Car Battery for post-season bot

i want to get a lot more speed and power on 4 CIMs and i want to use a car battery at 12v. Is this possible, and if not, can i use two EX batteries that we use at comps? I want 4 victors in it and dont know if the high AMP will cause the fuses to break. I also want to use one spike for a superstructure and run the compressor as well. Im planing on making a robot that can carry a heavy load, go fast, and also will have some cool superstructure that uses the actuators (i dont know what superstructure i will do, but know i want to use pneumatics). So, can anyone help and answer my questions about if its possible to use a car battery?


A car battery will not give you more speed or power. Only more runtime. Also, I would not recommend it as they are not sealed gel cel type. Just get a giant battery from BB battery or your local battery store. It shouldn’t cost too much. While you can use a car battery, I wouldn’t due to spillage and safety concerns.

Four motors or six doesn’t matter if you don’t get the reduction right to put the motors in a correct spot on their respective curves. A car battery will certainly let you run longer but you will be stressing the other components if you plan to run for a greater length of time then two or three minutes. Many teams are running very close to trip temperature on the breakers in a two minute match. You might have to redesign the electrical system if you plan on a longer run time. Whereas the kit battery is capable of several hundred amps in short bursts, a car battery is capable of 1000’s under the same condition. The choice of that battery will change a lot of design criteria.

well, i want longer battery life, that is good enough for me. My design was changed so i dont need extra power to the motors or go faster. I just need to have 4 motors running, a compressor, and one solenoid. So, i dont think ill over heat it with the EX battery we use now in comps. The motors wont be running when i use the solenoid to pressurize the actuator. I just want it to run a like 20-30 minutes minimum. I can add a lot of fans and heat sinks for over heating issues, and i dont understand why car batteries are not sealed. Well, how do i solve the amp problem?

I would be concerned about using the CIMs for a long amount of time. They do not have cooling airflow like the drill motors do. If I remember correctly the CIMs were designed for short use, something like raising the front trailer wheel on a camper.

Of course you can modify the motors for non-competition use, but I dont know if they even have the internal blower blades like the drill motors do?

You might want to look into something like an electric scooter motor, or electric wheelchair motors - something that is designed to be run continuously.

Many car batteries are of the sealed type in a sense. Our are a gelled electrolyte not a liquid, which allows them to be used in any configuration including standing up. Car batteries cannot be used that way. We pulled a dead chalupa motor apart just last night. There are no fans internal, they are designed for short term light load uses. Fans will help a little but not much if you are running heavy loads for long periods of time.

well, than is there a vey inexpensive motor/engine that can use a car battery? I can mount the car battery vertically, so there is not a problem there. The only problem is motors from what im gathering from this information. Oh, and the heavy load is a person, just to let people know. Im building a transportation device for a fundraiser for cancer, its call Relay For Life, and i want to build it so people can ride it around a track. I dont want gas engine. So, anyone know a cheap motor/engine that can work for my project? My max spending limit is like 100 bucks. But even that is very high. I wanted to use CIMs as myt team already has them.

You won’t need 4 CIM motors for that purpose. If you are low on funds and want to use KOP parts, try using the FP motors with the stock transmissions. Those things are designed to cart people around.

I see this project getting very dangerous very quickly. Do not mount the car battery in any orientation other than horizontal.

i can mount it in any direction. thats what i ment to say. i thought car batteries are mounted vertically, the battery orientation, not the mount. doesnt mater, i can mount the battery in 360x360x360 degrees. Any direction. I just need to modify the design to do that.

If you need more capacity, there are ‘car batteries’ that are sealed gell cells. Look at ‘Optima’ brand for one.

yeah. thanks. now the engine/motor problem is my issue. thanks again for your guys’s help.

I agree with Tom that two stock FP motors with transmissions are the best bet for you. You might need to follow up with a little different transmission (final gearing) to make up for the fact that you are driving bigger wheels than what the transmission is intended for. The kit battery might getyou around the track but a larger version of the same battery might be a better bet. You can buy new ones but there are various surplus shops around that might have used or surplus devices for sale. You will need to check around in your area. Since this is for charity, a local battery shop or car parts outlet might be willing to lend you or donate a battery of more capacity.

Im thinking of the 8 inche wheels, only because our team uses a 6wd on our comp robots and use 6’s for the wheels. We have a lot of 8 inch wheels. If those are not good, what will be. And, is there a way i can integrate 2 fp motors together. We have like 4 of them. Or will 2 be enough? A car battery will do the work, im almost positive from my research, so that will be the bigger battery.

I have seen people use old generators from car engines for small electric go-carts. Not alternators, it has to be a generator. VW bugs had generators up till around 72 or 73 (not sure the year they swithed to alternators).

There are two things that make these work well:

  1. the are designed for a 12V application
  2. they have a separate field winding that you can use to vary the speed. The stronger the field, the slower the speed (with more torque)

also they have fan belt pulleys already on the shaft. I would take a wild guess that you can get maybe 5HP out of one of these!

just to give you an idea, this is what they look like: the ground is through the metal housing, one connection is the armature, the other is the field

The smaller wheels should be better. I was envisioning you modifying a regular wheel chair rather than building up from scratch. The FP motor and transmission is used on ride toys for 60 pound kids as a single unit. Two of these should be good for up to 120 and may work up to 150 pounds total weight. The larger Chalupa motor is used on a scooter type device. I repaired one once for a friend and rode it for several minutes. I am well over 200 pounds (no I’m not going to get scientific and give you an exact weight.) and it carried me at a relatively quick pace. It did have a safety device that required you to get the scooter up to speed before the motor could be engaged. It contained a centrifical switch that closed when the motor was spinning at more than the minimum speed. It used a simple toothed belt transmission to couple to the rear wheel.

I cant find any lartger CIMs that will work with 12V. I found some at 24V, but i dont know if i can use Victor 883’s, we have a lot and want to use since we cant use them in comp anymore. I dont want to blow the speed controllers out. The robot, kart, im looking at weighing about 90 pounds max. and the person weighing about 200 pounds max. So it needs to be able to push 300 lb. Of course, im using two motors. but i need to know if i wont blow up the victors.

Ken, does that attach to the wheel to recharge the battery while it runs? Im very new at electronics outside of FIRST and guitar electronics. That will charge the 12V battery, but if i get a 24V, do they make them?

I believe ken was indicating that a generator can be used as a motor and it already has a pulley attached and a few nice mounting brackets. The larger CIM motors in the kit this year are the ones I was talking about. (we call the chalupa) If speed is not important, I would think you could use two of those motors with a larger 12 volt battery and you should be OK for once around the track.

well, im a little skeptic of using a lot of FIRST electronics because two years ago, i found this out today, that we tried building a go-kart and the electronics fried because of amp over heating the motors. Will the same thing happen with a lager battery. Thats why i want to get a car battery and bigger CIMs as the amps will be used and not fry the electronics. Thank god im not building without designing on this or i would have had an expensive problem. ahahah. thanks again for all your help.

What Al said - you can use a generator from a car for a motor.

I dont see any reason why you could not run it at 24 V - it will have 4 times the power. The limiting factor on motors is the current level that melts the armature, and the max speed (that rips the windings and commutator off the shaft).

There are specs for the Victors on the IFI web site. I think they are rated for 12V only, but check for yourself, they might have other ones intended for other applications?