PMNN4491D is the latest iteration of the PMNN4491 battery and is the only version available. PMNN4491A, PMNN4491AR, PMNN4491B, PMNN4491C are no longer available.
PMNN4491D is the same physical size shape and weight as previous versions. However, this version has a new V2 IMPRES chip inside which does not display on IMPRES v1 chargers.
Original IMPRES v1 chargers are the “Slanted” version Multi-Unit Chargers (MUCs), such as WPLN4218 and WPLN4211. These IMPRES v1 chargers will display NON-IMPRES BATTERY when PMNN4491D is inserted – as shown below.
These IMPRES v1 chargers (“Slanted” Multi-Unit Chargers) have display hardware and firmware that are not compatible with PMNN4491D’s internal IMPRES v2 chip. But they will still charge the batteries as normal.
To clarify, PMNN4491D IS an IMPRES battery and will charge on ALL chargers. ALL non-IMPRES chargers can charge PMNN4491D. ALL IMPRES v2 chargers can charge and calibrate PMNN4491D.
All status LEDs correctly show the current state of the charging process but the display will not.
IMPRES v1 Slanted” version Multi-Unit Chargers (MUCs) include*:
- WPLN4218 IMPRESTM original Multi Unit Charger base with 6 displays, sold in the following MUC kits:
- WPLN4219 (US), WPLN4220 (EURO), WPLN4221 (UK), WPLN4222 (AUS/NZ), WPLN4223 (ARG), WPLN4224 (KOR), WPLN4278 (BRZ)
- WPLN4211 IMPRESTM original Multi Unit Charger base with 0 – 1 display sold in the following MUC kits:
- PLN4212 (US), WPLN4213 (EURO), WPLN4214 (UK), WPLN4215 (AUS/NZ), WPLN4216(ARG), WPLN4217 (KOR), WPLN4277 (BRZ)
* There may be more. These are only the ones we know about.