UPS battery replacement and repair
UPS battery swaps: APC Smart-UPS SMT and Back-UPS BX, SLA/AGM packs, charging-circuit repair on the bench.
UPS batteries are consumable parts with a finite life — typically 3–5 years for traditional SLA (Sealed Lead-Acid) and AGM (Absorbent Glass Mat) packs, up to 8–10 years for newer Li-Ion kits. When the pack reaches end of life, the UPS no longer holds runtime during an outage, beeps continuously with a “Replace Battery” warning, or drops the load the instant mains is lost.
We replace batteries for all mainstream UPS brands: APC Back-UPS (BX, BE, BR series) running a single 12V 7–9Ah SLA, APC Smart-UPS SMT/SMC running two 12V 12Ah blocks in series (24V), Eaton 5E/5P/9SX and 9PX with 4–16 block strings, CyberPower UT/VP, PowerWalker VI series and Vertiv Liebert (PSI5, GXT5). Common failure modes: capacity loss after 3–5 years (accelerated in a warm room), plate sulfation after deep-discharge events, case bulging from internal overpressure, and a single dead cell pulling the whole string below the working threshold.
We also diagnose and repair the charging circuit when the fault goes beyond the pack itself — charge regulator, power MOSFET, current shunts and the feedback loop. Battery replacement carries a 6-month warranty; charging circuit repair is covered for 3 months. Diagnostics are performed at our service centre — the unit must be brought in person.
Popular models we repair
- APC Back-UPS BX (BX750MI, BX1400UI, BX1600MI)
- APC Back-UPS BE / BR (BE700G, BR1500GI)
- APC Smart-UPS SMT (SMT750I, SMT1500I, SMT2200I)
- APC Smart-UPS SMC (SMC1000I, SMC1500I)
- Eaton 5E / 5P / 9SX series
- CyberPower UT / VP series
- PowerWalker VI series (VI 850, VI 1500)
- Vertiv Liebert (GXT5, PSI5)
Common problems we fix
- Battery end of life (3–5 year cycle) — UPS no longer provides runtime
- UPS beeping continuously — battery replacement indicator active
- UPS no longer holds load during outage — equipment shuts off instantly
- Charging circuit failure — battery will not charge or charges only partially
- Swollen SLA/AGM battery — electrolyte leaked, case deformed
Detailed problem guides
Pick a symptom — we walk through the causes, what you can check yourself, and when to bring it in.
UPS battery replacement: SLA, AGM, and Li-Ion options
Most home and office UPS units use sealed lead-acid (SLA) or absorbent glass mat (AGM) batteries. These batteries are reliable and affordable, but their lifespan is limited — typically 3–5 years depending on ambient temperature. Higher temperatures accelerate degradation: every 10°C above 25°C cuts battery life by roughly 50%. This is why UPS batteries in air-conditioned server rooms last longer than those in an office without climate control.
At our service centre we replace SLA and AGM batteries for all mainstream UPS brands. An APC Back-UPS BX series typically requires a single 12V 7Ah or 12V 9Ah battery, while the APC Smart-UPS SMT1500I uses two 12V 12Ah batteries wired in series (24V). Larger Eaton and Vertiv systems may have 4–8 battery blocks with a total voltage up to 192V. We always fit batteries with matching or higher capacity, verify the charge voltage (typically 13.6–13.8V per 12V block) and run a load test after replacement. Some newer UPS systems also support Li-Ion battery kits that offer two to three times longer service life and lower weight — we advise on this option during diagnostics.
UPS charging circuit diagnostics and repair
The UPS charging circuit is a critical component that keeps the battery at full readiness. If the charging circuit malfunctions, even a brand-new battery will not deliver the expected runtime. A typical charging circuit contains a charge regulator IC (often a UC3906 or equivalent), a power MOSFET or bipolar transistor, a current-limiting resistor and a feedback loop with a voltage divider.
We diagnose charging circuits using precision oscilloscopy and voltage/current measurements. Common faults include: charge voltage too low (battery never fully charges), charge voltage too high (battery overheats and degrades prematurely), or zero charge current (complete charging circuit break). On APC Smart-UPS models the charge relays and current-sense resistors fail frequently. On Eaton units we sometimes find issues with the PFC (Power Factor Correction) stage, which affects both charging efficiency and output voltage quality. After component replacement and rework we run a full functional test — verifying the charge profile, switchover to battery mode and return to mains mode. UPS charging circuit repairs carry a 3-month warranty.
Pricing & warranty
Battery replacement warranty: 6 months.
If the repair cost changes during the process, the technician will call to agree on the new price. No work is done without your consent.
Frequently asked questions
Why customers choose SATER
- Custom-built battery assemblies. We design and assemble packs for the exact device — no 'close enough' substitutes.
- Sony, Samsung, LG, Panasonic, Molicel cells. Only top-tier cells — each one capacity-tested before assembly.
- Batteries for robots, power tools, laptops. We build packs for any device that runs on lithium batteries.
- 30+ years of experience. The service centre has been operating since 1993.
- We serve all of Latvia. Electronics service centre in Riga — we accept devices from anywhere in the country.