About this replacement
JVC GY-HMQ10 / GY-HM600E Series — 7.4V Li-ion Replacement Battery (SSL-JVC50 / SSL-JVC70)
This is a 7.4V, 4400mAh Li-ion replacement battery for JVC professional camcorders including the GY-HMQ10, GY-HM600E, GY-HM600EC, and GY-HMQ10E. It carries OEM part numbers SSL-JVC50 and SSL-JVC70 and fits the full GY-HMQ10 and GY-HM600 family. Capacity is 4400mAh (32.56Wh) — confirmed from product data.
- GY-HMQ10 and GY-HM600 platform fit: Both the GY-HMQ10 4K camcorder and GY-HM600 broadcast-format bodies run the same 7.4V rail and use identical SSL-JVC50/SSL-JVC70 connectors with the same BMS handshake protocol — that is why one cell covers the full lineup.
- Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on a GY-HM600E body. The BMS accepted the cell without fault flags, voltage held stable across the discharge curve, and the battery-remaining indicator tracked consistently through the full cycle.
- First-use charge cycle on a JVC body: On first install, charge this battery fully inside the JVC body or an OEM JVC charger before shooting. The GY-HM600 series BMS maps its battery-percentage display against the discharge curve only after one complete in-body charge cycle — skipping this step causes the indicator to read inaccurately from the first session.
Why the GY-HM600E battery percentage jumps erratically mid-recording
The GY-HM600 series maps its fuel gauge to a learned discharge curve stored in the BMS after the first full charge cycle. A new replacement cell has a slightly different open-circuit voltage profile than a worn original, so the body reads percentage against the wrong reference points until the curve is re-learned. This shows up as the indicator dropping sharply then recovering, or skipping from 60% to 20% without warning. One full in-body charge from 100% to 0% and back resolves it. After that cycle, the display tracks the actual state of charge accurately.
Camera shows no battery or rejects the cell on first install
The GY-HMQ10 and GY-HM600E bodies run a BMS authentication check on every cold install — if the cell voltage sits outside the expected window at rest, the body throws a no-battery or incompatible warning. A replacement cell shipped in storage mode can read as low as 3.0V per cell, which falls outside that acceptance window. Remove the battery, connect it to an OEM JVC charger or a compatible external charger, and bring it to at least 7.2V before reinserting into the body. One power cycle after that initial charge clears the rejection flag.