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I have a new 12 V, 7 Ah battery which reads 0 (zero) vokts. Let me explain the situation. I have a 800W UPS (for pc) whose battery wasn't giving enough backup. So I decided to replace the battery. I bought a new 12 V, 7 Ah battery and I think I accidentally connected positive wire with negative terminal of the battery and negative with positive terminal. Resultantly few caps and transistors blew and a little spark at battery terminal. I then corrected the polarity but the UPS wasn't starting because of blown up components. I left the battery connected with the PCB and put aside the the UPS for repair at later time. After about a month, I was checking for broken components to replace, I also checked the battery which read 0 volts on ammeter. When I checked the old battery which I had pulled from UPS, it reads 11 volts. So I connected the old battery with UPS PCB. Upon connecting the battery, 4 relays automatically turned on (confirmed over and over) probably due to broken circuit. I think self activation of relays sucked up all the juice from new battery (which reads 0 volts) and now it reads 0 volts. Can someone suggest me if the battery is dead or not and how to charge it if it is not dead.

winny
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Omaid_it
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    A lead acid battery that reads 0V is dead and in all probability not salvageable, especially if it has been left at this level of discharge for some time (which sounds like what has happened). – StarCat Jun 10 '21 at 14:02
  • is it exactly zero or approximately zero? – Kyle B Jun 10 '21 at 14:49
  • Yeah but as i told, it is new battery. Probably the relays causedthe battery to reach the 0 volt as relays operate in ma. Should I consider it dead or try to charge it with normal or anything special charger? – Omaid_it Jun 10 '21 at 14:51
  • It’s dead. See it as the cost of learning. – winny Jun 10 '21 at 15:00
  • I asked about the exact reading because SOMETIMES batteries have an INTERNAL FUSE. Does yours??? – Kyle B Jun 10 '21 at 15:21
  • It shows nothing on ammeter – Omaid_it Jun 10 '21 at 15:25
  • Its from LIDO 12V7ah – Omaid_it Jun 10 '21 at 15:26
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    @Omaid_it: A voltmeter reads voltage in volts. An ammeter reads current in amperes. Which are you using? – JRE Jun 10 '21 at 15:37
  • It is a AC/DC meter with range upto 1000v dc. I tested two batteries with it. One eeads 11v and other show nothing on the meter. It is generally used for household electricity testing – Omaid_it Jun 10 '21 at 15:40

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Can someone suggest me if the battery is dead or not

Any disconnected SLA that reads 0V is no longer serviceable and should be sent for recycling.

From what I have read, any nominal 12V lead-acid battery that has been at less than 10V for more than a few minutes is probably irreparably damaged. Yours is an extreme case.

References

RedGrittyBrick
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  • You are right. It may be dead. Can i give it a try and recharge it (if not hazardous) i mean if it is not going to burst – Omaid_it Jun 10 '21 at 15:34