I'd be a bit nervous about this purchase. I looked for HDC2472 at the Roboteq site and couldn't find it, I looked for it in the HDC24xx data sheet and couldn't find it there either, and I looked for it in the controller list in the Roborun software - AND IT IS THERE! It may be a discontinued product, but if so it is even older then the 2019 HDC24xx data sheet which lists a HDC2496 as discontinued, but doesn't mention the HDC2472 at all (but doesn't mention the HDC2450 either). I think that you should write ASAP to Roboteq and ask them what the status of that unit is - e.g. last date it was sold and whether there is a particular reason that they no longer sell it. If old, it may not be compatible with my software, but its firmware does include all of the functions called from my software so Roborun at least compiles my script for it without throwing errors.
Another warning sign. The ebay link in your message now shows
This listing ended on Tue, Nov 21 at 8:22 AM.
. Did the original listing say there were just 2 for sale? Is this a scam? Can you back out of this?
The max current discrepancy may also be a bit worrisome, but the two numbers may be 120 A max for 30 seconds and 80 A max continuous. The HDC2450 was and the HDC2460 are 150 A for 30 seconds and 80 A continuous. However, even a time-limited 120 A points to an older controller with smaller MOSFETS.
As for batteries, I'm with Burgerman on this. LiFePO4 is a better choice than LiTi because you can fit many more AHr in the same space, and that will greatly affect lifetime. A large LiFePO4 pack will outlast multiple wheelchairs! Also, with big capacity thermal runaway becomes a non-issue because the current draw will almost always be a small fraction of the maximum discharge rate, and a few seconds even at maximum discharge rate isn't going to cause overheating. HOWEVER, you must keep the total voltage of your pack, even during charging, to less than the maximum voltage tolerated by your controller.
Ciao,
Lenny