In article ,
Grunff wrote:

[snip]
The nature of the load is such that the current consumption is
very spiky - it may average to around 2A, but you get very
short, sharp spikes, probably of 10-15A.

Do you have an idea of the timing, of the shortest
duration of a current spike?

I need to be able to measure, with 1% or better accuracy, the
total energy dissipated in the load over the duration of the
experimental run.
[snip]
The only sensible way I can think of doing this is to use a data
logger, and sample V and I at a high rate thoughout the
experimental run, then calculate average power over the run,
then multiply by run time.

I'm not sure that Average*Time will get the total
energy. Don't you have Integrate the instantaneous
power over duration of the run time?

Take V+I readings at fixed time intervals (significantly
shorter than the shortest spike), multiply V*I, and
accumulate.

The multiply and accumulate could either be done in
real time, or the raw V+I data log could be processed
off-line, say with something like MathCad.

--
Tony Williams.