Thank you!  I've sent that home for further perusal!

Rusty

 

> -----Original Message-----
> From: plug-discuss-bounces@lists.plug.phoenix.az.us [mailto:plug-
> discuss-bounces@lists.plug.phoenix.az.us] On Behalf Of Joseph Sinclair
> Sent: Monday, July 23, 2012 3:47 PM
> To: Main PLUG discussion list
> Subject: Re: Laptop Battery Life
> 
> The full discharge-and-recharge was for NiCd batteries, and helped to
> limit memory effect, it does not apply to NiMH or LiIon batteries
> (anything fairly recent), nor did it ever apply to lead-acid and it's
> derivatives.
> LiIon is the only one that has particularly big problems if discharged
> to 0%; although it's best to not leave any battery fully discharged too
> long, for various reasons depending on chemistry.
> 
> It *used* to be that chargers were quite dumb and just "shoved" charge
> into a battery.  Most good quality chargers are much more nuanced than
> that today, and will charge at different rates depending on the charge
> state of the battery which further extends life.
> Most laptops, in particular, have quite intelligent chargers and will
> not overcharge the battery or charge too fast/too slow for the charge
> profile; this is particularly important for LiIon as overcharge and
> overly aggressive charge/discharge can result in thermal runaway (c.f.
> the various laptop "explosion" videos).
> 
> So, for LiIon, just charge it when you need to, and if you intend to
> store it for a while, discharge a bit (around 80%) and check it now-
> and-then to make sure it gets recharged before it drops much below 30%.
> For NiMH, it's a bit more nuanced, but still amounts to charge-it-when-
> you-need-to, just not as much to worry about when storing as long as it
> doesn't spend too much time completely discharged.
> 
> For both LiIon and NiMH, there are several common chemistries used
> (both are families of battery, not particular implementations), and
> each has different advantages and disadvantages.
> It's worthwhile checking which you're dealing with if you wish to
> maximize the life of your particular device.
> 
> These wikipedia articles have some very good details on the chemistry,
> including some of the differences for recent alternate chemistries.
> http://en.wikipedia.org/wiki/Lithium-ion_battery
> http://en.wikipedia.org/wiki/Nickel%E2%80%93metal_hydride_battery
> 
> I hope that helps, Rusty.
> 
> 

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