RC-Monster Forums - View Single Post - Are Zippy Lipos safe with a Castle MMM Speedy?

BrianG · 02.24.2009, 01:41 PM

To add to what Mike has said; The controllers mentioned are either airplane ESCs (HV110, turnigy) or ESCs with a lower current rating (MM). This could be due to FET choice, and/or ESC construction. It has been stated that an airplane ESC is not designed for the burst currents we see in car applications, so they have a higher total resistance (in FET choice, PCB traces, etc) so they tend to not to funnel as much energy as an ESC designed specifically for car use. And lower-current ESCs, like the MM, also have a higher total resistance, which helps to limit the potential current spikes.

An "ideal" ESC would be one that is as transparent as possible to current flow. This means 0 ohms of resistance. While that ideal is not practical, car ESCs designed for 1/8 scale (or larger) vehicles will have less resistance because of the currents they are designed to pass.

Also, lower-end packs tend to have higher internal resistance, which tends to increase the ripple current from a powerful system. I am willing to be that adding a few more low-ESR caps to the MMM when used with lower-end packs will drastically reduce ripple currents. Yeah, it's a band-aid, but not for the ESC, it's to compensate for the lower-end packs.

	(#20)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	02.24.2009, 01:41 PM To add to what Mike has said; The controllers mentioned are either airplane ESCs (HV110, turnigy) or ESCs with a lower current rating (MM). This could be due to FET choice, and/or ESC construction. It has been stated that an airplane ESC is not designed for the burst currents we see in car applications, so they have a higher total resistance (in FET choice, PCB traces, etc) so they tend to not to funnel as much energy as an ESC designed specifically for car use. And lower-current ESCs, like the MM, also have a higher total resistance, which helps to limit the potential current spikes. An "ideal" ESC would be one that is as transparent as possible to current flow. This means 0 ohms of resistance. While that ideal is not practical, car ESCs designed for 1/8 scale (or larger) vehicles will have less resistance because of the currents they are designed to pass. Also, lower-end packs tend to have higher internal resistance, which tends to increase the ripple current from a powerful system. I am willing to be that adding a few more low-ESR caps to the MMM when used with lower-end packs will drastically reduce ripple currents. Yeah, it's a band-aid, but not for the ESC, it's to compensate for the lower-end packs.