I've been investigating this for a little while now and would like some general feedback. David... you there?
I'll start off by saying, like Josh B, I'm cheap. I buy the cheap ESCs and batteries like most all of us here do. I still do my 80% margin of error on my power setups but am still not satisfied with the longevity of my batteries and how hot my ESCs get. I have a little bit of electronics background but only as a hobbyist. I know that the ESCs we all buy do not always come with the best of components. Particularly my concern is with the battery to ESC relationship.
Our ESCs typically do not use ultra-high-quality capacitors. I'll start with a good analogy I will quote from an RCGroups thread:
"Water running in a pipe and through a tap. Now turn off the tap quickly. You'll hear a loud knock/shock sound in the pipe. The water wants to continu flowing but it can't, for a moment the water pressure is much higher than the static water pressure. It's the same for a current that's switched off, because of the inductance it wants to keep on flowing, voltage gets higher. This is also what causes sparks (brush fire) in a brushed motor. The controller is like a watertap that's switched off (and on) very fast (8,16, 32kHz PWM) to get the desired current. Turning off the current, in combination with the battery wire inductance, causes voltage spikes because the current wants to continue on its course (ref. inertia of the moving watercolumn). Those voltages are higher than the battery voltage. The input capacitors (cylindrical) takes care of these spikes (they reduce the wire inductance). The longer the wires, the higher the voltage spikes induced in the wires, the harder on the input capacitors. They will get warmer, heat up and explode. This is caused by the wire inductance, not by wire resistance. Therefore, using thicker wire will not help much, it's not a bad idea either, but extra capacitors are the solution, thus reducing/compensating the wire inductance."
This quote is in relation to the effects of long battery or motor wires in an electric setup. That is not my concern. My concern is the effect of the spiking on the battery over time. With capacitors on the ESC that are not low ESR (equivalent series resistance) the spiking is potentially what is killing my batteries quicker than what I feel is ideal. Some batteries as quickly as 50 cycles.
Essentially my thought is that by adding capacitors will add in-line "water reservoirs" That will drain and fill during the spikes. More reservoirs or more capacity in the reservoirs will yield better results. The parts are cheap and weigh next to nothing. Even Castle Creations has a CapPack that is geared toward the long-wire applications.
For the more expert people out there... am I on to something, or just on something?
I'll start off by saying, like Josh B, I'm cheap. I buy the cheap ESCs and batteries like most all of us here do. I still do my 80% margin of error on my power setups but am still not satisfied with the longevity of my batteries and how hot my ESCs get. I have a little bit of electronics background but only as a hobbyist. I know that the ESCs we all buy do not always come with the best of components. Particularly my concern is with the battery to ESC relationship.
Our ESCs typically do not use ultra-high-quality capacitors. I'll start with a good analogy I will quote from an RCGroups thread:
"Water running in a pipe and through a tap. Now turn off the tap quickly. You'll hear a loud knock/shock sound in the pipe. The water wants to continu flowing but it can't, for a moment the water pressure is much higher than the static water pressure. It's the same for a current that's switched off, because of the inductance it wants to keep on flowing, voltage gets higher. This is also what causes sparks (brush fire) in a brushed motor. The controller is like a watertap that's switched off (and on) very fast (8,16, 32kHz PWM) to get the desired current. Turning off the current, in combination with the battery wire inductance, causes voltage spikes because the current wants to continue on its course (ref. inertia of the moving watercolumn). Those voltages are higher than the battery voltage. The input capacitors (cylindrical) takes care of these spikes (they reduce the wire inductance). The longer the wires, the higher the voltage spikes induced in the wires, the harder on the input capacitors. They will get warmer, heat up and explode. This is caused by the wire inductance, not by wire resistance. Therefore, using thicker wire will not help much, it's not a bad idea either, but extra capacitors are the solution, thus reducing/compensating the wire inductance."
This quote is in relation to the effects of long battery or motor wires in an electric setup. That is not my concern. My concern is the effect of the spiking on the battery over time. With capacitors on the ESC that are not low ESR (equivalent series resistance) the spiking is potentially what is killing my batteries quicker than what I feel is ideal. Some batteries as quickly as 50 cycles.
Essentially my thought is that by adding capacitors will add in-line "water reservoirs" That will drain and fill during the spikes. More reservoirs or more capacity in the reservoirs will yield better results. The parts are cheap and weigh next to nothing. Even Castle Creations has a CapPack that is geared toward the long-wire applications.
For the more expert people out there... am I on to something, or just on something?