microSD Card Write speed goes down to 512 KB/s

Hello,

I have a problem when writing to a Sandisk Ultra 128 GB microSD card that I use in my music player (Ibasso DX50).
When I copy music files to the card, for the first 4 or 5 files, the throughput is OK (between 4 and 10 MB/s), but systematically after a few files, the speed goes down to 512 KB/s.

I have the same problem using this card on another PC, so I assume the problem is with the SD card.

I formatted the card to FAT32, because I had problems with the native SD card format.
I did not notice the problem at the beginning, when the card was almost empty, but now the card is almost full, and I think the problem occurs more and more easily.

Thanks for helping.

Have seen many fake drives.
Test your micro SD card with h2testw
H2testw - Test for Fake USB Flash Drives | USB Pen Drive Apps

Hi,

The test on 28 GBytes gave the following results:

Average Write speed 5,6 MBytes/sec
Average Read speed: 4,8 MBytes/sec

These results are not very impressive, but at least they are in line with the best results I see when writing.
There is however a difference: when I put files on the card, it is located in the Ibasso connected to the PC via USB, but for the test, the card was in a SD card adapter.

Could it be that this is the reason for this speed problem ?
I will try to put the files using the adapter, to see what it gives.

Did it gave you that the SD is a 128G?

With the card in an card adapter, here is the result I got on another PC, testing only 1000 MBytes:
Warning: Only 1000 of 121925 MByte tested.
Test finished without errors.
You can now delete the test files *.h2w or verify them again.
Writing speed: 18.9 MByte/s
Reading speed: 64.0 MByte/s
H2testw v1.4


These results looks quite good.

Now, with the card in the music player, connected in USB, I get:
Warning: Only 1000 of 121925 MByte tested.
Test finished without errors.
You can now delete the test files *.h2w or verify them again.
Writing speed: 6.55 MByte/s
Reading speed: 15.6 MByte/s
H2testw v1.4


First conclusion: Card is really 128 GBytes.
Second conclusion: far better results with the card in an adapter.
Third conclusion: in both conditions, I do not see this speed decrease to 512 KBytes/sec... !

The only explanation I see is that something is wrong in the way teracopy puts the files on the card, and using windows copy is not better.