With a new formula in place for the next four seasons of Formula E, Williams Advanced Engineering reclaimed the single-spec battery tender from McLaren Applied Technologies, having also produced the Gen1 battery pack.
But reported difficulties in testing for multiple manufacturers during the off-season, as they look to develop their understanding of the all-new Gen3 car, have limited running in the initial testing phases.
It is understood that overheating of the cells, which can cause degradation and derating, was the key issue behind the problems. A change to the battery packaging design has thus been made to cure that.
Reigle told Autosport that the changes put in place were working, and that it should alleviate any "anxiety" ahead of the collective pre-season test at Valencia's Circuit Ricardo Tormo in December. Season 9 itself gets underway in Mexico City in mid-January.
"In simple terms, the packaging in which the cells sit had some challenges, and that meant that we had to change the packaging. So that led to a delay in testing programmes," said Reigle.
"And so really what you have is people feeling that anxiety; normally you would be testing the car, you would have a certain number of miles on it, we would go to Valencia in December, and then we'd race in Mexico, in a normal year where you're not changing.
"In this case, because we had some challenges with the cell packs, everyone's programmes are slightly delayed, and you've got that sliding door that is closing coming into Mexico.
"There's common issues or common challenges, and individual challenges. What I always remind the teams when we have our internal calls is 'let's make sure we're focused on the common challenges, not the individual challenges'.
"And so that's the car, it's working. We've solved the issue around the cell packs, there's not a huge amount of anxiety about that anymore."
After a World Motor Sport Council e-vote earlier in November, Formula E announced plans to introduce fast-charging pitstops later on in the coming season.
The delay in their introduction has been a consequence of those issues with the battery and, since the supplier of the in-car battery cells and those used in the in-race charger is the same, Reigle says that ensuring the car was in working order was the priority.
"The challenge we have is the supplier of the cells for the charger, the in-race charger, what we call the booster, is the same supplier as the cell packs for the batteries. So we needed to prioritise making sure that the batteries were a-okay before we can get the cell packs ready for the chargers.
"Those could be ready by Mexico, but ultimately there are all those things that are changing. Is it really advisable for the sport to say 'let's pressure-test that timing and make sure everyone has their charger, test them in Valencia and race in Mexico, because we have it available?'
"Or actually, should we use Season 9 as a way to demonstrate the capabilities of the Gen3 car, which would be a pretty significant uptick in performance?
"To use the comparison to sprint races and F1, we can then bring in new modes of racing. In their case, it's a different way of setting the grid, but also improving the entertainment on the Saturday.
"In our case, it's 'we have this technology, but let's not force it by January. Let's bring it in when we have a high degree of confidence that it can be implemented in the right way'. We have double headers, so it allows us to play with that."
