Why does our robot eat batteries

Why does our robot eat through batteries we go through a battery in like 1:50 second and the rest of the match we brown out when we move. We are running a 3 mini cim drivetrain (6 in total) with 3 775s and 1 bag motor for the rest of our manipulators and the 775s don’t run at full speed. Our drivetrain is geared for 17.5 fps so I’m a little confused where our battery is going. Could someone explain this?

Your robot doesn’t seem to have an excessive amount of power draw, of course that depends on how you drive it, how frequently you are moving actuators and how long your compressor is running.

You might want to look into this thread as some teams has problems with 2019 KOP Batteries

It depends a bit on the battery, like if it is old or has been used a lot then it won’t provide power for as long. If you’re using new batteries then I don’t know

Do you notice it browning out after using certain mechanism? Have you tested with a brand new battery? I would recommend not using this years KOP batteries, link to that thread above. definetly dont use the compressor all match, especially if you are only using for small applications

Our batteries are new 2018 season and 2019 our compressor will run 2-3 times a match it seems and 2 of our 775s run our elevator so…

notice any hot motors or tripped breakers?


could be a short somewhere thats not electrical taped well, could be a stalled motor, could be a bad connection to the pdp

Maybe the drivetrain but those are hard to get to.

How heavy is your robot?

Possible that some of the motors in your drivetrain are fighting other motors in your drivetrain. Check (1) polarity of all the motors (i.e. make sure that none are plugged in backwards), (2) connection between motor controller and motor, (3) configuration of motor controllers – check to makes sure that “Motor Output” parameters are the same for all the controllers (Can use the Phoenix Tuner to do this).

I’d also grab a brand new battery from your local Batteries Plus and see if it does any better. It’s possible that you just have crappy batteries.

130 total

I assume your frame isolation was measured in inspection? if it wasnt you should check it to see if you have a bad short.

1 Like

We checked it ourselves and there was no problem fyi this is our practice bot as well.

1 Like

Does this problem also happen on your competition robot?

Our practice robot last year was eating batteries for a while. It would stutter and brown out after running for a short period of time. One thing we did was apply a very short ramp on the drive train. So instead of applying 100% power to the motors right away when accelerating we would ramp them up over the course of maybe 200ms. Doing this helped.

I would check the resistance in your gearboxes and watch current draw, it sounds like something is working a lot harder then it should be. (We had a bad motor in one of our drive gearboxes.)


If you are geared single speed @17.5 ft/s @ 130lbs those drive motors are not going to be so happy. Can you post a power log from the drive station for one of these matches with the data for your drive pdp slots turned on?

1 Like

Seconding this. It would be very helpful to have DS logs

I have found that the most common reason for “eating batteries” is a robot that requires too much power to “skid steer” particulary for fast, single-gear (no shifting transmissions) robots. If the drive train has all high-traction wheels, all mounted in the same plane, so that all drive wheels contact the floor at once, then huge amounts of power will be needed to turn in place.

I haven’t seen your robot, but that’s my hunch – I would guess that you have either 4WD or 6WD with all traction wheels, and all in simultaneous contact with the floor.

Quick fixes are to replace some of the corner wheels with omni wheels (no lateral resistance) or, as an even quicker low-budget fix if needed or an experiment to help diagnose the problem, wrap slippery tape (like clear packing tape) around the corner wheels and see if that helps.


By chance are you running your drive base slowly over a long period of time? Electric motors are very inefficient in power usage when they are running slowly. Maybe you are drawing more current while your drive base is inching. Also check your compressor(if you have one) because that uses a lot of energy.