We are often asked how long a particular battery pack will run in a given vehicle, so here we will break down the process so you can calculate it for yourself..

First you must know the approximate current drain for your car. You can use the Mini-Meter Pro (See Tutorial Here) to measure this, but you only get a bench reading.

For on the track testing, you need a more advanced solution such as the MicroPower V2 USB E-Logger. This device goes in between your battery and the car and is small enough to be used on 1/28th scale cars. This 17 gram wonder gives you an amazing amount of information. The two data streams we typically are concerned with are voltage and current which are plotted below. After running typical laps for 8 minutes on an RCP track we determined that the average current draw is 1.2 amps for a Mini-Z AtomicBuilt Manhattan.


Graph Explanation: The blue line represents the voltage which started at 8.3 volts and gradually tapers off which is the advantage of lithium. You always hear about the flat discharge rate, but here you can actually see it. The red line represents the current which spikes as high as 8.2 amps, but averages 1.2amps over the 8 minute period. The gaps are crashes, with the largest gap being at the far end of the track, so it took longer to right the car. These will skew the average current, but for our purposes here, it does not matter. The time is plotted across the bottom and is measured in seconds. This test ran for 500 seconds or 8.3 Minutes.

Now to the hard part, break out your calculator and lets get down to business. First you need to know that 1 Amp is the same as 1000mA. The "m" in "mA" stands for "milli" which means 1000.

Lets assume we are running a 650mAh Mini-Z Car Lithium Ion Pro 2S such as the one in the Manhattan. We know the Manhattan requires 1.2 Amps or 1200mA of current and the battery pack is 650 mAh. The math will be as follows.

Consumption per Minute:
First we need to figure out how much current is consumed each minute of operation. The minute part is easy. Next you need to convert the 1.2 amps to 1200 mAh the simply divide the two figures as shown. What you end up with is the amount of current consumed per minute.

60 (Minutes) ÷ 1200mA = .05 Amps per minute

Battery Pack Stamina:
Now we are down to the nitty gritty. By dividing our pack mAh rating by the consumption per minute figure, we get the number of minutes the battery pack can sustain the demand.

650mAh x .05 Amps = 32.5 minutes

Note: This works for all types of batteries, Lithium, Ni-Cd, Ni-MH, ETC. Bear in mind that not all battery packs will deliver what they are rated. Take a look at our AAA NiMH Battery Comparison Data to see how the different batteries stack up.