C&D Technologies Dynasty High Rate Max UPS12-490MR, 141.2 Ah at the 20-hour rate

A discontinued high-rate block whose 490 is watts per cell, not amp-hours, and off by a factor of 3.5

C&D Technologies Dynasty High Rate Max UPS12-490MR, 141.2 Ah at the 20-hour rate is one of 7 battery systems tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.

C&D Dynasty UPS12-490MR dossier: 490 is watts per cell not amp-hours, 141.2 Ah actual capacity, discontinued status and its named replacement.

The number in this model code is the single most misread figure in the category. UPS12-490MR is rated 490 nominal watts per cell at the 15-minute rate, measured at 488 W on the datasheet table, and its actual capacity is 141.2 Ah at the 20-hour rate. A buyer reading 490 as amp-hours overstates the battery by roughly three and a half times, which is a sizing error large enough to leave a critical load unsupported. The block is a 12 V six-cell AGM unit weighing 100 lb across 13.57 by 6.80 by 10.81 inches, on quarter-inch UNC insert terminals torqued to 110 inch-pounds, with 2.3 milliohms internal resistance and a 10-year design life at 25 degrees C. Float is 13.65 volts plus or minus 0.15 across the block. Listings cover UL 1778, UL 924, UL 1989 and UL 94 V-2, plus BS 6290-4 and IEC 60896-2. Two commercial facts govern any purchase. The SKU is reported discontinued at manufacturer level with UPS12-495PLP named as the approved replacement at 142 Ah, though dealer channel stock persists. And the manufacturer itself is changing hands: KPS Capital Partners, owner since 2017, signed an agreement on 13 July 2026 to sell C&D Technologies and Trojan Battery to Stryten Energy, with the close pending.

Why it matters

This record exists to stop a sizing error. Watts per cell and amp-hours are different measurements of different things, and a catalogue that lists 490 without saying which one it is invites a buyer to specify a 141 Ah battery for a 490 Ah duty. The same trap applies across the whole high-rate UPS segment, which is why the rating basis belongs on every listing.

Who buys it

Owners of installed C&D strings buying like-for-like replacements, and UPS service contractors carrying high-rate blocks as spares. Because the SKU is discontinued and the successor carries a different part number, every purchase is a decision about whether to extend an existing standard or convert the string to the replacement product.

Role in the data center

High-rate battery strings inside UPS cabinets where the duty is a short high-power discharge rather than long-duration telecom backup.

Key specifications

Technical summary

Nominal voltage: 12 V across 6 cells Capacity: 141.2 Ah at the 20-hour rate Watts per cell: 488 W at the 15-minute rate, rounded to 490 in the model name Design life: 10 years at 25 degrees C Dimensions: 344.7 by 172.7 by 274.5 mm, 277.7 mm total height with terminals Weight: 100 lb or 45 kg Terminals: top-mounted quarter-inch UNC inserts torqued to 110 inch-pounds or 12.4 newton metres Float voltage: 13.65 VDC plus or minus 0.15 per 12 V unit, about 2.275 per cell Internal resistance: 2.3 milliohms at 60 Hz Maximum charge current: the 20-hour capacity divided by 5, in amperes Operating temperature: minus 40 to 160 degrees F discharging, minus 10 to 140 charging Listings: UL 1778, UL 924, UL 1989, UL 94 V-2, BS 6290-4 and IEC 60896-2

Configurations and options

Top-terminal construction in the high-rate case format, which is the opposite arrangement from the front-terminal telecom blocks and drives a different rack layout. Flame-retardant case variants appear across the wider Dynasty range under FR suffixes.

Compatibility and dependencies

One distributor cross-references this block as a replacement for a 506 W EnerSys DataSafe unit, which is the practical substitution path now that the SKU is discontinued. Charger float must be set to 13.65 volts across the block with temperature compensation, and C&D's maintenance literature gives a general guideline of minus 0.0028 volts per cell per degree F above 77.

Pricing and availability

Comparable secondary-market band: 187.08–212.49 $ per kWh. Trend: flat Lead time, new: Dealer channel stock only; discontinued at manufacturer level.

Lifecycle and maintenance

Valve-regulated lead-acid batteries age on the calendar rather than on cycles, and temperature sets the clock. The industry convention is a design life quoted at 25 degrees C with service life roughly halving for every 8 to 10 degrees C above that, which is why the same block lasts a decade in a conditioned data hall and half that in an unconditioned telecom cabinet. IEEE 1188, whose 2025 edition supersedes the 2005 standard, governs maintenance and testing and sets 80% of rated capacity as the replacement trigger. At a NERC-registered facility the obligations are explicit: 4-month voltage and ground checks, 6-month internal resistance checks, 18-month connection checks and a 3-year capacity test, which is the one paper trail that makes a used string assessable at all.

Common failure points

• Dry-out — A sealed cell loses electrolyte through the valve and capacity falls with no way to top it up
• Thermal runaway — Charging current and cell temperature climb together until the case swells or vents
• Grid corrosion — Positive grid corrodes over calendar time and capacity fades regardless of cycling
• Temperature ageing — Service life roughly halves for every 8 to 10 degrees C above 25, so a hot cabinet destroys a string early
• Post and terminal corrosion — Sulphate creep at the posts raises resistance and heats the connection
• String mismatch — Mixing ages or manufacturers lets one weak block set the capacity of the whole string

Inspection checklist

Manufacture date — read the date code on every block, because a stationary battery is priced on age against a design life quoted at 25 degrees C Ambient temperature history — service life roughly halves for every 8 to 10 degrees C above 25, so a hot cabinet consumes a 10-year battery in 5 Capacity test record — request the most recent discharge test, since IEEE 1188 sets 80% of rated capacity as the replacement trigger Test interval compliance — a NERC-registered site owes VRLA a 3-year capacity test, 6-month internal resistance checks and 18-month connection checks Internal resistance or conductance — compare every cell against the manufacturer baseline and against the string average rather than a generic number String matching — never mix ages or manufacturers in 1 string, because a single weak block drags the whole string down Float voltage and temperature compensation — verify the charger setting against the manufacturer's published coefficient Case condition — look for swelling, distortion and heat marks across all 6 faces, which indicate thermal runaway or chronic overcharge Post and terminal corrosion — inspect for creep and sulphate growth, and check torque against the published value Dry-out — a VRLA cell that has lost electrolyte cannot be topped up, so weight loss against the published figure is terminal Rating basis — confirm whether the model number encodes amp-hours or watts per cell; UPS12-490MR is 490 watts per cell at 15 minutes and 141.2 Ah at the 20-hour rate Warranty transferability — get the remaining term in writing, because EnerSys credits against 80% capacity rather than on a classic pro-rata schedule Shipping classification — sealed VRLA moves as UN2800 Class 8 with terminal protection and separation requirements Scrap floor — lead is about 60% of block weight, so a 132 lb block carries roughly 12 to 17 USD of scrap value at current prices Recycler channel — confirm a certified recycler will take the pull, since spent lead-acid falls under 40 CFR 266 Subpart G rather than the universal waste rule

Regional notes

North American product with British and international listings also cited on the datasheet. The pending change of ownership to Stryten Energy is the fact to watch for parts and warranty continuity, since the buyer would combine C&D with Trojan Battery under Atlas Holdings.