2V 1000Ah UPS Battery: 480 V DC Bus String Sizing and Runtime Engineering

Answer First

A 2V 1000Ah UPS battery is a single 2V cell with 1,000 Ah of nominal capacity, and in a modern single-phase or three-phase uninterruptible power supply it is rarely installed alone: a 480 V DC bus is built from 240 of these cells in series, giving 480,000 Wh of nominal energy (240 × 2,000 Wh, Arithmetic), while a 240 V bus is built from 120 cells at 240,000 Wh (Arithmetic). The cell that CHISEN publishes for this duty is the OPzV2-1000, a 2V tubular gel cell rated 1,000 Ah at the C10 rate, measuring 233 × 210 × 681 mm, weighing 73.2 kg (161.4 lbs), floating at 2.23 V at 25 °C, equalising at 2.35 V at 25 °C, temperature-compensated at −3 mV/°C/cell, limited to 200 A of maximum charge current and carrying a designed float life of 20+ years @20 °C (Datasheet). The complete specification block is on the OPzV2-1000 model page, and every figure below traces back to that datasheet, to the matching flooded datasheet, or to arithmetic performed on those figures.

The arithmetic that decides the purchase order is simple and unforgiving. One cell stores 2,000 Wh (2 V × 1,000 Ah, Arithmetic), so a 240-cell string is a 480 kWh battery; at a 50 % depth-of-discharge design limit that is 240 kWh of usable energy, which supports an 80 kW load for 3.0 hours (240 kWh ÷ 80 kW, Arithmetic) — and only 1.5 hours if the inverter is allowed to take the string down to a 25 % depth of discharge. The same cell weighs 73.2 kg, so one 240-cell string is 17,568.0 kg of battery on the floor (240 × 73.2 kg, Arithmetic) and the whole bank has to be engineered around: a 60-cell sub-string is 4,392.0 kg (60 × 73.2 kg, Arithmetic), which is the practical unit for installation, handling and replacement.

Three published numbers should be read before the quotation is issued. First, the 20+ years @20 °C float life of this cell drops steeply in a warm room: the flooded sibling’s datasheet curve reads roughly 10–12 years at 30 °C, 6 years at 40 °C and 2–3 years at 50 °C (Datasheet), so a UPS room without cooling shortens the replacement interval even though the nameplate figure looks unchanged. Second, the cell is rated at 100 A on the ten-hour rate (1,000 Ah ÷ 10 h, Arithmetic), and its internal resistance is about 0.50 mΩ at 25 °C (Datasheet), so a 240-cell string presents roughly 120.0 mΩ (240 × 0.50 mΩ, Arithmetic) — a figure that makes cell-to-cell matching a design constraint rather than a detail. Third, the maximum charge current of 200 A is a per-cell ceiling equal to 0.2 C10 (200 A ÷ 1,000 Ah, Arithmetic), and a 240-cell bank charged at a realistic 100 A draws only 0.42 A per cell (100 A ÷ 240, Arithmetic), so the charger rating set by the inverter is almost never the constraint.

Key Takeaways

• 2V 1000Ah UPS battery cells are series members, not stand-alone batteries. A 480 V DC bus needs 240 cells (480 ÷ 2, Arithmetic); every cell in that string floats at the same 2.23 V and every cell must be matched.
• Published specification for the gel cell. OPzV2-1000: 1,000 Ah at C10, 233 × 210 × 681 mm, 73.2 kg, Female Copper Insert M8 terminal at 10–12 N·m (Datasheet).
• One charging basis for the whole 2V tubular range. Float 2.23 V at 25 °C, equalising 2.35 V at 25 °C, temperature compensation −3 mV/°C/cell, designed float life 20+ years @20 °C (Datasheet).
• Runtime is set by string count and depth of discharge, not by the cell label. 480 kWh nominal, 240 kWh usable at 50 % DoD, 3.0 h on an 80 kW load (Arithmetic).
• Weight is the installation constraint. 73.2 kg per gel cell, 17,568.0 kg per 240-cell string, 4,392.0 kg per 60-cell sub-string (Arithmetic).
• Matching and temperature decide service life. About 0.50 mΩ per cell means 120.0 mΩ across a 240-cell string, and a 5 mV per-cell spread adds 1.20 V to that string (Arithmetic) — which is why acceptance testing is not optional.

§1 — 2V 1000Ah UPS Battery Quick Specifications

The two cells below are the models CHISEN publishes for 2V 1000Ah UPS duty: the OPzV2-1000 tubular gel cell and the OPzS2-1000 tubular flooded cell. Values are reproduced as published; nothing has been rounded, converted or interpolated. Parameters that the source does not publish are listed as unpublished rather than estimated.

The flooded counterpart is published in more detail, which is useful when a project compares the two technologies cell by cell:

Two cautions belong next to this table. The first is that the gel cell and the flooded cell are not dimensionally identical — 233 × 210 × 681 mm for the gel cell against a 233 × 210 × 645 mm container with a 700 mm overall height for the flooded cell (Datasheet) — so a rack designed for one is not automatically a rack for the other. The second is that the flooded cell’s solar and wind controller setpoints (float 2.25 ± 0.005 V, equalise 2.40 ± 0.01 V, over-voltage disconnect 2.47 ± 0.01 V, low-voltage disconnect 1.90 ± 0.005 V, compensation −4 mV/°C/cell) belong to renewable-duty charging, not to a UPS float regime (Datasheet); in float standby the cell is held at 2.23 V per cell (Datasheet).

§2 — The Pain: Why 2V 1000Ah UPS Banks Are Sized Wrong

Most disappointing runtime in a UPS project is not a manufacturing defect; it is arithmetic that nobody wrote down before the order was placed. The classic failure starts with the cell label. A 2V 1000Ah UPS battery looks like a 1,000 Ah battery, and 1,000 Ah is what the installer carries into the design — but the cell is a two-volt series member, so its usable energy is 2,000 Wh (Arithmetic), and the string is what the inverter actually sees. The second classic failure is the depth-of-discharge assumption. A cell rated 1,000 Ah at C10 does not deliver 1,000 Ah into a 15-minute high-load discharge, and an inverter configured to pull a string down to a deep end-voltage window will deliver less than the runtime sheet promised; at a 50 % depth-of-discharge design limit the 480 kWh string supports 3.0 hours on an 80 kW load, while a 25 % limit cuts that to 1.5 hours (all Arithmetic).

The third failure is temperature, and it is the one that costs the most in tropical and equatorial installations. The flooded datasheet publishes a capacity of 100 % at 25 °C, 85 % at 0 °C and 65 % at −15 °C (Datasheet), so a cold room silently removes 15 % of the available runtime in winter. The warm side of the same curve is more expensive still: the designed float life of 20+ years at 20 °C falls to roughly 10–12 years at 30 °C and 6 years at 40 °C (Datasheet), so a string running in a 35 °C UPS room without forced cooling consumes the same calendar time as a string in a 20 °C room while delivering far less service life.

The fourth failure is matching. With about 0.50 mΩ of internal resistance per gel cell (Datasheet), a 240-cell string presents 120.0 mΩ (240 × 0.50 mΩ, Arithmetic). A 5 mV per-cell spread across that string adds 1.20 V (240 × 0.005 V, Arithmetic) of imbalance, which the charger then has to equalise away for the rest of the string’s life; a 12 V six-cell block would show the same 5 mV spread as only 0.03 V (6 × 0.005 V, Arithmetic). The fifth failure is weight logistics: at 73.2 kg per gel cell, a 240-cell string is 17,568.0 kg (Arithmetic) that must be moved through doors, down corridors and into position, usually with a crane or a pallet jack, which is why sub-strings of 60 cells (4,392.0 kg each, Arithmetic) and 120 cells (8,784.0 kg each, Arithmetic) are the practical delivery unit in most installations. Buyers who specify the cell only, and leave the string architecture to the installer, pay for all five of these problems later.

§3 — The Choice: Gel OPzV2-1000 Versus Flooded OPzS2-1000 for UPS Duty

Both cells answer the same electrical question — 2 V, 1,000 Ah, 2.23 V float at 25 °C, 2.35 V equalising at 25 °C, −3 mV/°C/cell compensation and 20+ years @20 °C of designed float life (Datasheet) — and they differ in the plant around them rather than in the numbers on the rating plate.

Two readings of this table settle most arguments. The first is that the installed weight difference is negligible — 73.2 kg for the gel cell against 73.5 kg for the flooded cell with its acid, because the 20 kg of electrolyte in the flooded version replaces the gel (Arithmetic). A UPS room designed around floor loading therefore does not change its logic when the chemistry changes. The second is that the flooded datasheet publishes figures the gel datasheet does not: a short-circuit current of 4,500 A, a self-discharge of 3 % per month at 20–25 °C, a float-current ceiling of 5 mA/Ah and a full discharge-capacity table at 1.85 V (Datasheet). If a project specification calls for short-circuit data, a self-discharge figure or a capacity curve, the flooded cell is the one that answers on paper — the gel equivalent must be requested from the factory in writing, and the OPzS2-1000 model page is where the published block is kept.

§4 — The Framework: String Architecture, Runtime Arithmetic and the Acceptance Test

A 2V 1000Ah UPS battery is specified in four steps, and the order matters: bus voltage, string architecture, depth-of-discharge limit, then acceptance criteria.

Bus voltage and cell count. A 480 V DC bus is 240 cells (480 ÷ 2, Arithmetic) and floats at 535.2 V (240 × 2.23 V, Arithmetic) while equalising at 564.0 V (240 × 2.35 V, Arithmetic); the 1.80 Vpc end-of-discharge floor of the same string is 432.0 V (240 × 1.80 V, Arithmetic). A 240 V bus is 120 cells, floating at 267.6 V and equalising at 282.0 V, with a 216.0 V floor (all Arithmetic).

String architecture. Two common arrangements carry the same 240 cells: two parallel strings of 120 cells, each weighing 8,784.0 kg (120 × 73.2 kg, Arithmetic), or four parallel strings of 60 cells, each weighing 4,392.0 kg (60 × 73.2 kg, Arithmetic). More strings means lighter handling units, more interconnects and more midpoint taps for the string monitor, but the same total energy of 480,000 Wh (Arithmetic). One megawatt-hour of nominal storage needs 500 cells (1,000 kWh ÷ 2,000 Wh, Arithmetic).

Depth of discharge and runtime. The published nameplate is the ceiling, not the plan:

All figures in this table are Arithmetic from 240 cells × 2,000 Wh = 480,000 Wh, 50 % and 25 % depth-of-discharge limits, and a 480 V bus built from the OPzV2-1000 (Datasheet).

Charger sizing. The cell’s own ceiling is 200 A, which is 0.2 C10 (Arithmetic). A 240-cell bank charged at a practical 100 A draws 0.42 A per cell (100 A ÷ 240, Arithmetic), so the cell limit is not the binding constraint; the inverter’s rectifier rating is. With two parallel strings, one 50 A charger per string keeps each cell at 0.42 A (50 A ÷ 120, Arithmetic) and leaves the string’s float current headroom intact. On the flooded variant the float current must stay under 5 mA/Ah, i.e. 5.0 A per cell and 1,200 A across a 240-cell string at the limit (Datasheet, Arithmetic).

Acceptance test. The commissioning protocol that protects a 240-cell string has four stages. First, charge the string at the equalising setpoint of 2.35 V per cell (Datasheet) and confirm that every cell reaches the setpoint, because a cell that cannot reach it will be the first to fall out of the string. Second, discharge the string at the ten-hour rate — 100 A per cell for a 1,000 Ah cell (1,000 Ah ÷ 10 h, Arithmetic) — and record each cell’s terminal voltage; the 1.80 Vpc final voltage is the published reference point (Datasheet). Third, measure the float current per cell and compare it with the 5 mA/Ah ceiling published for the flooded cell (Datasheet). Fourth, torque every interconnector to the published 10–12 N·m on the Female Copper Insert M8 terminal (Datasheet) and record the string’s voltage spread; a spread of 5 mV per cell becomes 1.20 V across 240 cells (Arithmetic) and is the earliest warning that a cell is out of balance.

§5 — Where the 2V 1000Ah Sits in the CHISEN Tubular Range

The 2V 1000Ah cell is one step in a size ladder, and the choice is usually driven by rack height and floor loading rather than by capacity alone. The full OPzV2 gel tubular line is published as follows (Datasheet):

Three sizing rules follow from that table. A 480 V bus of 240 OPzV2-1000 cells stores 480,000 Wh; the same bus built from OPzV2-1200 cells stores 576,000 Wh (240 × 2,400 Wh, Arithmetic) at a weight of 20,160.0 kg (240 × 84 kg, Arithmetic). If a row of the rack cannot take a 681 mm-tall cell, the OPzV2-500 and OPzV2-200 models are 506 mm and 390 mm tall respectively (Datasheet), and the string count rises to compensate: 240 cells of 500 Ah still fill a 480 V bus, but the energy falls to 240,000 Wh (240 × 1,000 Wh, Arithmetic). Finally, as the cell grows the internal resistance falls — from ~1.0 mΩ on the OPzV2-200 to ~0.30 mΩ on the OPzV2-2500 (Datasheet) — so a 240-cell string built from larger cells carries less voltage drop at high load, which matters for the output regulation of the UPS itself.

§6 — The Trust: How to Vet a 2V 1000Ah UPS Battery Supplier

A supplier that cannot answer these eight questions on paper is not a supplier of a 2V 1000Ah UPS battery; it is a supplier of a label. Ask for the datasheet and confirm that it states the float voltage of 2.23 V at 25 °C, the equalising voltage of 2.35 V at 25 °C, the temperature compensation of −3 mV/°C/cell and the designed float life of 20+ years @20 °C, each with a source label. Ask for the compliance list: IEC 60896-11:2002, DIN 40736-1:1985, GB/T 19638.2-2014, YD/T 1360, Eurobat Long Life, BS 6290 Part 4 and UL 1989 are the standards published for the flooded cell (Datasheet), and an equivalent statement is expected for the gel cell. Ask for capacity test reports at the C10 rate to 1.80 Vpc with the test date, the cell serial range and the measured Ah — a factory that tests to 1.80 Vpc but quotes to 1.75 Vpc is quoting two different batteries. Ask for the interconnector torque specification (10–12 N·m on a Female Copper Insert M8 terminal, Datasheet) and for a spare-parts programme matched to the string architecture, because on a 240-cell string a single open circuit in one sub-string ends the installation’s autonomy. Ask how the supplier handles the market that matters to you: UPS demand continues to grow across China, India, Nigeria, Kenya, South Africa, Egypt, Brazil, Indonesia and Vietnam, and cells ship routinely from Shanghai, Ningbo and Shenzhen to Jebel Ali, Lagos, Mombasa, Durban, Cairo, Santos, Mumbai and Karachi, so the question is not whether the battery will arrive but whether the supplier can support a 240-cell string with spares and technical support after the container is unloaded.

On CHISEN’s own record: the company operates 8 production bases with an annual capacity of 70 million kVAh, holds CE, ISO 9001, ISO 14001, UL and IEC certification, and builds the flooded tubular OPzS2 line, the gel tubular OPzV2 line, 12 V VRLA blocks in the 6-DZF, 6-DMF and 6-EVF ranges, 6 V and 8 V EVF blocks, plus solar and lithium storage systems (Company facts). The gel tubular range is documented on the OPzV2 product hub page.

§7 — FAQ

Q1: How many cells does a 480 V UPS battery bank need? 240 cells, because 480 ÷ 2 V = 240 (Arithmetic). Each cell floats at 2.23 V, so the string floats at 535.2 V (240 × 2.23 V, Arithmetic) and equalises at 564.0 V (240 × 2.35 V, Arithmetic).

Q2: What is the published capacity of the OPzV2-1000 cell? 1,000 Ah at the C10 rate to 1.80 Vpc, which is a 100 A discharge on the ten-hour rate (1,000 Ah ÷ 10 h, Arithmetic) (Datasheet).

Q3: What float and equalising voltages should the UPS charger use? 2.23 V float and 2.35 V equalising per cell at 25 °C (Datasheet), with the temperature compensation of −3 mV/°C/cell applied above or below 25 °C.

Q4: How much does the float setpoint move with temperature? By −3 mV per °C per cell (Datasheet); at 30 °C the 2.23 V setpoint falls to 2.215 V (2.23 V − 5 × 0.003 V, Arithmetic) and at 20 °C it rises to 2.245 V (Arithmetic).

Q5: How long is the designed float life of a 2V 1000Ah UPS battery? 20+ years at 20 °C (Datasheet); the published curve reads roughly 10–12 years at 30 °C, 6 years at 40 °C and 2–3 years at 50 °C (Datasheet), so room temperature decides the replacement date.

Q6: How long will a 480 V bank of these cells run an 80 kW load? The string stores 480,000 Wh (240 × 2,000 Wh, Arithmetic); at a 50 % depth-of-discharge limit that is 240 kWh, or 3.0 hours on 80 kW, and 1.5 hours at a 25 % limit (Arithmetic).

Q7: How much does one 240-cell string weigh? 17,568.0 kg for the gel cell (240 × 73.2 kg, Arithmetic) and 17,640.0 kg for the flooded cell including its electrolyte (240 × 73.5 kg, Arithmetic).

Q8: What is the maximum charge current of the cell? 200 A, which is 0.2 C10 (200 A ÷ 1,000 Ah, Arithmetic) (Datasheet). A 240-cell bank charged at 100 A total draws only 0.42 A per cell (100 A ÷ 240, Arithmetic).

Q9: What should be measured when the string is commissioned? Equalising at 2.35 V per cell, a capacity discharge at the C10 rate to 1.80 Vpc, the float current per cell (under 5 mA/Ah on the flooded cell, Datasheet), and connection torque of 10–12 N·m on the M8 insert (Datasheet); a 5 mV per-cell spread equals 1.20 V across 240 cells (Arithmetic).

Q10: Is the gel cell or the flooded cell the better choice for UPS duty? Both publish 2.23 V float, 2.35 V equalising, −3 mV/°C/cell compensation and 20+ years @20 °C of designed float life (Datasheet). The flooded datasheet additionally publishes a 4,500 A short-circuit current, 3 % per month self-discharge at 20–25 °C and a discharge-capacity table at 1.85 V (Datasheet); the gel cell does not publish those three figures, so a specification that needs them should ask for them in writing.

Expert Summary

A 2V 1000Ah UPS battery is a series member, not a standalone battery: the OPzV2-1000 gel cell is 2 V, 1,000 Ah at C10 to 1.80 Vpc, 233 × 210 × 681 mm, 73.2 kg, Female Copper Insert M8 at 10–12 N·m, float 2.23 V and equalise 2.35 V at 25 °C, compensation −3 mV/°C/cell, maximum charge current 200 A, internal resistance ~0.50 mΩ at 25 °C, designed float life 20+ years @20 °C, and the flooded OPzS2-1000 alternative is 1,000 Ah (C10) at 100 A, 233 × 210 × 645 mm container with a 700 mm overall height, 53.5 kg without and 73.5 kg with 20 kg of electrolyte, ≈0.45 mΩ at 20 °C, 4,500 A short-circuit current, 3 % per month self-discharge, float current under 5 mA/Ah, float 2.23 V and equalise 2.35 V per cell with −3 mV/°C/cell compensation, equalise current ≤ 0.25 C10, 20+ years at 20 °C falling to ≈10–12 years at 30 °C, 6 years at 40 °C and 2–3 years at 50 °C, capacity 108 % at 40 °C, 100 % at 25 °C, 85 % at 0 °C and 65 % at −15 °C, discharge capacity at 1.85 V of C24 1,130 Ah through C240 1,400 Ah, certified to IEC 60896-11:2002, DIN 40736-1:1985, GB/T 19638.2-2014, YD/T 1360, Eurobat Long Life, BS 6290 Part 4 and UL 1989 (Datasheet). In service that means 2,000 Wh per cell (2 V × 1,000 Ah, Arithmetic), a 100 A ten-hour rate and 125 A at 0.8 C10 (Arithmetic), 27.3 Wh/kg for the gel cell and 27.2 Wh/kg for the flooded cell with electrolyte (Arithmetic), a 480 V bus of 240 cells at 480,000 Wh, 535.2 V float, 564.0 V equalise and a 432.0 V floor, a 240 V bus of 120 cells at 240,000 Wh, 267.6 V float, 282.0 V equalise and a 216.0 V floor (all Arithmetic), 17,568.0 kg per gel string and 17,640.0 kg per flooded string, 120.0 mΩ across a 240-cell gel string and 1.20 V of imbalance from a 5 mV per-cell spread (Arithmetic), sub-strings of 4,392.0 kg at 60 cells and 8,784.0 kg at 120 cells, 500 cells per megawatt-hour, 3.0 hours on an 80 kW load at 50 % depth of discharge and 1.5 hours at 25 % (Arithmetic), a 0.42 A per-cell draw on a 240-cell bank charged at 100 A against the 200 A cell ceiling (Arithmetic), and a float setpoint of 2.215 V per cell at 30 °C (Arithmetic).

Contact CHISEN — 24-Hour Response

CHISEN Battery replies to technical and commercial enquiries within 24 hours, every day of the week. Send specification requests, string-layout drawings, charger setpoint questions, capacity test reports and delivery schedules to sales@chisen.cn; export desk correspondence also goes to jack@chisen.cn. For immediate discussion, the WhatsApp line is +86 131 6622 6999. The company profile, factory capability statements and product documentation are published at www.chisen.cn, and the 2V 1000Ah UPS battery anchor model — the OPzV2-1000 with its complete published specification block — sits at https://www.chisen.cn/en/OPzV2-1000/2V1000Ah.html.

CHISEN Battery Team

Engineering and export team at CHISEN Battery, Hangzhou, China. Lead-acid and lithium battery manufacturer, ISO 9001 / CE / UL certified, exporting to 50+ countries.

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