KV and runtimes

[BrianG]

Yeah, but it's usually not that much in practicality. High kv motors, having fewer turns, have less resistance. So, current is higher, but resistance is lower. There are more losses to be sure, but it's not that much.

Take a monster truck; judging by the average runtimes people get, the average power required is around 300w.

Let's say we are using a 1515/1y (kv 2200) on 4s. With that 300w average power figure, the average current is around 20A. Losses are around 2.4w, which is 0.8%.

Same vehicle and average power, but with the 1515/2.5d (kv 1650) on 6s will have an average current around 13.5A. Losses would be around 1.8w, which is 0.6%.

See? Not really enough to consider IMO. Yeah, bursts currents/power will be higher, but those are short in duration. Even so, the percentage of losses will be in about the same proportion.

But we aren't really talking about high kv/low V vs low kv/high V comparisons really. The question seems to be: Given a specific voltage, what is better; high kv geared down or low kv geared up. But really, the end is the same.

[lincpimp]

Also worth some mention is vehicle weight and tire size...

I have found that most 4s combos are just not capable of handling a large MT with big heavy tires... Just going up to 5s makes a huge difference. Seems like that knocks off about 20amps draw, and makes the batts and esc alot happier. In an 1/8 buggy it does not really matter but in the heavier vehicle it does. Plus it all depends on battery quality too. If you plan to run a 30+c lipo you may get away with 4s, but going up to 5s will make it easier on the battery.

I do agree that the 2000kv motor will give good performance on 4-5s and if you are gearing for around 35mph it will run cool and produce great power on either voltage.

[littlegiant]

Originally Posted by BrianG

But we aren't really talking about high kv/low V vs low kv/high V comparisons really. The question seems to be: Given a specific voltage, what is better; high kv geared down or low kv geared up. But really, the end is the same.

Oh I see. Thanks.