Possibly!?
But for sure this would only allow 'a second stage of security' when charging the battery AND the N900 is up (savecpu running). When switched off no chance for userland savecpu program. So not really a reliable option for such task.

Since we are off-topic already anyway...

Is there a way to stop charging the battery before it reaches 100%? I have recently purchased a semi-functional N900 that I want to use as a kind of home server permanently plugged in the mains. To extend the battery life, I would like to stop it charging when it reaches something like 80% rather than 100%. Is that possible?

Sorry if asked/answered elsewhere (putting flak vest on ).

Technically the hardware is capable of it, and I sometimes used it in my own charge script. Dunno if replacement bme / kernel bme offers that tunabke though.

As for battery overheating, the bigger issue with poorly made batteries is impurities in the materials used, which may cause very local and small hotspots of heat. That is, a very small part of the battery is at 50C higher temp than 99.99% of the rest of the battery.

Indeed, one could say that the spark setting off a explosion in a gas-filled room is "overheated gas", but having a thermometer in the room provides very little help on avoiding that ignition

Don't keep them in a pocket where they can get humid - either from your body sweat, or from rain. I tested the battery - started off fine, cheap and around 1700mAh - but they dropped fast (to less than 1000mAh), and went dead in my pocket while skiing.

I have this "blue battery" as best: http://www.aliexpress.com/item/2600m...601760234.html

Maybe it can deliver 2000mAh - I doubt what they claim, and the factory that first produced them does not produce any more, but these look the same and they claim it is an improvement. I have tested batteries at 4000mAh - but these are bigger, made for Samsung. The size determines the capacity. The N900 is the only phone around where you can reset the charge, none of the Android apps work.

knuthf,
That's exactly the battery I was going to buy initially, but switched to the cheaper ones. How about some tests involving video playback?

This. I would love such option and charge only to 80% during casual usage, switching to 100% before traveling/etc. It can really improve battery life, reportedly (at least they're doing it in industry, where saving LiIon's from wear is more important than max capacity - like, in trains) BME replacement doesn't offer it yet, but it should be quite trivial for Pali to code, if only people express interest (he become quite used to fact that I'm the pesky one pushing some crazy ideas - like, optional gconf settings, that allows repl battery meter to get real values reported by chip, instead of outright lying, when battery is not calibrated - so I would be glad if it wouldn't be only me suggesting, this time ).

I really doubt that- with current technology adapted at factories level - you can put more than 1500 Q10 (measured when discharging with 1/10C current, 150 mA in this case) capacity -which translates to max ~1700 mAh relative capacity during normal N900 usage - into BL-5J form factor. Heck, even this require a little "abusing" of said form (making it thicker than usual).

That aside, I really distrust batteries that claim unrealistic values on cover. If you're outright lying, anyway, why to put best available cells inside? If you declare 2600 mAh, you can make even more money when using 800 mAh cells there, customer is still rip-off the same as in using 1500 mAh ones.

Also, historically, the best batteries (Scud and Polarcell) were always declaring real/rounded DOWN capacity.

/Estel

Couldn't resist posting an image of my charger for extra BL-5Js.

...er, that bright red capacity advertisement... I just wonder if estel's comment above applies

One just wishes....... imagine the dual battery life!!!

Good use of a 'droid

According to my tests, ~1300mAh. Not bad for their price.

yep i also want the same functionablity of setting charge thresholds as i am going to use it as some kind of server have been serching everywhere . 1 for it