About this replacement
Pure Avalon N5 / Evoke D4 Series — 3.7V Li-ion Replacement Battery (F1)
This 3.7V 8800mAh Li-ion battery replaces the original F1 cell in the Pure Avalon N5, Evoke D4, Evoke D4 Domino, Evoke D4 Mio, and over eleven additional Pure DAB digital radio models. It restores power to portable DAB+ receivers that have lost capacity through normal cycle wear. Voltage and cell dimensions match the original specification exactly: 70.50 × 73.50 × 19.00mm.
- Avalon N5 and Evoke D4 platform fit: These models share a common battery bay geometry and the same F1 cell format — identical connector pinout, cell dimensions, and 3.7V nominal voltage rail — so one replacement covers the full range without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Evoke D4 platform. The BMS accepted a full charge cycle without fault flags, and the protection circuit tripped correctly at the low-voltage threshold, preventing deep discharge damage.
- Post-swap station scan on DAB radios: After fitting this battery, run a full auto-scan from the radio's menu before manual tuning. DAB station lists are held in volatile memory and are wiped whenever power is fully interrupted — the radio needs a fresh scan to rebuild the complete station list for your area.
Radio cutting out mid-station at low battery
The DAB decoder inside the Evoke D4 and Avalon N5 requires a stable, consistent voltage to maintain stream synchronisation. When the battery sags below roughly 3.4V under load, the decoder loses lock on the multiplex and the audio drops out — even if the battery indicator still shows one bar. This is a decoder voltage floor issue, not a signal problem. Fitting a fresh cell at full charge eliminates the sag and restores clean stream decode.
Reception noticeably worse in low-signal areas after an old battery degrades
In weak DAB coverage areas, the Pure radio pushes its RF front-end harder to acquire and hold a signal. A degraded battery cannot sustain the voltage the RF stage needs under that elevated draw, so sensitivity drops and the signal-quality bar falls. This looks like a worsening of local coverage but is actually a power delivery failure. Replacing the cell and confirming voltage sits above 3.7V at rest resolves the issue.