How to run two 6v motors with a 20v battery

PeAcEmArE

New member
Ok so to fill you in my daughter has a little 6v disney frozen 3 wheeled scooter. It had one 6v motor and battery but it didnt drive well in grass. So i put a dewalt 20v max 5ah battery in it and it hauled but still gets stuck sometime because on one wheel spins. So i bought a second motor and installed it, but my problem is that with both motors hooked up they dont spin, but if i unhook one it works fine and both motors work, just not at the same time. It also has a forward and reverse selecter and a foot pedal switch. My question is do i need a different switch or how to i make both motors worj at the same time.
 

GoldDigger

Moderator
Staff member
The Dewalt battery pack may contain a current limiter for short circuit protection. It would sense the high current and lock out the battery until you disconnect. Repeat indefinitely.
Does it even click or twitch when you try to start with both motors?
You realize that you risk burning out the motor if you get stuck and keep on the throttle?
 
You could open the battery and re-route the jumpers.
If the 20v Max lithium ion battery is nominal 18v, then you will likely have a couple parallel banks of 5, 3.6v batteries connected in series.
So, if you parallel several banks of 2, 3.6v batteries in series, you will have nominal 7.2v. This will increase the Ah rating aswell.
 

MD84

Senior Member
Location
Stow, Ohio, USA
I would guess you wired the motors in parallel. I would try wiring them in series. A lot of the dual motor toys like that use two motors and have a switch which changes the motors from series to parallel connected for a low and high speed. They are not using a battery rated over three times the nominal motor voltage.

I would not recommend bypassing any of the current limiting features of the battery protection circuit. It is there for a reason. Some of the li-ion batteries are like a bomb. You want the protection in place.

You could also consider getting a speed controller from a scooter store. It would allow you to limit the current and also setup a variable throttle.

I would try them in series for a quick test. It will go slower but last longer and there will be less stress on the motors. They will probably still be faster than stock.
 
WHY 20V ?

WHY 20V ?

How are you connectting the two motors to the 20v battery ?
Why did you choose a twenty volt battery to start with ?
You need a better battery system.
Less volts but more amps.
What is the ratings of the two motors please ?
 

mgookin

Senior Member
Location
Fort Myers, FL
The Dewalt battery pack may contain a current limiter for short circuit protection. It would sense the high current and lock out the battery until you disconnect. Repeat indefinitely.
Does it even click or twitch when you try to start with both motors?
You realize that you risk burning out the motor if you get stuck and keep on the throttle?
Could he just put two battery packs in parallel?
 

cpinetree

Senior Member
Location
SW Florida
There is a whole forum for hacking "Power wheels" and the like
Forum Link: http://www.modifiedpowerwheels.com/forum/default.asp

Also just google power wheels hacking, there are tons of great ideas for making them go fast.

A few ideas for helping them in the grass is adding some studs to the plastic tires (Screws ran into them) as well as adding a rubber inner tube all the way around the drive wheels.

When I have added batteries I use 6v or 12v emergency light batteries (sealed lead acid), they are small and inexpensive. They also have larger ahr ratings.
You may want to stay around 1.5 to 2 times the motor voltage rating. As others have said, that will depend on whether you run the dual motors parallel or in series.

Have fun!!
 
Last edited:

GoldDigger

Moderator
Staff member
Quite true, it changes the amp rating
-But NOT the amp hour rating.
:thumbsup:
Quite false
Rewiring from series to parallel to get half the voltage and twice the amperage does in fact double the amount hour rating of the pack. Each half still has the original AH rating rating and there are two of them. But the product of AH and V, namely watt-hours. stays unchanged.
The fallacy is that we often speak of the. AH rating as reflecting the energy storage of a battery. It is proportional to the energy storage, but only if the voltage is kept constant.
 
Top