on 8/21/02 12:34 AM, Lallang_at_aol.com at Lallang_at_aol.com wrote:
>
> How does this work? Do you take an old NiMH battery that won't charge any
> more and stick it in the freezer? For how long? 3 months?
Here's the original post:
----I know this subject has been discussed to death.
My 2100 with the rechargeable NiMh battery I got from Philly Discounter's suffers from the "10 min. charge time - 4 hour continuous use life (using back light)" problem. I tried the "let it run out completely and recharge" solution a couple of times, but still had the 10 min. charge time. Monitoring the battery via DashBoard during the charge I saw a rapid rise in battery temperature which coincided with the percentage of charge in the battery. So I decided to conduct an experiment theorizing the rise in temperature was preventing the battery from, and erroneously showing the battery receiving a full charge.
1. I placed the battery in my freezer and cooled it to 32 F, wiped it to remove any condensation, then placed it back in my 2100 which was powered up with the AC adapter. I then immediately unplugged the AC and to my surprise the "discharged" battery continued to power the 2100 with back light on for 8 minutes, finally dying when it dipped below 10%.
2. I then rebooted the Newton with the AC. The monitor showed the battery taking a "trickle charge" for 9 min. until the battery temperature reached 41 F. Then it went into fast charge mode. The battery temperature gradually rose until it reached the ambient temperature 37 minutes later (82% charged).
3. I placed a small icepack wrapped in cloth at the very end of the Newton (not on top of it) to help keep the battery temperature cool. This kept the battery 3 degrees cooler than the ambient temperature. The battery continued to fast charge and reached 100% and trickle charge 16 minutes later.
Total charge time was 53 minutes. I then allowed the trickle charge to continue for another hour.
Disconnecting the AC, I left the 2100 on, with the back light on, and it ran for 11 hours 22 min. before shutting down.
I then recharged without cooling the battery and the total charge time to 100% was 48 min.
Seemed to work, at least for the short term.
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