Differences Between Lithium‑ion and Lead‑acid Batteries When Used with Inverte

Many commissioning faults of energy storage inverters stem from mismatched battery‑type settings. This article briefly explains the differences between the two battery types when working with inverters to help you avoid common pitfalls.
First, regarding BMS communication. Most lithium‑ion batteries come with a built‑in BMS (Battery Management System). When the inverter is set to lithium‑battery mode, it can read SOC, voltage and temperature data via communication, and protect the battery following BMS instructions. It also features a lithium‑battery‑only charge‑activation function, which can wake lithium‑ion batteries disconnected due to over‑discharge protection.
By contrast, lead‑acid, gel and AGM batteries generally have no BMS and no communication wiring. The inverter cannot obtain real‑time SOC values and can only estimate remaining capacity based on battery voltage. The charge‑activation function for lithium‑ion batteries does not work for lead‑acid batteries. Do not attempt to wake a deeply‑discharged dormant lead‑acid battery using lithium‑battery mode.
There are also differences in charge‑discharge logic. Lithium‑ion batteries support relatively deep discharge. Lead‑acid batteries are not suitable for deep discharge. Frequent operation at low charge levels will cause plate sulfation, shorten battery service life and generate current impact on the inverter.
For parameter configuration, the grid‑transfer trigger for lithium‑ion batteries can be set directly by SOC percentage. Since lead‑acid batteries provide no true SOC data, transfer can only be set by voltage threshold. You need to measure the actual battery voltage at the target capacity before adjusting parameters.
A key point: handling deep‑discharge dormancy. When a lithium‑ion battery cuts output due to BMS over‑discharge protection, enabling the inverter’s activation function may revive it. If a lead‑acid battery’s voltage drops below the inverter’s detection threshold, the inverter will fail to recognize the battery, and neither PV nor utility grid can charge it. You need an external dedicated lead‑acid charger for pre‑charging. After voltage rises to the detectable range, the inverter can resume normal charge and discharge.
For parallel expansion: parallel connection for both battery types only increases capacity while keeping system voltage unchanged. Use batteries of the same batch for parallel connection, and upgrade cables and circuit breakers according to total current.
Common reminder: Do not configure lead‑acid batteries under lithium‑battery mode. This will cause mismatched charging parameters, resulting in over‑charging or under‑charging. As the first step of commissioning, ensure the inverter’s battery‑type setting matches your actual battery.