Can I replace my lead-acid batteries with lithium in an existing 48V DC power system?

This is the most-asked question in the category and almost every answer available online is written for a caravan. Here is the industrial answer.

Often yes, but it is not a drop-in swap, and five things have to be checked before you order.

1. The charge profile. Lead-acid charging is a float-voltage regime with temperature compensation. LiFePO₄ wants a constant-current, constant-voltage profile and does not want to be held at 100% state of charge indefinitely. SOLiCORE’s charge voltage window is 56.8–58.4 V. A rectifier or UPS charger set for VRLA float will not charge lithium optimally and may not charge it safely. Check whether the charger has a selectable lithium profile, many modern rectifiers do, many installed ones do not.
2. The DC bus voltage window. Confirm the equipment tolerates roughly 40 V to 58.4 V, and compare that against its own input range.
3. Low-voltage disconnect and battery management system coordination. This is the one that catches people. A lead-acid system relies on the plant’s low-voltage disconnect to protect the battery. A lithium battery has its own management system that will open the circuit to protect itself. If the two are not coordinated, the battery can disconnect before the plant sheds load, which is not a graceful outage. Set the plant low-voltage disconnect above the 40 V battery cut-off.
4. Communications. Closed-loop control, where the battery management system reports its real state of charge and its charge and discharge current limits to the charger, is materially better than open loop. But the same physical interface does not guarantee compatibility. RS485 and CAN are transport layers; baud rate, message IDs, register maps, protocol version and firmware all have to align. Send us your inverter or rectifier model and we will confirm closed-loop support before you order.
5. Manufacturer support. Some UPS and rectifier manufacturers will not support a third-party lithium battery in their plant, which has warranty and service-contract implications independent of whether it works.

Where lithium clearly wins on retrofit: sites where weight or floor loading is a constraint, sites where footprint limits the achievable autonomy, sites running hot enough that VRLA life is uneconomic, and sites where the battery is cycled rather than purely on standby.

Where VRLA remains the better answer: pure standby duty in a temperature-controlled room where the incumbent chemistry is performing to expectation, installations where a battery management system in the DC protection path is unacceptable to the protection engineer, and as of 2026 in New South Wales, building and data centre installations where the fire engineering path for lithium is materially more demanding.