About this replacement
NiKon D300 — 11.1V Li-ion Battery Grip Replacement (KEL4A)
This 11.1V, 2200mAh Li-ion battery fits the NiKon MB-D10 grip used on the D300. It slots into the grip's battery chamber and powers both the camera body and the grip's vertical shutter controls. Capacity figure is 2200mAh as specified in the product data.
- D300 grip compatibility: The MB-D10 grip authenticates each battery slot independently through a separate BMS handshake. Both slots must pass authentication before the grip enables vertical shutter operation. A failed handshake on either slot keeps vertical controls inactive even when the camera fires normally.
- Bench tested on actual hardware: We ran this battery through the MB-D10's dual-slot detection cycle. The BMS reported correct cell voltage to the camera's info screen, authenticated cleanly in both slot positions, and the vertical shutter controls activated without delay.
- Dual-slot charge matching: When running two batteries in the grip, insert both at the same state of charge. The grip draws from whichever slot reads the lower voltage first. A large mismatch between cells forces one battery to deplete well ahead of the other, compressing total capacity.
Why the D300 grip drains one battery faster than the other
The MB-D10 grip does not draw from both slots equally at all times. It reads each cell's voltage and pulls from the lower-charge slot first, attempting to balance draw over the session. If both batteries start at significantly different charge levels, the grip locks onto the weaker cell and depletes it before switching. This produces a situation where one battery shows near-full capacity while the other is already exhausted. Starting both cells at the same charge level — within roughly 0.2V of each other — prevents this imbalance.
Vertical shutter unresponsive after battery swap in grip
The vertical shutter controls in the MB-D10 only activate when both battery slots are occupied and each battery passes its individual BMS authentication. If you swap only one slot and the replacement fails authentication — even briefly — the grip disables vertical controls for the entire session. Remove both batteries, reinsert the replacement, wait five seconds, then reinsert the second cell. The grip re-runs authentication on both slots and restores vertical shutter function once both cells read above the minimum threshold of approximately 10.8V.