In BenignBodger writes:

If the drawing is exactly what you have then the red and blue wire have
nothing to do with the motor running -- you could remove them completely
and the motor would still run. Problem is that those two wires 'apply the
brakes' on the motor when the switch is released. Basically the permanent
magnet DC motor acts a generator when unpowered and spinning and shorting
it out sucks up the power it is making bringing it to a semi-screeching
halt. Operating with a freewheeling motor/blade would make the mower less
safe and I certainly wouldn't do it although it would still cut grass.

Ah, you've just answered a related question I had with my (bought
used a year ago) Sears rechargeable battery mower.

(4 by 12V batteries in series - 48 volt)

The batteries caught on fire (yes, really) because.. (insert
a forehead slap here) the wires connecting the batteries
and leading off from them used... friction/slide on tabs.

A lawnmower is pretty much the poster child for vibration.

One wire came just a bit loose, was sparking... hot enough
to set that battery corner on fire...

No major damage, ust that first battery and the one next
to it, and also... the wiring between them and above.

So I put it back together with new batteries but there was
this one "extra" wire I sticking out that I couldn't
figure out where to place. Anyway, I turned on the unit
and it worked fine. Charges up a-ok, too. (oh, I
left the wire in place and capped off the open end).

But now that you've written your note, I realized
that, eyup, the blade keeps spinning a lot longer
now when I release the handle.

- now have to figure out where that wire should have
gone, or maybe just live with it now as is...

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