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I started poking things with my multimeter and it's interesting. I have a lithium battery in my flashlight and as the charge lowers the shown voltage on my multi meter lowers. But my Milwaukee battery don't. The power indicator on the battery shows halfway but they still read 18v.

I'm a total newbie to so why I don't know this.

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  • \$\begingroup\$ it depends on the load time contant C to C/20 or current in Amps and thus the ESR*I drop when the measurement is taken. Perhaps the Milwaukee has less load when testing it and counts coulombs. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 3 '17 at 2:19
  • \$\begingroup\$ The power indicator on the Milwaukee measures the voltage under load. When you measure with the multimeter it's unloaded. Also, a "18V" battery should be about 20~21V when full (5*4.2V), so 18V is indeed lower than full. \$\endgroup\$ – Wesley Lee Jun 3 '17 at 2:37
  • \$\begingroup\$ @WesleyLee Ah true, I just charged another battery and fresh off the charger it's 20.8v . \$\endgroup\$ – TheMidnightNarwhal Jun 3 '17 at 3:03

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