Life Is Good

One of the biggest reservations I have seen about battery electric motorcycles has to do with battery replacement costs. Just about any time I read the comments section of an article relating to EVs, someone brings up the question of battery replacement costs. Should this really be a concern when considering an electric motorcycle? Lets look at the numbers… For many EV manufacturers battery life is typically rated by charge cycle count to 80%, that is, how many full charge cycles a battery can endure until its degraded to the point where can still hold 80% of its original capacity. Tesla gives cycle counts to as low as 70% of original capacity for the Tesla Roadster. This point is considered to be battery end of life (EOL), but that certainly doesnt mean the batteries are useless and need to be replaced.

Lets do the math. The Brammo Empulse is fitted with Brammo’s Brammo Power™ BPM15/90 Lithium (nickel cobalt manganese chemistry) battery packs, rated at 1500 charge cycles to 80% of original capacity @ 100% Depth of Discharge. What this typically means is that the battery can handle 1500 full 0% to 100% charge cycles… a partial discharge / charge cycle would count as such, ie: 50% discharge then charge to 100% is 0.5 cycles. The average range for the Empulse is listed as 77miles (thats an average of city and highway figures of 121/mi city and 56/mi highway), now we can take this number and multiply it by the cycle count, and then by 90% (to account for linear capacity loss) so: (77 * 1500) * .9 = 103,950 miles to battery EOL. 103 THOUSAND miles for a motorcycle is a very long way, and at that point you still have a useful battery, it just holds 20% less juice resulting in 20% less range. Range for the Empulse at EOL is still 77/mi * .8 = 61.6/mi, so why not keep riding . That said, how many petrol burning motorcycles out there can go that far without the need for 1 or even 2 costly and time consuming engine rebuilds? Of course these are considering ideal conditions, so lets consider a worse case scenario where the battery is really put through the wringer and only lasts half that, only 750 cycles. 103,950 /2 = 51,975 miles, still much longer than most sport bikes will go without a rebuild.

To give prospective electric motorcycle owners a better idea of what they can expect from these batteries I have added another feature to the TCO calculator. After selecting an “E-Motorcycle” look at the right column, there is a line for “Battery Life”, just click the “More Info” button. The Battery Details window that pops up gives you a handfull of data based on battery cycle life numbers specified by the respective electric motorcycle manufacturer. Depending on battery manufacturer, chemistry, and a slew of other variables, battery cycle numbers vary from 1500 cycles to as high as 3000 cycles! The illustration also takes the data a step further and shows what kind of range to expect at the EOL (80%) and beyond, down to 60% of original capacity since degradation tends to be linear. Please note that I used city range for these calculations mainly because some of the bikes are not highway capable.

Now ask yourself, with batteries designed to last well beyond 100 thousand miles, is battery life really something to be concerned about?

Tags: Battery Life, Brammo, Electric Motorcycle, TCO, TCO Calculator

This entry was posted on Tuesday, July 3rd, 2012 at 6:13 pm and is filed under Brammo Awesomeness. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.