Osaka 3.36kWh Tubular Battery 12V (HT-3500)

Note: Osaka rate the HT range at over 1250 cycles at 80% depth of discharge, and 5000 cycles at 20% - the same battery, four times the life, purely from running it shallower. The usable figure shown here is taken at 80%, the deepest depth Osaka themselves test to; it is not a depth to hit every day if you want the battery to last. Tubular positive plates with thick negative plates, low-resistance PE separators, and float indicators so you can see the electrolyte level without guessing. Charge at 0.1C10 constant current for 12-13 hours, or constant voltage at 14.4-14.7 V for cycle use and 13.8-14.2 V standby; fully charged electrolyte reads 1.260 SG at 25°C. Flooded, so it needs topping up and a ventilated space - this is not an indoor-cupboard battery. Built to IEC 60896-11. 9 plates per cell. Overall height with terminals is 410 mm against a 373 mm container, so allow for the taller figure when sizing a battery box. One caution on the numbers. Osaka's Pakistani website and their 2026 international brochure disagree about this model code: the website (used here) says 280 Ah and 72.7 kg, while the export brochure lists HT-3500 at a lower rating and puts 280 Ah under a different code in its TT series. Confirm the rating on the label before you buy. Osaka is made by Pakistan Accumulators (Pvt) Limited, part of ACM Group, at Industrial Estate Hattar in Haripur - the same plant that makes Volta, on the same moulds. The Volta equivalent of this battery is a physically identical product in different livery, so compare the two on price and dealer support rather than on specification.