Here are some numbers from my sweep of batteries discharged at 4 Amps.

I ran two sets of batteries, so each statistic has one value for each battery. (I didn’t run a 2nd set of Eneloops because I didn’t have enough spare ones to form two complete sets.).

Larger values are better For all these statistics, except for Internal Resistance.

[LIST=1]

*]Vex NiMH 7.2V 2000mAh Battery

[LIST]

*]Runtime (down to 5.1V): 26m 19s, 22m 31s

*]Total mAh delivered: 1753.1, 1499.2

*]Voltage at end of 5 min: 6.409, 6.61

*]Voltage at end of 10 min: 6.372, 6.575

*]W•hr delivered in first 5 min: 2.1823, 2.2447

*]W•hr delivered in first 10 min: 4.308, 4.439

*]Internal Resistance: 0.248Ω, 0.224Ω

[/LIST]

*]Vex NiMH 7.2V 3000mAh Battery

[LIST]

*]Runtime (down to 5.1V): 40m 45s, 41m 27s

*]Total mAh delivered: 2711.1, 2762.5

*]Voltage at end of 5 min: 7.372, 7.305

*]Voltage at end of 10 min: 7.326, 7.276

*]W•hr delivered in first 5 min: 2.4953, 2.5041

*]W•hr delivered in first 10 min: 4.9399, 4.9284

*]Internal Resistance: 0.080Ω, 0.078Ω

[/LIST]

*]Vex NiCD 7.2V 2000mAh Battery *(discontinued)*

[LIST]

*]Runtime (down to 5.1V): 25m 13s, 23m 25s

*]Total mAh delivered: 1678.4, 1561.1

*]Voltage at end of 5 min: 7.176, 7.068

*]Voltage at end of 10 min: 7.117, 7.005

*]W•hr delivered in first 5 min: 2.4558, 2.4370

*]W•hr delivered in first 10 min: 4.8316, 4.7786

*]Internal Resistance: 0.118Ω, 0.115Ω

[/LIST]

*]Vex NiCD 9.6V 1000mAh Battery *(transmitter)*

[LIST]

*]Runtime (down to 7.5V): 5m 38s, 6m 27s

*]Total mAh delivered: 426.5, 460.3

*]Voltage at end of 5 min: 7.726, 8.327

*]Voltage at end of 10 min: n/a, n/a

*]W•hr delivered in first 5 min: 2.7262, 2.9283

*]W•hr delivered in first 10 min: 3.4181, 3.9171

*]Internal Resistance: 0.354Ω, 0.298Ω

[/LIST]

*]Six Eneloop AA cells in a Vex AA Battery Holder

[LIST]

*]Runtime (down to 5.1V): 0m 12s (yes, that’s correct!)

*]Total mAh delivered: 13.5

*]Voltage at end of 5 min: n/a

*]Voltage at end of 10 min: n/a

*]W•hr delivered in first 5 min: 0.0734

*]W•hr delivered in first 10 min: 0.0734

*]Internal Resistance: 0.675Ω

[/LIST]

[/LIST]

It takes a while to crunch all those numbers from the raw data (almost fifty thousand samples). It’ll take a while longer to get graphs up, but I wanted to post these results. They are not very surprising:

The new 3000mAh NiMH batteries are the best in every category when discharged at 4A. The 2000mAh batteries (both NiCd and NiMH) are close behind.

However, looking at the Watt•hours provided by the first five minutes of a transmitter battery, you will see it delivers more power because of its higher voltage. They were really struggling at 4A, though, and these transmitter batteries won’t be moving on to the 8A round.

The Eneloop batteries look like a complete failure from the data, but that was simply because they have too-high of an internal resistance to be useful at 4A. They were not fully discharging this quickly, but they simply couldn’t keep the voltage above 5V with a 4A load. I discharged this same pack at 0.5A and it provided over 2000mAh. They are very useful for Wii remotes and the like, but not much good for robots. They, too, will not be moving on to the 8A round.

Cheers,