Thursday, February 28, 2013

EV Winter Driving Techniques



Over the winter I've seen a number of online posts about EVers having some challenges with the range of their EVs, or lack of range on these cold days.  There is no getting around it, EVs in winter have shorter range, up to 40% on really cold days especially when running the heater.  All is not lost though, there are ways to hold onto some of that range Old Man Winter attempts to take away.  The techniques below are ones I use and they have helped me maintain an 80 to 90 mile range in 40 degree weather and in the 70 to 80 range when below 30, I've only had a couple of seriously short days in the 60s when it was so bitter cold I had to turn up the heats.  Keep in mind I'm used to over 100 miles range and my commute was 76 miles round trip, 85% highway, with no charging at work so maintaining what range I could was key.

Some of my techniques may seem extreme but when you have got to get back home without stopping to charge up every little bit of energy saved gets you closer to that goal.  Not all EVs have the same options as the BMW ActiveE, the EV I drive, but the concept is the same so read on.

PRECONDITION

This would have to be the most recommended thing you could do.  If your EV offers this option, and most do, USE IT!!  Why?  Simple, it warms up the battery, a cold battery is inefficient.  Some EVs warm up the interior, the ActiveE does and this means I can drive 10 to 30 or more mile (depending on outside temps) without turning on the heat before it gets uncomfortable.  This absolutely extends winter range.

CYCLE DEFROST ON AND OFF

Windows can get foggy in cold weather and you will need the defroster, front and rear.  For the windshield I just turn on the climate control and it defrosts pretty fast in the ActiveE, I don't need to hit the actual 'defrost' button which I feel uses way more energy.  The rear defroster I turn on and as soon as the rear window clears I shut it off.

USE ECO-PRO or the ECO mode your EV has

The ECO modes in EVs can make your ride feel slow but they are there for a reason, they make your EV use less energy.  If you want to maintain range turn this feature on.  The ActiveE reduces the power of the heater and the heated seats basically do not work so you will feel a little colder but go further.  If you have to use the heat keep the climate control at 70 or less (if you have a digital readout)...The ActiveE will default to 72 after pre-conditioning but I find 70, as long as you are bundled up, is comfortable even in eco-pro mode.

I sometimes toggle the ECO setting on then off just to boost the heater for a minute to warm up a tad.

The ECO PRO button on the ActiveE - ECO me

STAY UNDER 65MPH

Seriously....EVs use more energy at highway speeds and in the freezing cold the batteries are less efficient and must work harder to maintain those highway speeds - it is a range suck.  You are also taking in cold air over your batteries at a much faster rate.  Keep your speed under 65MPH or avoid the highway altogether....there are a few alternate routes for me where the speed limit is 45MPH or less, it takes me an extra 10 mins but I keep my range.

REGEN WHEN YOU CAN

Regenerative braking is allowing the electric motor to slow the car down, therefore, putting energy back into the battery.  Proper regen can extend range up to 20% which in the ActiveE gets us to 100 or so.  In winter 100 miles is really not possible but regen is still a very effective way to maintain winter range.  Whenever I can I regen, even if it is so slight you can hardly notice, every little % I can stick back into my battery is closer to getting me home.  The ActiveE has a great system where accelerating and regen is all done with the accelerator so simply throttling back, if you will, engages regen and I can modulate the power of it with my foot easily.  It works.  Each EV is a little different, but practice will make it so you can coast down a slight decline, regen, and keep up with traffic and not upset folks behind you.

TAKE IT EASY

Simple right, but I'm serious.  Chill out, no pun intended, when driving.  Think twice about passing the car ahead or beating that other guy off the line...it might be fun but you just cost yourself range.  Stay with the flow of traffic, plan ahead so you know if you need to gradually accelerate or decelerate for a decent regen.  Keep the power gauge needle (this is for ActiveE folks) within the first marker as best you can.

A shot of the ActiveE power gauge (right dial) and keeping the needle below the first marker

BUNDLE UP

Probably one of the most effective forms of range maintenance, bundle up.   Really bundle up, like you are going skiing, wear long underwear and warm boots like lined LL Beans or similar.  You can always change into regular shoes when you get to work.  I don't wear gloves or a thick hat because I feel like a dork - hey look at that guy whose car has a broken heater - anyway, a cap is fine, I do wear my coat with layers underneath.   Most gas car drivers do to.

USE THE SUN

I don't mean solar, I mean park out in the sun to warm up your batteries as well as interior.  It really works.

An example of the lot I parked at in Jersey City and results after my commute - warming the AE in the sun helped, you can see my ActiveE (Serenity) sunning herself on the roof

Plug in at work if you can - seems obvious but during winter more important than ever.  Even a standard 110 outlet will keep the batteries a little warmer and give you a decent charge so you can drive home with heat.

Got a heated garage at home or work...use it.  I don't, my ActiveE stays outside in the elements so I always precondition and sometimes I do it twice if the first precondition did not warm them up the batteries well enough and I need to go the distance

Should you worry if your car sits all day at work and the battery drops to low 30s?  Not really, there is not much you can do.  I've noticed that the battery warms up pretty quickly on the ActiveE once I get driving which tells me the battery temp showing is not the entire pack(s) - it must be an average.  Because if I let my car sit for a day and the battery reads 32 my range is way down and I'm burning energy in no time just by driving a few miles and the battery temp does not climb very quickly.  The picture below shows my battery temp after work and my range stayed at 50 left, going home I was comfortably within range and the battery warmed up to 44.

My battery after work...not really a big deal in the ActiveE, range was the same

How is an EV in the snow?  I can't speak for other EVs but I found the ActiveE to be pretty impressive and I've driven it in some very nasty conditions.  I'm not saying it is like a 4x4 but for a rear wheel drive car with all seasons it was better than I thought.  For example the Pulaski Skyway (Rt. 1/9 NJ) as a sheet of ice, a truly white knuckle experience but the car did amazingly well.  I chalk it up to its weight, it stays planted.  I also think putting the AE into eco-pro is a huge help for traction and not just range.  Since EVs basically have direct drive you have amazing control over wheel spin, there are no sudden thrusts of power like a gas engine gives, the power is linear in an EV so you can literally roll off from a stand still and maintain traction surprisingly well.

I've had a few occasions to drive the ActiveE in some nasty conditions, I was always impressed with it's ability to stay on the road

Can I park my EV outside in the elements?  Of course you can, I do.  I've never had an issue with charging outside, well maybe I had to chip some ice off but that was about it.  No damage to the car or charger.

One example of being ICE'd...literally 

This one was a bit more extreme, I had to wait for outside temp to warm up, still, no harm done.

How cold is too cold?  Well I have driven in temps below 5 degrees and just like any other car the EV feels the cold.  Range is down but the car is fine.

7 degrees is pretty cold but I've seen colder - EVs, just like any other car, do not like it this cold

After reading this you are probably wondering what advantages does an EV have over a gas car in the cold?  Still a few, other than the lack of pollution and the fact they are a blast to drive in hot or cold temps there are still a few...read on

No need to warm it up, just turn your EV on and go. Depending on your make of EV the electric heater warms up fast, yes it uses more energy but for quick trips that electric heater works well.  It also works for when you are parked somewhere, uses far less energy just stay stationary  Good for hanging out in a parking lot waiting for your passenger and staying warm, you can run the heater without polluting others or yourself.

You can precondition your EV - this means warming up the interior which can be done remotely, depending on make of EV, with an app. Do this in a gas car and you need to walk outside to turn it on (unless you have remote start) and run the engine for awhile wasting fuel and have exhaust fumes drift around.

They are still cheaper to operate.  Yes, my range is down so I charge more but gas cars are also less efficient in the cold but I still use no where near the amount of energy a gas car takes.  Plus, I do not have to winterize my car, no special engine oil needed.

Above are just a few of my techniques for keeping range stable during cold weather, fortunately my office has moved so my commute is now 60 miles round trip down from 76, I still don't have a place to charge up at my office but even on the coldest days I make it. I know there are many other techniques out there that may work for you so feel free to post them in the comments section, I'll post them in the blog.

Thanks

Chris