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

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- - Argument thread: Low specc batteries don't kill ESC's. Or do they? (https://www.rc-monster.com/forum/showthread.php?t=28164)

you guys know freezebytch is probably watching this thread and laughing his ass off knowing that he started a huge fight. If you notice he hasnt replied once to this. He started it, and hasnt said anything since then lol

Quote:

Originally Posted by T-birdJunkie (Post 381637)

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.

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.

Absolutely, if it's charged (pressurized) properly

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

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

Just another word for "pressure regulator".

Prove it.

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.

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.

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.

never in his life did SuicideNeil come across such a know it all who beleived he had all the answers, yet actually had so few. WE ARE NOT DISCUSSING WATER, IT HAS NOTHING TO DO WITH ESCS. You show me one, just one BL MT weighing 10lbs+ that can run on duracell AAAs @ 50mph+ and I'll eat my hat. Sub standard batteries suck, that is all you need to know. Whether CastleCreations need to look at different FETS is very doubtful- that use items that arent even available to other manufacturers, at the cutting edge of design and capability for their esc's operating spec- aint using cheap components to save a few bucks here and there. Escs are also far from simple, otherwise every man & his dog would be designing and selling them to enthusiasts- ever built a BL esc yourself chap?

If they say to use good lipos capable of suppling enough current to meet the demands of the system, then thats what you should do, not argue about fluid dynamics and how it applies to battery selection; it really doesnt...:sarcastic:

ThunderbirdJunkie never once claimed he knows it all.
He is ONLY in this thread to LEARN.
DC voltage...IN...is causing these issues, no?

Neil, rather than blasting somebody trying to grasp a concept that doesn't make sense to him, why don't you try, instead, answering the questions as to why?

:rofl: ignorance is bliss! and just to be a jerk alternators on cars do not produce alternating (ac) current. its dc, otherwise how the hell would you charge the dc battery. have to agree with linc on this, get over yourself t-bird. obviuosly the function and behaviours of electricity have eluded you. this is fine, could care less. but at the same time all slimthelineman was trying to do was put some info out there to help people why its a bad idea to use low amperage batteries with high aperage motors. i think its interesting how some people will try to rationalize anything anyway they can to prove their veiws are correct. two words to end all this water hubub, mutual induction.

all that aside why does nobody have the good stuff in their quotes? only the stuff that they feel like they can prove wrong somehow with all their infinate knowledge of electricity. its like i said, 120amp rated motor, 120amp rated esc, why the hell would you use anything less than a 120amp capable battery? it would be like using a fire hydrant that only gives 100psi and trying to use a pump truck to pull 1000psi through the hydrant.:whip:

its official slim is now a fluid dynamics expert cause i used a water analogy.

as far as not seeing freeze anymore probably just has to do with people being easier to argue with on other forums, or is lost as far as what some are saying. could be he just got bored, i know i am aproaching that point. the manufacture puts a recomendation on minimum amperage for your batteries. without knowing anything elese it would probably be best to do what they say. they know more about their product than anyone. like i said your electrical system is only as strong as its weakest componet.

so lest be nice to our dc input ac output controllers and give them what they want. i think the question at this point should have been why use crappy low amperage batteries on a super powerful brushless setup?:neutral:

88gtanotchback is confused....

_paralyzed_ thinks 88 gta notchbacks are a sick one run car. 350 tpi ftw:yes:

Quote:

Originally Posted by slimthelineman (Post 381661)

:rofl: ignorance is bliss! and just to be a jerk alternators on cars do not produce alternating (ac) current. its dc, otherwise how the hell would you charge the dc battery...

Not to argue, but car alternators DO produce AC. Actually, three phase AC. Then it's just rectified to DC...

'pinkpanda3310' thinks 'sneezebutt' had little intension of arguing about water in this thread.... but that's what 'sneezebutt' got.

Quote:

Originally Posted by BrianG (Post 381667)

Not to argue, but car alternators DO produce AC. Actually, three phase AC. Then it's just rectified to DC...

Linc 'rectifies my..... oh wait, forum ettiquette:neutral:

Quote:

Originally Posted by BrianG (Post 381667)

Not to argue, but car alternators DO produce AC. Actually, three phase AC. Then it's just rectified to DC...

well there you go, can always stand to learn something new if you are willing. just so happens that Brian G is the one opening my eyes a little wider most of the time:lol: its funny i just finished replacing the altenator in my wifes civic cause the regulator went bad. never would have guessed it rectified the current to dc, even though its called an altenator:rules:

slimthelineman is glad there are forums with people way smartet than me and willing to share those smarts, especially them street smarts:lol:

Quote:

Originally Posted by _paralyzed_ (Post 381666)

_paralyzed_ thinks 88 gta notchbacks are a sick one run car. 350 tpi ftw:yes:

88gtanotchback thanks ya, even tho most consider it a mullet mobile. And since 88gtanotchback is not contributing to the thread consider him outsky.:mdr:

So nobody can explain what ripple current is?

In a switching power supply, the voltage coming out of the O/P rectifier and into the O/P inductor is a positive-polarity square wave. The O/P inductor and O/P capacitor(s) filter that into a DC voltage. The current through the inductor is a DC level (which goes to the load) with triangle-shaped AC current riding on the DC level. The AC current is due to the charging of the inductor (during the switch "On" time) and discharging of the inductor (during the switch "Off" time). If things are designed properly and operating normally, the inductor never "fully" charges (saturation), nor discharges fully. Almost all of the AC current, several amps rms, goes through the O/P capacitors rather than to the load (if it did, the ripple voltage would be fairly high). While a capacitor's DC resistance is very high, its impedance to AC depends on the frequency of the AC. In the 100KHz range, that impedance is milliohms (thousandths of an ohm). By way of contrast, the effective resistance on the load in the computer is much higher (e.g., if the O/P voltage is 2V and the load current is 20A, the DC "resistance" is 100 milliohms). So it is entirely normal for the capacitors to be conducting several amps of ripple current, as this is due to the capacitors' smoothing action.

What is impedance? In a capacitor, it has 3 basic components in series with each other: an ideal capacitor; the ESL, equivalent series inductance, of the leads; the equivalent series resistance of the leads, the foils, and the electrolyte. Impedance is the vector sum of the capacitive reactance [1/(6.28xFxC)] X(C), the inductive reactance (6.28xFxL) X(L), and the ESR. At relatively low frequencies, X(C) is basically the impedance. As frequency increases, the impedance falls until the ESR is greater than the X(C), and the ESR is basically the impedance. As frequency continues to rise, the X(L) becomes greater than the ESR, and the impedance is basically the X(L). P/Ss and VRMs operate in the frequency range where the impedance and ESR are approximately the same.

If the capacitor is conducting ripple current, it is dissipating power (I^2)(ESR), which is heat. The higher the ripple current, the more the heat. If you exceed the ripple current rating, the cap will overheat, unless the ripple current is so high that hydrogen gas is being generated. So the failure mechanisms with excessive ripple current are electrolyte evaporation and evaporation- or gas-related venting.

To me, post #34 explains it. Combine that with post #45 and that is how esc's can die from ripple.

I have heard the water analogy before and didn't particularly like it as it was explained to me by someone with less knowledge of electricity than myself. With pressure you have explained it better. I guess it wasn't recieved well on rcm as some people here like the more technical answers.

The above mentioned posts are quotes from Pdelcast and his company.