can i run 6v ride-on motors on 12v battery? mattel power wheels ones.

i have a mattel power wheels kids ride-on jeep. it has two 6v
batteries, which have expired. the thing has a hi-lo speed and
reverse switch, which pretty much does what it says. i am guessing
that at low speed and reverse it runs the motor at 6v, and at high
speed it runs it at 24v? i have a battery i want to use to replace
(v expensive to buy replacement mattel batteries 6v 9Ah) which is from
a PC's UPS, it's 12v and 12Ah. I can't see that it would be
possible to wire it as 12v/24v, as i would only have a total of 6
cells. but would wiring it straight in and using it as 12v/12v
damage the motor? any other suggestions? thanks
Reply to
kk
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Replacing two 6 volt batteries with two 12 volt batteries will probably damage the motors and possibly the switches, the wiring and the driver and nearby pedestrians. Replacing the two 6 volt batteries with one 12 volt battery will work, except there is no terminal to connect to that will give you the 6 volt slow speed.
Reply to
John Popelish
Two 6V batteries gets you 6 and 12V. Doubling the voltage to 24V doubles the current, and quadruples heating in the motor, probably a very short life.
The low speed option is not well designed, because you're running one battery down more than the other, then connecting the run down one in series with a more fully charged one.
I'd just run it on 12V and be done with it.
Reply to
Dave VanHorn
the motor? any other suggestions? thanks
Well, you can cause the switch to insert a series resistance for the "low" speed. The resistor would go from the wire that USED to go to the 6 volt "tap" to the "high" side of the 12 volt battery.
It would not give the same "response" as the 6/12 dual voltage operation but acceleration would be smoother.
Where to get the resistor? Maybe try using "tin" cans cut such a way to maximize the length of the current path. Open both ends, cut down the seam, attach the wires (nuts and bolts and washers) and "adjust" by cutting slots from the top and bottom.
Reply to
John Gilmer
You can buy 6 V 10 AH batteries at McMaster-Carr for about $15 each. Theyn are mostly for emergency lights, but should work well in this application.
Jon
Reply to
Jon Elson
Isn't 6V too low for a 12V motor, likely not to run at all (under load) rather than go slowly? It would certainly cause uneven discharging.
Remember, he said, "i am guessing that at low speed and reverse it runs the motor at 6v", so he hasn't measured the voltages or traced the connections.
Reply to
Tom Del Rosso
One thing to keep in mind when doing a project like this is what is known a ?power density'. This is the amount of power (V*I) your battery can supply safely. It is mostly a function of the battery chemistry. For example, lead acid and ni-cad typically have a higher power density than Li-ion.
So what happens if you over draw the battery? It could just fail to recharge, or it could meet a more violent end. My opinion is I wouldn't want my kid anywhere near this thing when I am finding out. If you don't have a power density rating for the UPS battery, don't risk it.
Reply to
EE
1) In a permanent magnet DC motor, torque is proportional to current and no load speed in proportion to voltage. Starting such motors at lower voltage is a GOOD IDEA.
2) The technique of half/voltage is routinely used in battery operated drills. Yes, it "unbalances" the discharge of the batteries, but that's life.
Reply to
John Gilmer
A simple automatic switchover can be used to run the motor at 6v off each battery on alternative goes, so the energy draw approximately balances. Or the batteries might even get paralelled. But what Mattel have actually done is another question.
Replace 6v batteries with 6v batteries. Having a car that only does top power is not a sensible option IMHO.
No need to buy them from Mattel, but you do need to ensure theyre suitably rated.
Regards, NT
Reply to
N. Thornton
On Tue, 18 May 2004 22:46:29 GMT, "Tom Del Rosso" put finger to keyboard and composed:
Not so long ago I traced the wiring for a ride-on tricycle which used two 6V 10AH SLA batteries. It was wired exactly as the OP described.
- Franc Zabkar
Reply to
Franc Zabkar
You can get 6 v 10 Ah gel cells for ~ $18.00 each at Mouser - maybe that is significantly better than Mattel batteries price?
Reply to
ehsjr
Hi...
And could I respectfully add that if you do use non-original subs that you fuse 'em as close to the batteries as you can possibly get?
In addition to epoxy'ing or something the terminals?
The batteries will deliver an awful lot of hot and hurt to tiny fingers that decide to "fix" the car like daddy does - and use metal "tools" to work with :(
Yep, I've been accused of being over-protective :)
Take care.
Ken
Reply to
Ken Weitzel
Speaking as a former Mattel Engineer (I do not represent Mattel in any way at present)...
How old is your power Wheels vehicle? Did you buy it before October of 1998 when million of them were recalled?
There have been 116 fires and over 1,800 overheating incidents involving short-circuiting, melting or failing with this toy. At least nine children received burns, and there has been $300,000 of property damage to 22 houses and garages. Also, there were 71 incidents involving the products' failure to stop, resulting in six minor injuries when the vehicles hit something. Mattel paid $1.1 million and recalled 10 million Power Wheels vehicles, which cost $27 million.
The battery chargers (even in the new models) do not stop when the batteries are fully recharged, which is one reason why you are shopping for new batteries. Pick the wrong replacement and it could rupture from overcharging.
Reply to
Guy Macon

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