Get Home Strategy.

[Ianashdown]

Just had my first ride today.  About 45 miles and a combination of Freeway, City and some twisty bits.  I got home with 25% battery remaining which seems about right.

As I was getting close to home I starting thinking "What could I do to stretch the mileage if I was running really low?"

My thought was are there certain things you can do, ways you can ride etc to extend your remaining charge to try and make sure you get home?  I've seen mention of an Eco mode and think that would be a great software update, but until then what is the strategy?

Ian
SoCal

[Jeff]

As I was getting close to home I starting thinking "What could I do to stretch the mileage if I was running really low?"

Unfortunately the primary answer is simply 'go slower.'  It takes a certain amount of energy to move you through the air at speed (keep the dash display on the +/- kW consumption metric to see how much), and look at how much you burn while going 70 mph versus how much you burn while going 25 mph.

Your primary enemy is air resistance -- there are some ways of mitigating that problem with fairings or by tucking behind a windscreen, but alas an 'Eco' mode wouldn't do much, as you still need the same amount of kW to move through the air at speed.  A few of us have found that as long as you're gentle on the throttle, you get slightly better range in Sport mode, because of the stiffer regen.

On the way up to Thunderhill once I was on I-5 N and realized I wasn't going to make it at the rate I was burning up energy on the freeway, so I exited the freeway and traveled on the frontage road at ~25 mph the rest of the way.  Made it to Willows with literally 0% left -- if I hadn't done that I wouldn't nearly have made it.

[JeffK]

And don't think with 5 miles to go and some 8 percentage kW that you're going to make it and race home.
The sofware will protect the batteries and you'll be stranded with a two mile walk home ahead of you at 2 am.

Don't ask me how I know blink of an eye from 8 to 0 % SOC.

[benswing]

Basically take it slow, like Jeff wrote. 

After taking 2 summer trips of 4,500+ miles, that is the way to go.  Air resistance is the biggest thief of range.  Even in sport mode, if you can control your throttle hand with small adjustments instead of accelerating quickly, you can get a few more miles out of each charge.

[Athlon]

fo slow and regen as much as possible with the gearbox , every time you use the breake you are wasting energy

[Ianashdown]

Hi,
I get the go slow part, although I don't understand it!
I was really wondering things like is Regular Mode more economical than Sport Mode and guess that it depends on the road as much as anything.  If it is tight and twisty the regen of sport mode may paly a significant role.  But on the straight and level are the equal?

My Sunday ride is from my Home in San Clemente up Ortega Highway to the Lookout.  It's 32.5 miles door to door.  It is twisty for much of it and it is also 4K Ft so I figure Sport mode going up and in the twisty bit on the way down, then on the straighter flatter ground on the way back is where I'll be in trouble I think.  There is a charging station that is 8 miles from home so that might be my Plan B.  If I can get there!

There's no walking of to get a gallon to get you home with this bike!!

Ian

[Shinysideup]

I get the go slow part, although I don't understand it!

Hi Ian -

If you want to understand in depth:

http://en.wikipedia.org/wiki/Drag_%28physics%29

Or this quote from that source is the short version:

"Note that the power needed to push an object through a fluid [like air] increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power."

Bottom line: Just remember 2X as fast needs 8X the power. The slower the better.

I've found a windshield (MRA Vario) gives me about a 10% boost in range. When I rode my Empulse from San Francisco to Ventura, CA, I tried lots of tricks, including turning the bike off and coasting down a long mountain in neutral. I rode all back roads and tried to keep my speeds below 40 mph. When I was forced to use a freeway, I rode in the right lane at 55 mph, speeding up for closing traffic and slowing down when my mirrors were empty. A couple of times, I rode on the right shoulder on broad country highways that had them, with my right blinker on.

Although Sport mode recaptures more electrons with its stronger regen, for hypermiling it's best, if traffic allows it, to accelerate slowly (I like 3rd gear Sport and a gentle throttle hand for startups), maintain a constant speed, and decelerate gradually and long ahead of a stoplight so, hopefully, you can get going again without having to stop. Although regen helps, it's not as good as not having to lose speed at all. Think of your experience riding a bicycle: much easier to maintain a constant pace than coming to a full stop and standing on the pedals to get going again. That's why bikers run stop signs. (Unless they're messenger a-holes!) Slow is your friend. Smooth is your friend.

Carrying your charger and bumming electricity also helps! I usually offer the donor a dollar. Most refuse.

If you ever get below 20% SOC, be sure to NOT accelerate hard, because doing so can force a shutdown quicker with a low state of charge, in my experience.

If you ever do get a battery shutdown (I've had one in 20K miles) you can try turning the bike off (after moving to a SAFE area!) and letting it sit a while. Batteries can rebound a bit. Mine got me home when I was two miles away, the whole time flashing all the green lights and the message bar screaming at me to recharge the batteries. Yet it ran, and up a steep hill (slowly). And I ended up, after midnight, in my own warm bed on a cold night. All's well that ends well!

[benswing]

The modes simply adjust the amount of power delivered at different throttle angles.  The motor will use the same amount of power to accelerate the same regardless of mode.

For example, you can accelerate slowly in sport mode or accelerate to the max in eco mode and use the same power.

A better example is that if you are cruising at a constant speed it doesn't matter which mode you are in, you will use the same power to maintain that speed.  Going 55mph in Eco mode used the same power as going 55mph in Sport mode.


Sent from my iPhone using Tapatalk

[flar]

In general, the efficiency of an electric motor doesn't vary a lot over its range, but it does have a speed where it is most efficient.

In another thread (I think it was) Brian mentioned that the most efficient running was to keep the motor around 5K RPM (small variations for Sport vs Eco and R vs. non-R, but still in the 4K-6K range).  If you think like an ICE bike and try to keep RPMs down with higher gears then you may actually be using more power, the motor wants to spin.

For steady state running, find the gear that gets you close to 5K.  Or, think of keeping the tach needle pointed in the direction you want to go...

For acceleration, I would think that lower gears would require less power to accelerate you - both because the torque multiplication is higher there and because they keep the RPMs up where the motor is more efficient, but I don't think we've heard an authoritative word on that from the factory.

[flar]

My get home strategy has always been to get off the highway.  There's a reason the bike is rated for 58 miles at 70MPH and 120 miles in the city.  Even with all of the accelerations and stops in the city cycle, you still go more than twice as far as steady state on the highway.

[Shinysideup]

For acceleration, I would think that lower gears would require less power to accelerate you - both because the torque multiplication is higher there and because they keep the RPMs up where the motor is more efficient, but I don't think we've heard an authoritative word on that from the factory.

I thought the same thing, but found that I get better range by starting off in 3rd. Or it seems that way. Lacking authoritative data, it's probably because I just don't expect much acceleration in 3rd and am careful to roll on the throttle slowly. Also, I don't expect to be thrown forward by Sport regen in 1st gear, so I back off the throttle much further away from stop lights and perhaps gain a few more electrons by doing so.

I did a very informal test by watching my power consumption figure while climbing a fairly steep hill near my house. As far as I could tell, the power consumed was not significantly different, for the same speed of 15 mph, between 1st gear and 3rd gear. I was surprised by that, but it may be the case that my measuring method was just too crude.

But I recognize that the plural of "anecdote" is not "data."  

A long time ago, I believe it was Brian that mentioned he knows a hypermiler in Oregon and AFAIK, we've never heard his tips on this forum. Maybe between them, they have actual data?

[flar]

I did a very informal test by watching my power consumption figure while climbing a fairly steep hill near my house. As far as I could tell, the power consumed was not significantly different, for the same speed of 15 mph, between 1st gear and 3rd gear. I was surprised by that, but it may be the case that my measuring method was just too crude.

That seems in line with what I've heard about electric motors and how their efficiency defies standard logic. It's part of the reason why most of the folks talking theory about the value of the gearbox dismiss range as a reason to have gears and why the justification for the gearbox comes more from an "acceleration vs. top speed" tradeoff.

But I recognize that the plural of "anecdote" is not "data."

In my dictionary, the plural is listed as "Fox News".  (Grins, ducks, and runs...)

[Richard230]

Here is the solution to your problem of getting home when you battery pack is drained.  Get the Impossible Bike and carry it in your backpack while you ride your Empulse: 

http://news.motorbiker.org/blogs.nsf/dx/idea-back-up-electric-motorcycle-for-electric-motorcycles.htm