I was worried I had a current drain somewhere so I bought one of these.
Its not terribly accurate but should be good enough to pick up a serious drain somewhere, and its cheap compared to the highly accurate meters which go into the hundreds of pounds.
http://www.maplin.co.uk/p/uni-trend-...mp-meter-n41nc
Its DC voltage resolution is 0.01A and accuracy is 2%+5 units (0.05A) up to 40A range.
So if you had a normal parasitic drain in the D2 sleep mode of around 0.1 to 0.2A the reading could be +/- 0.05A out but the error is small enough.
So for example if your parasitic drain turns out to be 0.4A you will know that's too high, even with the +/- 0.06A error its still too high.
My car's reading was 0.18A and it does not kill a 31Ah battery after 10 days. So in my case the reading may be a bit high as at that rate it would drain 43Ah in 10 days.
stats here
http://www.uni-trend.com/en/product/2014_0730_827.html