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I've spent a very long time trying to work this out, but some websites seem to conflict the information - or I'm completely missing the point.

I have a rechargeable battery:

  • 2600mAh
  • 4.2V max charge voltage
  • 9.62Wh energy
  • It is to charge from a vehicle 12V or 24V (battery runs through a circuit board...it's designed for vehicle tracking).

    What I'm trying to work out is:

  • The A - is it 2.6A? Is this the same as Ah? Meaning it will only last about the 2.5 hour mark before running out of juice.
  • The approximate charge time. I was using 12V but then read the max charge voltage on the side of the battery
  • I have one of the batteries connected to a PSU, but the current needle flips up a few bars, then drops straight back down. The battery was flat, so I'm not really sure what's happening. Appreciate any help understanding this.

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    migrated from physics.stackexchange.com Apr 20 '15 at 5:37

    This question came from our site for active researchers, academics and students of physics.

    • \$\begingroup\$ You need to know what current your tracking device consumes to find out how long your battery will last. You also need some extra information to find out how long it would take to charge your battery. So the information you provide is not enough to answer these questions. It is also possible that your battery is indeed faulty. \$\endgroup\$ – akhmeteli Apr 10 '15 at 9:14
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    The rating 2600mAh (or 2.6Ah) means the battery will produce 2600mA for one hour, or 1000mA for 2.6 hours of indeed 1mA for 2600 hours. The rating is the current multiplied by the time the battery can produce that current. In practice the rating depends on the current. The figure of 2600mAh will have been obtained for whatever current is optimal for that battery. Running at higher or lower current will give a shorter lifetime.

    Incidentally, the 9.62Wh rating is the current times the voltage times the time. So in this case the voltage times the current times the lifetime is 9.62Wh. If the battery voltage $V$ was constant the 9.62Wh would just be the 2.6Ah times $V$ (so presumably the battery voltage is around 3.7V). However the battery voltage changes as the battery discharges, so the relationship between the Wh and Ah ratings is a bit more complicated than this.

    As for your questions about charging, it's impossible to comment without knowing exactly what sort of battery it is. If it is a 3.7V battery that sounds like a lithium ion battery, in which case you may well have cooked it by connecting it to a 12V PSU. Lithium batteries need a special charger.

    It might be worth you asking on the Electrical Engineering SE as they tend to be more interested in the nitty gritty of anything electrical. But if you do post there be sure to give as many details about the battery as possible.

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