Last week’s revelation that peak power won’t increase in season three as per the sport’s roadmap has left many scratching their heads. First, we’re told that peak power output will increase every year of Formula E’s formative period. Then, we see no change at all to the 200kW ceiling (or the 28kWh permitted energy capacity) for the first three seasons. What’s going on?

At the heart of the matter lies the common chassis, the battery – and funding.

The original specification of the race battery called for 150kW peak power, 133kW power for race mode and a design life of two years. The design process itself was less than ideal, with Williams Advanced Engineering brought only after the chassis and battery safety cell were already determined. Effectively, the Williams designers were presented with a box and told to fill it with whatever they liked so long as the cells didn’t weight more than 200kg and delivered 150kW for three laps at a time in season one. The battery had to then integrate smoothly with a motor, inverter and gearbox from yet other suppliers.

(Read our detailed exploration of the Formula E battery development process here.)

The resulting car was a bit of a Frankenstein creation. Yet, the chaps at Williams duly delivered.

Then, the goalposts moved. When the teams and the sport’s promoter realised that the battery had more latent capacity (and when it became apparent that, at 133kW, the cars would simply be too slow), the first season outputs were upped to 200kW peak power, used in qualifying, and 150kW in race mode.

Williams compromised, allowing the power hike but insisting that a refresh of the batteries be undertaken after one season, rather than two.

The company deserves a lot of credit for developing the battery in a very short space of time and getting it tested, approved (to UN freight specification, no less) and manufactured for the entire grid before the first race.

What’s more, there was only one recorded battery fault in the whole of the first season, a connector issue with Daniel Abt’s car in Putrajaya which was traced to an assembly error. That’s despite a few incredible shunts, such as Heidfeld’s Beijing aerial smash (Williams reported that the battery was working perfectly after that incident: remarkable). Other reported battery faults turned out to be issues elsewhere in the powertrain.

Much wrangling took place about raising outputs in season two. The teams, drivers and sport’s organiser wanted the cars to go faster. The Williams technical experts were concerned that their battery was being pushed too far beyond its design parameters and wanted to keep the power outputs the same as they were in the first season. There was a suggestion, too, that the cash required to undertake the revamp wasn’t forthcoming.

In the end, for season two, power for race mode was raised to 170kW. Peak power and energy capacity remained identical to season one, however, at 200kW and 28kWh respectively.

Every race has been extended in season two without the energy capacity limit being extended beyond 28kWh. This means that, despite additional power being available, drivers can’t actually go much faster in the race lest they use all their energy and fail to make it to the end. In a neat quirk, the additional laps thus protect the battery while allowing a headline power hike. Coincidence or design?

Williams is no longer supplying the dielectric fluid required by the battery system as part of its support package, either. That caused a few headaches in Beijing 2015, when at least a couple of teams suddenly realised they weren’t going to get the fluid from Williams on site and had to go shopping for the very specific chemistry in China at the weekend.

Season three was originally set out as the year when constructors would be able to introduce their own batteries. In view of the development time and cost required, Formula E teams have decided instead to stick with a common battery from Williams for another two seasons. Other battery suppliers will be asked to participate from season five to create a competitive landscape, which is when the sport plans to migrate from two cars per driver to one. A common chassis contract will also go out to tender for season five, with the idea being to retain a spec chassis for two or three further seasons.

But a planned power hike to 250kW in season three has been scrapped, with peak power remaining at 200kW. That will increase to 220kW in season four and then 250kW in season five, barring any further meddling with the technology roadmap. By season five of the original roadmap, the cars should have been operating at 300kW peak power with 40kWh capacity. Even that is seen by many as not nearly radical enough for a top level racing series that wants to be seen as an honest-to-goodness technological testbed.

Within the paddock, many are pointing fingers at the battery. “The battery has been the biggest disappointment so far,” says one senior paddock source. “We’re all being throttled by the battery. Development hasn’t kept up with overall powertrain evolution because we’re stuck with a single supplier and they have a monopoly. We’d see a lot more progress if we opened up the competition but the investment is pretty high.”

Therein lies the crux of the matter. No one can accuse the Williams battery of being archaic. It shares DNA with the electronics in the Williams F1 car, as well as other cutting-edge high performance vehicles. Designing batteries to cope with the rigour of racing, within a specified box and all to a very tight budget is not a project to be sniffed at. Competition would undoubtedly produce other solutions; whether or not these would be superior to the existing product is an open question (just look at how the spec first season powertrains continue to perform strongly against bespoke second gen systems).

It’s worth bearing in mind that the teams have collectively agreed to keep Williams in the frame for another two seasons. Would they be doing so if they really felt the company was being stingy in its tech development?

Formula E constructors aren’t about to get a whole lot happier with Williams, however. Under the 2016 technical regulations, the weight of the cells is allowed to increase from 200kg to 230kg, while the overall weight of the car is to drop from 888kg to 880kg. Given that the spec chassis isn’t expected to change and that teams can’t modify it, it seems that powertrain constructors may have to shave some 40kg from the components over which they have control – the motor, inverter, gearbox and rear suspension. That’s a big ask.

What’s more, the news that Williams will be partnering Jaguar’s season three entry has caused controversy, given that they alone know the exact composition of the battery and have access to a wealth of data from the entire paddock. If the FIA could be persuaded to allow teams more live telemetry, that might go some way to helping, of course.

The good news is that, with the roadmap reworked, there should be less of a performance disparity when the series moves to a single car per driver. “Season five cars will be either as fast or faster than season four cars, because of the way the phased power increase will now work,” says our source.

Financial sustainability is another key factor to consider. The investment to develop new batteries of the sort that Formula E requires – ones which can stand up to the violent acceleration and regen braking, which must perform exactly as asked, which can remain cool despite wheel to wheel battles, which can be freighted around the world and which (and this is a big one) are safe enough that they won’t blow up on hitting concrete walls (or other cars) at speeds into the three digits – is substantial.

Phasing in battery development over the next three seasons will allow meaningful R&D to take place while keeping teams operating within their means.

What’s most important to the longevity of the sport is to set out a plan for the next three to five years that will give other OEMs and tech manufacturers the confidence to invest in the sport and that will keep a grid where every team can be competitive. Come season five, we may well see three or more battery manufacturers and a grid full of big car makers, all because of where we are today.

Despite seeming to slow down overall technical development, then, the latest technical roadmap may actually (by attracting more OEMs) accelerate the sport’s development. And that can only be a good thing.