General ESC Theory Discussion

[BrianG]

With the discussion of high ESC ripple current and the effect of using lipos that aren't quite up to the task, I was thinking of ways to help with this. What about using an inductor in series with the + battery line?

Yes, the wires would have to be quite large (probably litz wound), would weigh a few ounces, and there may be slight v-drop. But, an inductor is essentially a current storage device (via the magnetic flux), much like a capacitor is a voltage storage device. And an inductor opposes a change in current flow. So, the inductor will ramp-up/down current flow during high/low changes in current. Wouldn't thins help to reduce ripple current and voltage spikes getting to the battery? And since the ESC is constantly providing somewhat of a load (even when not driving a motor), inductor kickback should be minimal. Thoughts?

[GriffinRU]

Originally Posted by BrianG

With the discussion of high ESC ripple current and the effect of using lipos that aren't quite up to the task, I was thinking of ways to help with this. What about using an inductor in series with the + battery line?

Yes, the wires would have to be quite large (probably litz wound), would weigh a few ounces, and there may be slight v-drop. But, an inductor is essentially a current storage device (via the magnetic flux), much like a capacitor is a voltage storage device. And an inductor opposes a change in current flow. So, the inductor will ramp-up/down current flow during high/low changes in current. Wouldn't thins help to reduce ripple current and voltage spikes getting to the battery? And since the ESC is constantly providing somewhat of a load (even when not driving a motor), inductor kickback should be minimal. Thoughts?

No, No, No...

Only capacitors, and just a good bank of ultarcaps will convert low current LiPo into short-term (need to define voltage drop and timeframe, formulas available) high current killer power pack.

Inductor can be in motor leads, but not in power. Ripple current covered by capacitors, voltage drop can be covered by ultracaps and zeners (in one half).

[tom255]

Is it possible to buy Ultracaps somewhere? How expensive they are?

[zeropointbug]

Originally Posted by tom255

Is it possible to buy Ultracaps somewhere? How expensive they are?

Maxwell Technologies has some RC size ultra caps that would work wonderful for high powered BL setups. They are C size cells, 2.5v/120Farads IIRC.

I will get link in next post...

[lutach]

Yes, www.maxwell.com, www.enerland.com and www.maxfarad.com. The ones I'll be gatting are he size of a button cell just a bit bigger then the ones found in digital watches.

[lutach]

Originally Posted by GriffinRU

No, No, No...

Only capacitors, and just a good bank of ultarcaps will convert low current LiPo into short-term (need to define voltage drop and timeframe, formulas available) high current killer power pack.

Inductor can be in motor leads, but not in power. Ripple current covered by capacitors, voltage drop can be covered by ultracaps and zeners (in one half).

Artur,

I'm going to get the caps I told you about. I have to try it out and see where they stand.

[BrianG]

Originally Posted by GriffinRU

No, No, No...

Only capacitors, and just a good bank of ultarcaps will convert low current LiPo into short-term (need to define voltage drop and timeframe, formulas available) high current killer power pack.

Inductor can be in motor leads, but not in power. Ripple current covered by capacitors, voltage drop can be covered by ultracaps and zeners (in one half).

Yeah, kinda figured, but doesn't hurt to ask...