Re: [EVDL] Adding J1772 capabilities to a conversion
[quote]John O'Connor wrote:
> Doesn't the ability of the MM PFC-xx to control input current depend on
> the pack voltage relative to AC line voltage?
> For example is I am charging a 144v pack from 120v I thought the current
> knob defined max input current.
No. Consider your example.
Let's say you set the current knob such that you get 20A into your pack at the start of charge: 20A * 144V = 2.88kW. Neglecting losses due to charger inefficiency for the moment, 2.88kW / 120V = 24A input.
As your battery charges, the DC output voltage of the charger increases, but the input remains at 120VAC. If you charge to 2.4Vpc, then you expect to see 20A into the pack until the voltage reaches 173V. 20A x 173V = 3.46kW. Again neglecting losses, 3.46kW / 120V = 28.8A input.
Note that this example requires that you have at least a PFC-30, since for 20ADC output from 120VAC results in an input current greater than 20A. The PFC-xx chargers are limited to xx amps maximum on either the input or output, so if you set the current knob on a PFC-20 to allow 20A into the pack while plugged into 240VAC, you'll get the expected 20A, but if you then plug into 120VAC, you will see lower DC current as the charger limits the AC input draw to the 20A maximum allowed by the hardware.
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