Planning the route

One important question to answer is: can I complete my trip without running out of energy? Ideally, you want to be able to make the entire trip on a single charge, since charging is very slow, especially when compared to gasoline (see below for some numbers). There is a trade off between speed and range: The faster you go, then less far you can travel. The effect is the same with gas, but it’s not nearly as pronounced.

Brammo claims that the Empulse can travel 100+ miles, but at what speed? According to Nissan, the Leaf can travel 139 miles under “ideal driving conditions” (read 38 mph, no A/C). At highway speeds (read 55 mph, which seems slow to me), they claim 70 mile range. At more realistic Florida highway speeds of 75 to 80 mph, the range would be a lot less. I consider speeds under 65 to be dangerously slow for a Florida highway as 95% of the traffic will be trying to pass you.

Here are some estimates of how far the Empulse will be able to travel based on speed. Note that these estimates are based on a 10kWh battery and protomech’s numbers, which are in turn based on “Zero’s range numbers and commute logs from one of the [Brammoforum] members”. Until we have real data from the real Empulse, these will have to do.

• Urban – 45 mph → 91 miles
• Rural – 55 mph → 77 miles
• Highway – 65 mph → 63 miles
• Fast – 70 mph → 56 miles

Since my commute will be about 75 miles, I’m going to be limited to traveling at Rural speeds, with perhaps some Urban and Highway speeds added to the mix.

I have three routes planned out. All Highway, Some Highway and No Highway. If the numbers I am using are correct, No Highway would get me there with energy to spare, Some Highway might get me there if I was very careful, and All Highway would leave me stranded. Note that these numbers are conservative, since they do not take into account Dense Urban speeds of 35 mph or less, which will make up part of the route.

All Highway

• Distance: 81 miles.
• Time: 1h 29m.
• Urban: 4.3 miles
• Rural: 14.4 miles
• Highway: 62.2 miles
• Energy requirements: 12,297 Wh > 10,000 Wh!

(Note that the markers denote changes of speed. A-B is Urban, B-C Highway, etc.)

Some Highway

• Distance: 75 miles.
• Time: 1h 41m.
• Urban: 22.4 miles
• Rural: 27.5 miles
• Highway: 25.1 miles
• Energy requirements: 10,055 Wh ~ 10,000 Wh

No Highway

• Distance: 74 miles.
• Time: 1h 53m.
• Urban: 38.1 miles
• Rural: 36.3 miles
• Highway: 0 miles
• Energy requirements: 8,910 Wh < 10,000 Wh

Taking the No Highway route, I would be certain to not run out of energy, but it adds another 12 minutes onto an already long ride!

An important consideration to bear in mind is that the battery is expected to lose capacity over time. So while I may be able to hypermile the Some Highway route and make it for a year, I may not have enough battery to do that any more after a few years.

One possible solution for being too close to the range of the bike is to charge up along the way. There are a couple of issues to consider: Location and time.

Charging Locations

An ideal charging location would be:

• On or very near my intended route.
• About half way, or towards the end of the route. (It takes less time to charge the first 25% than the last 25%, so the more empty when you start charging, the more energy you can get per minute, up to the limit of the charging system.)
• Has a J1772 plug.
• Free!

At this time, there are two possible places that I could charge up the bike along the way:

• Carl Black Chevrolet

They sell Volts so they have J1772 chargers on hand. Unfortunately, I’ve been getting some mixed messages from them – the salesman that I had talked to at the dealership said that the sockets were reserved for the dealership’s own cars, and one of the reviews on PlugShare corroborated with that. On the other hand, another review (I guess from the manager) asserted that the plugs would be available to everyone. I won’t really know if a socket will be available until I try to use it.

• University of Central Florida

This is a solar powered charging station that is a little bit off my route, but it’s unattended so presumably open to everybody. It has 120 V and 240 V supply, but the 240 V is a NEMA 6-20 socket rather than a J1772. To use it 240 V, I would have to bring along a portable charging station with a J1772 plug that would sit between the 240 V supply and the J1772 socket on the bike. (Or I might be able to do something simpler.) Alternatively, there is a 120 V socket I could use. It’s in a pay parking lot, but I’m not sure if I would need to buy any parking time to charge up. A phone call to UCF might answer that question.

The PlugShare website is a great resource to finding available places to charge. Once I have my Empulse, I plan to make a grand tour of as many charging stations that I can, try charging there and then review them all. Right now I can only ask hypothetical questions like. “If I had a electric bike, would you let me charge here?” is not nearly as revealing as “Where can I charge my electric bike?”

Charging time

It takes a very long time to charge a 10 kWh battery. Based on Brammo specs and a comment from Brian Wisman, this is how long it will take to charge the Empulse’s battery:

• 120 V – 10 hours
• J1772 – 3.5 hours

Those number are not all that meaningful. A more interesting question is: How long to I need to charge to be able to get 10 more miles? Or: What is the charging speed in Extra Miles per Hour of charge?

The answer to those questions depend on how fast you plan on traveling, since the faster you go, the more energy you will need. Here is the answer to the charging speed question:

Using a J1772:

• 45 mph → 26.0 emph (extra miles per hour of charge)
• 55 mph → 22.0 emph
• 65 mph → 17.9 emph
• 70 mph → 15.9 emph

Using a 120 V supply:

• 45 mph → 9.1 emph
• 55 mph → 7.7 emph
• 65 mph → 6.3 emph
• 70 mph → 5.6 emph

For, for example, if I expect to run out of energy 5 miles away from home on the highway (65 mph), then I need to charge for about 17 minutes (5 miles / 17.9 emph = 0.28 hours = 16.8 minutes).

It turns out that for total travel time, it’s almost always going to take less time if you travel a bit slower rather than stop on the way to charge up. That is why it is so important that your bike can take you to your destination without running out of energy along the way. Tesla understood this and put a huge battery into their car. Emph for gas is a lot faster. According to protomech: “50 mpg bike is about 2400 miles per hour, considering a 4 gallon fillup in about 5 minutes.”

Perhaps in the future there will be other options to fill up faster, or fill up along the way without having to stop. But for the moment, we have to deal with the limits that we have.

P.S. Many thanks to protomech for doing a lot of the math for this post.