jonescg wrote: the whole thing is a sealed unit,
Everything can be opened!
so I'm not sure how you would change it.
I thought that the PDF had some clues. Some models might be harder than others, of course.
There is no serial port either.
Not officially. I strongly suspect that the CAN bus versions have a serial port available on two of the pins of the 7 (?) pin connector. Maybe the non-CAN versions do too. I suspect that the serial port is also how they overwrite the programs. But the protocol doesn't seem to be documented.
How do these chargers work anyway? Surely if the maximum output is X volts, then the pack, connected in parallel with the charger would reach X volts?
Eventually. Initially, the pack will be down by 10-20 volts, and trying to lift a discharged pack to maximum charge voltage immediately would take say 200 amps. So initially, the charger's output drops to below maximum, so as to draw only the maximum that the charger can supply (in your case, 10 A).
At this point the current will have dropped and the whole thing would be consuming a small amount of energy just keeping things topped up?
Right. After some hours, the battery will reach the CV voltage, at which point the current will be much lower, say 6 A. When the current reaches a certain low value (say 2-5 A for one minute), the charger will decide that the pack is full and terminate the charge, drawing almost nothing from the mains, and not charging the cells any further. That cutoff current varies with the capacity of the pack (for 200 Ah cells, the cutoff current should be about twice the value for 100 Ah cells, for example). This is one of the choices you make when you select the charging "algorithm": you choose a combination of a CV voltage, and a cutoff current.
I think it may be possible to overcharge lithiums by leaving them indefinitely on "float" charge, even if the voltage is still within specification.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.