I'm interested in getting a solar or hand-crank charger for my N810, and I was wondering if anyone else had any stories to share about non-traditional charging.

I'm currently leaning towards getting this little number. At $21, you can't go wrong.

Although I don't have experience with a non-traditional charger, there have been numerous discussions here. Try using the search feature in the top menu line. I used "solar panel" as key words and quite a few threads were returned.

I've just (as in yesterday) bought a Freeloader solar charger. My N810 is now flat and the Freeloader has had its first charge - which has to be done through a USB connection.

I'll plug it in and see what charge it gives later on.

Here are a few links that I've found during my research.

This other thread contains an endorsement of the Solio Hybrid 1000.

This hand-crank product page has a comment that mentions the N810.

Still, I wonder how the hand-crank chargers work exactly. It says that you can wind for 2-3 minutes and then charge for 8 minutes. If you want to give a tablet a full charge, how long would you need to wind for? How long would it take to fully charge the battery that is built into the hand-crank charger? If you fully charged that, would it give you any indication that subsequent winding would be wasted?

In my experience with alternative chargers (and just equipment in general) usually something that claims to have that many features and costs that little is pretty much a waste of money. Contrary to what some may think, Solar equipment (especially efficient/useful solar equipment) is not cheap. Yes, you can buy a tiny solar panel that puts out 1W at 0.5V for about $5, but it's worthless for anything but powering an LED (which begs the question... without a battery why would I want to power an LED with daylight?).

I've tried a few hand-crank type devices and there it's simply a matter of practicality, especially for the tablets. Depending on the make and model it's possible to use them to generate sufficient power to at least keep the tablet running (don't even think about using them charge it from the off state) but how useful is a tablet after spending 5 minutes cranking a dynamo so you can get an extra 30 seconds of power out of it? Cranks are great for extremely low power devices, but as efficient as our NITs are, they certainly aren't "three ultra-bright LED" efficient...

It's also important to keep in mind that the NITs themselves require a certain amount of current to even engage the charging mechanism to let you power the battery (whether the tablet's on or not!), which I believe is somewhere around 500mA or higher (could be wrong), which most alternative chargers won't put out. The only one that I've found to be effective is the Solios because they have their own internal battery that the solar cells charge directly, and so as long as the battery has sufficient power it can provide enough current to actively engage the NIT charging circuits (the panels on the Solios are also much more efficient than the lower end guys). Cool device, but it's not cheap, so you have to think about your application and see if you can justify the costs.

-Rob

You might keep an eye on the PowerMonkey. It's $110 now but I bought it a month or two ago with an $80 rebate (which they did indeed honor), and maybe that rebate will show up again. I haven't used the solar part yet (I live in Seattle, and sunshine here has been as common as Bigfoot), but the rest of the thing works very nicely and gives me hope that the solar charger will, too. Also, the PowerMonkey's overall approach (having the solar trickle into a battery that can then be attached to the Nokia once it's all charged) may circumvent the problems that jolouis mentioned above.

Here it is, at the moment without benefit of rebate: http://tinyurl.com/4xqn9z

Well, I picked up the charger linked to in the original post, and I guess jolouis can go ahead and give me a big "I told you so". I tried charging the tablet from flat while it was off using the solar panel, and I didn't get any charge from it at all from 8 hours sitting in the sun. Either the sun wasn't strong enough (and it was about as strong as it gets), or the solar panel is too weak, or it was poorly assembled. Using the crank charger was recognized as charging the device. Unfortunately, I tried cranking it for 15 minutes while the n810 was turned on, and it made no appreciable difference in the charge level (according to battery-status). I'll try another experiment with the n810 turned off and report back sometime. If I was actually going to some place where power would be scarce, I would recommend buying a REAL solar charger rather than a gimmicky gadget.

I did get this $12 cheapo solar charger to charge the N810, but very slowly - like an all day affair.

http://www.harborfreight.com/cpi/cta...emnumber=41427

This unit, when configured to do 3V seems to be able to do about 250ma in bright sunlight. So doing the math 1500 / 250 = 6 hours, but that is at 100% efficiency I think reality would have been about 10 hours. I only tried it for an hour or so just to see if the battery would actually increase in charge any and it did but slowly (I used that command-line "Battery-Status" program to see the real numbers) and so I am just estimating a total charge time based on this. Oh and make sure the unit is in standby with the backlight turned off too. With the unit on and in somewhat normal use (browsing Internet over wifi) I saw a slow battery drain in that I could possibly run the unit all day like this on the combo solar + battery before the battery ran down, which might be useful.

Anyway, what you can do is get two of these things and wire them in parallel. This would probably charge the NIT in a more reasonable length of time. Note that this unit does NOT have a Nokia compatible power connector. I used tha alligator clips on to an adapter that came with my 3rd party mobile power adapter for my test.

What I really want to be able to do is take the N810 on an all day hike with the GPS tracking my route. The unit would be with the screen off most of the time, but with the GPS on and running Maemo-mapper. I haven't tried it yet, but so far running Maemo-mapper with the screen on and "Auto Center" on appears to be one of the fastest ways to drain the battery. Perhaps I can learn how to tweak the settings of Maemo-Mapper to not be such a power hog.

I think the most sensible solution is to use an AA portable 'phone' charger. Here's a link to an example, but I have no idea whether this charger will work with the N8xx.
http://www.amazon.com/Datexx-Power-B.../dp/B000M8UYDI

Why?

1) Lithium AA batteries are cheap and abundant. Check ebay to see what I mean.
2) AA batteries are small and easily transported.
3) AA Batteries are high capacity (Sanyo makes a mean 2700mAh NIMH AA)
4) AA chargers can also be small. Eg. An energizer charger I have folds to about the size of the N8xx, sans batteries
5) Portable phone chargers themselves are cheap and can be a DIY weekend project (for the more adventurous).
6) You can use the charger practically anywhere at any time, so you don't need to power down to replace a battery, or find a sunny patch.

}:^)~
YARR!

Sincerely, Corrupt

Yes, I may go that way (AA Battery pack). Three NiMH cells in series should work quite well unless I go with one of those fancier units with an inverter inside. The three cell series combination alone should provide at least the run time that the built in battery can provide itself. I guess it would be best to start off with the external pack connected to a NIT with a fully charged internal battery so that the external pack isn't trying to charge the internal pack (I'm assuming this would be less efficient), then when the external pack dies, it switches over to the fully charged internal one.

From following the thread here at ITT about "reasonable" requests for the upcoming N900, I stumbled on specs for what is likely in the N810 as a power system (TWM92230 IC). Unless Nokia added some extra protection, here is a warning:

1) If the input voltage ever exceeds 5.5 volts, very bad things will happen.

2) It is recommended that the input voltage stays under 4.5 volts, with 3.6 volts being ideal.

Note that a lot of aftermarket power supplies are unregulated. This means that an unregulated supply rated at 3.6 volts under load, will produce 1.4 times that or 5.4 volts when unloaded. So be careful not to blow out your NIT! I would measure the actual voltage of any non Nokia power supply you propose to use.

I've also discovered that a lot of aftermarket chargers designed for Nokia phones (as in has the correct voltage and the correct power connector), can not produce the current required to properly run the battery charger and/or the NIT itself. I got one that cycles on and off at about a half second rate. I've measured that it does this while delivering (or at least trying) about 400 milliamps to the NIT. I'm guessing the the NIT is wanting to draw more than this but less than the 890ma that the factory charger is rated to deliver. I have not determined for sure if it is the charger overloading and shutting down or if it is the Nokia's charging circuit that shuts down because the input voltage sags too low. Since the solar panel does seem to work at a measly 250 ma, I expect it was the aftermarket charger cycling. It seems that all charging action stops at about 3.2 volts however.

Anyone know where you can get those tiny Nokia 2mm power connectors?