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

Allright, im in all out war with this dipstick from RCU who continuously states that there is no way that todays brushless systems, especially the ESC are damaged by batteries that are subpar both in quality and specc.

I was under the impression from day one of owning my first brushless truck, the Savage Flux that using Lipos and especially nimh batteries that are incapable of feeding the MMM with enough current results in the MMM going *poof* as we have seen many times before with alot of peoples MMM setups. But is this truly not the case? This guy states that the lipos should be exploding and smoking as a result of using below specc batteries for an application. Well, I sure as hell aint seeing Lipos going puff, but I sure as hell am seeing alot of MMM making smoke when the Lipos or Nimh arn't up to par.

We discussed this topic at length already. So why the hell is the theory that subpar batteries ARE NOT responsible for ESC failures appearing?

http://www.rc-monster.com/forum/showthread.php?t=24142

http://www.rc-monster.com/forum/show...ighlight=zippy

I want this settled once and for all, are using batteries either lipor nimh that are not up to specc capable of ruining ESC's or is it caused by some other force of nature according to this guy?

http://www.rcuniverse.com/forum/m_10...m.htm#10025159

I'm seeing MMM' going poof in these vids, not lipos.

[YOUTUBE]91oQcK585eQ[/YOUTUBE]


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[YOUTUBE]Wf00JUvU2QI[/YOUTUBE]

[radioman193]

I dont see how a battery would be at fault ..
the only way would be is if the pack was marked wrong........

and it was a higher voltage than marked.
and the chances of that are VERRY slim.

looks like a average esc failure

the second vid dont know for shure.. but i dont see how a cap can make a esc fail as the cap is on the Voltage INPUT side of the esc not on the Output of the FET's of the motor output.
a short there would make it fail yes .

and the third just look at the landing all types of things could have went wrong...............


a Bad spec battery would just not come up to the rated voltage or amperage or the "C" rating and would just be like a low battery.
and a low batt would NOT do this.

[Arct1k]

Yes bad batteries cause ESC's to fail - Yes damaged CAPs cause ESC's to fail - Yes manufacturing defects can cause ESC's to fail - YES damaged motors can cause ESC's to fail - YES water can cause ESC's to fail - YES mechanical damage can cause ESC's to fail - YES damaged servos can cause ESC's to fail - Excess voltage can cause ESC's to fail (although my good old MM took 6s like a trooper)...

Basically a lot can cause ESC's to fail...

[What's_nitro?]

IIRC the reason inadequate packs could harm the ESC was due to ripple current, ie. the batteries' resistance was too high and was causing the voltage to sag under load, then rebound to a level the ESC couldn't handle. Feel free to correct me if I'm in any way incorrect.

[radioman193]

if the voltage was to "sag" it would be like runing on a low batt ..

so under that
that would be every time your battery went low your esc would smoke.
I don't see this.

i have seen ALOT of esc's go bad in plenty of ways and for plenty of reasons.

but in all my time in electronics and teaching electronics I My self have NEVER seen low voltage make a device fail that catastrophiclly with total distruction
but low voltage can damage the low voltage regulator.

The first video by the amount of smoke it was NOT the battery it was the drive fet's that Failed that is The Only way you will get that mutch smoke and fire.
as 12 to 24 fet's fail but most of the time only 2 to 4 will "give up the ghost" .

and if a servo kills a esc it would not smoke that bad as there is ONLY 1 to 3 regulators and seperate from the motor drive fet's that is used for the servo drive inside the esc and 1 small transistor dont have the mas or material to produse that mutch Venting smoke and or fire.
and not all three will go as the design for a 3 stage regulator only the first or the last one will go.

we use to burn fet's and older style regulators up for fun in electronics class my students got a big kick out of it
and were learning at the same time.

[Arct1k]

Anyone have an advil!

Freeze/Radio - Ripple is correct... I suggest you search on that term and perhaps filter on user BrianG or Patrick (aka CEO Castle).

There have been numerous posts on how ripple kills esc's - Back EMF voltage from braking when running close to ESC's max rating is the other culprit.

[bryan]

Originally Posted by Arct1k

Anyone have an advil!

Freeze/Radio - Ripple is correct... I suggest you search on that term and perhaps filter on user BrianG or Patrick (aka CEO Castle).

There have been numerous posts on how ripple kills esc's - Back EMF voltage from braking when running close to ESC's max rating is the other culprit.

I told you guys

[Arct1k]

Search: Keyword(s): ripple ; Posts Made By: Pdelcast

[pinkpanda3310]

If the voltage is constantly sagging the system draws more amps to make up for the power loss and hence compiles the problem. If the LVC is set high that can sometimes be triggered too. If they are running maximum volts then ripple is most likely, as Arctik saying.

[Arct1k]

Originally Posted by pinkpanda3310

If the voltage is constantly sagging the system draws more amps to make up for the power loss and hence compiles the problem. If the LVC is set high that can sometimes be triggered too. If they are running maximum volts then ripple is most likely, as Arctik saying.

Not really - An ESC is never always pulling current from the battery it is a very fast switch pulling current very fast through each phase. You don't even see this pattern on an Eagle Tree as it is happening so fast.

The max voltage point was related to back EMF when braking - the breaking force is converted back into energy and shunted via the ESC into the battery. These spikes can be very high... If they get too high and the battery can't take the energy quickly then the ESC can say enoughs enough... This is worse when ESC's are running close to there rated voltage as the ESC obviously has less voltage "head room".

Have a look through BrianG and Patricks posts...

[pinkpanda3310]

Why does the voltage sag then?

[slimthelineman]

cant take it anymore, lets not forget people, these are AC MOTORS. which equals inductive load. the esc does not pull power from the batteries, the MOTOR does. the esc simply meters the flow to give linear throttle control. highest current draw is at startup not wot like a brushed motor. the motor will take all thats available unless something stops it, the esc. if the power is not there to be taken from the battery the motor will fry anything in its path in an attempt to get what it wants, usually the esc. setup will dictate how much load is present, ie. gearing. higher gearing means more load and more heat. the easiest and most relevant example is the NEC's requirement for voltage in our homes, no lower than 116 and no higher than 124. try running an ac appliance on 100 volts and see what happens. so yes crummy batteries CAN fry a speed control. caps and other componets cant keep up with the giant surges from the motors when the voltage in the pack dips below the point where it can supply the current being drawn.

[slimthelineman]

next time your a/c kicks on watch how the lights dim momentarily. this is the max current at startup im talkin about. if voltage is low on your service the breaker will trip in your panel instead of blowin stuff up. maybee we should ad breakers to our esc's and be done with all this nonsense for good. lol....

[slimthelineman]

ok, it would appear that late nights, drinkin, and assumptions have gotten ther best of me once again. seeing three phases on a motor meant a/c in my mind, but 3 phase brushless motors are indeed a reality. oops! yes im highly oppinionated, and yes im a jerk but still it would seem that the same principals of an a/c motor would apply to a 3 phase d/c motor as well. if im wrong feel free to lay in as deep as you would like, wont bother me a bit, but being as hard headed as i am, will probably still argue anyways out of pure pleasure at that point!

[T-birdJunkie]

Oh, Freeze, u so crazy.