Expert Query: Fastest power charging rates

[HomesIckAlien]

Hello all, Is there a lithium battery charging guru out there who could advise me?

i've been thinking about charging rates. I've always gained the best performance (i.e. fastest time to green fully charged light) from the supplied n900 charger, but was wondering if using the adapter with older chargers was comparable.

Over the years i've amassed a wide range of nokia chargers, and arranged them in various rooms around the house & at work rather than carrying a charger around & plugging in & unplugging along with the USB lead i've used them all to charge my n900. This has made me wonder:

1. Is it possible to measure the rate of charge from Xterm?

2. What are the critical factors for a charger to charge at the fastest rate? My A-level physics is rusty ...am assuming it's current rather than voltage?

3. On a particular old charger, I once left it charging all night without getting the green battery full light. Does this imply that the n900 was actually consuming more power than it was receiving ...or that the charge rate was extremely slow?

4. Does the USB power output vary according to whether the laptop is under load, on battery etc?

5. How much power does an unused charger draw ?

Any batterycharging gurus out there who would know ?

[ndi]

1. Yes, lshal | grep battery.voltage.current gets you current voltage
2. Current counts, but it's down to the electronics in the phone. I doubt you can really-fast-charge it. Desktop stand only.
3. There's a thread about that I started here (http://talk.maemo.org/showthread.php?t=39291)
4. No. With a known device, it outputs 5 volts, 500 mA. With a non-identifying hardware, 5V 100 mA, always.
5. Very little. About 5-10% of max rating on a SMPSU model (lightweight charger). It supplies about 5V 1A roughly 5W (around), so about 50 mW draw when not charging.

[pelago]

1. Yes, lshal | grep battery.voltage.current gets you current voltage

Does that work while charging?

[ndi]

Yes.

There's got to be a way to stop charge, right? Only percentage and full dots stuff that goes 0-8 aren't.

There are several topics on the issue, including my suggestion that the bloody battery should turn red and show level instead of the useless animation thingy.

There's a batlevel thing in repositories that uses the percentage, if it would use the voltage it could do this. But it's very, very beta. Suggestion has been made.

[HomesIckAlien]

Thanks ndi for your comprehensive answers.....very helpful.

But now I have a stupid question: How do I generate the | (bar) figure on the n900 ???!

On my PC keyboard it's above the \ key.....

[Rob1n]

It's on the Sym popup menu (Blue arrow button + Ctrl button).