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How many watts a 4 amp charger should pull from a wall


NECway
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I bough a 4 Amp charger for my Tesla from China. I expected the charger to pull 336 watts from the 120 volt home circuit. 

But, I'm measuring with a kill-a-watt meter and all it is pulling is 175 watts. That implies that it is a 1.5 Amp charger.

Am I correct in the calculation or I'm just calculating it wrong?

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14 minutes ago, NECway said:

I bough a 4 Amp charger for my Tesla from China. I expected the charger to pull 336 watts from the 120 volt home circuit. 

But, I'm measuring with a kill-a-watt meter and all it is pulling is 175 watts. That implies that it is a 1.5 Amp charger.

Am I correct in the calculation or I'm just calculating it wrong?

There are two things to distinct - how many amps battery would get from a charger and how many amps charger can deliver. For example, if battery is near to full charge it wil draw less than one amp, even from 100A capable charger. 175 watts at 84 volts gives us about 2,08 amps. So it may be just a 2A charger, but advertised as 4A. It happens, I've seen a 50 000 mAh powerbank equipped with just one 4 000 Ah cell inside ?

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10 hours ago, NECway said:

I bough a 4 Amp charger for my Tesla from China. I expected the charger to pull 336 watts from the 120 volt home circuit. 

But, I'm measuring with a kill-a-watt meter and all it is pulling is 175 watts. That implies that it is a 1.5 Amp charger.

Am I correct in the calculation or I'm just calculating it wrong?

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

The max current only flows wirh an empty battery - the fuller it gets, the less power (watts) are used...

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