[CVB]

Hi - I'm brand new here. Just took the EV plunge about a month ago. Will post about charge points at some point - we are still charging on a 3 pin external socket with the granny charger but that has been pretty OK so far. Have a 30KWH Leaf - 2017 with about 10,000 miles on it.

So, question 1, my wife drives 5 miles to work and then maybe 5 or 10 miles while at work and then 5 miles home and she does this M-Tu-Wed. So, that's like 20 miles/day so in a normal week she could just charge at the weekend and then on Wednesday night...

Is it better to do a small "15/20 mile" charge 3 times or better to do one "60 mile" charge from a perspective of battery longevity? THANKS.

 

[80698]

I don't think it makes a huge difference either way. The only thing to avoid is leaving the battery for a long time at a very high state of charge, or a very low state of charge. I Personally allow it to run down a bit if I am doing short trips rather than constantly running only between 80% and full charge. I don't think there is much wrong with that though, as long as you do occasionally give the battery a full charge and discharge cycle. For a 30kWh LEAF I think if you were REALLY wanting to give the battery an easy life, only working between 20% and 80%, and giving it a rapid charge maybe once per month are the best way to keep it at its best health, but again that's not to say that you would do significant damage by just using it however you want and not worrying too much.

Obviously if this is your only car, make sure you have a rapid charger not too far away or to keep a bit of charge in the battery as a back up should you need to take an emergency trip out somewhere unexpected.

 

[CVB]

THANKS. If we were going on a two week holiday, obvoiusly should be left unplugged. Should one try to make sure charge level was not at 100% for such a holiday? Better to leave it at like 80%. Or is two weeks still considered a "short time"?

 

[Tandy0]

I try to keep mine around 50% whether using it or not. I only charge fully for a long journey.

 

[dk6780]

80% is higher than ideal for two weeks. It'll lose 1-2% over that time keeping the 12v battery topped up but better to leave it 30 - 50%.
If you don't ever need the higher capacity for unforseen trips then only charge it when it gets below 30% and up to around 60%. The difficulty there is setting the charge timer to achieve this, but you'll get used to it.Don't be too anal about it - 80% will not harm and it is better to err towards too much rather than suffer range anxiety amplified from it being the other half!

 

[DBMandrake]

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:

How to Prolong Lithium-based Batteries - Battery University

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%....