Performance with  LiFePo4 cells V 1.2  2013

LiFePo4 cells unlike lead acid batteries can deliver upto 90% of their capacity. If they are new for the first 400-700 cycles even a little more than that.

 

So if you install a 10 KW (10000 watts) battery pack (Voltage * Amps = Watts) it delivers upto 9 KW to your engine within one hour.

 

Now, what performance can you expect. This mainly comes down to the efficiency of your boat hull, the water conditions (wind, waves etc.) and the speed. Please note, that planning hulls are not realy suitable for electric drives.

 

Example

 

10 x 4.5 meter catamaran | 3 tons | high efficient displacement hull

 

High quality induction electric motor, inboard

 

No wind, no stream waves upto 0.8 meter

 

 

 

 

 

 

 

 

 

 

 

 

Add at least 10% in power output requirement for safety reasons

 

Compare energy consumption petrol outboards to electric outboards

 

An average indicator for petrol engines is 0.20 litres per HP / hour

A 20 HP petrol engine at full throttle will use 4 litres / hour

A 40 HP petrol engine at full throttle will use  8 litres / hour

 

If you run a 20 HP engine which uses in average 2 litres per hour, you are operating at around 50% of the engines capacity, but the output will only be at around 40% due to the lower efficiency. The 20 HP equivalent would be a 13 KW electric outboard engine which requires a maximum of 15 KW input power. At 40% this are 6 KW. As the electric induction motor has an almost linear torque and efficiency curve, unlike DC motors or petrol engines, the 40% output are allmost linear to the 40% input.