Chinese USB adapter and connected to the iphone. I'm not sure this charger is up to the job really, but more on that later. I flicked the power switch and the phone began to charge. After about 20 minutes or so it had reached 25%...



Yay, so good so far. The Powerfilm can cartainly charge up the batteries enough to transfer a usable amount of juice.

But, about 15 minutes later and....



At 33% the batteries in the USB charger ran out of juice - at least I think that's what happened. It could be crappy electronics in the Chinese USB charger. To check I dropped the batteries out and placed them in pairs in the 4 Sevens Quark AA and set the torch to high mode which is 100 lumens or thereabouts. I got 7 minutes and 4 minutes respectively before the torch dropped out of regulation and dimmed significantly.

So there you have it. The Powerfilm AA charger is capable of putting enough juice into 4 AA batteries to give an iphone 24% charge and run a 100 lumen torch for 14 minutes, after 7 hours in a windowsill. Useful or not? I dunno. Maybe. Enough to keep all your gizmos juiced up on the go? Hmmm, not on it's own, not unless you were exceptionally frugal. But it is pretty much what I expected. Tomorrow I'm going to repeat the experiment, but with just 2x AA batteries in the PowerFilm, test the levels in a Garmin GPS and then try a runtime test with a single AA headtorch to see what kind of useable light I can get. Maybe this setup isn't enough to keep an iphone juiced, but it might be enough to keep a headtorch and GPS running, we'll see.

Obviously direct outdoor sunlight at the hight of summer will make a big difference, but this gives a good benchmark of what to expect for the other 51 weeks of the year. The reality is though, at this performance level in these conditions, the weight of the charger doesn't really pay for itself. For the same weight penalty of this charger and 4 eneloops, you can carry about 12 lithium AA's. I suppose if you were isolated from a battery source for weeks at a time or had no money to buy batteries, then it may make sense, but for the casual UK hiker, especially ultralight hikers, carrying this charger doesnt rationalise.

[Mr Happymoose]

Thanks for doing this Martyn, definitely following with interest.

[earthman]

Thanks for doing this Martyn, definitely following with interest.

+1 on that.

[Martyn]

Updated.

[uzumlubay]

Probably better suited to where I am - we get about 300 days sunshine a year although just at this moment raining.

[Martyn]

Probably better suited to where I am - we get about 300 days sunshine a year although just at this moment raining.

Most definitely. If it charges up just a little bit in the UK, it'll work just fine in Turkey. I cant criticise the charger per se, it's just that we dont get enough sunshine here to make it a viable option, especially given the availability and proliferation of AA batteries. Solar energy is doable here, you just need camparatively huge panels to compensate for the lack of sunshine.

[Mr Happymoose]

As you say, the thing you put the batteries in to charge the phone could have been at fault, cheap Chinese electronics and all that. The other thing I wonder is, if you were using this for an emergency situation would a more basic phone be workable, just something to allow you to make calls and texts kind of thing. To be honest, with the weather you had today, I'm impressed you got any charge at all!!

[Martyn]

As you say, the thing you put the batteries in to charge the phone could have been at fault, cheap Chinese electronics and all that.

True but 14 minutes output from a 100 lumen torch would suggest the batteries were near flat. I guess a charger with fancy electronics could have squeezed a bit more into the phone, but not much.

The other thing I wonder is, if you were using this for an emergency situation would a more basic phone be workable, just something to allow you to make calls and texts kind of thing. To be honest, with the weather you had today, I'm impressed you got any charge at all!!

Well yes, my "outdoor" phone is a Samsung B2100 and runs continuously on standby for 14 days on one charge. It probably would work with that phone. But then is a charger necessary with such long runtimes? You have to weigh it against carrying just AA batteries and the USB charger. It'd be months and months before resuable batteries became more weight advantageous than light, disposable lithiums.

[paulrbarnard]

I have a couple of these. MY kids just took one to France with them to charge up the camera batteries. I'll let you know how they got on when they get back tomorrow.

The main reason I got them was to charge the camera batteries on long treks. One daughter is going to Thailand and another to Bolivia for extended trekking away from power supplies.

[Mr Happymoose]

True but 14 minutes output from a 100 lumen torch would suggest the batteries were near flat. I guess a charger with fancy electronics could have squeezed a bit more into the phone, but not much. Well yes, my "outdoor" phone is a Samsung B2100 and runs continuously on standby for 14 days on one charge. It probably would work with that phone. But then is a charger necessary with such long runtimes? You have to weigh it against carrying just AA batteries and the USB charger. It'd be months and months before resuable batteries became more weight advantageous than light, disposable lithiums.

Good point!

[Martyn]

I have a couple of these. MY kids just took one to France with them to charge up the camera batteries. I'll let you know how they got on when they get back tomorrow.

The main reason I got them was to charge the camera batteries on long treks. One daughter is going to Thailand and another to Bolivia for extended trekking away from power supplies.

In fairness, charging an iphone from this charger in todays weather is asking a bit much. It did put a useful amount of charge into it, in spite of mostly overcast and cloudy skies. So The charger performed well for what it is. In areas with much more sunshine, I would expect it to do quite well. But for the UK, you either need a bigger charger, or live with fewer gadgets.

[ANDYLASER]

I see this item as something which can be used in a basecamp scenario. Tie it to the top of your tent for a couple of days solidlly. If your GPS starts with a full charge, you have a couple of days to get a reasonable charge back into the batteries while you run down the second set.

[earthman]

Just a thought, would it fully charge a set of batteries during an evening of artificial light? This could be it's main use, here in the UK? LOL
Have you got a 100W+ bulb hanging from your ceiling? LOL

[Ren]

As you say, the thing you put the batteries in to charge the phone could have been at fault, cheap Chinese electronics and all that. The other thing I wonder is, if you were using this for an emergency situation would a more basic phone be workable, just something to allow you to make calls and texts kind of thing. To be honest, with the weather you had today, I'm impressed you got any charge at all!!

That one of the attractions of http://spareone.com/spareone/spareone-emergency-phone

Removing the battery to battery charging, which has to be inefficienct particularly given how difficult it is to charge batteries via sunlight here.