BusyDizzys

Follow up:

The charger. I guess this would be called a slo/trickle charger since it takes 16hrs+ to fully charge the batteries according to the instructions.

It outputs 1.25V at 130Mah. Takes 4 AA batteries and was made in Ireland...

Test Results (Click for the bigger picture)

From Wikipedia :

A  fully-charged cell measures 1.4–1.45 V (unloaded), and supplies a nominal average 1.25 V/cell during discharge, down to about 1.0–1.1 V/cell (further discharge may cause permanent damage in the case of multi-cell packs, due to polarity reversal). This voltage varies depending on the discharge rate of the cell (lower discharge loads result in an increased voltage output for longer periods, approaching the 1.4 V unloaded cell voltage).

Under a light load (0.5 ampere), the starting voltage of a freshly charged AA NiMH cell in good condition is about 1.4 volts;[12] some measure almost 1.5 volts. This voltage falls rapidly to about 1.25 volts at 10% depth of discharge (DOD) and then remains almost constant until the cell is over 80% discharged. The voltage then falls rapidly from about 1.2 volts down to 0.8–1.0 volts at which the cell is considered "flat" in most devices

This actually does fit in with the findings pretty closely, what we can assume from this is that the 1 battery is in much better health than the other, which is also about right as no 2 batterys are ever made equal. Hopefully now that they have been discharged enough I can recharge them a few more times and see if we have regained any of the lost capacity.

Conclustion :

Managed to run the vibrators motor at max speed for around 3 hours. Considering there 9 years old and have been used what must be 100's of times there doing ok so far.

To do :

Our next test we shall be using a torch and a childs toy car, its quite hard to find devices that use only 1 battery, I think using 1 battery at a time would give a better overall result. As we know no 2 batteries are created equal.