Raspberry Pi Forums

Hi!
I'm thinking about buying the Sony SF16UX SD Card:
http://www.sony.co.uk/product/sd-expert ... ations#tab
But I see in the specifications tab, that this card could consume 800mA of current. Can anyone say that that would be too much for sure, or shall I give it a try?

Thanks,
newpipe

I am not an SD card expert, but after reading your post, I seriously questioned whether an SD card could possibly use that much power, so googling turned up the following document, indicating that SD cards can use significant power during data transfer.

https://www.sdcard.org/downloads/pls/si ... 110225.pdf

Two quotes from above, note what I found is a year and a half old:

> Most card connectors limit the maximum current at 500mA. A card slot that can support more than 500mA will require a special connector to handle the higher current.

> The maximum current of a card is up to 500mA and the card also needs to satisfy the temperature requirement of Ta=85 deg.C.

But that is a lot of power, I would guess something would crash if it actually used 800mA as the RPi itself only takes 700mA input as I recall, how could it power a card requiring more than that without crashing?

But I also wonder if it was a typo - there are references to high numbers of mW that are closer to 800 as in the following from above page:

> In the case where EMPC is set to 0, the card total power shall not exceed 720mW (3,6V x 200mA).

You might call or email Sony to ask if the card actually uses that 800mA.

When I saw that much power requirement of the SD card I also couldn't believe that. That's one of the reasons why I asked in this forum. I hoped that someone can say for sure, that must be a typo.
I don't really want to ask the Sony support. I don't really think that I'll get an qualified answer. I'm just not going to buy this SD card.

Now I'm wondering if the reason for the big number of incompatible SD-Cards (for the Raspi) is caused by the fact that many SD cards are still consuming too much power...

newpipe wrote: Now I'm wondering if the reason for the big number of incompatible SD-Cards (for the Raspi) is caused by the fact that many SD cards are still consuming too much power...

I think you have something here and am confused as to why this is not a standard part of the debugging regimen. (or why the max raspi SD max ma supply etc. is not as widely known as similar USB constraints.)

In fact, I have a Transcend 16gb class 6 card, raspi, and a card reader.
Using my pc and the card reader I can not copy 1gb to the card, because the card always unmounts in the middle of the transfer. Using my laptop w integrated card reader, I have no problem. Using the raspi, *** I get usb wifi problems and processes hung in syscalls w stack dumps in syslog.
Recently I moved the ext4 partition to a USB stick. Now, instead of dieing every 4ish hours, it dies every several days.

I just bought a class 4 sandisk 16gb and using the same card reader as above, i copied 1gb without issue.

The lesson? I think SD card power issues are huge contributors to stability issues and info surrounding this should take higher priority when buying/debugging a setup. (Is there even a point on the board to measure this w a multimeter?)

*** I think these issues are correlated but have not proved it absolutely. I will switch to the sandisk card this week and i expect that i will be much more stable.

Michael