The operating and storage temperature limits of UPS Systems are a function of the batteries utilized within those systems. Nova Electric offers a variety of battery options to use with our rugged, militarized UPS Systems, to fit any application. Battery choices involve tradeoffs between performance, cost, expected life, size, and other factors – but as a general rule, exposure to higher temperatures decreases overall battery life and increases run time, while exposure to colder temperatures increases overall battery life but reduces battery capacity. This applies to all batteries used on all UPS Systems in the industry, regardless of manufacturer. As per industry standard, run time, expected life, and other performance parameters in Nova Electric Data Sheets are provided at +25°C, and apply after a new battery has been cycled (discharged / recharged) up to three times.
Standard VRLA Batteries: The most common batteries are standard sealed, maintenance-free VRLA type cells. These are rated for -20°C to +50°C operating and storage, shelf life of ~3 months at +25°C ambient, and an overall expected life of 3-5 years rated at +25°C ambient. These are the least expensive types of cells, and a good choice for general-purpose applications where no extreme temperatures apply. At prolonged high temperatures (average greater than +25°C but not more than +50°C,) they will self-discharge at the rate of ~0.75% per day at the high end, and life expectancy will drop to ~9-18 months. Conversely, at prolonged low temperatures (-20°C,) run time will be exponentially reduced to almost zero.
Premium VRLA Batteries: Where extreme temperatures apply, Nova Electric offers a variety of Premium Batteries, which are available with an operating range of -65°C to +80°C, shelf life of ~12+ months at +25°C ambient, and an overall expected life of 8-12 years rated at +25°C ambient. These cells also have the added benefit of being much more resistant to shock, vibration, and high humidity environments, making them the ideal choice for military applications where compliance to MIL-STDs is critical.
LiFePO4 Batteries: Where weight savings are of paramount importance, Nova Electric offers advanced LiFePO4 Batteries which have several main advantages, including:
- 4X higher energy density than lead-acid battery: The gravimetric energy density of the LiFePO4 battery is ~130 WH/kg, almost four times higher than that of a typical Lead-acid battery, at 35 WH/kg. For the UPS user, this means far greater run times while running on battery, without any space penalty.
- Light Weight: Despite the vastly higher energy density, the LiFePO4 battery packs are, in most cases, only 1/3 the weight of conventional lead acid packs. So for applications where weight savings are critical, the use of LiFePO4 batteries can result in significant reductions in overall system weight.
- Long Life: LiFePO4 battery packs typically achieve a minimum of 2000 cycles with 50% capacity remaining. This is equivalent to the 8-12 year expected life the very best sealed, lead acid batteries offer. Further, LiFePO4 batteries do not suffer from the “memory effect” of some conventional lead acid batteries.
- Better Voltage Regulation: Unlike the Lead acid battery, the LiFePO4 battery terminal voltage remains relatively constant during high rate discharge. This equates to much better performance during high rate (short time period) discharges, yielding a much better AH performance during this type of application, typical in UPS systems.
- Wide Temp Range: LiFePO4 battery packs are typically sold for operation between -20°C to +60°C, charging between 0°C to +55°C, and storage between -20°C to +55°C. This is equivalent to the ranges that only some premium sealed, lead acid batteries offer.
- Safety with power: Safety is equivalent to or better than the traditional lead acid type, without the risk of explosion or fire outbreak associated with some other new battery technologies. The LiFePO4 battery has hybrid characteristics: it is as safe as the lead-acid battery and as powerful as the lithium ion battery.
- A Greener Battery: The eco-friendly LiFePO4 battery packs are recyclable and non-toxic.
- Battery Management: All LiFePO4 Batteries are provided with a Battery Management System (BMS) which protects the battery cells within the Nova LiFePO4 Battery pack. The BMS will protect the cells to be sure they do not go outside of the normal limits of cell voltage of the minimum discharge voltage of 2.5 V (typical, but can vary slightly depending on brand and discharge rate,) the working voltage of 3.0 V – 3.3 V, and the maximum charge voltage of 3.65 V. The BMS also provides short circuit protection which prevents high current in the event of an external short circuit.
Nova Electric has well over 50 years of experience in designing and manufacturing Rugged UPS Systems for the most demanding military applications in the world. Please don’t hesitate to contact us for more information about our various battery options.