{"product_id":"sumitomo-t-400s-replacement-battery-108v-3400mah-li-ion","title":"Sumitomo T-400S Replacement Battery 10.8V 3400mAh BU-15","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eSumitomo T-400S — 10.8V Li-ion Replacement Battery (BU-15)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 10.8V 3400mAh Li-ion battery for the Sumitomo T-400S digital theodolite. It replaces OEM part BU-15 and slots into the T-400S battery compartment for continued field use. Voltage and capacity match the original pack exactly.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eT-400S and T400S compatibility:\u003c\/strong\u003e\n    Both model designations refer to the same instrument platform. The BU-15 connector pinout, BMS handshake protocol, and 10.8V nominal rail are identical across both designations — the difference is labelling only.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We cycled this pack through instrument power-up, angle measurement sequences, and sustained horizontal circle drive loads. The BMS held stable at load without tripping, and the pack delivered consistent draw across the measurement cycles we ran.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003ePost-install calibration before field deployment:\u003c\/strong\u003e\n    After fitting this pack, run a full calibration cycle through the T-400S instrument menu before taking it to site. The instrument maps battery state during that routine. Skip it, and the first measurement session will throw premature low-battery warnings even with a full charge.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBMS cutoff when the T-400S initialises its horizontal drive motor\u003c\/h3\u003e\n\n  \u003cp class=\"bpw-desc-p\"\u003eAt power-up, the T-400S runs a self-check that briefly drives the horizontal circle motor to find its zero reference. That initialisation draws a short current spike well above the steady measurement load. An aged or partially depleted cell can't sustain the spike, and the BMS trips before the instrument finishes booting. A fresh pack resolves this — but if it happens on a new battery, let the pack charge to full before the first power-on. Starting the instrument with a partially charged new pack can still trigger the same cutoff.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eT-400S display shows incorrect battery percentage after pack replacement\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe T-400S uses a voltage-threshold method to estimate charge state, not a fuel gauge IC. When a new pack goes in, the instrument's internal reference still reflects the discharge curve of the old cell. The percentage shown will read inconsistently — often jumping or displaying low — until the instrument recalibrates its threshold against the new cell's curve. Run one full charge-to-discharge-to-full-charge cycle through normal instrument use. After that cycle, the display percentage stabilises. If it still reads erratically, check that the terminal voltage at the pack connector reads 10.8V ± 0.2V under no load.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43360632930394,"sku":"BWCS-STU400SL-1","price":42.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43360632963162,"sku":"BWCS-STU400SL-2","price":49.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43360632995930,"sku":"BWCS-STU400SL-3","price":54.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-STU400SL-1.webp?v=1778616135","url":"https:\/\/batteryweb.com\/products\/sumitomo-t-400s-replacement-battery-108v-3400mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}