Lithium Polymer lifespan

[Godsongz]

My older 3835 (approaching 2 years) is starting to show some odd battery issues. I can fully charge it and have the power level drop to 75% within a minute of taking it off the cradle, but not always. I can be reading an eBook for a half hour and lose 20% of my charge, but not always. Its just not consistant. Whats the approximate lifespan of the Lithium Polymer battery? Can I expect more and more oddities as the battery gets older?

On the bright side, I have a 3 year extended warranty from Best Buy on this device. If the battery falls short of 3 years, I can get a brand-new PDA out of this.

[toxostoma]

Keep in mind that battery monitors aren't particularly accurate at returning a percent remaining. What I'm wondering is are you really getting shorter battery life when the monitor suddenly drops? Or is your battery life consistent? On an older battery, it wouldn't suprise me if the reading of % remaining got more erratic.

There's an excellent freeware application call batmemtime. It allows you to tell how long you're PDA has been running since it's last recharge. This should give you some idea if your battery is giving you a charge that lasts for a consistent amount of time, or if a charge lasts longer one time and shorter the next.

[Godsongz]

Thanks, I'll try that.

[Janak Parekh]

Keep in mind that battery monitors aren't particularly accurate at returning a percent remaining.
Perhaps, although the 38xx iPAQs' battery monitors were better than most (1% increments, has special readouts from the battery, etc.) 2 years does sound like close to the limit, Godsongz. I wouldn't be surprised if the battery is simply aging. A typical Li-Ion or Li-Poly battery is designed for 500-1000 charge cycles, after which the capacity steadily drops.

--janak

[rob_ocelot]

Keep in mind that battery monitors aren't particularly accurate at returning a percent remaining.
Perhaps, although the 38xx iPAQs' battery monitors were better than most (1% increments, has special readouts from the battery, etc.) 2 years does sound like close to the limit, Godsongz. I wouldn't be surprised if the battery is simply aging. A typical Li-Ion or Li-Poly battery is designed for 500-1000 charge cycles, after which the capacity steadily drops.

--janak

My experiences with Li-Ion batteries and their chemistry has been that the batteries are basically cooked after about two years, wether you use them or not, and only somewhat related to the recharge/discharge history of the battery. Time is essentially the main factor.

The 500-1000 charge cycles statistic you quote sounds suspiciously like a number you would hear for NiMH batteries.

Getting back to the dilemma of the original poster:

When I first saw that the IPAQ had a non-removable battery (at least to the casual consumer) I was particularly aghast, since I envisioned that in about 2 years time hordes of people would be sending in their IPAQ's to be 'repaired' by Compaq for failed batteries. Out of warranty those 'repair' costs would have been quite a sum of money.

OF course this hasn't really happened. I think though the voiced concerns of 2+ year old IPAQ owners have become a drop in the bucket in relation to the larger number of people who own PocketPC's today. Are there even enough original IPAQ owners around here to poll to see if they have had to explore other battery options such as a replacement from PPCtechs or a DIY kit?

I applaud HP for using swappable batteries and it's one of the reasons I bought a 4150. I've still got my somewhat long-in-the-tooth Jornada 690 HPC running to this day because someone on the Jornada design team had the foresight to make the batteries user-swappable (and also for the godlike qualities of the Jornada 600 series 24 hour extended battery!).

Regards,
Rob S.

[yslee]

I have a 2 year+ 3660, the battery has gone to hell, and here, from my POV, repairing it doesn't make much sense, money-wise. Add to the fact I'm outside of the US and the shipping on them repair kits make it even worse.

After this experience, I'd really like swappable batteries, but such PDAs are still in the minority in the market (and being quite smitten with the Treo 600, it's certainly a big minus for me :( ).

[Janak Parekh]

The 500-1000 charge cycles statistic you quote sounds suspiciously like a number you would hear for NiMH batteries.
Hmm, you might be right; however, it's worth pointing out that various battery guides, including my favorite one (http://www.technick.net/public/code/index.php?load_page=http%3A//www.technick.net/public/code/cp_dpage.php%3Faiocp_dp%3Dguide_bpw2_c10_06%26PHPSESSID%3Dca21855f80b1e68cac6c1311c7798a63), suggest that Li-(Ion|Poly) batteries are affected both by time and by charge/discharge cycles. My original 3600's batteries are quite shot at this point, but I don't consider the cost of a DIY kit to be that unreasonable. OEM batteries aren't that cheap anyway.

--janak

[Godsongz]

Ok, I know, I resurrecting an old and dead thread here, but I'm the one who started it originally and there's a new twist.

Battery life on my old 3835 actually seemed to have improved for whatever reason over the last couple of months, until today. Now after having sat in its cradle all day I plucked it out and was stunned to see that my battery was at 0% charge! I thought perhaps it wasn't sitting perfectly down in the cradle and therefore didn't charge, but I put it in there again over 1/2 hour ago and the charge is only up to 5% so far. This is really odd. Am I looking at the last sputtering dregs of life in this poor old Lithium Polymer battery?

[ctmagnus]

I would leave it until it's fully charged then see how fast it drains before I start worrying.

fwiw, I'm lucky to get more than 16 hrs out of my 3670 before the battery dies. So I kame sure it's on AC at least 12 hrs out of every 24 hr period that it's in use.