Which Release version are you using?
When I tried to enter in "mem" on Release 2.1 (version = 146) I get the following message:
[ 880.979996] pci_pm_suspend(): sdhci_pci_suspend+0x0/0xc0 returns -16
[ 880.980015] dpm_run_callback(): pci_pm_suspend+0x0/0x1b0 returns -16
[ 880.980029] PM: Device 0000:00:01.3 failed to suspend async: error -16
[ 881.001417] PM: Some devices failed to suspend
sh: write error: Device or resource busy
Are you getting the same output?
I will investigate more about this and as soon as I get results on how to use these states I will post them in here.
In the meantime, a workaround can be using the Release2 . With this image I did not receive errors and you can try to measure the power consumption, fortunately you will get better results.
I am using the "edison-image-ww18-15" Release. I did not get those errors. When you get that you just need to execute "systemctl stop wpa_supplicant" but the problem is that after you execute it again it will not go to mem state.It will work again after you reboot it.
I just want to know how to achieve those 13mW? even in mem state it will consume around 130mW.
There is some discussion about this @ Measured power consumption of Intel Edison | Michael Hirsch, but the short of it the edison can achieve this low power consumption with the original software loads, but some of the bug fixes in the newer loads draw more power.