Hi all, so it works like this.........
The default charging rate is 1C. It isn't possible to override this and save anything greater into the memory. Each time one wants to charge a single battery at greater than this the additional amps need to be entered either by choosing a charge rate in 5A increments manually from a drop-down list or to enter the desired value by increasing in 0.1A increments.
Before doing this, it's necessary to check the split of the charger's capacity between the two channels (normally 50/50) and increase channel one to 99%. Using a saved profile for a 'fudged' capacity (in 5,000mAh multiples) it's possible to load channel one in multiples of 5.0A as above. The charger will start its run until it reaches its 25A output limit. I haven't tried it on a single battery as this would mean charging at 5C. However, with four batteries (2 per channel), it won't go above 25A output.
So by my thinking, if I ever get round to connecting 8 batteries they will only be charging at around 3 amps each i.e. 0.5C. Looks like I've bought a pup if I ever want to do 8 batteries at 1C.