Your clamp meter may not like reading pwm and will lie to you. The BTS7960 is expected to get hot if there’s 11Amps flowing. It is not a perfect switch.

Does your clamp-on meter measure DC amps? Please edit to include the make, model and link to datasheet.

@Kartman Yes, I thought so, but then I measured it with a multimeter. The result turned out to be the same.

Agree with @Kartman, you must be making an errant measurement. I can't think of any scenario where you could be this inefficient. You would have to be dissipating 320-187 or 133 watts in your circuitry.

@Transistor My clamp meter is "Unit ut 210e", also I measured current with multimeter(Unit ut39c)

@Transistor drive.google.com/file/d/0B4Jyby-tjH5oNnlQQmY1RktSUnc/view datasheet for clamp meter

Please edit all the information into the question. Don't sprinkle it through the comments where people have to search for it.

@JohnBirckhead I want to tell you about a situation I observed, I tried the same circuit with a dc-dc converter. The battery and cables didn't get too hot but when I used pwm modulation battery and cables became really too hot. So if the measurement was wrong in the first method, wouldn't the battery be at the same temperature when I used a converter?

@oğuzkaançomoğlu again, please edit your question to include all information you gave here in the comments into your question. Thank you!

@oğuzkaançomoğlu no, battery temperature has little to nothing to do with all this.

1) Cables getting hot can be cured by using thicker cables - what gauge wires are you using for the high-current paths? 2) What is the current rating of the DC-DC convertor that you used? Did you check its output voltage during the test?

#oğuz kaan çomoğlu, I found your question interesting. I happen to have a BTN79xx driver module and a Rigol DS1054 50MHz scope to display the V-I waveforms. So perhaps I would spend this gloomy lock down Saturday afternoon to do some PWM efficiency evaluation. Now a couple of questions: (1) I read the UT201 clamp meter manual and I am surprised to read that it is for both V-I of AC and DC, as accurate to the order of 1mA. / to continue, ...

/ continued, ...Or please let me know how you calibrate you meters. (2) I only have US$5 cheapy multimeters with the max current range of only 10A. So I will be doing small currents tests under 10A. I wonder if you have already done low current tests OK, and only found problem with bigger currents? Comments and counter suggestions welcome. Cheers.

#oğuz kaan çomoğlu, (3) BTN79xx handles huge current, so it is important to sense current for alarm and security, (also for speed feedback control). You might like to skim my answer to the following question, to get a rough idea of how to do hardware fiddling for current sensing. (3a) Anything wrong with connecting L298Ns in parallel? electronics.stackexchange.com/questions/556772/…. (3) Are you OK to do DIY soldering work, like what described in the above question?

#oğuz kaan çomoğlu, Your yr2004 7960 is similar to my yr2008 7971b, except a couple of years older. (4) Do you have any reason to prefer one over the other? If not, I would write an generic answer applicable to both drivers. (5) 7971B's PWM freq is max 25kHz. I usually start off with a very low frequency, say 1kHz. (5) Do you have any particular preference on PWM frequency? If not, I will start with 1kHz, 50% dc. BTW, I for reliability/repeatability, I will us a cheapy manual/uart control digital sq wave sig gen for PWM test. Ah, lock down lunch time. See you later. Cheers.

#oğuz kaan çomoğlu, just now I casually googled for more 7971b things that I don't know that I don't know. (6) I read that many Infineon devices seem manufactured in ShenZhen, and this might be a problem, because MIC products usually more easily fall off the truck and go to the grey market. I see that 7971b IC prices on TaoBao varies in a big range, sometimes double or higher, so I usually go to a reputable shop for which I have a VIP account. Is your 7960 module from eBay? You might have be a quality assurance problem! :)

#oğuz kaan çomoğlu, (7) I also read TaoBao shops' ads saying the my BTN7971B has replaced your BTS7960. So now I wouldn't care much about 7960 and focus on 79711b. Sorry about that.

@oğuzkaançomoğlu Your Uni-T UT 210E has a "VFC" feature which is a low pass filter, cutting off at 400Hz. So if you are measuring VI values of PWM frequency above 1kHz, say, signal might be much attenuated, and thus causing wrong reading you got. But I am just guessing, only 20% sure. Anyway, you can (1) Disable VFC mode, or (2) set PWM frequency much below 400Hz.