IS THE MAXIMUM ENERGY PER LAP ROUTINE CONFUSING?
It can be. But there’s an easy way to think of how IndyCar’s hybrid will be regulated: Before each race, the series will declare how much hybrid energy can be used per lap. That will be expressed in joules, which is a standard international measurement of energy like kilojoules and megajoules. But what we’re looking for from IndyCar is how many seconds the ERS power can be used each lap.
Just like IndyCar says how many seconds of P2P is available, I’m hoping the series will start announcing how many seconds of ERS power — deployment — can be used on each lap. I’ve asked them to do this to make things easy for everyone to digest, and so far they haven’t, but we’ll see if that advice is taken in the future.
HOW WILL THE SERIES COME UP WITH THAT PER-LAP USAGE TIME AT EVERY RACE?
It will be based on the length of the lap. IndyCar is looking to size the ratio of usage to be the same, no matter how big or small the track. Longer tracks will have more ERS deployment time; shorter tracks will have less, all done to give the same approximate contribution of power on a lap that’s 18 seconds or 118 seconds.
WHAT’S THE ESTIMATED DEPLOYMENT TIME PER LAP THIS WEEKEND?
The series has set a limit of 280 kilojoules per lap at Mid-Ohio, and based on the predicted lap times, look for something in the range of eight seconds of that 60hp ERS deployment to be available if drivers keep charging the ESS throughout the lap.
The series also just adjusted the kJ limit to open the event on Friday to 310kJ in the first practice session, which should bump the usage time to around nine seconds per lap.
At Iowa next weekend, it’s 105 kJ, and based on the recent test there, it was around three seconds of ERS power per lap.
WILL THE ERS POWER BE AVAILABLE ALL WEEKEND, EVERY WEEKEND?
Yes. That 60hp/33.2 lb-ft of torque is activated in practice, qualifying, warm-up, and the race.
For road and street courses, the ICE’s P2P is only turned on for the warmup and the races, which would give approximately 120hp when P2P and ERS is deployed at the same time.
IS THAT SOMETHING WHERE EACH DRIVER WILL GO LOOKING FOR THE BEST PLACES TO USE THE ERS?
I’m sure some might, but a lot of pre-event simulation is being done by Chevy, Honda, and each team to identify the corners, straights, and situations where it’s most advantageous to harvest and deploy. I expect most drivers to have an idea of where/when to use the ERS before they head out for the first practice session, and then use the session to confirm what simulation forecasted.
INDYCAR’S ERS UNITS CHARGE AT A FAST RATE. CAN DRIVERS BRING THE ESS UP TO A FULL CHARGE IN ONE BRAKING ZONE?
My IndyCar race engineer friends tell me, no, they cannot. They expect to need two to three braking events per lap to take the ESS from being “empty” to a full state of charge.
Drivers don’t have to fully charge the ESS before they use its power again, but an effort will be required from the drivers to frequently harvest energy under braking on the road and street courses to replace any energy they use as added horsepower.
WHERE DO WE THINK DRIVERS WILL USE ERS POWER AND TORQUE THE MOST?
Out of slow corners, or onto long or important straights.
It can be used anywhere on track, so there are no limitations there. And it could be used as a second form of push-to-pass towards the end of a straight, but to start, most teams have told me they are thinking “slow corners, or onto long or important straights.”
THIS COULD MAKE THINGS REALLY BUSY IN THE COCKPIT, RIGHT?
Indeed. Double deploying will be a very real thing on road and streets coming out of those slow corners/onto long straights in the races.
Consider all of the driving that needs to be done with precisely steering the car, balancing the brake and throttle, shifting, possibly harvesting on the way into the corner, and then powering out of the turn, dealing with any over steer or understeer, and any wheelspin, and possibly trying to dodge or pass a car, and hitting the push-to-pass button, and hitting the ERS deployment button.
It’s a lot to do, first of all, and it’s a lot to get right, and done in the proper order. Mistakes will be made as drivers try to get the rhythm down.
IS THIS A HIGH VOLTAGE OR LOW VOLTAGE ERS PACKAGE?
Low voltage. It works up to 60 volts, which is low enough to not require all the safety measures found in IMSA, for example, which has an ERS package that delivers up to 800 volts.
If there’s an issue with the ERS, I don’t expect to see drivers climbing from the cockpit and doing special jumps to get away from the car. Same for mechanics and crew members.
Also, there’s no red light/green light system on the DW12s to say if the car is safe or unsafe to touch because the system was designed to be low-voltage and safe from the start.
MOST HYBRID RACING SERIES USE HIGH-VOLTAGE LITHIUM-ION BATTERIES INSTEAD OF SUPERCAPACITORS. WHY DID INDYCAR GO AGAINST THE GRAIN?
It had no choice. Due to that tiny volume of space it chose to work with in the bellhousing, there was no hope of fitting a lithium-ion battery into that cavity. For that to happen, a brand-new car would be required that has space carved in the tub — likely behind and below the cockpit under the fuel tank — to mount a decent-size battery.
And since Honda/HRC US had so little room in the bellhousing to design and install an ESS, it had to select comparatively miniature supercapacitor cells — they’re about the size of a thick can of Red Bull — and were able to stack 20 of them together in a square-ish case.
Supercapacitors cannot hold anything like the amount of energy found in lithium-ion batteries, so IndyCar’s ERS quickly delivers and recovers its energy, which is unique in the world of racing. But it isn’t stunningly powerful, all due to the absence of a stout ESS.
Lithium-ion batteries can do the big power, and can provide it for longer durations, but unlike supercapacitors, they are slow to recharge under braking.
IndyCar’s ERS acts more like a drag racer with short but fast bursts of power, and it also recharges at the same rapid rate it deploys, but they don’t have a lot of sustained power or range.