Battery Testing

This test was carried out around 2010-02-05 using the CarComputer and MotorSpeedController to measure the voltage, current and temperature and store the results every second. The load used was RPod's light bulb loads. This consist of a bank of 5 x 12V 50W halogen spot light bulbs.

The batteries tested were the RR11 and RR12 batteries. These were the ones that were new at the 2008 final. They were raced in the 2008 final, had a test discharge to 11.8 Volts prior to the 2009 final and were then used at the 2009 final. They were the ones that unexpectedly collapsed in Dan's last stint of the 2009 final.

Below are the discharge graphs for RR11 and RR12. The tests where done at 20 degrees C and at about 21Amps. The graphs only show the Voltage. RR12 looks fine, it gave out 48 AmpHours down to 11 Volts (90% discharge) and so with a full race discharge (10.5 Volts) would have given about 52AmpHours.

RR11 is a different story however. This gave only 22 AmpHours .... It is obviously faulty in a big way. This is strange as it is part of the same pack that RR12 is and has been used in the same way as RR12 and for only two races.

The only difference that I know of is that during the battery tests before the 2009 final we discharged RR11 only to 11.8 Volts while we discharged RR12 further to 11.3 volts. This should have made RR12 worse than RR11 however ... These tests showed that RR11/RR12 looked fine although the test of RR11 did not discharge it very far.

The SG readings of RR11 were even across the cells but had a quite high value of 1275, more than any of our other batteries. RR12 had an SG value of 1250. Another thing of interest is how much the voltage recovered after the load was switched of on RR11, much more than RR12 ...
BatteryTest graph