What is the total cost of ownership compared with VRLA?

It depends almost entirely on whether the battery cycles, and most published comparisons are unreliable because they compare a lithium design life against a VRLA field life. Here is the honest structure.

Where lithium wins clearly, cycling duty. On a daily cycle, VRLA delivers hundreds of cycles and lithium delivers thousands. Over fifteen years a cycling VRLA installation may be replaced three or four times, and on a remote site each replacement is a site visit, freight, labour, decommissioning and disposal, usually several times the cost of the battery itself. Lithium’s higher purchase price is recovered on the second replacement it avoids.

Where lithium wins on secondary factors, hot and space-constrained sites. Lithium’s usable depth of discharge is 80–95% against 30–50% design practice for cycling lead-acid, so you buy roughly half the nameplate capacity for the same usable energy. It is materially lighter and smaller, which matters where floor loading, rack space or cabinet volume is the binding constraint. And it does not follow the VRLA temperature-life curve, so hot sites do not consume it.

Where the picture is much less clear, pure standby duty in a controlled room. A UPS battery cycling a dozen times in its life will be replaced on calendar ageing, not cycles. Lithium’s cycle advantage is worth nothing there. What remains is footprint, weight and temperature tolerance against a higher capital cost, a battery management system in the protection path, and in New South Wales as of 2026, a materially more demanding fire engineering path in a building. Reasonable engineers reach different conclusions on those trade-offs. We will work through yours with you rather than apply a default.

What to include in your own model: purchase price, installation labour, the number of replacements over the asset horizon, replacement labour and freight to your actual site, decommissioning and disposal cost, monitoring cost, cooling energy, floor space, and any fire engineering or room upgrade the chemistry triggers. Leave any of those out and the answer changes.