There's a lot that can be done to minimise degradation of Lithium Ion batteries, the following is a good article to help understand the factors at work:
Discover what causes Li-ion to age and what the battery user can do to prolong its life
batteryuniversity.com
A quick summary of the article above - there are three main factors that affect degradation - depth of discharge, high state of charge and high temperature.
Leaving a battery at a high state of charge (generally considered to be over about 80%) for long periods of time can increase age related degradation significantly - and this effect is multiplied by high temperatures. This is shown in table 3. Age related degradation occurs even when the car is not being used.
So if you're going on holiday or planning not to use the car for more than a few days in a row try to leave the car at less than 80% charge. Also even when you are using the car daily it could help to use the charge timer to only charge the car up soon before you need it again rather than it starting to charge as soon as you get home each night so that the length of time spent sitting around at 100% is reduced. (For example if you leave at 7am in the morning set the charge end timer to 6am)
The other major factor is depth of discharge. A depth of discharge of 100% means completely discharging the battery from 100% to (near) 0%, a DoD of 60% means discharging the car to 40% etc...
High depth of discharge causes more degradation per mile. So if you have a full charge range of 100 miles and need to drive 100 miles in a week, it causes far less battery degradation to recharge at 50% then run down to 50% a second time than let it go all the way down to 0% before charging. See Table 2. (The Leaf battery is closest to a LiPO4 in that table)
If you do lots of small trips and a full charge can potentially last you many days you can choose to either wait until you really need to charge or charge a bit sooner - if its no inconvienience you are better to charge again when you get to 50%. However don't charge again if you're still above 80% if you don't need the range as that will just increase the time you spend near 100%....
