Re: Kids Power Wheels Motor questions

From: lemonjuice (exskimos_at_anonymous.to)
Date: 02/01/05 

Date: 1 Feb 2005 08:37:32 -0800

On 31 Jan 2005 11:09:59 -0800, "Tom" <ace@mypad.com> wrote:

>I went to a local battery shop to buy a new battery for my son's
>power wheels, and the guy talked me into buying a $15 lawn tractor
>battery. It was great for about 3 hours, and then one of the motors
in
>the power wheels burnt up. The original battery was 12V, and I assume
>the motor burnt up because of the larger current capability, or the
>increased duty cycle (allowing him to go longer before a recharge and
>cool down).
>
>I wanted to know if I should try and place a current limiting circuit
>in front of the motors to keep this from happening again, or possibly
a
>temperature shutdown on the motor? Any ideas?
>
>Thanks,
>Tom

More information would be needed on the kind of motor you're using.
Its possible that the newer battery has a lower internal resistance so
it doesn't support well the current generated by the back emf of the
motor... or more precisely the circuit doesn't.

Motors normally use 6 times more current when starting then when in
operation and the normal procedure on limiting these inrush currents is
using a shunt capacitor.
If there is no AC conversion circuit a thermistor may be a better idea.
Good luck.

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