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Compass Marine How To | all galleries >> Welcome To >> iPad Charging - How Much Energy? > Data Point 100% SOC @ 2:41 PM = -4.36 Ah's
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Data Point 100% SOC @ 2:41 PM = -4.36 Ahs

Data Point 100% SOC @ 2:41 PM = -4.36 Ah's

As in many other observations one can easily see how much more efficient it is to remain DC throughout the entire charging process.

To go from 0% SOC to 100% SOC using straight DC>DC, as opposed to DC>AC>DC we saved 1.28 Ah's of energy (5.64 Ah - 4.36Ah = 1.28)!!!

Put another way when using the 400W inverter and Apple 120V adapter to charge this iPad it uses 29% more energy to for a complete charge cycle.


Total Charge Duration = 4:41

Total Energy Consumed = -4.36 Ah

Average Current = 0.8A -1.1A

So what's the bottom line?

If you want to charge as efficiently as possible, stay with DC!

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Guest 12-Dec-2015 20:21
To charge efficiently we turn 'airplane mode' on, and the Apple devices seem to charge much more quickly. It would be interesting to see how much less this actually used compared to your previous tests. Also, we ensure wifi and Bluetooth are off if not used,. Wifi especially is a 'chatty' protocol and will get very busy looking for networks,, using your battery unnecessarily.
Again, thanks for honest and usable articles.
Andrew cook 02-Mar-2014 22:44
As always, meticulous methodology applied to real world concerns. (It's not just boating dammit).
This is particularly rewarding since when we rewired (every inch except the engine harness) I decided to go 12v only on our 34' 1987 trawler.

Aboard at the dock 120v to charger, hot water, and 1 fwd tool outlet (unplugged when we are away). Of course no generator , we are cruisers not barbarians!

Thanks as always for your work. Andrew / Diligent