<img src="https://i.canddi.com/i.gif?A=0cfe735d8ca3730193f3a939628c109d">
Learn more

Get the latest from Ultralife, Accutronics & SWE

Are you still using SLA batteries?

[fa icon="calendar"] 01-Feb-2021 14:11:00 / by Rob Brown

Rob Brown

Did you know that the lead acid battery is over 160 years old?  Since its invention, there have been many improved variations such as the first sealed, or maintenance-free, lead acid (SLA) that was introduced in the mid-1970s.  However, in 1996, an alternative chemistry – Lithium Iron Phosphate (LiFePO4) – was introduced that can serve the same applications with significant advantages.  Ultralife Corporation developed a full range of batteries using this chemistry to provide OEMs with a lower cost, reduced weight and easier-to-integrate option.  Here we explore these advantages and introduce the newest member of the Ultralife LiFePO4 family.


Lower Cost

Lower Cost of LiFePO4 over SLA BatteriesWhen total cost of ownership (TCO) is considered, Sealed Lead Acid batteries have a much higher TCO than Lithium Iron Phosphate.  The main expense with SLA is the frequent need for maintenance and a high self-discharge rate that causes the need for trickle charging.  With LiFePO4 batteries, maintenance charging only needs to be performed once every four to six months, which also saves energy.

Additional cost savings can be had with LiFePO4 batteries thanks to their extended service life.  Where SLA may need replacing on a yearly or even bi yearly basis, in applications such as security and alarm panels, Lithium Iron Phosphate can last for up to 7 years.  Yet the advantages go even further, as runtime is also 40% longer than current SLA batteries in medical carts, powered scooters, small motives and UPS lead acid markets.  Not only can cycling reduce to 100% depth of discharge but cycle life can exceed 1,500 cycles (compared to just 300-500 for the best ‘cyclic’ lead acid batteries).


Easier Device Integration

In addition to cost, time is a major factor in the product development lifecycle, with OEMs endeavouring to streamline the process from concept to launch.  Sourcing the right battery for the demands of the application can be time consuming, so ensuring the correct system voltage and/or capacity is critical.  LiFePO4 batteries simplify the process as they can be connected in a variety of series and parallel arrays to make different voltages and capacities available.  Take the URB121000 for example, up to five of these batteries can be connected in series and up to four in parallel.

(OEMs considering using multiple batteries should contact Ultralife for advice)

Once the battery has been selected, it also needs to be integrated safely into the product.  Ultralife LiFePO4 batteries contain built-in protection electronics to prevent over-charge, over discharge or over-temperature. This makes the battery self-dependent and robust enough for use in medical or government and defense equipment.


Weight Reduction

Lead acid is heavy and is less durable than nickel- and lithium-based systems when deep cycled.’ (Battery University)

Ultralife LiFePO4 Lead Acid Replacement batteries are three times lighter than lead acid batteries of the same energy. Replacing lead acid with Ultralife LiFePO4 will significantly reduce the weight of an existing system and have operational benefits in mobile/transportable equipment such as medical carts and robotics.

The table below shows Ultralife Corporation’s range of SLA replacement products that are suitable for such applications, their associated weights and other key specifications.

Model Number



Nominal Dimensions
(L x W x H)



Typical Capacity




URB6450 Thumbnail


70 x 48 x 100mm 6.4V 4.5Ah 29Wh


URB1270 2020 Thumbnail


152 x 65 x 92mm 12.8V 7.5Ah 96Wh


URB12200 Thumbnail


181 x 76 x 165mm 12.8V 20.0Ah 256Wh


URB12350 Thumbnail


195 x 127 x 165mm 12.8V 32.0Ah 410Wh


URB12550 Thumbnail


256 x 132 x 200mm 12.8V 55.8Ah 714Wh


URB12550-22NF Thumbnail


228 x 138 x 208mm 12.8V 52.7Ah 675Wh


URB121000 Thumbnail


340 x 170 x 210mm 12.8V 100.0Ah 1280Wh


And now… introducing the newest LiFePO4

The newest LiFePO4 2021 1


    Model Number:  URB12400-U1-SMB (Smart U1)

    Typical Voltage:  12.8V

    Typical Capacity:  38.4Ah

    Typical Energy:  492Wh

    Nominal Dimensions (L x W x H):  209 x 136 x 182mm

    Typical Weight:  5.44Kg (11.99lb)

The latest addition to Ultralife’s arsenal of Lead Acid Replacement also offers value for money, easy integration into the device and less weight than SLA, it:

  • Can be charged and discharged more than 2,000 times before requiring replacement
  • Gets manufactured at Ultralife’s ISO 9001 and ISO 13485 certified facility in Newark, USA
  • Has a low weight of 5.44Kg (11.99lb), roughly the same as 10 basketballs
  • Ships pre-qualified with Ametek Powervar and Tripp Lite Inverters, making it a ‘drop in’ replacement for medical carts

Many medical carts have already made the switch to using LiFePO4 batteries due to its longer cycle life. Cycle count can be accurately measured, and remaining runtime communicated using an integrated System Management Bus (SMBus) interface; allowing the battery to talk to the host device.


As demands of OEMs change, batteries must develop to serve those needs. Ultralife Corporation are proud to have introduced the smart U1 to the SLA replacement product range to provide advanced power management, the next step in the history of LiFePO4.

View LiFePO4 Brochure      Learn about the Smart U1      Contact Us

Topics: Products & Services

Rob Brown

Written by Rob Brown

Marketing Executive with over 10 years' experience.