Re: [mowbot] batteries

robin nospam at
Sat, 26 Oct 1996 01:57:51 +0100

DON AUTRY <Don.L.Autry nospam at> wrote:
> What does stall amps on a motor mean, it this the amount of
> current it takes to get the motor started?
It's the current the motor takes just at the point where the load is
too much for it and it stops turning. You need to design drive circuits
to cope with stall current just in case your robot runs in to a wall,
but with effective power cut-outs (tachos, touch bars) it won't be
necessary to cope with such a high current for very long. For that
reason most motors specs quote stall current.

It's harder to get figures for starying current because it is less than
the stall current so doesn't affect the design much. There aren't many
motors in RS that do list starting current; those that do seem to quote
from 2 to 3 times the normal operating current.

Although I've had my ideas on motors scaled up a bit since my early posts,
I still remain to be convinced that we need to budget more than 1A per
motor even under difficult conditions. But to experiment is to know,
so sooner or later someone is going to have to buy some motors and try
a mock-up.


Copyright (C) 1996 R.M.O'Leary <robin nospam at>  All rights reserved.
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