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I recently purchased an IcyBreeze Portable Air Conditioner and Cooler for an upcoming camping trip. I want to run it on low for two nights, or about 16 hours. With this in mind, I purchased the following portable power source

The capacity is advertised as 42000 mAh.

The IcyBreeze page indicates the amp draw is 1.0 A on low.

This battery life calculator suggests I should get about 29.4 hours of battery life (using 42000 mAh capacity, 1000 mA draw, and the consumption rate of 0.7).

With a fully charged power source, I plugged the cooler in using the wall adapter, set it to low, and ran it until it stopped. I only got about 5 hours of battery life - far less than what I was expecting.

Clearly I am misunderstanding something about the battery life calculation. So I guess I have two questions:

  1. How can I more accurately estimate battery life for this setup?
  2. A little off topic, but the portable power source is still well within the return window, and I an open to alternative suggestions for how I might get 16 hours of battery life with a portable power source (non-generator).
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  • \$\begingroup\$ Datasheet says 2.5 hrs on high so your consumption was medium \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 19 '18 at 3:23
  • \$\begingroup\$ Your link for power source says it has 146 Wh capacity. Which means that the internal battery can supply 12V at 1A for about 12 hours. Given that there are several DC-DC converters running, including 12-V outlet, efficiency will eat into this capacity. The other spec (for mini-fridge 50W) says 2 hr, so the actual output capacity is 100 Wh, which means only 8 hrs at 1A 12V load. \$\endgroup\$ – Ale..chenski Jun 19 '18 at 3:55
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You have fallen prey to confusing specmanship.

Start with the cooler. The data sheet says that its battery is 12 volts 10 Ahr. This is 120 Whr. At high power, this will last 2.5 hours.

Now, about your power source. Yes, its battery is rated for 42 Ahr. However, that is produced by a 3.7 volt (nominal) Li-ion battery. Note that the data sheet says the total energy is 146 Whr. This is about 20% higher than the cooler's battery, so figure on an endurance (from the power source only) of 1.2 x 2.5, or 3 hours.

So, the cooler will run about 2.5 hours on its own battery, and the power source will run an extra 3 hours, for a total of about 5.5 hours. Does that sound familiar?

Please note that your power source has a 120 volt, 1 amp AC output. Since this draws 120 watts, at that level the power source will last for 146/120, or about 1.2 hours.

The key is that 120 volts (the output) is about 32 times greater than 3.7 volts (the battery voltage). So, in order to keep the power equal, a 1 amp output at 120 volts will require about 32 amps from the battery, and your 42 Ahr battery is not going to last very long.

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