Voltage vs. PWM controller & wire size
Ok, there is a recent thread out there MPPT vs. PWM and some post were a little confusing to me. Instead of hijacking his thread I started a new one. My set up is two 208 watt Sony panels with 28....
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Calkidd wrote:
Ok, another question concerning this. Correct me if I am wrong, but from what I understand the input amperage going into a PWM charge controller will be the same output amperage?
look at the IV curves at the sharp panel you linked.
Note the power @15v is 120 watts, the current ~8A (both in FULL light).
PWM controller connects the panel directly to the battery and the panel operates at batt voltage. When the batt voltage rises to meet the controller's set point (of say 14.5v) the controller disconnects and reconnects the panel to the battery very fast to maintain this set point. Disconnected, the panel adds zero power to the battery (see IV curve Voc, 36v, ZERO amps). As the batt charges at this set point, more and more time is spent disconnected. The controller's logic determines when to change to float or 'finish' charge.
8A in then zero amps in then 8 then 0 then 8 then 0 ...
The time spent on/off determines the avg current to the batt.
On 1/2 the time then 4A, on 1/4 time then 2A, all this is dynamic as the lighting/loads/temp etc changes the controller changes the on/off time to maintain the set pt voltage and determine when to change to another set pt.
