A while ago I tried to connect 4AA batteries to my N800 and used a diode to prevent the power from the internal battery to go to the external ones. This seemed to in some extent charge the internal battery but it got impossible to get any sense out of the battery indicator on the N800 and it seemed that it did empty the int. battery when the v of the ext. batteries had dropped a bit.

Are there some people here with a bit more knowledge of electronics than me that could tell me how to get use of all the 2500 mAh that I have in my AA batteries, some kind of charger chip that I could solder together. If I could get this to work and got some 3000 mAh batteries to add to the internal 1500 mAh I guess I could run the tablet three times as long.

Mabye the voltage needs to be pumped from 4.8v to 5v and expecially when the batteries starts to run low and the voltage drops. Mabye the N800 charger uses some kind of pulse to charge the tablet like some battery chargers do...

Is there someone else that has attempted something similar?

Maybe this would work:
http://www.instructables.com/id/Mint...d-USB-charger/

Someone that want to share some thoughts?

Hi,

You may want to check the charger but I think that they are rated at 7v. Even the usb to charger adapters have a bump up chip so that they deliver 5.7 volts I think.

The minty box type solution would be good but you may want to look at a slightly higher output voltage from the chip and if so perhaps more than two AA otherwise they will drain pretty quickly. It won't be like strapping on an extra 2500mAh you will get loss in the conversion and then you will be charging the internal battery so you will also get loss there too.

Also I think that the charger is rated at 800mA so your chip should be able to drive that as well if you are trying to charge from flat or at least die gracefully.

Anyway all that info should be on the back of the charger I think.

Nokia do an external battery for some of their mobiles that use the same charger so it is possiable. You may want to look at some of the specs for these and compare with what you are putting together. ( DC-1 and DC-8 are the model numbers for these).

Anyway if you do get it working I would be interested in what you do get going.

Nokia.de has a charger unit with batteries. I found it as accessory for N800: http://www.nokia.de/link?cid=EDITORIAL_766994 . No idea where detailed tech specs would be available...

The text
"Wenn Sie unterwegs viel Leistung benötigen, ist das Nokia Extra Power DC-8 eine besonders leistungsfähige Energiequelle, die sich entweder an einer Steckdose aufladen oder über Batterien, die Sie unterwegs kaufen, mit Strom versorgen lässt."
translates to "If you need a lot of power on the move then Power DC-8 is particularly powerful source which can be loaded via AC or supplies power via batteries... ".

Nokia.com does not offer DC-8 as far as I can see.

Thanks for the tip, I'm thinking about a thing that i heard that batteries should be charged with some kind of pulse, wonder if that is a good practice or if it's enough to get a regulated voltage at 5.7-7v and figure out how many mA to put in to the device.

One other thought would be to try and connect regulated 3.7v directly to the internal battery connectors...

If charging from the power connector should be used then you need to charge the battery at least as fast as it drains during WiFi and heavy CPU load, in that case you onely would have to connect it when the internal battery runs low... Otherwise you would need to have the external pack connected all the time...

I'll look at the DC-1 and DC-8.

wouldn't it just be easier to use this product? http://www.newegg.com/Product/Produc...82E16875999020
even comes with the right tip for the IT's.

The local Best Buy had a series of battery power supplies and tips for various phones and pocket PC's. They had a set for Nokia phones that included the voltage boost circuit.

The tip assortment was $15.00. I already have a 4xAA power source with a USB plug from Wal-Mart that cost $10.00. Should work well together.

Yep, the device like bac listed (or a homebrewed equivalent) plus that set of plugs sounds like it'll do the job.

I read one post in another thread about someone who had his N8** drained of its charge after being plugged into the device linked to above. Could he have just been guilty of leaving it plugged in for a long time with empty rechargables, or something like that? Or are these external battery packs really not so reliable?

And is the battery effected any more by a charge from an external battery pack than from the proper AC/DC charger? Basically, can it hurt the battery's lifespan in any way more than if you were to always use the charger?

I actually have the product I listed above, it slowly charges my 770, but not really good enough that I would use it as a charger. I find it much better to use it to supplement the on-board battery. For example I watched several movies once over a 10 hour stretch and the internal battery barely discharged while i had the tekkeon plugged in.

On a different note, seems Newegg is no longer selling the product, but here is the company link http://www.tekkeon.com/site/products-mypowergo.php

Sounds good. Good to hear that it works well as a supplemental battery. I want it for backup power on the move, in which case waiting around for something to charge isn't really an option anyway.

The Tekkeon is still available all over, and in another thread someone mentioned that Canadian Tire carries them under the name Neko or something--for $15.

Yup - CTC sells the same Tekkeon one under the NOMA brand name. Works like a charm!