charging from USB for 4 hours and still going...
 

I have never had the phone charge via USB before and 4 hours is double the time it takes the wall charger to fully charge my device. Is this normal?

Re: charging from USB for 4 hours and still going...
 

Who knows, my phone charges on USB in 3-4 h, but on wall charger it will not charge at all - I can keep it on wall charger and battery will not be depleated but it will not charge as well.

Re: charging from USB for 4 hours and still going...
 

I am sure there is a reasonable explanation for both our cases...

Re: charging from USB for 4 hours and still going...
 

USB chargers take longer than the wall charger, wall charger takes about 1.30 hour while the USB charger takes about 3-4 hours. I once heared a theory but im not sure weather its right or not saying that the USB charger is more stable than the wall charger and makes the battery last longer.

Re: charging from USB for 4 hours and still going...
 

The green light is on after 4 hours and 40 minutes.

AgogData I hope you are right and also I hope my battery is not fried :P

Re: charging from USB for 4 hours and still going...
 

well if both chargers and the N900 charges the battery to the same voltage then the battery will not last longer with one or the other.

Re: charging from USB for 4 hours and still going...
 

USB outputs lower mAh than the wall charger, it also takes about that long if you use an old Nokia charger with the adapter that comes with the N900

Re: charging from USB for 4 hours and still going...
 

You are correct. When a battery has been discharged, it has a low internal resistance when it is connected to a charger. If the charger can provide 900ma current, then the battery will heat up until the internal resistance goes higher. If you use your usb port on a computer to charge your battery, you are limiting the current to about 500ma. This also limits amount of heat being dissipated by the battery during charging. Less heat, longer battery life. In the old days, we used a formula to determine the proper charge current for a battery. If a battery was rated at 1200ma hours we would limit the charge current to 10% of that, or 120ma. Then people insisted on being able to do a "quick charge". Instead of charging at the 120ma, they built chargers that charged at a much higher current. now, instead of replacing batteries every three years, they had to replace every year or even every six months.

Re: charging from USB for 4 hours and still going...
 

You guys are one of the best reasons why I don't want to give up my N900 :D

Re: charging from USB for 4 hours and still going...
 

I think your n900 is hungry.

Re: charging from USB for 4 hours and still going...
 

However, that is never the case with a heavily discharged battery. If you overload the USB port, the voltage will drop.

Re: charging from USB for 4 hours and still going...
 

Nah... it's just not used being connected to inferior computers... :P

Re: charging from USB for 4 hours and still going...
 

Voltage is regulated by the bq24150 chip. In both cases, it will not supply the target 4.2V to the battery at the start of charge from near-empty, because that would need more current than wall charger and usb combined could provide ;-)

At the end of charge, both methods will reach the same battery voltage.

Re: charging from USB for 4 hours and still going...
 

Just to clear up your statement, the chip in your PC is rated at 4.75v to 5.25v at 500ma. Your N900 takes that voltage and regulates it down to the 4.20 volts to charge the battery.

http://pinouts.ru/Slots/USB_pinout.shtml

Re: charging from USB for 4 hours and still going...
 

Make sure the display is off while charging to prevent large discharging while charging over USB.

Turning off the display will use less power and a 'fuller' effect of charging over USB will be seen.

Re: charging from USB for 4 hours and still going...
 

I charge my N900 via the wallcharger every night, whether it needs it or not, to guarantee a full charge next morning. It's connected for 8 hours or so. Never noticed any battery issues and I've been doing that for 16 months.

Question: I also have a brodit active car mount, and a USB type wall charger with microUSB adaptor. I use both of these infrequently to top up as and when needed, the car charger more so. Is this likely to affect the battery life in any way?

Re: charging from USB for 4 hours and still going...
 

Generally, Li-Ion loves to be charged often. So yeah, put it on charger whenever driving

Re: charging from USB for 4 hours and still going...
 

Do you have smart reflex turned on ?, it takes much longer to charge when SR is enabled.