I have purchased this lithium polymer battery (11.1V, 5500mAh), to power a robotics project. The project uses a Raspberry Pi, three continuous-rotation servo motors, a couple of LEDs and a Sparkfun Geiger Counter.
I've also set up a voltage regulation circuit, as shown with the battery below.
The battery is behaving very strangely. Firstly, very loud cracking noises were made when I accidentally short circuited it. Is this normal? Secondly, when testing it with a multimeter, both the (fairly thick) wires got very hot. The ammeter setting (when I turned the dial to the one with the 200 on it) showed a ridiculously high reading – something in the range of 26A. When I plugged the battery into the voltage regulation circuit and turned it on, the LED (5V), came on dimly briefly and then faded out quickly. I thought that the regulator had failed and the LED was burnt out, but when I checked by connecting a power pack, it was fine.
What's gone wrong? Do I need to get a smaller battery? Is my circuit for voltage regulation wrong? Do I have a faulty regulator?
Thanks for your help,
Archie
simulate this circuit – Schematic created using CircuitLab
Best Answer
The amp meter has ideally a zero internal resistance, so when you connect it directly without anything in series you're basically shorting the battery. Hence the high current reading. Since you have a high current the wires get hot because of all the power they are dissipating.
Best case scenario, you're battery simply need to be recharged. I wouldn't be surprised if it was damaged though. Maybe somebody with more experience on batteries can add on that.
As a general rule, remember that an amp meter always goes in series with the component which current you want to measure. If nothing else is there, you will short the circuit.