36V 50Ah, 80Ah or 100Ah: which size suits an older 36V golf cart?

Direct answer: Choose by energy and current, not by size, because all three are listed with the same 385 × 338 × 245 mm case. Estimate the energy of your longest regular trip, add a reserve, and pick the smallest pack that covers it; then check that its continuous current covers the cart’s controller. On hilly routes, the current check often points to the 80Ah or 100Ah pack.

Page figures. 36V 50Ah (S3856): 38.4V, 56Ah on the capacity row, 2.15 kWh, stated range 24–32 km (15–20 miles), 27 kg, 50A continuous, 200A for 10s, standard charge 22A in about 2.5 hours. 36V 80Ah: 3.07 kWh, 36–46 km, 31 kg, 80A continuous, 200A for 10s, about 3.5 hours. 36V 100Ah: 3.84 kWh, 48–64 km, 34 kg, 100A continuous, 200A for 10s, about 5 hours. All three list 43.8V maximum charge, 30V cut-off, IP67 and the same case size.

A point to confirm: the “50Ah” model lists 56Ah, and its 2,150 Wh matches 56Ah at 38.4V (our arithmetic). Ask Redway which capacity applies before you rely on it.

Energy. If your longest trip uses, for example, 1.5 kWh, the 50Ah pack leaves little reserve and the 80Ah pack leaves more (illustrative numbers). Measure your use if you can; the stated ranges come without published test conditions.

Current. Older 36V carts often have controllers rated well above 50A. On hills the motor can draw near the controller’s limit for longer than 10 seconds. Find the controller’s rating on its label or in the manual and compare with 50A, 80A or 100A continuous. If the controller can draw more than the pack allows, the BMS may cut out on climbs.

Old wiring and charger. Check cables, lugs and the charge receptacle; corroded or undersized cables cause voltage drop and heat. The charger must have a lithium profile with a maximum at or below 43.8V; a lead-acid charger with equalisation must not be used. Cart accessories that took 12V from part of the lead-acid string need a DC-DC converter, see DC-DC converters. Our post on 36V-to-48V conversion covers the other option. Before you order, write down the cart’s make, model year, controller rating, tray dimensions and your longest regular trip, and send them with your question; that information is enough for the supplier to confirm which of the three packs fits and whether any wiring changes are needed.