Wednesday, August 21, 2013

Brammo's Wismann explained some factors at Indianapolis prior to the race

From Facebook
Just before Sunday's eRoadRacing race in Indianapolis, Brian Wismann posted a long "here's the latest from Team Brammo" on Facebook that gave some interesting details.

First and most heartening is that the Brammo paddock had a constant stream of visitors "since Friday" which is typically a slow day.  As Brian said, the real competition is the gas powered bikes, the MotoGP, Moto2 and Vance & Hines XR1200 series all of which were also racing that weekend.  I hope Brian agrees with me in saying that while this season has been a competition between Brammo and Zero (thanks to other teams who didn't show up) the real competition is to win the hearts and minds of the gas bike riders.

Second is the gearing required for Indianapolis. Their first thought was to gear the bikes for the long straight in the front, but then the bikes weren't good for the "VERY tight and technical infield section of the course".  A gearing change on Saturday worked really well for Eric, but made a negative impact on Shane.  For the race they reverted the setup on Shane's bike to what they'd used on Friday.  Given the margin by which Shane beat Eric on Sunday, that was a good choice for him. 

During last weekend they'd also switched cell suppliers. This is something Brian had told me about at Laguna Seca, but he didn't want to name the supplier. Shane's bike crapped out during the Laguna Seca race, and Brian is using that as proof the old "RR packs were getting tired and were in dire need of replacement cells". The new battery cell sponsor and supplier is Farasis Energy, of Hayward California. Brian described them as "fantastic cells that are proving to be just the ticket for dealing with these long straights at Indy" and that the "capacity at high C-rates is awesome!"

Let's explain the jargon a bit.

In batteries "C" is a charge or discharge rate where it is fully charged or fully discharged in one hour.  When we say a battery is "10 amp-hours" that means either a discharge rate of 1 amp for 10 hours, or a discharge rate of 10 amps for one hour, or maybe a discharge rate of 2 amps for 5 hours.  The problem with that is that batteries behave differently at high discharge rates than they do at low discharge rates.  Usually you can get more amp-hours out of a battery at low discharge rates, than you get out at a high discharge rate.

The sort of behavior that would make me say "capacity at high C-rates is awesome" would be for the battery pack to maintain its voltage at high discharge rate, and to provide all the amp-hours you need at a high discharge rate.

For example - to pull some numbers out of thin air that I have no proof that any of these numbers are accurate ...

I believe the Empulse RR battery pack voltage is 360 volts nominal.  To run at 150 kilowatts at that voltage means a 416 amp discharge rate.  If their pack is 15 kilowatt-hours, at 360 volts means it's a  40 amp-hour pack.  For a 40 amp-hour pack, a 400+ amp discharge is at a 10C rate.  That's a very high discharge rate.

Again, these aren't the actual numbers for the Empulse RR's but they're close.
Jeremiah Johnson (64)
Ted Rich (28)
Shelina Moreda (38?)
Clearly closely battling for 4th/5th/6th places
from Facebook

As for Shelina Moreda and her results with the Empulse TTX. He said they made some big changes for the qualifying round on Saturday, including giving it a new fairing. Brian said that while she did run faster, it "still wasn't enough to improve her position against the competition." In this case "competition" means the Zero S's at the race. Brian went on to say "At this point, we're hoping their performance is not be sustainable over the race distance." But, of course that didn't turn out to be the case.

As I discussed in Monday's posting, there is more to this equation than who has the best bike. There's also a question of rider skill. But weighing between Kenyon Kluge, Jeremiah Johnson, Shelina Moreda, and Ted Rich, I'm not sure that set of results are due to rider skill as the primary determining factor. Yes, Moreda had just raced in the Vance & Hines XR1200 Harley race just before the eRoadRacing event, and there's a case to be made for rider fatigue. But at Laguna Seca, I think if Moreda and Rich hadn't crashed out in the first lap the results might have been similar to what they were in Indianapolis.

The practice rounds at Laguna Seca, the practice rounds at Indianapolis, and the race results in Indianapolis, all had Moreda on her Empulse TTX finishing behind the Zero's.   There is a trend here, and it doesn't say good things about the Empulse TTX.

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