Hi,

I`m going on a 2 week bike-travel in summer and want to use my N810 for navigation. The Problem is, I won`t be able to charge it so I need some kind of external power.

My charger has an output-Voltage of 6,15V (without the device connected to it) - So I asked myself if it is possible to charge the n810 (and run it directly) with an external 6V Battery (like this: http://www.online-batterien.de/shop/...erie6Vlose.jpg), just connected to a 2mm charging-Plug - without any electric circuit between.

What do you think? Could I demage it by doing that?

Actually, you need a regulated 5v supply to plug in to your power jack. A battery may start out at 6v, but it drops in voltage as you use it. What I suggest is using a 12v battery with a simple circuit that gives you a regulated 5v output. You can buy them in the form of an adaptor that plugs into your 12v power outlet of your car which has a dc output of 5v rated at a current of 1amp. I would buy a lead acid (rechargable) battery rated at 17 ampere hours.

Here's a novel answer to biking holidays:

http://www.voltaicsystems.com/
( solar powered backpacks with batteries built in, designed to charge mobiles.)

Don't have one and they're a bit expensive but I'm sure there will be lots of cloned products in no time at all.

The 2mm charging spec has a current and voltage window of acceptable electrical supplies. At 6V the maximum current is somewhere around 1000mA. That 6V battery you linked probably consists of 4 cylindrical D or F size alkaline or heavy-duty batteries. It's capable of providing far more than that. So no, I wouldn't use that.

If you get two of them you can get 12V out of them, and use a car charger. Those I've tested even work when supply voltage drops below 12V, the better ones are still working at 6V input, so it would extract most of the juice out of the alkaline/heavyduty based batteries too (when connected in series to start off at 12V).

Just a guess, but two of those non-alkaline batteries you posted could probably when combined with a reasonable efficient car charger power GPS+display use for 50 hours.

You might also be interested in devices such as the Tekkeon MP1550 which can charge your N810 from 4 AA batteries. Maybe 4-8 hours of power per set of 4 AA NIMH. Would be less with alkalines.

First, thanks a lot for your answers.

The solar-stuff looks cool. But: too expensive and bad for cloudy days.

A lead acid battery with 12v and 17 Ah is too heavy (about 6kg). Even two of the 6v batteries I supposed and a car-charger are much - I`ve lot of other gabbage to transport. But if theres no other solution its a good idea! I even have a car charger here - but no Idea if it`s efficient... but I don`t think so... its a cheap 4€ part from ebay.

What if I use an 1A low drop regulator like this: http://www.national.com/ds/LM/LM2940.pdf, together with 2 capacitors as voltage regulator between the battery and the device? Then there are 5V and max. 1A Output - enough for charging?

That voltage regulator will do the job. Yes, use the 5v output device. You still have to decide on a battery. Is it for just all-day use and can be charged at night? If so, you don't need the 17 Ah battery. Half of that will do.

I use and always recommend the Tekkeon - TekCharge MP1550 for applications like that. Oddly enough though, if a DoubleA battery powered solution won't work for you, then try out one of the 18000mah Energizer battery packs. You'll get a crazy amount of recharges off of it, and it'll work well for when you have to be in the wild and still use your GPS.

According to Nokia 2-mm DC Charging Interface Specification Nokia N810 can use different voltages. So yes - an external charger is possible. On the other hand this is not what you probably want. If you buy 2-3 cheap Chinese batteries you will have more energy than most external chargers can provide (because during the charging process most of the energy is lost in the air as temperature).

Note that the spec has 5V as an unacceptable voltage. Though with luck inaccuracies in the regulator and inaccuracies in N810's voltage measurement add up and make it work anyway..

From 4,65V to 5,2V "Special Chargers" are accepted...

I saw there are USB-Cables for charging like this one: http://www.amazon.de/gp/product/B000...pf_rd_i=301128

USB has 5V. I suppose this will work. Parts are ordered - I`ll try to build an external charger for with usb-port now. Into the box will be enough space for 4 AA batteries. Also there will be a possibility to connect an external battery like the big 6V mentioned in the first post. This will give me the additional possibility to charge my mobile phone and my Ipod with it.

The cheap chinese batteries are REALLY cheap, thats right. But some days I will need the 810 for more than 12 hours (GPS for Navigation but even more important: Tracking with maemo mapper). And if theres no possibility to charge for 3 days I allready need about 10 of them. And then a break with the duration of 10 charging-cycles (at night I want to sleep and not get up every hour). An external solution is just best for me. Even with bad efficiency.

Is there a possibility to run the 810 without the battery inside it, just with external power? I tried it with my charger, doesn`t work. Maybe it`s more efficient to run it directly with the external device than the way round the internal battery...