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DC motor voltages used on battery lawn mowers; 40, 60 vs 80 affect blade torgue?
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videobruce:
Background on current battery operated lawn mowers;

The current marketing hype seems to center around the voltage of the  battery packs, not the 'watt-hour' capability (which it should be). As with all battery operated devices, especially L-I, run time and torque (in this case) or lack of, are the biggest problems.

The 'motor' used in these mowers rotation speeds appears to be similar with many; 2800 low, 3300 rpm high. The common battery voltages are 40, 60 & 80/82 volts. There are also 36 & 56v, but those are with limited models. They all are Lithium-Ion (no mention which of the six specific types they use of course).

The question; Is a 80v system better for torque than a 40v system with the same watt/hr battery capability (40v 4 amp vs 80v 2 amp, both equate into a 160 watt/hr pack)??
DDunfield:
You can design a motor to meet a certain torque spec. no matter what voltage it runs on (within reason).
I'd expect the higher voltage motors to be slightly better in terms of efficiency, as IsquaredR losses in windings and wiring should be less.

Dave
(No actual experience with lawnmower motors specifically).
Siwastaja:
Completely irrelevant number; an internal implementation detail which doesn't matter much. Of course, as typical with marketing, meaningless numbers are given a lot of bullshit marketing weight.

In a similar way, you can have a 12V 500W light bulb, or a 230V 15W light bulb.
Siwastaja:

--- Quote from: DDunfield on April 25, 2019, 01:01:10 pm ---I'd expect the higher voltage motors to be slightly better in terms of efficiency, as IsquaredR losses in windings...
--- End quote ---

Nope, this is wrong - assuming same weight of copper in the windings, to get the same A*turns and torque, the I^2R loss is the same regardless of the design voltage...


--- Quote ---... and wiring
--- End quote ---

... but this is true, assuming the same copper weight in wires. So, thicker cables must be used to compensate.
Zero999:
And guess what thinner wiring will be lighter, therefore boost efficiency, in a self-propelled lawnmower.
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