Fully discharge battery every month?
- Thread starter kmaluo
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WattsUp
Well-known member
IMO, this isn't very good advice from the "experts". Perhaps some phones may indicate a more accurate battery level following this procedure, but I would think that would be more of a software issue than a battery issue. Deeply discharging any lithium-ion battery is harmful to the battery.
Also, while your cell phone will typically contain a single battery cell, the battery in an EV is actually made up a many hundreds, perhaps thousands, of individual cells. The car doesn't just contain a single "giant" lithium-ion battery cell, nor does it work like one. The car's battery management software tracks the charge in the different groups of cells within the battery, knows which groups are almost empty, which are full, balances the charge between them, etc. Put simply, an EV already manages the battery for maximum performance on its own, thank you very much. There is no need to "second-guess" the car and take any explicit actions to "manage" the battery yourself (with a couple very simple exceptions).
Perhaps the only real thing you might do explicitly help your EV battery is avoid keeping the car fully charged for extended periods of time, which is also considered harmful. Instead, keep it just "somewhat" discharged. Personally, I find this easy to do simply through everyday usage. For example, I charge at work and, by the time I drive home, some of my charge has obviously been consumed (fortunately, my commute is pretty short). Thus, my car spends the majority of its time sitting at home partially discharged.
The other thing you can do is simply help keep the battery cool. Keep the car garaged if possible. When out and about, park in shady areas (to avoid direct heat) and on light surfaces versus dark surfaces (to avoid radiant heat). Also, depending on your car (and certainly this is true of the FFE), keep the car plugged in when it's very hot outside (to allow the car's battery management system to maintain the optimum battery temperature).
Also, while your cell phone will typically contain a single battery cell, the battery in an EV is actually made up a many hundreds, perhaps thousands, of individual cells. The car doesn't just contain a single "giant" lithium-ion battery cell, nor does it work like one. The car's battery management software tracks the charge in the different groups of cells within the battery, knows which groups are almost empty, which are full, balances the charge between them, etc. Put simply, an EV already manages the battery for maximum performance on its own, thank you very much. There is no need to "second-guess" the car and take any explicit actions to "manage" the battery yourself (with a couple very simple exceptions).
Perhaps the only real thing you might do explicitly help your EV battery is avoid keeping the car fully charged for extended periods of time, which is also considered harmful. Instead, keep it just "somewhat" discharged. Personally, I find this easy to do simply through everyday usage. For example, I charge at work and, by the time I drive home, some of my charge has obviously been consumed (fortunately, my commute is pretty short). Thus, my car spends the majority of its time sitting at home partially discharged.
The other thing you can do is simply help keep the battery cool. Keep the car garaged if possible. When out and about, park in shady areas (to avoid direct heat) and on light surfaces versus dark surfaces (to avoid radiant heat). Also, depending on your car (and certainly this is true of the FFE), keep the car plugged in when it's very hot outside (to allow the car's battery management system to maintain the optimum battery temperature).
I would invest in one of those reflective windshield sun shades. Like most cars made today the Focus has long windshield with large black dash area. The windshield acts like a solar thermal collector that will heat up the interior of the car. This heat then will slowly warm the battery. Too much heat over a long enough periods will age the batteries more quickly. So plugging in your car on those really hot days will keep the battery cool. After check under the hood I found a heat exchanger in the air conditioning system. This heat exchanger is also tied into the liquid thermal cooling system that helps keep the batteries cool. Unlike the Leaf that uses a simple fan to cool the batteries, the Focus uses chilled liquid to cool the batteries when plugged in.
I purchased a sun shade a few weeks ago, and that really helped to lower interior temperatures. The thermal cooling system only seems to engage when charging over a certain amperage. I've never heard it activate on 110V or 220V Better Place charging stations.
Susan
Active member
This is a great conversation. Thank you both for all of this good information. 
v_traveller
Well-known member
I think I may have posted these links before, but it might be worth doing again...
Here's a link to an article on EV battery care, pretty much sums up anything else out there on the subject:
http://www.plugincars.com/eight-tips-extend-battery-life-your-electric-car-107938.html
Here's a link to an article that's much more technical, includes a link about "smart" batteries and why they may need the full-discharge calibration, refers to a built-in "fuel gauge":
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
... and here is one of the articles that promote this periodic full discharge (there are others):
http://gizmodo.com/how-to-take-care-of-your-smartphone-battery-the-right-w-513217256
The above article has a link to an Apple tech note:
http://support.apple.com/kb/ht1490
The reason Apple gives for the full discharge calibration points to the way their battery system is designed... for their laptops only, which have removable batteries with a separate microprocessor. It says that their products with built-in internal batteries (i.e. iPad) don't need to be calibrated.
So... I'm guessing that our FFE's battery system is designed such that it doesn't need this recalibration procedure.
Here's a link to an article on EV battery care, pretty much sums up anything else out there on the subject:
http://www.plugincars.com/eight-tips-extend-battery-life-your-electric-car-107938.html
Here's a link to an article that's much more technical, includes a link about "smart" batteries and why they may need the full-discharge calibration, refers to a built-in "fuel gauge":
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
... and here is one of the articles that promote this periodic full discharge (there are others):
http://gizmodo.com/how-to-take-care-of-your-smartphone-battery-the-right-w-513217256
The above article has a link to an Apple tech note:
http://support.apple.com/kb/ht1490
The reason Apple gives for the full discharge calibration points to the way their battery system is designed... for their laptops only, which have removable batteries with a separate microprocessor. It says that their products with built-in internal batteries (i.e. iPad) don't need to be calibrated.
So... I'm guessing that our FFE's battery system is designed such that it doesn't need this recalibration procedure.
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