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I help organize a robotics competition in my home town. For the past 16 years, we provided each team with two 12v battery powered drill. They were cheap, easy to find and provided us with 4 batteries, two chargers and two motors. The battery chemistry was NiCd and provided us with two easy access port.

They shorted them, they depleted them, they beat them up to death and nothing spectacular ever happened. Only one time did one basically inflated.

However, NiCd 12v drills aren't available anymore. The industry defacto standard is now 12v Lipo or 18v Lipo. From my understanding, Lipo are much more tricky to use in term of charge, discharge, c rate etc..Furthermore, it gives access to all the intermediary cells on the battery connection header.

With that in mind, my questions are:

  1. Am I right to assume that those batteries are more dangerous to use by error prone teenagers?
  2. Are there any way to mitigate any risk?
  3. Bonus: what kind of chemistry would you recommend instead? I know I can't ask for a specific product suggestion, but having a general idea of what chemistries are safe would be really helpful.
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1) Yes, defective Lithium batteries may burn or explode, but properly handled and protected, they are safe.

2) Not knowing what exactly you're doing:

  • Riggid packaging, so people can mishandle the battery without blowing up.
  • Prevent short circuits, deep discharging and overcharging with proper protective circuits.
  • Train your teenagers what happens if you treat a battery wrong. There are tons of videos on youtube. Don't do plain theory, but also add explosions and burning batteries. Teenagers (and adult engineers) love explosions.

3) I would recommend staying with Lithium Ion batteries. Best you can get on the market and as long as someone knows what they're doing, they're pretty safe.

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  • \$\begingroup\$ To give context, we open the drill, cut the wires that are going to the trigger, remove the trigger and expose the wires that are coming from the motor...now they get 4 wires 2 for the motor and two for the battery socket. They use the battery to power the robot through a 30 amp fuse. I saw people shorting batteries quite often to be honest. \$\endgroup\$ – Simon Marcoux Sep 5 '18 at 17:19
  • \$\begingroup\$ Perhaps there won't be another robotics competition hahaa. Shorting lithium ion is a risky game. Perhaps stick to some big NiMH batteries or alkaline cells. \$\endgroup\$ – TestDeviant Sep 5 '18 at 17:30
  • \$\begingroup\$ @TestDeviant this right there is the sole reason why I wrote that question in the first place. However, the spotlight is pointed toward Lithium Ion to the point where nothing else is really ''there'' on the market... \$\endgroup\$ – Simon Marcoux Sep 5 '18 at 18:19
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    \$\begingroup\$ While the drills might not be available, there are plenty of NiCd battery packs on the market still. Perhaps you should consider supplying your teams with piecemeal components. Not as convenient as just buying a drill, but certainly safer. \$\endgroup\$ – Maple Sep 5 '18 at 19:29
  • \$\begingroup\$ Perhaps a polyfuse or overcurrent protection device could be used in line with one of the battery leads, that way each time the leads are shorted your protected. I've never used them before. Just an idea. \$\endgroup\$ – TestDeviant Sep 5 '18 at 20:01

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