I recently ordered an R3000 set and am installing as OEM carts get low (see attached) rather than wait for a printer message.
The date on the cartridge boxes was May, 2013 (14 months old), so a preemptive battery replace was done before filling (kudos to IJM for the spare). The new batteries measured 1.55v whereas the old batteries were 1.45 and 1.39v, about 25-33% in to their expected life time.
Question for IJM: is there a way to measure voltage under load (eg. when the battery is in the sensor) from the exposed sensor traces without a sensor reset/failure? This would allow removing/replacing a cartridge much quicker and would give a more accurate measurement than no-load.
Question for all: has anyone measured battery voltage for the old battery when battery replacement corrected an issue? This would help understand the actual low-voltage point.
For the future I'm going to go with the S type as the service life is about 2x (wikipedia, Button_cell).