I have a device that consumes 10W and I have a 12V x 4.5Ah = 54Wh lead-acid battery, does that mean that my device can work continuously for 5.4 hours?

Does the same concept apply to lithium batteries?

  • \$\begingroup\$ That depends on how you power the device from the battery. \$\endgroup\$
    – Hearth
    Commented Sep 25, 2022 at 22:19
  • \$\begingroup\$ just directly, without intermediaries \$\endgroup\$ Commented Sep 25, 2022 at 22:36
  • \$\begingroup\$ check the battery datasheet ... 4.5 Ah specification may be for a draw of 225 mA over 20 hours ... larger current draw may deplete the battery sooner than expected \$\endgroup\$
    – jsotola
    Commented Sep 25, 2022 at 22:51
  • 2
    \$\begingroup\$ This is a correct approximation. For a more precise answer, check the battery's datasheet. \$\endgroup\$ Commented Sep 26, 2022 at 2:12
  • \$\begingroup\$ Only theoretically. It is never a good idea to completely drain a battery, especially a lead acid battery, as this will shorten its lifespan. A better target is 50%, so that would leave about 2.7 hours for a 10W load before recharging. More detailed information (amount of cycles you can reasonably expect from the battery with which level of discharge) should be in its datasheet. Lithium batteries are slso not immune to damage when completely drained but can generally take a much deeper discharge before being damaged. \$\endgroup\$
    – StarCat
    Commented Sep 26, 2022 at 6:11


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