Problems about battery

Hi,I’m a member in VEX team in China,and our members got a problems(Maybe I got terrible English lol)
We found out our batteriescannot be used for more than 2 races,but it’s not enough for training(We had only two battries TAT).
How do you extending the service duration of battries?Can controller be supported of paralleling battries?We’re waiting.

Hello to prolong your battery life don’t fully discharge it after every run. Or wait till it dies. Northeast Battery | Blog | Prolong Battery Life I found this article hope it helps. Unfulenlty for v5 you can only use one battery , unlike the cortex counterpart.

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Hi @SparkKnight, welcome to the VEX Forum!

The only way to run a robot for longer on a single charge of a given battery is to reduce the amount of power the robot consumes.

Take a close look at all the mechanisms on your robot to see if any are experiencing too much friction. Bearings that are slightly misaligned with each other, low strength shafts that are slightly bent, and moving parts rubbing against stationary parts can all be big sources of friction. One thing you can do to feel for the amount of friction is to take the motor(s) off a mechanism and feel how hard it is to rotate the mechanism by hand. For something that spins continuously (like a drivetrain), if you spin it up by hand it should spin freely for a good while (10 seconds or more) before coming to a stop. Some fine-tuning may be needed to get things running smoothly (precise location of bearings, adding spacers, etc.)

You can also use a bit of lubricant on shafts or gears to reduce friction – just be sure to follow rule R8b when doing so.

Another thing to look out for is motor temperature – if a motor is hot to the touch after driving the robot around for a while, that’s energy from the battery that is being used to heat up the motor instead of driving the robot, and a sign that there may be too much friction in that mechanism.

If your batteries are particularly old then wear on the battery itself might be a concern – the maximum capacity of lithium batteries does drop over time, and may drop faster depending on various factors. If the robot gets different run times on different batteries, that’s probably why.

It could also be none of the above. 4-5 minutes (roughly 2 matches) does seem a bit on the short side for a single battery charge, but if you are running all 8 motors flat out the whole time, that might just be as good as it gets.

Of course, buying additional batteries will also help you run the robot longer before needing to stop to charge.


Hey @SparkKnight, Welcome to Vex :smiley:!While I don’t exactly know what you mean, it might just be a faulty battery.

Thanks for your advice.But I found more problem:
Our robot use six motors to drive,when it runs for a while,the robot will stop and battery will blinking red light.What’s the problem?

This article has more information about what the different flashing lights on the battery mean:

According to that page, a flashing red light (5 flashes/sec) in the position closest to the button means the battery is “critically low”.

If you start with a fully-charged battery, roughly how many minutes can you drive around before the red light comes on?

Have you taken a look at your drivetrain for sources of friction? If you take the drive motors off and spin the wheels up by hand, they should spin freely for a while (>10s) before slowing down significantly.

You mentioned you have two batteries – do they both last the same amount of time? If you’re getting the same short runtime out of two different batteries, then the problem is less likely to be with the batteries themselves.


We haven’t have full-charged battery in this time.At begin 3 green light has on and It used about 5 minutes?
By the way,Out teacher ordered more batteries.

Over time the capacity of lithium ion batteries do degrade, so maybe your battery has just been used a lot.

you see this doesn’t work right now as batteries are very much out of stock

capacitors wear out