Ok, not EV related but a quick question about battery charging. I just bought a new Sony Vaio laptop. There is a battery management setting that only allows the battery to charge to 80% full - they claim that this increases the amount of cycles and hence the life of the battery. Does this make sense? If it works, I am ok with it as I plug in most of the time but occasionally have the need for extended battery power. If no science behind this then would prefer to keep it at 100% charge for when I need it.
Indeed this is common practice with Liion and Lithium Polymer chemistry. The other charging technique we use is not allowing discharge past 80% state of charge. I've LiPo packs which have seen 400+ cycles using this strategy as opposed to full charge and discharge which can limit lithium polymer to 200 or less charge cycles. Another advantage is the inter cell balance doesn't go nearly as out of whack with these limits.
Hope this helps to answer your question, you may want to look at your power management control panel.. I know on my laptops I can choose if it charges to 90% or 100% (Mac Book Pro 13" running Windows 7 and OSX).
Undercharging should minimize the damage from storing it at 100% charged. With some planning ahead, you can have the full charge when you need it. Shouldn't take long to charge the last 20% after you change the settings.
Thanks - yes the battery management setting is easily adjustable. Nice thing is that the battery on the Vaio is easily changeable (many PC's I looked at have integrated batteries now that are near impossible to remove) so when it does degrade it will be an easy swap! Will keep it at 80% for now and change it when I need the extended use...
As mentioned in another thread about top charge - when I was doing RC Lipoly cold temp testing (discharge/charge) somewhere around 4.1V/cell during charge temperature noticeably increased. I would think Sony realized minimizing internal cell temps via reduced top charge correlates to less cell degradation.
