Motors, Batteries, and Chains

MarkCrCo

OK so I stripped two motors and batteries out of some rechargeable drills. The first diagram is my current set up. It works fine when the wheels aren't on the ground. The motors are connected to a chain drive that increases the torque and reduces the speed. If I put it on the ground the chain immediately jumps of the motor sprocket. I was thing that if I put the batteries in a parallel configuration that runs both motors This might help the problem. I think it would reduce the speed but even if I cut the speed in half I'd be OK. Maybe not so much with the reduced torque but I'll have to try it to know. I'm concerned about recharging the batteries in this parallel configuration and also not even sure this will do anything for me. Any ideas or suggestions that don't cost more money??? The last diagram cut off the motors and one battery when I uploaded it but hopefully you can see the idea.

Hal Albach

A chain being thrown off a sprocket usually is caused by either misalignment of driving and driven sprockets or too much slack in the chain. Circuit wise, the first two circuits are the same and result with the motors still running at the same speed. The third circuit has one side of both motors tied directly to the batteries, so the motors will only run in one direction.

When drawing SPDT switches in a diagram, the three points of the switch form an acute triangle. The point furthest away from from the other two points is usually the common lead. The way you have it drawn threw me off at first. If a DPDT switch then a light dashed line is drawn between the two "swinging" arms of that switch to show mechanical linkage.

MarkCrCo

My circuit drawing tool isn't all that good or I am not good at using it. The third diagram I deleted the "wire" that should still come down to the lower motor wire of the upper motor. It also deleted the motors and the second battery when I uploaded it. I didn't know if the load caused by both motors running from a single power source would have any effect,

MarkCrCo

I also didn't know what would happen when they were recharged with this parallel setup still in place. also all the switches are actually relays controlled by the micro controller.

Hal Albach

IMHO, I would charge the batteries separately, especially if you are using the charger that came with the drill.
You might want to look at setting up a PWM driver for each motor so that the motor speed can be reduced. Your current setup applies full battery power to the motor, putting a lot of stress on all your mechanical components at startup.

MarkCrCo

This hopefully will be a prototype for a real product so I don't think the average consumer would want to pull the batteries out to recharge them. They already have to do that for the controller. The board that was in the drill has some connections that were probably a potentiometer based speed control but I haven't figured them out. I bought some digi-pots but haven't made that work ... yet.I guess the best setup is the existing one with more precise chain alignment.