Picture: the ePropulsion kit mounted on a fishing boat during the preliminary tests
Preliminary tests – Introduction
The tests described aimed to assess the 3 different set-ups (EZ, ePropulsion, and ICE outboards) in similar conditions of vessel, weight, weather, route, and speed. A circumnavigation of the Lolwe island was chosen as standard route, and the tests were conducted in 2 different speed modes:
- Sport Mode: boat propelled to the maximum allowable speed.
- Eco Mode: slightly reducing the speed to save fuel or energy and increase the overall coverable distance.
A total of 6 valid trips were recorded and will be discussed below.
It is important to understand that the purpose of the testing was to gather some valuable insight regarding operation in different conditions, to be able to provide guidelines to the final users, become more aware of the actual value proposition and verify whether the performances meet the expectations.
Preliminary tests – EZ e-outboard and ICE
A first round of tests aimed to compare performances and energy needs of an ICE and an equivalent e-outboard. A few trips around Lolwe island, first with a 10HP ICE and later with the EZ S10 were completed with each trip involving the same boat and similar loads. For this test, the EZ e-outboard was propelled to the maximum allowable speed (Speed Mode).
In Sport Mode, it was observed that the EZ e-outboard kit was able to maintain the maximum speed only for 8 km, after which the speed was reduced considerably, reaching performances equivalent to energy saving mode (Eco Mode). The reason for this behavior seems to be related to a voltage reduction in the battery modules. With the e-outboard being used at its
maximum power, the speed kept on reducing coming to a complete halt when voltage reached 43V, which is the bottom admittable threshold for the EZ S10 input voltage. At that point the e-outboard was swapped with the backup ICE outboard to allow complete the trip.
Another similar test was later performed with the same route, but with two boats of similar weight and length; the first vessel was equipped with the EZ e-outboard used in the previous test and the second with a ICE. Both vessels travelled together in close proximity, proceeding at the same cruise speed. This time the electric outboard was set in Eco Mode, which limits the power and the speed to around 8-10 km/h. The boat equipped with ICE followed at same speed rate. It should also be noted that in the last few kilometres the weather conditions got slightly adverse, with presence of waves and wind, imposing a higher power consumption and reduction in cruise speed.
As expected, the energy and fuel consumptions dropped compared to the previous Sport Mode, and the e-outboard successfully completed the trip with 50% of the usable battery capacity remaining (4.6 kWh).
When comparing the cumulative distance over time between the Sport and Eco Modes, it can be observed that the e-outboard presented similar performances in terms of covered distance and duration of the trip but consumed around half of the energy if operated in Eco Mode. From a preliminary assessment, the explanation for this phenomenon is that the high current required to navigate in Sport mode caused a significant drop in voltage supply from the Bodawerk batteries; because of the low voltage supply below the optimal range, the EZ outboard was not able to deliver full power and speed.
For this reason, the e-outboard kit was able to meet the ICE speed performances only for the initial 8 km.