USE S10 Efficiency

One of the most provoking questions I get asked is how far can I go on a charge? While most people get the easy answer (40-45 miles), there really is much more to it than that. The quest for range really turns into a quest for efficiency- and what better way to figure it out than have some good, hard data.

If you want to go far, you either need to reduce vehicle mass or add power. There are many ways to do this. You can add battery capacity by adding more cells or changing chemistry. The vehicle weight can be reduced (remember F=MA still applies). You can even change your driving route (less hills) and habits. Driving slower gives better efficiency, that’s hard to do when you have an idiot on your tail. The habits one is easy to change- and with an Emeter you can get really good feedback as to how much you can change on your own!

Before making the decision as to what batteries will work best for you, one really needs to have data. As this is usually the largest amount of money you will spend in a single chunk on your EV, this decision takes a lot of agonizing- just read the Evlist archives! But I have never really seen any good, usable data on the web.

So here I’ve lined up my normal drive into work. 15.1 miles, mostly flat but some hills. 1.1 miles to the freeway, then it’s 65-70mph in the carpool lane for about 13 miles. The rest is surface streets into work. It’s a reasonably rough schedule for an EV, mostly because of the speeds involved. I leave the tailgate down, that’s worth about 1Ahr over the course of the drive.

I take data on my Palm through the RS232 port on my Emeter. The Evdash program can be found on the web. The data is taken every second, so the transients are definitely missed- take it with a grain of salt, it’s a good set of data for a baseline, a poor set for absolute maximums.

Results are as shown. Voltage is voltage is voltage; Positive amperage is drive current, negative values are regen:

Summation of the results are as follows;

Total Time: 19.08 minutes

Volts: 292.5min, 367.5max

Amps: -75regen, 165 drive

AmpHrs: 16.59

KWhrs: 5.13

SOC change: 29%

So the efficiency of the vehicle is about 340Whr/mile on this route, these speeds, etc.

I’ve listed the data here, dissect it as you wish for your own learning!

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