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Posts: 68 | Thanked: 4 times | Joined on Mar 2007
#1
I read in quick start guide for the N800 that it shouldn't be left plugged in all the time. Is this one of those batteries that you have to let run down almost all the way before plugging in or it loses memory (or something like that)? I got into the habit with my IPAQ just to leave it plugged in all the time (like at work and overnight), but don't want to reduce the life of the battery in this new unit if this is not a good practice. Any confirmation that I should not leave this plugged in, essentially all the time (when not in use)?
 
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Posts: 1,605 | Thanked: 1,601 times | Joined on Mar 2007 @ Southern California
#2
I had a question about this as well... The guide doesn't say you have to run the battery down before charging, but it does warn not to overcharge. Most devices know when they're charged and stop charging when they are -- or start using AC power once they're plugged in.

Does anyone have an answer to this?

Tim
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#3
If you search the forum this has been discussed in more detail before.. but the short of it is that lithium batteries can't be overcharged, or to be more precise, it's very dangerous (fire, explosions) to overcharge them even a little so the N800 (and all devices using lithium-ion batteries) has charging circuitry to turn off charging when the battery voltage reaches a certain level. In addition there's also a protection circuit in the battery itself that will disconnect if the voltage passes 4.3 volts (if this happens you'll need special equipment to re-connect it). But this won't happen unless the N800 charging circuitry fails.

In other words, you can't accidentally overcharge.. because the N800 charge circuit switches off the charging when it's full. And lithium batteries aren't trickle-charged, so it won't continue charging again until the voltage has lowered a bit.

It's been one report (that I'm aware of) on this forum about a puffed-up battery, this is almost certainly caused by a faulty battery and not because of overcharging in general (btw if this ever happens - don't punch a hole in the battery, it can burn. Very dangerous. Must be disposed of properly -- call the device vendor.)

Nokia, as other manufacturers, used Ni-MH batteries in the past (and before that, Ni-Cd). These batteries were very different: First, they needed a very long initial charge, secondly the charger was a simple timer-based thing and thus you could overcharge if plugged in without discharging, and thirdly there was what was called a "memory effect" (well it wasn't really that, but the result was the same) that made it essential to fully discharge the battery quite often in order to retain full capacity. Now, the problem with Nokia is that they have left instructions for the old Ni-MH batteries all over the place in manuals meant for new Lithium-Ion powered devices. This has created a lot of confusion, unfortunately.

With lithium-ion batteries it's like this:
- Give it a good charge now and then, 4-6 hours is ok. They go quickly to "apparently full", but that's when the real charging starts. It isn't full until the device tells you it's not charging anymore.
- Avoid discharging. This kills the lifetime of lithium batteries. The exception is in the beginning, you may discharge it a couple of times first (but even here you shouldn't floor it completely. This _will_ reduce the capacity and lifetime of the battery.)
- Don't be afraid of topping up the battery whenever you get the chance. This won't hurt the battery.
- Finally: _if_ something goes wrong with the battery or the battery protection circuits it is very dangerous.. although this doesn't happen often (because of the double protection: One circuit in the device, a second in the battery).

Read all about batteries at http://batteryuniversity.com/
which is a great site someone told me about a long time ago.
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Last edited by TA-t3; 2007-03-14 at 21:51.
 

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#4
My guess is it is a response to all the batteries blowing up lately and the fact that Lithium Ion batteries have a habit of wearing out when maintaining a full charge all the time.

I've had PDA's, Laptops etc. that although they were "portable" they were plugged most of the time. The batteries can wear out being full all the time. IBM even had this listed on most of their laptops for a long time but didn't put it in such bold print.

Although there are circuits in most batteries to prevent over-charging they aren't fool-proof. Some like my Dell seem to charge to full but if you leave it plugged in the battery goes dead - so the circuit stops charging all together once full and doesn't start charging again until the device is unplugged and plugged back in.
 
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#5
Laptops are a bit different, mainly because they tend to be a bit warm inside, and in the office they tend to stay on the mains power at all times.. the combination of temperature and 100% charge isn't good for lithium batteries, they like to be a bit cooler or to keep the charge a bit lower (they can handle temperature a bit better then). All laptops here at work are quickly reduced to 10-15 minutes battery lifetime because they are 24/7 on mains.. after I replaced the battery in mine I now use it off mains a lot of the time and the capacity is still good after a year.

I used to charge my T3 PDA over night every night, and sometimes mid-day too, and after two years the battery capacity was still good. But it's a lot cooler, which seems to make a big difference, combined with the different usage pattern (charge, use battery a bit, charge..)
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Posts: 84 | Thanked: 4 times | Joined on Apr 2006 @ California
#6
How about buying 3rd party N800 batteries on Ebay? I think these are made in China and cost about 60% less than the official Nokia battery. Do you think these batteries could damage the unit?
 
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#7
Originally Posted by tabletfan View Post
How about buying 3rd party N800 batteries on Ebay? I think these are made in China and cost about 60% less than the official Nokia battery. Do you think these batteries could damage the unit?
Unlikely, though of course there are absolutely no guarantees. You simply don't know about the quality. I've used them before but about the only thing I've noticed is that the capacity seems to be less than stated and it will decrease more rapidly than you might expect. Not the best quality, but ok for a backup when you're away from a outlet.

Larry
 
Posts: 34 | Thanked: 0 times | Joined on Jan 2007
#8
Don't ever buy a battery off of eBay. It is likely used(worthless) and repackaged or counterfeit or both. I haven't had much luck with eBay except for some old Commodore stuff purchased.

Anyway everything TA-t3 said is spot on.
 
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Posts: 3,220 | Thanked: 326 times | Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)
#9
Originally Posted by thebeck View Post
Don't ever buy a battery off of eBay. It is likely used(worthless) and repackaged or counterfeit or both. I haven't had much luck with eBay except for some old Commodore stuff purchased.

Anyway everything TA-t3 said is spot on.
A year ago I bought two batteries and an extra charger (I was actually only interested in the charger, the batteries were a bonus) on eBay from "that supplier" in Hong Kong. Bar the fact that their capacity is slightly less than the original (which the seller acknowledged in advance), they're still going strong.

I'm probably the famous lucky buyer...
 
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