Battery Report

[ZenEngineer]

Usually I hook up my reader once a week to upload new books, so battery charge has never been an issue. Today I just finished reading Anathem by Neal Stephenson and have not charged since uploading that book three weeks ago. Stats: reading for 21 days (dense material, but a good read), ~ 2200 page changes, a BBE file from the Sony Store, but I also have 800 RTF/PDF files on an SD card which apparently uses more battery, and I still have one bar showing on the battery display.

That's good enough battery performance for me. It means I can probably get through a two-week trip without recharging.

[MickeyC]

That's about what I get with an SD card. Usually, I leave it un-inserted and get just over a month

[InspectorGadget]

That's what I got when my 500 was new. Now, I'm lucky if it lasts for two weeks, no card, sitting in my backpack (NO pageturns). And when it gets down to one bar, it's pretty much the same as no bars because it'll die suddenly.

I blew my extended warranty in a Refurb replacement for a 2-week battery, and you know what I got? A crappy refurb with a 2-week battery. Then, just outside the refurb warranty period (3 mo), the screen started blowing rows and columns down in one corner.

I got screwed. No more extended warranty (limited to 1 replacement), no more refurb warranty. Read the fine print. It amounts to institutionalized fraud.

Charge it every week and be happy.

- The Inspector


P.S.: Zen, was Anathem good? I love Stephenson.

[ZenEngineer]

Originally Posted by InspectorGadget

P.S.: Zen, was Anathem good? I love Stephenson.

Yeah, better than Baroque Cycle.

[pilotbob]

Originally Posted by InspectorGadget

That's what I got when my 500 was new. Now, I'm lucky if it lasts for two weeks, no card, sitting in my backpack (NO pageturns). And when it gets down to one bar, it's pretty much the same as no bars because it'll die suddenly.

If you are ambitious you can try to buy a new battery and change it yourself. I know there is another thread the specifies the battery used in the 500. Although I'm not sure if anyone has cracked one open and done this. Perhaps you can be the first, and post photos and directions. Pretty soon many 500 owners are going to want to freshen their battery.

BOb

[InspectorGadget]

Originally Posted by pilotbob

If you are ambitious you can try to buy a new battery and change it yourself. I know there is another thread ...

Great point. I'll track this down. I really should have just done this at the outset -- I even briefly considered it because I'm an electronic engineer and I've actually done this before with Palm devices and several other products. Usually by the time your battery is degrading in a device, the battery technology has advanced to the point where you can get a form-fitting replacement cell that could even have an extra 10-20% capacity over the original.

But at the time I thought "I don't need another project right now and besides, I have a WARRANTY..." Silly me.

- The Inspector

[HarryT]

Originally Posted by InspectorGadget

But at the time I thought "I don't need another project right now and besides, I have a WARRANTY..." Silly me.

- The Inspector

Can one consider a degradation of battery life to be a fault? It is, after all, a natural feature of lithium ion batteries. That's the reason that I personally prefer to buy devices which has a user-replaceable battery.

[InspectorGadget]

Originally Posted by HarryT

Can one consider a degradation of battery life to be a fault? It is, after all, a natural feature of lithium ion batteries. That's the reason that I personally prefer to buy devices which has a user-replaceable battery.

It's a good question, to be sure. I suppose it's a matter of degree and extent of effect. In a nutshell, I judged the PRS-500 to be abnormally degenerating (but I wasn't working with full information about the cell quality and system discharge profile).

Yes, LiIon cells degenerate somewhat over their lifetime, but if maintained well they will perform very well over a long lifetime. Many appliances (and their chargers) and standard usage practices abuse the battery and cause a self-fulfilling prophecy of premature cell degeneration.

Case in point: My digital camera battery is now three years old and still lasts forever. I actually have two which I discharge "fully" to equipment battery warning each time and then swap them, charge the depleted one, and take it off the charger immediately when charged. They have not perceptibly lost life.

As a good comparison, I have two laptop battery packs. One I discharge deeply when traveling and then recharge it fully. I use it about a dozen times a year, about the same cycle as the eReader battery. The other battery pack sits in my laptop while I use it at my desk with the adapter/charger plugged in. In the space of a year and a half, the one that's always on the charger has a lifetime of about 15 minutes now. The one that doesn't sit on a charger has 2.5 hrs of its original 3 hr lifetime.

So, in the case of my PRS-500, the capacity had dropped to half in the space of less than a year, with EXTREMELY light use. If you don't leave a LiIon on a charger, and only recharge it a half-dozen times in that year, it should have 75-85% of its original capacity (that's capacity to charge and discharge, not holding a charge for a year!). In the case of my eReader, it had dropped to 50% -- lasting two weeks or less with NO page turns. Plus, as soon as it hit one bar, it would suddenly shut off only a handful of minutes of use later. Both of those are signs of a bad cell degenerating spontaneously and raising its internal resistance significantly.

I judged it to be a poor cell. Now, after reading the reports of other people, and judging by the performance of the crummy refurb they sent me, this degeneration appears to be the rule rather than the exception. Either they use marginal cells, or the quiescent load of the reader is very high (which I've pretty much deduced from the self-discharge), or both.

I'm going to trade this 500 in on a 505 (or maybe a 700 if they institute the trade-in policy for it in the near future). Then when the cell deteriorates in that one, I'm going to replace it myself with a very high-quality cell.

Thanks for your question. I love talking about batteries. I'm even correct some of the time.

- The Inspector