Chargers: the often overlooked but essential first step to electric aviation
Originally Posted on Nov 21, 2022, Updated on Jan 27, 2023
In aviation, the plane gets all the attention and photo ops. However, it does not work alone. Chargers may be overlooked, but they are essential.
Before you can fly an electric plane, like the Pipistrel Velis Electro, you need a source of electricity that matches the input needs of the battery and e-plane system. It sounds simple to plug in, charge and go. However, when an industry is new, there are lots of questions and decisions to get started.
Standards need to be set so that every e-plane manufacturer does not require a different system. Airports want to avoid the cost of duplicate charging systems. However, when an industry is new, the standards need to be established and confirmed as acceptable.
In the case of electric aviation, Pipistrel has the first certified e-plane and it is designed for a 400 volt AC input to the charger. This is not a standard North American voltage. We are accustomed to the 120 volts at household plugs and the 240 volts for major appliances like electric stoves or driers. These lower voltages could be used, but would result in longer charging times.
The next higher voltage level is 600 volts which is supplied to larger users. So, the first step to provide electricity to the Velis Electro is to have a step-down transformer made to convert the 600 volts to 400 volts. Then you need conduit to safely run the high voltage line to where you want to plug in the charger. These steps were completed by our partner, Waterloo Wellington Flight Centre (WWFC), in preparation for the arrival of the Velis Electro.
Next, we need approval from the Electric Safety Authority (ESA). They inspected and approved the transformer and conduit installation. However, when they looked at the cable that came with the charger, it was not certified in Canada. It does not matter that it has been safely used for two years in Europe. A higher capacity, certified cable is required before approval will be granted in Ontario. Also, an electrical line drawing of the charger is required.
The output side from the charger to e-plane uses a GB/T 20234 plug-receptable combination1, one of the connectors used for electric cars, so that is acceptable. We just need a new input cable and plug configuration. A solution will be found, but it highlights one of the first challenges facing electric aviation. Chargers are an essential starting point to the electrical system and although they are built to comply with a safety standard, they are not standardized internationally at this point in time.
While Pipistrel has chosen a 400 volt input, other e-plane manufacturers are proposing 600-700 volt input. The charger for the Velis is rated at 20 kW, but other chargers will have 50 kW or higher capacity to charge bigger batteries in shorter times.
Who should be making the decisions regarding charger standards? Aircraft manufacturers want to promote their unique chargers. Airports and infrastructure providers want standard units that can be used for different types of e-planes. Charger manufacturers would like to supply generic units to meet the needs of multiple e-planes. Ultimately, all the systems need to pass the standards of local electrical safety authorities before they can be used.
By working through solutions for the first e-plane, the University of Waterloo (UW) and Waterloo Institute for Sustainable Aeronautics (WISA) hope that the process will be faster and more standardized for those who follow.
- Pipistrel Vertical Solutions. Off - board M20 portable charger instruction manual. Document No.: IM-801-00-40-001
Update (January 27, 2023)
We replaced the European cable that is not certified in Ontario with an 8 AWG 5 conductor SOOW cable that is recognized. It is rated for heavy duty applications, a maximum voltage of 600V, and is water, oil and abrasion resistant. The new plug and receptacle are pin and sleeve devices that conform to IEC standard 60309. Finally, since 32A is not a standard fuse rating in Canada, the charger’s fastest charging setting of 20kW at 32A was achieved by installing three 35A fuses (one per phase) inside the disconnect switch. Thank you, Ted.
In addition, the manufacturer has upgraded the charger manual with an electrical line drawing that meets the needs of the Electrical Safety Authority. This should remove one of the barriers to prompt approval for future charger installations.
Additional photos:
Paul plugs in the Velis for its first charge in Canada.
Ted, the electrician, energizes the system by throwing the switch at the transformer.
