Looks like pito is correct, old cards use less power.
I did some tests with two cards, an older SanDisk 1 GB SD and a new SanDisk 16 GB high end microSDHC.
new:
Manufacturer ID: 0X3
OEM ID: SD
Product: SE16G
Version: 8.0
Serial number: 0X3752B221
Manufacturing date: 10/2013cardSize: 15931.54 MB (MB = 1,000,000 bytes)
flashEraseSize: 128 blocks
eraseSingleBlock: true
old:
Manufacturer ID: 0X3
OEM ID: SD
Product: SD01G
Version: 8.0
Serial number: 0XFB5C4F70
Manufacturing date: 12/2006cardSize: 1015.81 MB (MB = 1,000,000 bytes)
flashEraseSize: 32 blocks
eraseSingleBlock: true
I ran the new dataLogger example in the 20140806 version of SdFat GitHub - greiman/SdFat: Arduino FAT16/FAT32 exFAT Library.
I used a Teensy 3.1 so there would be no level shifters or regulators.
First I put a 4.7 ohm resistor in the ground line and looked at the voltage on a scope. See the three attached traces. The scale is 100 mv/div so with the 4.7 ohm resistor, the scale is about 21 ma/div.
There are two views of the new trace, the full trace at 2 ms/div and a magnified portion at 500 us/div. Notice that the current stays higher, about 10 ma for about 6 extra ms.
If you look at the two 500 us/div traces, the write current in the trace is higher for the new card.
Edit: I added a third version of the new trace at 2 usec/div for fun.
I also put a handheld DMM in the 3.3V line to check idle current. I found that the cards went through at least two states. The new card immediately drops to about 500 uamp then sleeps at about 70 uamp . The old card immediately drops to about 200 uamp and sleeps at 60 uamp.
The dataLogger example is a current hog since it calls sync() after every data point. That will cause at least two reads and two writes for each data point. If you remove the sync calls after each point, the power use will drop a huge amount.
