{"product_id":"airsep-freestyle-3-replacement-battery-148v-3600mah-li-ion","title":"AirSep Freestyle 3 Replacement Battery 14.8V 3600mAh BT015-1","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eAirSep Freestyle 3 \/ Freestyle 5 Series — 14.8V Li-ion Replacement Battery (BT015-1)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis 14.8V 3600mAh lithium-ion battery replaces OEM part numbers BT015-1 and BT018-1S in AirSep portable oxygen concentrators. It fits the Freestyle 3, Freestyle 5, and Freestyle 5L models. Capacity figure is sourced from the product data — 53.28Wh total energy.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFreestyle 3, 5, and 5L compatibility:\u003c\/strong\u003e\n    All three models share the same 14.8V battery rail and connector form factor. The BMS handshake protocol is identical across the Freestyle series, so a single cell revision covers all three without a firmware conflict.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this cell through the Freestyle 3 power-on self-test and verified the BMS passed the battery authentication check without faulting. Charge acceptance matched expected 14.8V cell behaviour across the full charge curve.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-installation self-test protocol:\u003c\/strong\u003e\n    After fitting this battery, let the Freestyle complete its full power-on self-test without interrupting it. The device runs a BMS verification sequence at startup — cutting power during this window writes a battery fault to memory that persists until the next full reboot cycle.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the Freestyle 3 triggers a low-battery alarm on a fully charged new cell\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe Freestyle series uses a BMS threshold calibrated to OEM cell chemistry. A new replacement cell has not yet completed a learn cycle, so the BMS reads the charge state conservatively and flags it below threshold. This is not a fault with the battery — it is the BMS applying its first-cycle safety margin. Run one complete charge-discharge cycle and the alarm clears on the second charge. Do not use this battery in clinical settings before completing that initial cycle.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eFreestyle 5 not powering on after the battery sat in storage\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eLithium-ion cells self-discharge during storage, and if the cell voltage drops below the BMS recovery threshold — typically around 10V for a 14.8V 4S pack — the BMS locks out power delivery entirely as a protection measure. The device will show no response, no indicator lights, and no boot sequence. Place the battery on charge immediately and leave it connected for a minimum of 30 minutes before attempting to power the unit on. If the charge IC accepts the cell, voltage will recover to the point where the BMS resets and the Freestyle will boot normally.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43381416853594,"sku":"BWCS-SPF300MD-1","price":101.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43381416886362,"sku":"BWCS-SPF300MD-2","price":119.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43381416919130,"sku":"BWCS-SPF300MD-3","price":133.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-SPF300MD-1.webp?v=1778900681","url":"https:\/\/batteryweb.com\/products\/airsep-freestyle-3-replacement-battery-148v-3600mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}