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HelicopterMain Discussion › what happens to an ESC if I plug
01-22-2013 11:46 PM  4 years agoPost 1
nobato1

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USA

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what happens to an HV ESC if I plug a 6S pack, and then I plug another 6S pack in series using a switch mechanism, before I advance the throttle? Using a 200A ESC and a 500kv scorpion motor.

.

if I had a nickel for every time I said I told you so

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01-23-2013 02:25 AM  4 years agoPost 2
nobato1

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USA

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anybody?

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01-23-2013 02:31 AM  4 years agoPost 3
dw12

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pennellville new york u.s.

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Seems OK to me,I basically do the same thing with an HV setup with the exception of the switch. Also,if the throttle was advanced the ESC should not arm.

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01-23-2013 02:32 AM  4 years agoPost 4
Justin Stuart (RIP)

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Plano, Texas

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In my opinion: The ESC will initialize to 25 volts, and then once it sees the voltage spike to 50 volts it will probably shut down or burn up (depending on the kind of ESC you are using).

I guess you could do the experiment if you want and report back what happens, but I fear you will irreversibly damage your ESC.

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01-23-2013 02:41 AM  4 years agoPost 5
dw12

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pennellville new york u.s.

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I would trust Justin's opinion.

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01-23-2013 03:24 AM  4 years agoPost 6
nobato1

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USA

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reason I ask is we have 2 already burned up at the shop.

was wondering if ANY ESC can take a drastic change in voltage on the fly

these are MGM 25Kw 63V 200A controllers

a fellow insist on testing them with a power supply. starting with about 30V and them increasing the voltage to 60V. upon increasing the throttle, puff.

i said that even with this very expensive power supply, controllers can see too much ripple and blow up. the voltage change is not helping either as the ESC may see this as a spike and go nuts, shut down or blow up.

I have no previous experience with MGMs. Will try the same setup with 16S lipos next instead of the power supply.

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01-23-2013 02:37 PM  4 years agoPost 7
Santiago P

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South West, Ohio

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Would not a change in voltage supplied to the ESC once initiated be deadly to it.

Santiago

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01-23-2013 03:17 PM  4 years agoPost 8
darren heaver

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rochester, kent, england.

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I can't see how you are going to split the circuit to connect the second battery without causing power down ? As all switches electronic or mechanical have different opening and closing time even if it is only ms will the ESC not see this ?

" one day I will learn to fly till then I will just hover"

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01-23-2013 04:48 PM  4 years agoPost 9
anhquan1

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Marrero,LA USA

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What kind of switch you plan to use? If your ESC work, With that much current draw I think your switch gonna smoke first. Unless you use some very heavy duty switch.

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01-23-2013 04:56 PM  4 years agoPost 10
JKos

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Redondo Beach, CA

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Would not a change in voltage supplied to the ESC once initiated be deadly to it.
Why? What part of an ESC rated for X volts becomes not capable of handling X volts because it was initiated at Y volts (where Y is less then X)?
What kind of switch you plan to use?
I don't think he really means that he is going to use a switch. It was more a way of saying, if I change the input voltage after initialization, what happens.

I just about guarantee the power supply is the problem.

- John

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01-23-2013 05:12 PM  4 years agoPost 11
anhquan1

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Marrero,LA USA

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I don't think he really means that he is going to use a switch. It was more a way of saying, if I change the input voltage after initiallization, what happens.
Got it

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01-23-2013 05:33 PM  4 years agoPost 12
nobato1

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USA

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there is no switch. i wanted to change the focus from the power supply to the change in voltage on the fly as the failure cause

although it is a seriously expensive and robust industrial power supply, i have my reservations using one, and not batteries

when the ESC worked, the motor windings became very hot to the point of melting the thermocouple epozy that is keeping it in place

i been pulled in to fix this mess

do all agree the power supply has to go?

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01-23-2013 05:43 PM  4 years agoPost 13
Justin Stuart (RIP)

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Plano, Texas

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Can we see pics of what you're working on?

What kind of ESC are you using?

What kind of power supply are you using?

Do you have access to an oscilloscope?

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01-23-2013 05:54 PM  4 years agoPost 14
nobato1

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USA

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no pics, sorry
MGM TMM 25063-3s, Type DN-B15 ESC
100V 800A DC, dont know the power supply brand
oscilloscope right next to it

.

if i had a nickle...

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01-23-2013 05:56 PM  4 years agoPost 15
JKos

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Redondo Beach, CA

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This one: http://mgm-compro.com/index.php?tid...s-32-bit-system?

Note that it is rated for 15S. You mention trying 16S, above.

BTW, the manual specifically states: "!!! Using of power supplies for controller feeding is strictly prohibited ! Only battery for feeding is permit." A similar warning will be found in just about every ESC manual.

Also, "!!! Do not SWITCH OFF controller or PLUG OFF BATTERY when motor RUN or when it is still turning – that may lead to damage or destroy of the controller !!!"

- John

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01-23-2013 07:23 PM  4 years agoPost 16
nobato1

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USA

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It looks same but is this one:
http://mgm-compro.com/industrial/in...-high-power-hbc

i noted most that from the manual. thing is
further down on bottom of page 2 it says you can use power supplies:
controllers support NiCd, NiMH, Lipol, Li-Ion, A123, acid (Pb) cells and possibly any other new battery type (universal settings) which may have not even existed at the time of the controller production or also with power supplies (for more please see PDF file below)

manual : MGM en-manual-hbc-b15-011111-a1.pdf

15S limit: thanks got that clear, have a 14S setup ready

thank you for taking the time to help
will post an update after attemping with 14S

.

if i had a nickle...

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01-23-2013 07:45 PM  4 years agoPost 17
JKos

rrProfessor

Redondo Beach, CA

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You would certainly think an industrial controller would be designed to work with a power supply.

- John

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01-23-2013 08:57 PM  4 years agoPost 18
nobato1

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USA

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i can tell you the power cables are too long, likely creating inductance and/rippling

cables from the batterie to ESC will be as short as possible

.
if i had a nickle...

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01-29-2013 01:33 AM  4 years agoPost 19
nobato1

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USA

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switched to 14S li-po and short power cables today, it ran perfect

also learned the power supply voltage surges and floats up-down when is turned on and when the throttle is advanced

imo this surely is driving the esc nuts, the now dead ones

it may be a $10k power supply but is not fit for the job as is

thank you all for all your comments
will push the batteries hard tomorrow

.
if i had a nickle...

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01-29-2013 02:00 AM  4 years agoPost 20
dkshema

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Cedar Rapids, IA

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The ESC will initialize to 25 volts, and then once it sees the voltage spike to 50 volts it will probably shut down or burn up (depending on the kind of ESC you are using).
I would suspect that if there is any initialization going on, it would be any auto LiPo voltage cutoff circuits and nothing more.

As for initializing to switch a given voltage, that doesn't happen. The battery voltage is commutated by the MOSFETS in the ESC. There is a "high side" MOSFET and a "low side" MOSFET with two of the three motor windings connecting them at any given moment.

The "high side" MOSFET simply switches the available voltage to one of the three motor phases at any given time. Whether that voltage is 25V or 50V, the ESC doesn't care (as long as you don't exceed its overall ratings), and doesn't know. The "low side" MOSFET simply switches one of the two remaining motor phase windings to Ground at any given moment.

Current flows from the +volt supply, through the ON high side MOSFET, through one winding, then is connected inside the motor to a second winding, whose other end connects to the low side MOSFET to ground. With both MOSFETS are ON, current flows, you get a magnetic field, and the armature rotates due to the fixed magnets in your motor.

If anything is going to get confused by doubling the input voltage, more than likely it would be just the low voltage cutoff point. You're not going to confuse the MOSFETS, you're not going to confuse the PWM controller, you're not going to confuse the commutation sequence.

-----

A bit more thought about the subject. There MAY be a problem if you switch in the second pack WHILE the motor is turning and being commutated by the ESC. The duty cycle of the PWM controller will have to instantaneously change as the extra voltage is suddenly applied. The "on" time of the MOSFETS is a function of the voltage applied to the ESC and the current speed setting of the throttle. The PWM controller will modulate the duty cycle of the voltage applied to the motor windings based on applied voltage and the speed the controller is attempting to maintain.

Suddenly doubling the input voltage may require an instantaneous decrease (perhaps by half) of the duty cycle. The current control loop will also be similarly affected. Perhaps the PWM and current control loops cannot respond to instantaneous doubling of input voltage. Just a thought, but something to be considered.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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HelicopterMain Discussion › what happens to an ESC if I plug
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