I recently found my lost LED Lantern after one year in my old garage, but unfortunately it wasn't worked when I turned on.

I opened it and checked if the charging circuit was fault, but it wasn't because I tested charger circuit with another small sized rechargeable battery(I didn't know if it is lead acid or another) and battery had charged fine.

Then I though battery was fault and I was right, this 4.0V 2.0Ah rechargeable sealed lead acid battery even not charged with a power pack(I tried adjusting voltage from 3V to 6V even 12V, even not charged).

Its voltage remained 0V when I tested with my multi meter.

The Lantern is Rikon and Battery is a RB420C model, bigger than the good small battery I tested.

I can't think why this small torch battery which even not used for more than one year charged fine, but this wasn't.

Any help is needed me to determine what to do, replace bigger battery with my unsuitable small battery(because both batteries are very different) for the lantern or any step to take this dead battery back to life?

Worked Rechargeable Battery: Worked Rechargeable Battery

Dead Sealed Lead Acid Battery: enter image description here

Thanks in Advance.

  • \$\begingroup\$ Is it at all not possible to buy a new battery and replace it? \$\endgroup\$ – Captain Caboose Apr 25 '17 at 13:29
  • \$\begingroup\$ I will, but I can't sure why this battery not charging a bit. I am posting images in order for you to understand. \$\endgroup\$ – user147321 Apr 25 '17 at 13:30
  • \$\begingroup\$ Well, I am no expert but I am currently learning but all batteries have an expiration and that can go by slower or faster depending on the environment conditions. \$\endgroup\$ – Captain Caboose Apr 25 '17 at 13:32
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    \$\begingroup\$ It's dead jim. Get a new one \$\endgroup\$ – Voltage Spike Apr 26 '17 at 3:56

If a lead acid battery is left for too long in a discharged state it becomes unusable through a process called Sulfation. This Wikipedia article describes it in greater detail.

Unfortunately, it's not reversible so your only option is replacement.

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  • \$\begingroup\$ Yeah, your battery's dead and not revivable. In general, if any battery ever reads zero volts (as opposed to some finite value less than its rated value) at its output, it's probably beyond repair. \$\endgroup\$ – Hearth Apr 25 '17 at 14:01
  • \$\begingroup\$ @Felthry But why the small rechargeable battery worked? It also left too long in a discharged state. But I can't sure if it is lead acid or not. What can its type as you can see in picture? NiCad? \$\endgroup\$ – user147321 Apr 25 '17 at 14:03
  • \$\begingroup\$ I haven't got a clue what type of battery it is. But batteries don't just stop working after a predefined date; it depends on environmental conditions as well. Some batteries will fail before others, that's just how things go. \$\endgroup\$ – Hearth Apr 25 '17 at 14:06
  • \$\begingroup\$ Lead acid batteries fail in different ways. Some just won't hold a charge very well any more, while others go open-circuit if the plates fail completely. \$\endgroup\$ – Simon B Apr 25 '17 at 14:29
  • \$\begingroup\$ Thanks all, I determined to buy a new RB420C Battery, but what will happen if I replace dead battery with one in the picture? This battery and dead battery has small voltage difference of 0.5 V. \$\endgroup\$ – user147321 Apr 25 '17 at 14:52