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There is something I totally don't understand about an amperage. According to spec. AIO FC has 5 A and 6 A ( 5 seconds). However, sometimes I see in OCD far beyond 5A and 6A. And FC, ESC are OK. Shouldn't they burn down?

More about my ignorance. As I understand, more C is better in LiPo. Let's take very good LiPo battery: "TATTU R-Line Version 5.0 V5 6S LiPo Battery 1200mAh 22.2V 150C 6S1P XT60 Plug RC FPV Racing Quadcopter Drone Battery"

According to spec. :

Discharge Rate: 150C
Max Burst Discharge Rate: 260C

1c = 12 A
12 A * 150 = 1, 800 A !!!

What ??? !!! ESC that can handle 1, 800 A !

Please, enlighten my ignorance

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  • $\begingroup$ I have a feeling that your misunderstanding is related to burst vs. continuous current limits, but I'd like some more information. Could you link to product pages for the items you're talking about (AIO FC and battery) so I can validate your math? $\endgroup$
    – ifconfig
    Jul 31, 2022 at 20:08
  • $\begingroup$ I didn't take "Max Burst Discharge Rate", but just "Discharge Rate". I am not talking about any specific FC but general principal. Nevertheless, take for example Mobula6 FC. happymodel.cn/index.php/2019/11/22/…. About a battery: genstattu.com/… $\endgroup$ Jul 31, 2022 at 20:42
  • $\begingroup$ "My calculations were wrong and my physics were abominable." - that what Einstein would say about me. LOL. $\endgroup$ Aug 1, 2022 at 20:51
  • $\begingroup$ Keep in mind not every component is designed to work together. That 1S 5A FC/ESC AIO will indeed light on fire if you run it in a 5 inch build that can pull 120 amps in a punchout (which is where you'd use that battery). If you run it in a tiny whoop on 1S, as designed, it will handle the up to 5A per motor pretty reliably, and handle higher current bursts for short periods. $\endgroup$ Aug 3, 2022 at 15:20
  • $\begingroup$ Max current is not max power if the voltage is near 0 $\endgroup$ Aug 7, 2022 at 0:33

2 Answers 2

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sometimes I see in OCD far beyond 5A and 6A

Those specs are probably per motor, so 4 motors could pull 20A.

And I think you mean OSD, for On Screen Display.

1c = 12 A

Nope, 1200mAh is 1.2A, so 1c is 1.2A

I think some battery manufacturers measure C ratings as the maximum the battery will produce when shorted across a current meter. It will do that once, briefly and then die. As basic rule of thumb, if your battery gets hot, you're overloading it and shortening its life.

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However, sometimes I see in OCD far beyond 5A and 6A. ... Shouldn't they burn down?

This is the difference between a rating for continuous, burst, and instantaneous current flow:

  • Continuous: maximum constant current load over a long period, e.g. >15s
  • Burst: maximum temporary current load over a short period, e.g. <15s
  • Instantaneous: maximum spike of current load over an ultra-small period, e.g. <0.5s

In the case of the Tiny Whoop FC you link to, the rating for continuous current load is 5A and the burst current limit is 6A. This does not mean, however, that the electronics aren't capable of momentarily supplying more for a very short period of time. This is likely what you're seeing.

more C is better in LiPo

I'm not sure if I would say it's necessarily better. All it means that the battery can supply more current to the motors.

What ??? !!! ESC that can handle 1, 800 A !

No. First of all, you cited specs for the battery's maximum discharge limits, not those of the ESCs. The weakest link in the battery-ESC-motor chain will be the first to fail, so an over-speced battery can cause the ESCs to die if you try to push too much current through it.

Second of all, I think you made an arithmetic mistake. The conversion factor between C's, battery capacity in Ah and a current in A is $\text{Ah}\cdot\text{C's} = A$. Therefore:

  • Max continuous discharge rate: $150C \to 1.2 \cdot 150 = 180A$
  • Max burst discharge rate: $260C \to 1.2 \cdot 260 = 312A$

It should be noted that the C-ratings marketed by consumer battery brands are often overstated, so it's likely that measured discharge limits in the real world will likely be substantially lower than this.

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