Don't do too many deep discharges of the battery

[pdagal]

Be careful of repeatedly draining Lithium Ion and Lithium Ion Polymer batteries below 10% repeatedly. Several battery info and OEM manufacturer sites have this info, as do some of the Pocket PC manuals and support sites (they've been using Lithium Ions on high drain devices for a while, after all). Here's an exerpt from a long, dry but very informative article on battery technologies from TechNick.net:

"Most rechargeable batteries prefer a partial rather than a full discharge. Repeated full discharge robs the battery of its capacity. The battery chemistry which is most affected by repeat deep discharge is lead acid. Additives to the deep-cycle version of the lead acid battery compensate for some of the cycling strain.

Similar to the lead acid battery, the Li-ion battery prefers shallow over repetitive deep discharge cycles. Up to 1000 cycles can be achieved if the battery is only partially discharged. Besides cycling, the performance of the Li-ion is also affected by aging. Capacity loss through aging is independent of use. However, in daily use, there is a combination of both.
. . .
The loss of charge acceptance of the Li-ion/polymer batteries is due to cell oxidation, which occurs naturally during use and as part of aging. Li-ion batteries cannot be restored with cycling or any other external means. The capacity loss is permanent because the metals used in the cells are designated to run for a specific time only and are being consumed during their service life."
http://www.technick.net/public/code/index.php?load_page=http%3A//www.technick.net/public/code/cp_dpage.php%3Faiocp_dp%3Dguide_bpw2_00_toc

I'm not saying a Smart Lithium Ion battery doesn't need to "learn" its capacity by going through a few charge cycles, but I wouldn't deep discharge the NZ90 battery repeatedly. Having accidentally deep discharged an iPAQ with an Lithium Ion Polymer battery a few times, I can tell you I lost 1/2 the runtime on the battery as a result :( If Lithium Ion batteries are drained down to 0%, then they may not accept a charge anymore because they've got a cut-off protective circuit that can prevent recharging (because the battery may short internally).

[Unregistered]

pdagal,

Maybe that explains why I ended up taking my NZ90 back and exchanging it for another. My battery performance was not that great to begin with, but after 2 complete drains and recharges, it was worse.

I drained my new one to only 10% today - I think that's what the Sony people recommend. Hope it runs better than the last one did.....

Thanks for the information.

[markga]

wow! Thanks for that info pdagal!! Good to know

[pdagal]

Here's a bit of info about rate of discharge limits for Lithium Ion batteries from the same site/book that may explain why the NZ micro-manages the battery drain from the camera and flash:

"Li-ion/polymer batteries are electronically protected against high discharge currents. Depending on battery type, the discharge current is limited somewhere between 1C and 2C. This protection makes the Li-ion unsuitable for biomedical equipment, power tools and high-wattage transceivers. These applications are commonly reserved for the NiCd battery."

1C = current draw equal to battery capacity over 1 hour. So for a 1000 mAh battery, that means drawing 1000 mA over a period of 1 hour.

The manuals for the last two prosumer digicams I've owned actually state that I shouldn't use Lithium Ion batteries, but rather NiMH or NiCd because the camera and/or batteries may be damaged during high drain activities (taking several pix w/flash and optical zoom). I suspect the NZ has power managment circuitry and software to protect the Lithium Ion battery from any possible damage due to over-draw of current. Obviously, my cameras don't ;).

[starstreak]

Now thats interesting.

[SprSaiyan8]

yes i must say this is interesting thanks pdagal

[ArK]

yeah I was worried about that and so I stopped fully draining the battery. THanks u confirmed my fear.

[MVives]

I have heard of this issue before: after struggling with poor cordless phone battery life (NiCad), I found similar info on Lithium Ion batteries. Long story short:

- NiCad batteries have the "memory effect" and must be cycled fully (don't charge without discharging).

- Lithium Ion batteries should not be fully discharged, as discussed in this thread. They can otherwise be charged / discharged at will.

- NiMh batteries seem to be similar to Lithium Ion in this regard.

Here are some more details (in somewhat poor English): http://www.batterybarn.com/takecare.htm

Unfortunately, I have all three kinds of batteries: Lithium Ion in my Clie and IPod, NiCad in my cordless phone and electric toothbrush, and NiMh batteries for my Game Boy Advance. Sigh!

Strangely, the manual for my old Thinkpad laptop with a Lithium Ion battery actually recommended cycling occasionally... and it helped! Also, the Clie manual does not say one way or another whether full cycling helps or hurts.

[Rossi01]

Very good comments about the batteries. Thanks to the posters!

I have a Clie N760C, which battery charge lasts around two weeks with normal use (no music playing, for example).

I also have a Sony camcorder DCR-PC100, which original battery could never handle completely filling a mini-DV tape and a 64Mb memory stick. I had to buy the biggest model in order to do that. But even the bigger one does not handle a full tape and a full 128Mb memory stick.

In a couple travels I runned out of battery on my Clie and because I forgot the charger I had a dead "paper weight" with me, which I had to re-synch upon returning from travel.

One of the reasons I've been considering the NZ90 is the possibility of having spare batteries. I was thinking how great it is not depending on those batteries. Actually, any battery.

My experience with rechargeable batteries taught me to not trust them. I really miss my Palm III letting me changing its two AAA batteries and be "good to go". I can find those batteries anywhere and can even use rechargeable NiMH batteries.

Now, it seems to me, after reading several posts and reviews here and other websites that the NZ90 has a bad battery bug. Otherwise its power should not vary that much.

Am I missing something? I am VERY close to going to a store and getting one. But still holding a little bit more because of this power issue.

This battery issue seems to be a lottery. I simply do not want to "get the prize" and my NZ90's battery not being able to take even a few photos with flash on.

[TritonB7]

I did a full decharge when i first got my nz90, after the first time I started to charge it when the battery got to 25%

[starstreak]

same here. except for my very first unit. I couldn't really drain it to below 10%.

[kkerruish]

>>>I suspect the NZ has power managment circuitry and software to protect the Lithium Ion battery from any possible damage due to over-draw of current. Obviously, my cameras don't .


PDAGAL -

This falls in line with a theory I have regarding the 8-10 second startup time for the camera...

Given the limited power the Clie has...and the massive drain the battery takes initially when going into camera mode, I think there might be an alternate temporary holding cell that gets charged when going into camera mode, so that the flash is immediately available.

I view this something along the line of disposable cameras...where you have to hold a button down to transfer charge from the internal battery to the flash for each shot.

Just a theory, granted...and I really don't know...but it does make some sense as to the time necessary to start the camera app.

If Sony didn't disable the camera during this startup time - how many people would complain because the flash wasn't available?

Additionally - perhaps it's the way Sony has engineered the device to protect it from long term drains per your posts on the do's and don'ts of lithium ion batteries?

Anyway - my 2c...:)

Ken

[starstreak]

I would complain without a flash. I knew how junk the camera was without one. :) But still I want a longer lasting battery. :) I'll trade with Ark. hehe