Hi guys. im currently working on a project for AIS ship tracking and the part of it is a remote ap which will be connected via wireless to provide data outlet for the tracking device(as it has to access the Internet). i have successfully deployed the system in the remote locations before but not without easy access to power as this is going to be. i must lower the power consumption to lower than 5W (whole system and my TRACKER uses 2.1W which is not reducable. So i was wondering if power consumption of devices could be lowered by trimming the firmware to bare essentials? i already have soldered off the indicator leds and removed linear regulator in favor off DC-DC BUCK Stepdown regulator (increasing efficiency to 94%) Any creative input will be appreciated
Can you please describe your system a bit more detailed?
Underclock the CPU and RAM.
I have measured a TL-WA701 to use about 0.75 watts-- that is entirely stock hardware with a standard OpenWrt build.
Goes like this:
Internet router ---> via cable(LAN and POE(custom made)) ---> SX763 #1
SX763 #1 ---> PtP Wireless link 2.4GHz abt. 750m (as crow flies)---> SX763 #2
SX763 #2 ---> via cable (LAN ONLY) --->Comar SLR300(actual ais receiving device that needs net access)
SX763 #2 also provides an Wireless AP on remote location (since i have net to this point it seamed logical to allow it)
SX763 #1 is powered by custom POE (48V) from mains. it also has an backup battery for abt. 2 hours of runtime (in case of mains failure) this battery is also powering the Internet router(ISP). It has a Yagi antenna bought cheap of ebay
SX763 #2 is powered from a 12V solar battery directly. it has no sun power reserve of at least 7days. this one also has the same antenna
It is how it works now with out a problem currently for 70days wo restarting and whole system has been in operation for more than 4years. occasional minor glitches, software updates and mechanical damages but no problems. Sometimes foliage growth in the fresnel zone would drop the rate from maximum to abt 12Mbit but after clearing the path again it works without a hitch.
Now im about to get the other part of the system (SX763#2 (or other router) and SLR300 to a mountain terrain where is hard to get to, no road whatsoever, last leg of 700m Altitude diff. is by foot only and very difficult to traverse. Heavy battery and solar panel that will power the whole station have to be minimized to max extent to be light so that it can be carried up. and also robust to endure the elements(enclosure will be made). Everything should fit under the solar panel and only AIS and Wireless antenna can be above. Wifi Antenna pointing to SX763 #1. Range of wireless link will be around 1350m and i tested the quality on the field and works but i think SX763#1 shoud be exchanged by something more powerfull, i have on hand a TPLink CPE210 that i think will do the job. sorry for the long post... 
how would one go about with downclocking?
shit i just read your post again. at first i think 7.5W that is ok, i can maybe lower it a bit. but 0.75W would be a dream. do you think that WA701 could do the wireless job (1350m with that cheap ass antenna of mine?)
Not sure if this would help http://forums.whirlpool.net.au/forum-replies.cfm?t=2159920 but this guy has used a wr703 for a link and it is very low power. 0.5W range.
hello again. on my progress...
i have found that TpLinkCPE210 uses 1W of power when running wireless, all leds on and running md5sum /dev/urandom (to get the processor working hard). i will dimension my batteries and solar panels with this consumption in mind. thanks for your help