Argument thread: Low specc batteries don't kill ESC's. Or do they?

[T-birdJunkie]

Originally Posted by lincpimp

The battery has to be able to output a stable voltage at high current levels while also having low internal resistance to keep from getting hot, and also accepting a charge back from the regen brakes. The esc has the task of controlling the motor and ducting the electrons to and from the battery.

I am by no means in full understanding of how this stuff really works, but I do know that the battery is the single most important part of these brushless systems. I have experiemented with alot of different batteries and there is a difference.

Originally Posted by slimthelineman

enough with this water crap. it is not the same, nice try though. you might be an expert in that area, congrats. when have you ever worked with REAL electricity?

Never. 480 is as high as ThunderbirdJunkie has worked with. We are talking sub-30 volts here, though, so none of that has any bearing on this conversation. We are simply talking SIMPLE DC systems, such as what deliver power to the ESC.

show me water that will seek a path to ground at all costs.

You are aware that electricity only seeks a ground simply because it's charged, and it's going to something that's charged oppositely, right?
We are constantly surrounded by electricity whether we are near electrical devices or not. Is ThunderbirdJunkie going to get zapped to death just sitting here, typing this out? In theory, it could happen, should the power supply on his computer go kaput, but that's another conversation for another time.
Water under pressure will go to wherever the pressure isn't. That is all there is to it. Go turn on your hose; it's going to come out the end, right? Not flow backwards. The unpressurized end of the hose is the ground.

is it going to jump out of your cup? no.

Absolutely, if it's charged (pressurized) properly

if you stand too close to a full pool will the water arc out and hit you because you are dry no.

Funny thing about this. If everything around you is a high pressure water system, and you yourself are unpressurized, absolutely it will.

show me a pipe which water will flow through that has a resistance value.

It's called mechanical resistance. Also known as friction.

show me a capacitor for water that will correct power factor(voltage lagging behind current)

Just another word for "pressure regulator".

water in no way behaves like electricity other than the fact that it flows.

Prove it.

sure electrons do the same but they dont flow through a pipe or hydrant or any of that.

Ah, metaphors are lost on you. If you don't understand anything about hydraulic systems why don't you spend your time learning about how they work rather than telling everybody how they don't work.

electrons flow due to a difference in potential.

And fluids flow for the same reason. If there wasn't more pressure behind the fluid pushing it to where it was going, it wouldn't be going that way.

Anyway, done dissecting your post. It's fruitless and it will solve nothing. Your mind is made up, and you're choosing to, rather than explain what's going on, chide somebody for asking questions in an effort to understand this mystical "ripple current" that spikes and stuff, and more to the point, have somebody explain why it kills ESCs.

Originally Posted by BrianG

Sheesh guys! lol.

The water analogy works for a very basic understanding of electricity. It works ok for the most part when dealing with DC, but falls apart very quickly with AC. And our ESCs running pulsed DC is effectively AC (no one said AC has to be a sine wave). So, it is very difficult to use the whole water example effectively.

In short, water pressure=voltage, restriction in a hose=resistance, water flow=current. That's about all you can do.

Slim: Actually, if you think about it. Water would "jump" from a cup if enough pressure is present. It would either blast a hole in the bottom (signifying breakdown of the "insulator" which is what happens with HV), or splash out.

Thank God somebody understands the analogy. A very basic understanding of DC is all ThunderbirdJunkie is after, and why voltage spikes would come from being drawn, and why this
This isn't an alternator in a car, where (since it generates alternating current electricity) voltage must be regulated, the voltage is (for the sake of argument) constant under load from the battery (yes, everybody is aware of voltage drop, etc etc, no need to nitpick...), why would it spike from the battery?
What would cause two 7 cell batteries on a Flux to spike to the point that it would surpass the MMM's 6S 24ish voltage max? Two 8.4v batteries, 9vish fully charged, shouldn't jump past 24v?

Everybody seems to be hung up on the fact that electricity isn't water and ignoring the fact that there are legitimate questions being asked.

Remember...input voltage is DC. Doesn't matter what the output is, unless what's frying is the switching mechanism, which the more ThunderbirdJunkie reads on the issue, it seems to be the caps and the fets smoking themselves from not being able to switch fast enough to deal with the ripple current, which again, points to more of a hardware issue with the speed control rather than a battery issue.