Re: External battery pack for N8x0/770.
 

Some time ago, I bought an Energizer brand charger that is made for cell phones. It takes two AA cells and has tips for different model phones, including Nokia. After all this discussion, I finally decided to try it out.

Running "mplayer -loop 0" with a ten minute Superman cartoon, the N800 battery alone ran for just two minutes shy of five hours (which amazed me greatly). For the last 40 minutes of that time, the N800 beeped at me every five minutes and said "low battery".

Doing the same test, but also with the Energizer supply plugged in to the N800, I got seven hours and nine minutes. This was using alkaline cells. The Energizer came with lithiums, which should give even better results. I didn't want to waste expensive lithiums on a test.

Both tests ran until the N800 shut down (sort of). With the Energizer plugged into the N800 power jack, the N800 tried to shut down, but kept rebooting. I finally hit the power button to shut it down. The N800 also did not give "low battery" warnings with the Energizer plugged in.

Not a huge difference, but for a power pack that you can hold in your palm, an extra 2+ hours isn't bad. What really surprised me was that the N800 battery alone lasted so long while playing video. I normally use the N800 for ebooks and occasional surfing and get 6-7 hours with those activities.

Re: External battery pack for N8x0/770.
 

I'll try it out this weekend - I use my precious much too much during the week to be able to live without it long enough to test this - I'm quite confident that I will see a lot more time than you are seeing. I'm thinking I'll get more like 12-15 hours.

I'm using 4 AA Sanyo 2700 mAh batteries in the Tekkeon 1550 with an official Nokia CA-100 cable - and the stock Nokia BP4L battery that came with my N810.

Re: External battery pack for N8x0/770.
 

Good post.

Mind to tell us how do you run the system? You max it out like what I did, almost max audio and max out brightness? MMC or internal flash boot? Presumably BT/WiFi off? Thanks,


bun

Re: External battery pack for N8x0/770.
 

I had the brightness set at exactly half, which is what I usually use. It seems plenty bright enough for me. The audio was 5 steps down from max. I didn't want to hear that Superman cartoon for several hours. I wouldn't think that the volume would have nearly as much impact on battery life as brightness.

I wasn't necessarily going for maxed out settings, as I wanted to see how long it would run with more typical settings.

Oh yeah, WiFi/BT off. Normal Flash boot.

Re: External battery pack for N8x0/770.
 

N800 Fuly Charged battery running without Tekkeon under the same conditions, how many hours?


bun

Re: External battery pack for N8x0/770.
 

Same question: what is the baseline, i.e., just running the tablet with the same conditions/setup but without any ext batt pack? Without that piece of information, the results are less useful.


bun

Re: External battery pack for N8x0/770.
 

just buyed this:
http://tinyurl.com/5s87au

seems to be very well done and 'versatile' :)

Re: External battery pack for N8x0/770.
 

This item is for powering device off but it works only if charger is not attached, otherwise it will just reboot. This is meant for situations when you (re)boot to boot menu and realize you wanted to turn device off instead.

What you expected it to do for you in this case? Also you say that you had attached power source (IOGear battery pack) when you selected this item and the device just powered off? It did not reboot immediately like it does with charger?

Re: External battery pack for N8x0/770.
 

what about this http://tinyurl.com/5olbh6 (about 5 euro) + 8 AA uniross hybrio (about 19 euro) and some diods to lower the voltage and save against the inversion recharge (many battery pack, if discharged, are recharged by the device you want to recharge !) ?
so:
2100*8=16800*1.2=20160/5.4 =about 3700mAh of capacity ?
seems not too difficult to made....

all for about 25euro.

sorry for bad english ;-)

Re: External battery pack for N8x0/770.
 

8 * 1.2V (assuming NiCd/NiMH voltage) is 9.6 V; that, one silicon (i.e. normal rectifier) diode, and a ~9 Ohm resistor of appropriate power rating should yield a workable power supply, which will fall inside the Nokia specifications (for I-V characteristic at least).

8 * 1.5V, OTOH, is 12 V; the maximum voltage permitted is 9.3V, so this would be outside the charger spec and potentially harmful to the device.

Edit: Oh, and your calculation is wrong; the capacity in Ah is the same as for one cell, since you connected them in series. You don't pick up any by reducing the voltage with passive elements; the extra energy dumps as heat, so make sure your resistor is rated for the resulting power. (9W, if I calculate right...)