Variable power 21'' SP-mower

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I just purchased the 21'' self-propelled EGO mower.

While mowing, the motor continuously changes its power.  (I don't mean the self-propelled action, just the power of the blades.)  I am not talking about overheating because it starts to do this even after a couple of seconds of mowing.  Is this normal: does the machine adapts its power to the length of the grass somehow?  Yesterday there was a short time the power was so powerfull I think my neighbours might have been expecting a helicopter landing close-by.  The battery was also empty much quicker than the week before when I mowed for the first time.  At other times, the mower barely makes any noise, making me check whether it was actually cutting or doing nothing at all (it was still cutting, by the way).

As I cannot find anything in the manual or on this forum that indicates the power changes all the time, I post this question.

Another question: the manual says to clean the motor ventilation part.  Where exactly is it located?  I clean the blades and remove the grass on the bottom.

Thanks and best regards,

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Pieter Schevenels

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Posted 3 years ago

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David HD, Champion

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Official Response
Pieter, if you have nothing "interesting" to read this weekend, then spend your time reading this great article on "What is a Brushless Motor and How Does it Work?" by Chainsaw Journal.  This article breaks down the "how" and the "advantages" of a brushless motor.  This article was written about the EGO 56V Chainsaw, even though I don't own or need a chainsaw, but it was very informative with great exploded views of a "brushless motor."  I am a visual person and this article was perfect for my taste, hope you will enjoy it!

Advantages of the brushless motor:
  • The lack of brushes ensures that there is low friction during the operation of the motor and reduced production of heat, therefore, increasing the durability of the motor.
  • The minimal heat and motor wear due to lack of mechanical contact on the motor vastly improve power transfer and electrical efficiency that leads to increased performance and power.
  • The increased efficiency of the brushless motor helps to prolong battery life up to 50% or more.
  • There is no sparking and the motor produces less electrical noise.
  • Heat dissipation is better since the stator where the windings are located are connected to the case.
Disadvantages of the brushless motor:

The initial cost of the motor is high due to the need for commutating devices such as the encoder and a controller or drive.