I have been using the nokia phone charger first with my n770 and now with the n800 and have had no problems. tim On 04/03/2007 15:28, Paul Klapperich wrote: > On 4/3/07, Eric Cooper <ecc at cmu.edu> wrote: > > On Tue, Apr 03, 2007 at 01:33:10PM -0400, andrei raevsky wrote: > > > Just lemme know if I can use the same charger on my phone & N800 > > > and I promise to get off your collective backs - at least for a > > > while > > > > Since the phone charger is rated for less current than the N800 > > requires, you would risk damaging the charger -- possibly overheating > > or catching fire -- but probably not the tablet (unless it's consumed > > in the same fire :-). I'd recommend against it. > > Normally I would agree with this statement, but I'm not sure if I would in > this case. Based on previous mailing list posts, it seems the N800 > essentially connects the charger port directly to the battery. Charging is > basically controlled using pulse-width modulation--that is, the port is > switched on and off with the percent on time and percent off time varied > depending on amount of charge. This necessitates a current limited supply, > as nothing is done to limit current in the device--equivalent resistance is > equivalent to the battery internal resistance, which is going to be very > small. > > Because the proposed power charger is of lower current, you're correct that > the N800 won't be damaged by it. The battery will surely charge slower, but > there shouldn't be any damage. I would be surprised to see any damage to > the charger as well, though. It's true, the charger will be running at 100% > current draw for much of the charge cycle, but this is true for any battery > charger supply, and is definitely true for the charger built for the N800 > for the reasons explained above. It is possible that a PSU has inadequate > cooling to hold it's max rated current draw indefinitely, but I find that > highly unlikely for the charger built for the N800--and one would assume > Nokia probably uses the same technique in their mobile phones, so I'd > expect that to be unlikely of any Nokia charger. > > If you can find a charger that provides greater than the amount of > > > current required, it would be fine. > > No, this could be worse. Once the current is too high, the PWM will not be > able to react fast enough and damage could occur. Generally, you're thought > is a good rule of thumb, but not based on how this device is constructed. > > Ideally, an equivalent charger to the N800 would be best, but a lower > current equal voltage supply should also be adequate. > > An unscientific test would be to charge your phone and your N800 both from > a dead battery. If the charger gets noticeably hotter charging the N800, > you probably don't want to do that again. > > On 4/3/07, andrei raevsky <raevsky.andrei at gmail.com> wrote:well, how abouyt > > > using the N800 charger on the phone, the other way around? > > If the phone uses the same method as the N800, charging the phone with the > N800 charger might not be a good idea as it could damage the phone. > > > I'd recommend you stick with the adapters meant for the units. > > > --Paul
