How to look after a tubular battery
A tubular battery rewards a few minutes of care every month or so with years of extra life. Most early failures come from the same handful of habits: tap water in the cells, dirty terminals, a hot corner, and being run flat too often.
Updated 27 September 2026
A tubular battery is a lead-acid battery built for deep, repeated use, which is why it suits solar. It holds liquid electrolyte, water and sulphuric acid, and a little of the water is split off every time it charges. Most of the care it needs follows from that.
Top up with distilled water only
The level in each cell falls as the battery charges. Top it up with distilled or battery water, never tap, RO or mineral water, which leave salts in the cells. Never add acid: the acid stays in the battery and only the water is lost.
Fill to the level mark or float indicator and no higher. An overfilled cell spills acid when the battery charges and corrodes the terminals and the stand.
Keep the terminals clean and tight
White or green crust on the terminals is corrosion, and it resists the current like a partly closed tap. With the system switched off, clean it away, dry the terminals, and coat them lightly with petroleum jelly. A loose terminal heats up under load, so check the connections are tight.
Give it air and keep it cool
Charging releases a small amount of hydrogen, so a tubular battery belongs in a ventilated place, well away from sparks and open flames. Heat is its other enemy: a battery in a hot, closed room or in direct sun ages faster. A shaded, airy spot on a stand, off a damp floor, is ideal.
Do not run it flat every day
How far a battery is discharged each day decides how long it lasts. When we size a system, we plan on using only half of a tubular battery’s capacity in a normal cycle, which is what lets it last. If your battery is regularly running down to the inverter’s cut-off, the battery bank is too small for what you run, and our hybrid solar calculator will show what size it should be.
A battery left discharged for days also suffers, so let the panels or the grid recharge it fully when they can.
Check the charging settings
The inverter or PCU must be set for a tubular battery. Settings meant for another battery type can undercharge or overcharge it. If a new battery is fitted, ask whoever installs it to confirm the settings.
Follow the manual, and keep the warranty card
Each battery comes with the manufacturer’s own care instructions and warranty terms. Keep the warranty card and the invoice together. UTL’s tubular batteries list warranties from 36 + 24 months, as on the UIT16036, to 60 months on the UST1560.
If you would rather not maintain it
A sealed, maintenance-free battery needs no water at all; UTL describes its 170 Ah USB 17100 that way. A lithium battery needs no water either, and lasts far more cycles; see how to look after a lithium battery and tubular or lithium for solar.
Questions we are asked
What water goes in a tubular battery?
Distilled or battery water only. Tap water, RO water and mineral water carry dissolved salts that build up in the cells and shorten the battery's life. Never add acid; the level falls because water is lost in charging, not acid.
How often should I top up a tubular battery?
Check the level regularly and top up when it drops towards the minimum mark, following the manual for your battery. It falls faster in summer and when the battery is worked hard, so check more often from May to July.
Is there a tubular battery that needs no topping up?
Yes. Sealed, maintenance-free batteries need no water. UTL describes its 170 Ah USB 17100 as maintenance-free. Lithium batteries need no water either.