Rick Findley
11-17-2007, 12:26 PM
Attached is a work sheet I used to track battery performance. Since my memory is short, I decided to write them down.
Tools need: Multi-meter, Stop-Watch and constant discharging device (I use a string of bulbs at 30 amps). Computer with MS Excel Program. Enter all Data Left to Right in rows, below the time line.
Connect the Multimeter to the Discharge Device. Start the Stopwatch, and discharge at the same time, watch the multimeter.
You will immediately get a high voltage reading like 7.5 to 8.2 - this is the "burst" you get the first few laps of a heat! Write that in the start column.
Then every 15 seconds record the voltage. The chart will generate the graph below.
What it means: With this knowledge of that battery, take it to the track, pay close attention to how the car/battery performs.
Gives you a baseline for any one particular battery to compare to in the months to come.
Compare several batteries "side by side".
Gives you a baseline from which a "race battery" becomes a "practice battery". New batteries to old batteries.
Depending on the motor - gives you an idea of how many RPM's your motor will run at a particular mark. With batteries, you will always loose RPM's during a race.
Irregardless of the discharge amperage, as long as it is the same from test to test, you can track the battery's performance.
On the track a motor does not place a consistant load on the batteries, so this theory and benchmarking only.
Only with experience, on the track and on the bench you will get an idea of how/what battery works for you!
The examples in the graph show that not all batteries are the same when they are new!
Tools need: Multi-meter, Stop-Watch and constant discharging device (I use a string of bulbs at 30 amps). Computer with MS Excel Program. Enter all Data Left to Right in rows, below the time line.
Connect the Multimeter to the Discharge Device. Start the Stopwatch, and discharge at the same time, watch the multimeter.
You will immediately get a high voltage reading like 7.5 to 8.2 - this is the "burst" you get the first few laps of a heat! Write that in the start column.
Then every 15 seconds record the voltage. The chart will generate the graph below.
What it means: With this knowledge of that battery, take it to the track, pay close attention to how the car/battery performs.
Gives you a baseline for any one particular battery to compare to in the months to come.
Compare several batteries "side by side".
Gives you a baseline from which a "race battery" becomes a "practice battery". New batteries to old batteries.
Depending on the motor - gives you an idea of how many RPM's your motor will run at a particular mark. With batteries, you will always loose RPM's during a race.
Irregardless of the discharge amperage, as long as it is the same from test to test, you can track the battery's performance.
On the track a motor does not place a consistant load on the batteries, so this theory and benchmarking only.
Only with experience, on the track and on the bench you will get an idea of how/what battery works for you!
The examples in the graph show that not all batteries are the same when they are new!