Kids Power Wheels Motor questions

[Tom]

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

 

[Active8]

On 31 Jan 2005 11:09:59 -0800, Tom 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?

Not sure why it burned, but I'd expect the other motor to go also if
it's a matter of you doing something wrong. Knowing if the motor
really draws more current from the new batt would be nice as would
the temperature rise.

Aside from that. AFAIK, lawn mower batteries are not made for deep
cycle use. Maybe the batt revolted Maybe someone at the toy mfg
can tell you more about the original batt. Beware of salesmen.

--
Best Regards,
Mike

 

[John Woodgate]

I read in sci.electronics.design that Active8 <reply2group@ndbbm.net>
wrote (in <13lvkf2azya1z.dlg@ID-222894.news.individual.net&gt about 'Kids
Power Wheels Motor questions', on Mon, 31 Jan 2005:

Aside from that. AFAIK, lawn mower batteries are not made for deep cycle
use.

Yes, they are. That's precisely how they are different from car
batteries.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[keith]

On Mon, 31 Jan 2005 22:46:44 +0000, John Woodgate wrote:

I read in sci.electronics.design that Active8 <reply2group@ndbbm.net
wrote (in <13lvkf2azya1z.dlg@ID-222894.news.individual.net&gt about 'Kids
Power Wheels Motor questions', on Mon, 31 Jan 2005:

Aside from that. AFAIK, lawn mower batteries are not made for deep cycle
use.

Yes, they are. That's precisely how they are different from car
batteries.

No, that would be "marine" batteries. Lawn-mower batteries are starting
batteries, just like car batteries, but smaller.

My vote here is a short-life motor. The motor may have even taken the
original battery down. Brushes in these things are always suspect.

--
Keith

 

[John Doe]

Active8 <reply2group@ndbbm.net> wrote:

On 31 Jan 2005 11:09:59 -0800, Tom wrote:

....

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?

... Knowing if the motor really draws more current from the new
batt would be nice as would the temperature rise.

Just in case the suggestion is not clear to everyone else in the
world. I think that means to measure the current with the old
battery and with the new battery, assuming the user is capable. Then
you know.

Aside from that. AFAIK, lawn mower batteries are not made for deep
cycle use. Maybe the batt revolted Maybe someone at the toy mfg
can tell you more about the original batt. Beware of salesmen.

 

[John Woodgate]

I read in sci.electronics.design that keith <krw@att.bizzzz> wrote (in
<pan.2005.02.01.03.07.18.431527@att.bizzzz&gt about 'Kids Power Wheels
Motor questions', on Mon, 31 Jan 2005:

On Mon, 31 Jan 2005 22:46:44 +0000, John Woodgate wrote:

I read in sci.electronics.design that Active8 <reply2group@ndbbm.net
wrote (in <13lvkf2azya1z.dlg@ID-222894.news.individual.net&gt about 'Kids
Power Wheels Motor questions', on Mon, 31 Jan 2005:

Aside from that. AFAIK, lawn mower batteries are not made for deep cycle
use.

Yes, they are. That's precisely how they are different from car
batteries.

No, that would be "marine" batteries. Lawn-mower batteries are starting
batteries, just like car batteries, but smaller.

I'm taking about battery-powered *electric* lawn mowers. Don't you have
them? Maybe not, because they won't mow all your acres of lawn without
recharging. Suitable only for 10 m^2 European lawns.(;-)

--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[lemonjuice]

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.

 

[lemonjuice]

On Mon, 31 Jan 2005 19:52:20 +0000, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> farted

Temperature shut-down is the best solution. You don't know what
current
is too high but you can make a better guess at what temperature is too
high.
LMAO

Well thats because you are purely rubbish in your head.
Do you know what a motor is or how it works?

 

[Active8]

On Tue, 1 Feb 2005 17:50:19 +0000, John Woodgate wrote:

I read in sci.electronics.design that lemonjuice <exskimos@anonymous.to
wrote (in <1107275852.797630.62240@c13g2000cwb.googlegroups.com&gt about
'Kids Power Wheels Motor questions', on Tue, 1 Feb 2005:

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.

Both paragraphs are utter rubbish.

lemonjuice and Dr. Slick are both trolls, John.

--
Best Regards,
Mike

 

[John Woodgate]

I read in sci.electronics.design that Active8 <reply2group@ndbbm.net>
wrote (in <p0imgt0xsr83$.dlg@ID-222894.news.individual.net&gt about 'Kids
Power Wheels Motor questions', on Tue, 1 Feb 2005:

lemonjuice and Dr. Slick are both trolls, John.

So it appears. Appropriate anti-troll measure implemented.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Dave VanHorn]

Could be that the motor simply failed..

These are medium sized DC brush PM motors, geared way down.
I don't see any significance to a change in impedance in the battery, the
motor's resistance would be much larger, at least till the brushes start to
wear out.

 

[keith]

On Tue, 01 Feb 2005 20:17:50 -0500, Dave VanHorn wrote:

Could be that the motor simply failed..

These are medium sized DC brush PM motors, geared way down.
I don't see any significance to a change in impedance in the battery, the
motor's resistance would be much larger, at least till the brushes start to
wear out.

The brushes wearing out was my immediate suspicion. In a cheap device
like this is may even be the motor bearing giving it up, but I agree any
battery that could supply a load like this would have a siuffifiently low
series resistance that it wouldn't matter to the motor's longevity.

My point above was that a "lawn tractor" batter y was a starting battery
and not really suitable for this use, though it wouldn't contribute to the
death of the motor in any case.

--
Keith

 

[keith]

On Tue, 01 Feb 2005 11:41:35 -0800, lemonjuice wrote:

On Mon, 31 Jan 2005 19:52:20 +0000, John Woodgate
jmw@jmwa.demon.contraspam.yuk> farted


Temperature shut-down is the best solution. You don't know what
current
is too high but you can make a better guess at what temperature is too
high.
LMAO
Well thats because you are purely rubbish in your head.
Do you know what a motor is or how it works?

Stick some zinc in one ear and a nail through the other and
see if there is any juice. Somehow I doubt it!

--
Keith

 

[Rich Grise]

On Mon, 31 Jan 2005 11:09:59 -0800, Tom 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).

This is what it sounds like, actually. How big is the replacement battery
compared to the original, and is it, in fact, a deep cycle?

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?

If it's a duty cycle problem, then yes, this should prevent it. How long
of a ride did the kid used to get?

Good Luck!
Rich