Can you add a second lithium battery in parallel to extend golf cart range?

Direct answer: It can work, but only with the battery maker’s approval for parallel use, two identical batteries at the same voltage when connected, fusing for each battery, equal cables, and enough continuous current from both together for the controller. In many carts, replacing the single pack with a larger one is simpler and avoids current-sharing problems.

Parallel limits. The 48V 50Ah (S5156) page lists up to 4 in parallel, 51.2V, 2.56 kWh, 50A continuous and 200A peak for 10 seconds, at 33 kg and 460 × 334 × 247 mm. The 48V 100Ah (S51105) page lists 5.12 kWh, 100A continuous and 200A peak, but does not state a parallel limit, so ask Redway before paralleling it.

Matching. Use the same model, capacity and BMS, ideally from the same batch. Charge both fully and separately, then check that their voltages are within the maker’s tolerance before connecting. See matching state of charge before paralleling; the principle is the same at 48V.

Current sharing. Two batteries in parallel share current according to their internal and cable resistance. Unequal cables make one battery work harder. If one BMS trips under a hill-climb, the other battery takes the full controller current and may trip too. Each battery’s continuous rating should still cover a good share of the controller’s demand.

Wiring. Fuse each battery at its positive terminal, use equal-length cables to common busbars, and connect the cart’s main leads across the bank so both batteries see the same path. Mount the second battery securely; loose heavy batteries are a hazard.

Charging. The charger then charges both; total charge time increases unless charger current is raised within the batteries’ limits. Gauges and apps may show each battery separately.

When one pack is better. The 48V 150Ah lists 7.2 to 7.68 kWh in a 510 × 410 × 235 mm case, about 55 kg. One larger battery means one BMS, one set of cables and no sharing issues, if it fits the tray. See 48V 100Ah vs 150Ah range.

Weight. A second battery adds weight; check the cart’s payload, especially on four- or six-seat carts carrying passengers.

Test before relying on it. After installation, drive the longest, hilliest loop with a full load, watch the app or gauge for both batteries, and check cable and terminal temperatures at the end. Repeat after a month, because a small imbalance in age or cabling shows up over time.