Running N800 Without Battery?
 

Hi Everyone,

It occurred to me that the N800 could be very useful as a home device set permanently in place somewhere (e.g. on the wall or on a desk) and always on, running from the mains electricity supply. It would save a lot of messing about, booting up a PC to check email for example or to listen to or view media. Also when Skype arrives for it in the UK it would make a good speakerphone.

Since the battery does not like to be overcharged does anyone know if it's possible to run the N800 from the mains without the battery in the machine? I know I could try it but I've just bought it and I'm too scared of damaging it. :D Has anyone already done it?

Thanks
Biggles

Re: Running N800 Without Battery?
 

Someone (I forget who) told me it won't start up without the battery present.

You could try to remove the battery from a running N800 (after plugging it in first, obviously!), but I'm not going to guineapig that one.

Re: Running N800 Without Battery?
 

Hi Karel,

I don't blame you for not wanting to try it. I suppose I could just accept that the battery life would be shortened (so long as it doesn't catch fire or anything equally nasty). I could always buy another battery if I need it.

Thanks for the reply.

Re: Running N800 Without Battery?
 

We need some kind of dummy battery, maybe...

Re: Running N800 Without Battery?
 

Oh, re your overcharging remark: I don't think it is possible to overcharge LIon batteries in normal circumstances. At least not without things inside the N800 having gone seriously wrong first. I know Nokia writes in the manual that you have to be careful with keeping the N800 plugged in, but that's just lawyer talk combined with general ignorance.

I would suggest getting a cheap copy-battery off eBay and using that for a "plugged-in N800".

Re: Running N800 Without Battery?
 

A dummy battery or a cheap battery both sound good, although I don't think I would have the technical know-how to risk making a dummy one. I've noticed that the prices vary widely for the N800 battery. I will see what I can find.

Thanks
Biggles

Re: Running N800 Without Battery?
 

A powerseller at ebay Germany sells them for EUR 12.90 incl. shipping in Germany.

But then I wonder if it is really a good idea to keep those chinese batteries all the time under power? They may explode or such and then Nokia would say "I told you to use the original batteries".

Nokia makes a big fuss about the originality their batteries.

Re: Running N800 Without Battery?
 

I wouldn't mind using a Nokia battery for peace of mind even though it would cost more. I'm more interested in the "always on" convenience of it. I've seen pictures of the N800 mounted in the headrests of car seats and that's when I thought of mounting it on the wall at home. Of course I would make sure I could remove it easily if I needed to take it with me. :)

Re: Running N800 Without Battery?
 

I don't think a "dummy battery" would do the trick, as the N800 seems to be able to draw more power than the wall wart will provide. I know about a week ago I was playing an internet radio stream, and despite the fact that it was plugged in, the power eventually ran out. At that point, it rebooted into the "charging" screen and proceeded to start recharging.

Though, more tests could certainly be done to figure out where the break-even point is.

Re: Running N800 Without Battery?
 

That's an interesting point. It sounds like the rate going out from the battery is greater than the rate of charge going into the battery. This suggests that the mains power supply doesn't bypass the battery when it's plugged in. I find this a bit odd since you can run the machine from the mains while charging the battery. Maybe when it dropped into charging mode, it just needed to be switched back on? :rolleyes:

Re: Running N800 Without Battery?
 

1) OK, I took the battery out plug-in the power, N800 will not come on.
2) I not to sure you can assume you can over charge the battery.

Re: Running N800 Without Battery?
 

You are more brave than I am. Thanks for that. I think I will try to run it with battery in and on mains power and see if it switches off eventually. Then while it is charging I will see if I can switch it back on. If so then I could just leave it like that and it should stay on forever. (I hope :) )

Re: Running N800 Without Battery?
 

I use it a lot while it is charging. Mostly remote via ssh and vnc. Not problem and no reboots.

Re: Running N800 Without Battery?
 

That answers my question. Thanks.

Re: Running N800 Without Battery?
 

How about putting the charger on a timer so that it turns off for a couple of hours, say, twice a day? Like Karel, I don't think that overcharging is a potential problem (though I'm only going by what I read somewhere, which may not be reliable). On the other hand, I believe it is bad for the battery to keep it fully charged all the time, hence my suggestion of a timer.

Alternatively, you could just turn the power off every now and again when you think of it, and turn it back on when the battery has run down to about 40%. (That's what I do with my notebook.)

Re: Running N800 Without Battery?
 

I'm one of those saps who actually think that Wikipedia makes mostly sense, so this is where I got the mustard:

http://en.wikipedia.org/wiki/Lithium_ion_battery

There are basically only two things that will damage a Lithium-Ion battery: prolonged storage without any charge, and age. That's right: Li-ion batteries have this in common with us humans that they start dying from the day they were made.

There's more interesting reading on that page, but the main thing is that a fully charged battery at room temperature will die sooner than a half-charged one in the fridge.

If it doesn't explode, of course...:D

Re: Running N800 Without Battery?
 

Li-Ion cells like the one in the n800 are a very sophisticated brand of battery, as it actually features its own charging/safety circuit. What it does is cutting the charge when the battery is full, and waiting until the battery is drained enough to begin charging again. This was not the case in the old days with Ni-MH technology, as they where not subject to such extreme consequences when overcharged. Therefore the Ni-MH where generally trickle charged because of a, in most cases, "dumb" charger. My point is that a Li-Ion battery does not take any harm from being mildly recharged now and then, because it has no real memory effect. Which is again a trait of the old Ni-MH technology. It can however be dangerous to use non-authorized Li-Ion batteries as they are probably not subject to same tests and standards as the originals. Furthermore the charging circuit might not be as efficient as the original, and that can lead to overcharging and consequently explosion! I am not sure about he "fake" battery but i think it would be difficult to cheat the charging mechanism. A recommended read is:
http://www.batteryuniversity.com
It's an extensive resource for battery knowledge and care.

Re: Running N800 Without Battery?
 

Even though it can't be overcharged, the lifetime of the battery is slightly shortened if it stays on 100% charge _at all times_. At least in combination with some heat.

That's why laptop batteries simply don't last at all if you keep them on the mains all the time -- they're a bit warm inside, as well as being at 100% charge.

Lifetime is drastically improved if it's a bit cooler though, so it's not as bad as that for a device like the N800.

More on this on the batteryuniversity link in the posting above.

Re: Running N800 Without Battery?
 

This is fascinating stuff. I never expected so many posts. :) I think that the idea of switching the mains off periodically is a good one. The timer is too. By the way, the battery is lithium polymer not lithium ion. Is there any difference between the two?

Re: Running N800 Without Battery?
 

from the website which so many of you have quoted above, a few things are learned:

1. You cannot overcharge a modern Li-Ion battery. They are designed to stop charging once full capacity is reached.

2. Discharging a Li-Ion battery too much will kill the battery. However, there is protection circuitry installed to prevent that as well.

3. Charging a Li-Ion battery more frequently is better than charging it less frequently, as can be seen by looking at the battery lifetime / charge count chart. The battery capacity is shortened if you wait too long to charge it.

4. Li-Ion batteries do better in cooler ambient temperatures as it prevents nucleation bubbles.

My suggestion, based on the facts is to use the battery that came with your device, and keep it plugged in. There is probably a circuit which is broken when you disconnect the battery, so making a fakie will likely fix that, but then you'd have the device trying to charge the fakie all the time. You wouldn't want that! If it's inside, hooked to the mains, in AC you will be fine.

If you are good at making electronics, your best bet would be to remove the battery, disconnect the charging port, and wire up some leads to the battery terminal which will give you the proper voltage and amps ( 3.7v / 150mAh ).

Re: Running N800 Without Battery?
 

Lithium Polymers shouldn't explode as easily :rolleyes: and have a longer shelf life (but not dramatically longer).

Oh, and they can be made into exciting new shapes no battery has had before!!! (Sorry, I'm not very good at Marketing Speak)

Re: Running N800 Without Battery?
 

I replaced the lithium-ion battery in my T3 with a lithium-polymer. The latter is moldable to some extent, so I could fit a larger-capacity battery by shaping it (a bit like very tough clay).

Electronically the li-po are the same as a lithium-ion batteries, w.r.t. charging/overcharging/undercharging etc.

Had to get an internal overcharging protector installed though, as this was an RC battery - they are sold "raw".

@spiderx: Good summary! I've been going on and on about lithium batteries for several months here, but your shortlist got it all I think. I tend to waste much more space.. :)