Battery use over time.

[FreepZ]

Here's a graph I made using log data that plots battery use vs speed. There are several sets of data for several days of recordings.



The full details are here.

Notes:

• The "Freeze" data are from when I tried to make my 77 mile run in freezing temperatures (There are two because I accidentally hit the kill switch on the way).
• 0% is when I arriverd with with 0% left (Melbourne to Orlando)
• 15% is when I arrived with 15% left (Orlando to Melbourne)
• On the last two (3/11, 3/12), I had to stop on the way the charge
• The SoC drop per miles appears to get worse as the battery gets older.
• The scale of the SoC axis is wrong. Multiply everything by 100 to get the correct %drop per mile. Oops!

Battery degradation over time is to be expected, with Brammo stating %80 of original capacity after 1500 cycles. I'm at way less than 100 cycles, but the battery seems to have a marked drop in capacity compared to when it was new.

I sent the logs over to Brammo to see if they think the degradation is normal, but I haven't heard back from them yet.

Some notes about how I got that data (if anybody is interested).
I'm using Flar's logging code to extract the data. Every time the battery State of Charge (SoC) drops by about 1%, I see how far the bike has traveled and calculate the average speed over that 1% drop. Using the SoC and distance, I can calculate the SoC per mile. I round the speed to the nearest whole MPH, and average all of the SoC drops for that speed.

[protomech]

Eyeballing a trendline shows a ~2.25% drop in SOC per mile at 55-60 mph, seems high. That's about a 45 mile range. Have you done any runs at warmer temps, 60+ degrees?

Temperature, headwind or sidewind, and rider aero profile probably make more difference in SOC rate variation than battery degradation at this point. That's a guess though.

Very cool dataset : )

[FreepZ]

I've added an estimation of Max Range to the spreadsheet. (I.e. Take the SoC change per mile and use it to calculate how far I can go with 100% battery.)

Brammo claims 120 miles at 19 mph average, and 56 miles at 70 mph sustained.
From my data collection, I see that at I can indeed get over 180 miles at 19 mph. But my range estimate is down to around 40 miles by the time I get to 55 mph. I don't see how I can get anywhere near Brammo's estimate without trailing a truck or with a brisk tail wind.

And you can be sure that when I'm riding, I keeping that RPM as close to 5k as I can, and I'm laying flat on the bike to be as streamlined as possible. Also, the weather was fairly warm during the 0% and 15% rides.

One of these days I'm going to take the bike on the highway and hold a steady 70 mph for a few miles. At this point I would be very surprised to see a maximum range estimate above 30 miles.

I think that the graph is fairly interesting, and once I figure out how to do it, I'll add it to Flar's Enspector.

As a side note, I have to say that it's very handy to have the log files and something to read them. The alternative would be to strap a GoPro to the bike and keep it pointed at dash, and then transcribe all of the info to a table. Doable, but very tedious.

[frodus]

The EPA test cycle is likely different than your driving conditions, speed, acceleration, etc.

Do you have the latest BMS firmware on the bike?

[Gavin]

I would email Brammo

They might want to see your log files...

If I remember right, Wes was getting over 50 miles on a charge and he was riding fast

G

[protomech]

Moving average for the EPA UDDS is around 30-35 mph. The 19 mph average is total distance for the test loop divided by the total test loop time; but the test loop contains significant stationary periods with the vehicle at idle. When you remove those you can get a more accurate moving average.

Multiple reviewers have noted 50++ mile ranges for sporty riding. I don't think that means < 50 mph riding. Either you're riding in much colder temps or something else is up with the bike.

[00049 (AKA SopFu)]

My last ride was 63 miles, about 5 of which were over 50mph. I used 114% of the battery (got 20% back from a  short quick charge during, and ended with 6%). It was a balmy 34F. I'll wait to pass judgement until after the break-in oil change and can rev the motor over 5k.

[protomech]

I'll say too on the Zero I see around a 20-30% indicated range drop from 70-90F temps down to 30-35F. Quite a bit more than I thought had expected.

Supposing the Empulse battery works similarly, 40 miles @ 55 mph should translate to 50-57 miles @ 55 mph in nicer temperatures. That's still far lower than it should be.

[Virtually Yours]

I'm having a similar issue... My commute to work is exactly 6.5 miles with stop and go traffic. I was able to track my average speed on the same route in my car and I average 25 mph. I use anywhere between 8-10% charge one way. I admit I like jack rabbit starts but for the most part I keep in the center lane and just keep up with traffic. I figured that if there was something wrong I would have got an error message... This week I did a little extra running and so far I rode 47.5 miles and used 63% of my battery capacity. So I'm averaging 1.33% SoC per mile. On a positive note I commute to and from work all week on a single charge. So by the end of the week my SoC is <20%. I charge up at work on a 110v (solar power) so I was thinking that between the low SoC and leaving the bike plugged in a couple hours after a full SoC that my batteries should be in a healthy condition...

[7racer]

this is great info!

how much more drastic is this change in Sport mode?

[protomech]

I was able to track my average speed on the same route in my car and I average 25 mph.

Is that a moving average? My 12.5 mile commute takes approximately 25 minutes (~29 mph overall average), but approximately 25% of the distance is traveled at or accelerating to 55+ mph, 50% at 45+ mph, and 25% at 35+ mph. Stops, turns, and sporadic stop-and-go traffic lower the overall average, so it's sometimes not a very useful tool for predicting energy usage.

[Virtually Yours]

I was able to track my average speed on the same route in my car and I average 25 mph.

Is that a moving average? My 12.5 mile commute takes approximately 25 minutes (~29 mph overall average), but approximately 25% of the distance is traveled at or accelerating to 55+ mph, 50% at 45+ mph, and 25% at 35+ mph. Stops, turns, and sporadic stop-and-go traffic lower the overall average, so it's sometimes not a very useful tool for predicting energy usage.

Yes a moving average. The speed limit is 50 mph with plenty of red lights. Although maybe not the best for predicting energy usage; the bike has been very predictable. I know exactly how much SoC I need to get to work or home. Next I'm going to start taking the Interstate more places...