Some of the dataloggers have the possibility of monitoring an event such as
a switch on/off, but not all.

I think I have finally come up with a simple method - I will just use two
independent temperature loggers. One in the ice-box and one just above the
condenser fan. The latter will get an upward spike in temperature when the
compressor comes on. This way, I should be able to plot box temperature vs
compressor on/off cycle. This should do it.

Thanks for the input.

GBM

"nimbusgb" wrote in message
oups.com...
simpler is to take a couple of turns of the positive feed to the
compressor round a reed switch. Pump on, reed closes, pump off reed
opens. A lot simpler than having to read the current.

Ian M