Dead battery!

[JamesCH95]

Everyone keeps saying check the battery terminal to make sure it didn't short, if it did, there would be large scorch marks on the chassis where it made contact (I've seen 6awg get arc-welded onto metal by shorting). Also, check your breaker block, there was a mfg warning that said stuff inside of it may come loose during shipping and you should open it up to check for loose hardware, that could be the cause of all your problems. I would also try using a current sensor (not FIRST one, the one on a multimeter) to measure how much current you are drawing while running. In 2003 we were drawing 60amps with the bot up on blocks and the current sensor helped us pinpoint the problems (loose electrical connection and one of the transmissons). Good luck!

[Sparks333]

Originally Posted by JamesCH95

Everyone keeps saying check the battery terminal to make sure it didn't short, if it did, there would be large scorch marks on the chassis where it made contact (I've seen 6awg get arc-welded onto metal by shorting). Also, check your breaker block, there was a mfg warning that said stuff inside of it may come loose during shipping and you should open it up to check for loose hardware, that could be the cause of all your problems. I would also try using a current sensor (not FIRST one, the one on a multimeter) to measure how much current you are drawing while running. In 2003 we were drawing 60amps with the bot up on blocks and the current sensor helped us pinpoint the problems (loose electrical connection and one of the transmissons). Good luck!

On the multimeter with as a current sensor:
You want to watch out with this one. Most multimeters have three ports: a sensitive voltage/resistance port, a ground, and a high-amperage port. Most meters are set up with the sensitive port and ground, and if current is measured with that probe, it will fry the meter. Even the high-amperage port has a limit. On mine, it's 10amps for 15 seconds. If you run, say, 50 or 60 amps through it, it's toast in no time flat. Read your multimeter carefully to see what its current limit is.

Sparks

[Burne S]

Question: Our team kinda lost (As in completely drained) a battery over the course of testing. We've tried almost every suggested place on the site, but nothing worked.

We need replacements and spares. Where might we find FIRST competition-legal batteries?
~Burne

[Sparks333]

Originally Posted by Burne S

Question: Our team kinda lost (As in completely drained) a battery over the course of testing. We've tried almost every suggested place on the site, but nothing worked.

We need replacements and spares. Where might we find FIRST competition-legal batteries?
~Burne

If you read a bit farther back, you'll notice that ahecht said that a sealed Lead Acid battery (the kind we use) will be trashed if voltage goes too low. That tallies with my own knowlege of SLAs, and I think others would agree. In short, I think that you guys are sunk. Look around for other batteries, or maybe contact FIRST.

Sparks

[Al Skierkiewicz]

Guys,
The gell cell batteries we use can be totally discharged without damage under normal loads. A dead short is not a normal load. In the event the battery we are discussing came in contact with the frame quickly, there is likely nothing more than a scrape where the contact took place. Arcing and burn marks are indications of high resistance contacts for low voltage DC. A completely discharged battery will take several hours to recharge even using the 6 amp charger.
Don't discount the possibility that the battery sustained mechanical damage when used in a robot that ran into a wall. You are dealing with a device that has a lot of mass, and that mass is concentrated in defined areas within the case. Lead is not nearly as strong as steel and a fracture in any connective structure (internal connections and plates) will result in battery failure.
The batteries are available from a variety of sources, including battery stores, McMaster and Digikey. Be sure that you order is the ES or EX type battery.
Most multimeters only can display and measure 10 amps or less and are internally fused for protection. The popular Fluke meters have two internal fuses, one for 300 mA and one for 10 Amp. To measure current on the robot, you need a current probe. Fluke makes a few nice ones but they are almost as expensive as the meter itself. They clamp on to wires under test. Remember that they can only measure current on one wire at a time. If you measure both the positive and negative leads of a motor at the same time with a clamp on probe, there will be no current measured.