microSD 2GB card and power consumption


I am working with an embedded system which uses Sandisk microSD cards to store log files. So far we have tried it with Sandisks microSD card with 2GB capacity. what we have discovered is that different cards (different individuals but still the same model) might consume very different amounts of power.

For instance our solution consumed 790 uA at 4,5 V with one card. We then tried with another card and otherwise the very same setting. Then the consumption was 256 uA. The consumption is calculated using arithmetic mean during a time period of 10 minutes. During this measurement the card was initialized and powered but the card was only written to once during this time period.

We also tried to put our device in a logging mode and the result was 955 uA with one card and 429 uA with the other. These measurements was also during a ten minutes interval but here a block of the SD-card was written every 7 seconds. 

Is there anybody else that has experienced big power consumption differences using the very same model of SD-card?