Quote:
Originally Posted by elvenic
So, if I understand this correctly, the Sony's PRS-600 battery will die after 300-400 charge-discharge cycles.
Does it mean that every time I connect/disconnect the device to the computer via USB cable, I start new charge-discharge cycle? So if I use Calibre to download newspaper feeds and connect the PRS-600 to the computer every morning to copy those feeds to the device (which means I connect/disconnect it at least once a day), will the battery die in approx. 1 year?
If I connect/disconnect the device 2 times a day, will the battery die in 6 month?
(Horror: if some day I connect/disconnect 300 times, will the battery die next morning?)
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Adding to what Kolenka has already stated, it also depends on what the final voltage the LiPo battery is at when fully charged. LiPo (Lithium Polymer), has a nominal 3.7 Volts, and is fully charged at 4.2 Volts. Most of the articles you read about LiPo cycle life being in the range of 300-500 are ones charged to the full 4.2 Volts per cell. Life can be greatly increased by backing the final Voltage to 4.1V per cell.
We can assume the PRS-600 has only one cell because the mains charger only outputs 5.2V and for two cells at 4.1V each, it would need to be at least 8.2V output -- actually more.
Here's some things you can do to lengthen battery life:
1. Do not run it fully down more than necessary. It is better to top off and let it get to no bars and recharge than it is to run it until completely dead. It appears, from various comments, that it has quite a reserve once at zero bars, so zero bars *should* be a safe cutoff point.
2. If you think it may sit for an extended period of time, run it down to three bars and use the full shutdown. LiPo cells do not respond well to being stored with a full charge, nor do they like being stored fully discharged. Not that we can measure it easily, but a LiPo cell loves being stored at approximately 3.85V.
Fact: LiPo cells start deteriorating as soon as they're manufactured and there is nothing we can do to stop it. You can slow it down by following good care habits.