ZA_Fourie

Has anyone compared the difference in performance, motor and esc temps etc. etc. when using Low voltage (2 cell setup - 7,4V) and a larger pinion (34t) or using high voltage (4 cell setup - 14,8V) with a smaller pinion (18t)?

The 2 cell setup will be lighter in weight but will require more torque, and the top rpm will be half of the 14,4v setup.

The 4 cell setup will be heavier and use less torque but the top rpm will be much higher.

And why is nobody runnning their cars like this?

ThePanda

iTrader: (68)

Its less about if it can be done, but if it should be done. I wouldn't want to run anything other than a 2s is any 1:10 vehicles. They are just no made to be able to take the power. Other than 4wd sct. But still. Overall though higher voltage is more efficient and will give you cooler temps and longer runtimes, but you usually apply this to 1:8 with 4s v 5s v 6s comparisons.

oeoeo327

iTrader: (75)

Most 1/10 scale vehicles don't have the room to accommodate 2 full-sized batteries, or 1 4 cell pack. Even if the space were available, the chassis would be so poorly balanced that handling would become an issue.

1/10 scale cars designed to run on 4 cells would require a "clean sheet of paper" approach to design from practically every aspect to work well; everything from chassis to electronics would require significant changes.

ZA_Fourie

But what if the 2S setup with the larger pinion is taken to 1/8 scale racing?

ThePanda

iTrader: (68)

What exactly are you asking here?

Some people do run lite ⅛ e buggy with 2s or 3s and sct size electronics on small indoor tracks, but I'm not sure that's what you mean?

ZA_Fourie

I want to use a smaller spur gear and larger pinion to make up for the lower voltage.

Let say the current setup in my 1/8 buggy is 62t spur 18t pinion and 1900kv motor with 14.8 lipo. The total rpm comparision would be 18/62*1900*14.8 = 8163 rpm on the centre diff, less torque but higher rpm.

What I want to achieve is use a 48t spur with 32t pinion, 1900kV motor but use a 7,4V lipo setup. The total rpm comparision would be 28/48*1900*7.4 = 8201 rpm on the centre diff, but more torque less rpm.

Then I can use a single 2S pack which will save weight...

metalnut

iTrader: (36)

Go for it. It's an experiment. Compare run times, acceleration, etc.

orangutanracer

iTrader: (2)

I fail to see how a 2S setup will be lighter than a 4S setup, unless your willing to give up run time.
Let's assume you want the vehicle to have the same amount of power.
Volts x ampere hour (Ah) = watt hours
7.4v X 7000mAh = 51.8
14.8v X 3500mAh = 51.8

A 2S 7000mAh battery weighs really close to a 4S 3500mAh battery.

With the 2S setup will need twice the current to deliver the same power as a 4S setup. The increased current will cause everything to run hotter.

The problem is when racing the battery setup you run is dictated by the rules. If I was just bashing I would run the the higher voltage set up every time.

metalnut

iTrader: (36)

Higher voltage is definitely more efficient, as stated above. Heat loss, etc., is much less, so given the chance to go 2S vs 4S, I'd go 4S.

But like I said, nothing wrong with experimenting.