Manuals · flooded tubular
Four 200 Ah tubulars are a UPS. They are not a 5 kWh LFP.
Covers Osaka 12 V 200 Ah, Phoenix TX-2500, AGS 200 Ah, Exide TR 1800–2500, and the same chemistry sold under shop stickers. Brand pages: Osaka, Phoenix, AGS, Exide (Atlantic LFP is a different product — use LFP).
What it is
Flooded lead-acid with tubular positive plates. You add distilled water. You equalise. You do not discharge past ~50% if you want more than two summers. A 12 V 200 Ah nameplate is 2.4 kWh on paper and about 1.2 kWh usable at 50% DoD. Four in series ≈ 48 V and ≈ 4.8 kWh usable — the same usable energy as one Dyness DL5.0C, with more weight, more room, more water, and 1,000–1,500 cycles instead of 6,000.
Pick: fans + lights, 2–3 year cash horizon, existing UPS room. Skip: daily 1.5-ton AC, new hybrid default, anything you were told is “the same as lithium.”
Wiring a 48 V string
- Four identical batteries, same brand, same age, same capacity. Mixing a new Osaka with a two-year Phoenix in one string cooks the weak one.
- Series: + of battery 1 to − of battery 2, and so on, until you have 48 V across the ends. Those ends go to the inverter BAT+ / BAT− through a DC breaker.
- Inverter battery type = AGM / FLD / flooded / USE with the carton voltages for tubular, not PYL / lithium. Lithium voltages on a flooded string boil them dry.
- Equal cable lengths. Fat cable (the inverter sheet — often 25–35 mm² for 6 kW). Thin jumper wires are a fire.
Never mix tubular and LFP on one port. Never put six batteries “for more backup” in a wild series-parallel without the inverter supporting it.
Water
Distilled or battery-grade only. Tap water in Lahore / Karachi / Multan is mineral soup — it plates the cells. Keep plates covered; do not flood the vent. Check monthly in summer, every 6–8 weeks in winter. Dry plates in June is a dead battery in August.
Charge and equalise
The hybrid / UPS has a bulk / absorb / float map for flooded. Leave it. “Boost every night” boils water and warps plates. Equalise only as the carton / inverter flooded program says (often a periodic higher-voltage sit). Do it with caps loose or rooms ventilated — hydrogen is not a joke in a closed cupboard.
Daily use
Stop at ~50% if you can see a monitor; if you only have a beeper, treat the first low-voltage alarm as stop, not “ten more minutes of AC.” Heat in a Pakistani UPS room is the other killer — ventilation, not a blanket over the case. After a deep shed, let the string recharge fully before the next deep cycle.
End of life
One battery in a four-pack going high-resistance takes the string down. Replace as a set, or at least match age/capacity. Dumping acid in the drain is illegal and stupid; use a recycler the shop already uses.
If you are buying new in 2026 for a hybrid house, read LFP instead. Tubular remains the right answer for a cheap fan UPS.