volts/amps question

this maybe a kinda thread jack, but its not too far off.
If the motor and gearing stays the same but the volts go up say from 4s to 6s Will the amp draw go up as well. Or will it stay the same because the gearing didnt change. I understand and correct be if im wrong but, if you gear down, the amp draw will drop as well correct? Or if you use a lower kv motor it will drop as well, but if the motor stays the same and just the voltage goes up. I know it will go faster(watts will go up) but will the amp draw go up as well, Or will the amp draw drop?

[speed demon]

Wow looks like I started something.

Let's say for instance on my rustler with the medusa motor running 4S then putting in a 5S but gear it down too the same speed will I have the same run time given both bats are the same mah?

I just got done doing some speed runs geared 35/76 and it's fast but want to go more but I'm out of room for more gear unless I go milling out the slot on the motor plate.

Would like to get abit more run time but have enough power to gear up for some sick speed(with a 5S) and keep my motor nice and cool.

My MM with fan now was 121 with the 5 tooth larger gear. My motor was up to 136 but without the fan for over half the run(nasty end over end over end over end crash). Thanks

[skellyo]

Originally Posted by speed demon

Let's say for instance on my rustler with the medusa motor running 4S then putting in a 5S but gear it down too the same speed will I have the same run time given both bats are the same mah?

It's unlikely that scenario will happen. You'd have to make sure that the gear reduction itself reduces the current draw by roughly 20% with the 5S setup. I'm not sure that gearing for the same speed with both batts would do that. I think the only way you would really know how close you can match the current draw of the setups is to run them on an Eagletree or similar datalogger.

[skellyo]

Originally Posted by dubkatz

this maybe a kinda thread jack, but its not too far off.
If the motor and gearing stays the same but the volts go up say from 4s to 6s Will the amp draw go up as well. Or will it stay the same because the gearing didnt change. I understand and correct be if im wrong but, if you gear down, the amp draw will drop as well correct? Or if you use a lower kv motor it will drop as well, but if the motor stays the same and just the voltage goes up. I know it will go faster(watts will go up) but will the amp draw go up as well, Or will the amp draw drop?

Yes, the current will go up when you go from 4S to 6S with the same gearing. Yes, gearing down will help reduce the current draw of the motor as you have reduced the torque load on the motor. At a given voltage, a lower kv motor of the same style will have a lower current draw. If you take that lower kv motor and apply a higher voltage, say 6S, it's possible it could still draw more current than a higher kv motor on 4S depending on the motor being used. However, the idea is that if a motor running on 6S draws the same current as a higher kv motor on 4S, you have essentially increased your power output by 50% while keeping power dissipation in the motor equal between both setups. Based on that, it's quite easy to see why a HV setup is preferable to lower voltage with high kv.