{"product_id":"rollei-es1020g-mp3-player-replacement-battery-37v-2900mah-li-polymer","title":"Rollei ES1020G MP3 Player Replacement Battery 3.7V 2900mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eRollei ES1020G MP3 Player — 3.7V Li-Polymer Replacement Battery\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 3.7V, 2900mAh lithium-polymer battery fits the Rollei ES1020G portable MP3 player. It replaces the original cell when capacity fade shortens playback sessions or the device stops holding a charge. Dimensions are 97.53 × 53.68 × 4.90mm — confirm these against your existing cell before installing.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eES1020G platform fit:\u003c\/strong\u003e\n    The ES1020G runs a single-cell Li-Polymer architecture at 3.7V nominal. This replacement matches that voltage rail and physical footprint, so the board's protection circuit reads the cell correctly on first connect.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through charge and discharge on a Li-Polymer test rig. The BMS handshake completed without fault flags, and the protection circuit tripped correctly at the low-voltage cutoff threshold — no false shutdowns during mid-cycle draws.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install charge cycle:\u003c\/strong\u003e\n    After fitting this cell, run a full charge before first use. Media players frequently enter deep-discharge protection after extended storage, and a slow trickle from the charger is what pulls the BMS out of that locked state before normal charge current resumes.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBattery percentage jumping after cell swap on the ES1020G\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eAfter replacing the cell, the ES1020G's fuel gauge often reads inaccurate percentages for the first few cycles. The on-board voltage-threshold indicator was calibrated to the discharge curve of the original — often degraded — cell. A new cell has a flatter discharge profile, which the indicator hasn't mapped yet. Run two or three full charge-to-discharge cycles and the percentage readout will stabilise against the new cell's actual curve.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003ePlayback cutting out before the battery indicator shows empty\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis happens at the tail end of the discharge curve when cell voltage sags below the audio amplifier's minimum operating threshold — even though the indicator still shows charge remaining. The amplifier draws a short burst of current during audio decoding, and a weakened or deeply cycled cell can't hold voltage through that spike. With a fresh 2900mAh cell, the voltage floor stays above the amplifier's cutoff point throughout the usable charge range. If cutouts persist after installation, charge to 100% and allow the BMS to complete a full initialisation cycle before testing.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381340799066,"sku":"BWCS-RE1020SL-1","price":25.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381340831834,"sku":"BWCS-RE1020SL-2","price":28.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381340864602,"sku":"BWCS-RE1020SL-3","price":31.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-RE1020SL-1.webp?v=1778900029","url":"https:\/\/batteryweb.com\/products\/rollei-es1020g-mp3-player-replacement-battery-37v-2900mah-li-polymer","provider":"BatteryWeb","version":"1.0","type":"link"}