Leaking Batterys

[Alan Anderson]

Originally Posted by MWB

the battery came off of the charger at around 13v we tested it.

Unless it sat for a few hours first, or you put a small load on it for a few minutes before you tested it, you were measuring the battery's "surface charge". That tells you almost nothing about the actual state of health of the battery. A badly sulfated plate, or even a broken one that only has a small fraction of its bulk actually connected, can still be charged to full voltage. It just won't have anything like the capacity it should.

A stack of hearing aid batteries can also read 13v, but they won't run a robot.

[MWB]

On our driver station after running the robot for awhile it read at about 12.6 so the battery is in good condition. They have only been to one regional.

And for the hearing aid batteries... it might be able if you stack them and then wire them in parallel.

[Ryan_Epperson]

Thank you for this wealth of knowledge. As a former FIRST student and 3 year mentor i did know that running the batteries below 10.5 volts can ruin them.

All of the batteries are stored in upright positions and mounted in the robot in a horizontal position. None of them have been dropped or damaged in any way. We think that it's a combination of the battery voltage dropping and rookie luck of getting 2 bad batteries.

As a result of this, the team is looking into doing a load test this summer to further our knowledge of the batteries and understand for ourselves why the problems occurred. Thanks for the link to the load tester!

We are also looking into making is a rule to mount batteries in a vertical position in the following rules to help avoid any possibility of leaking because of the orientation of the battery.

- Ryan Epperson
Team 3256 Mentor