The PWM controller is in essence a switch that connects a solar array to the battery. The result is that the voltage of the array will be pulled down to near that of the battery.
A PWM controller is not a DC-DC transformer. The PWM controller is a switch which connects the solar panel to the battery. When the switch is closed, the panel and the battery will be at nearly the same voltage. Assuming a discharged battery the initial charge voltage will be around 13V, and assuming a voltage loss of 0.5 V over the cabling plus controller, the panel will be at V PWM = 13.5V.
| Model | BlueSolar PWM-DUO LCD-USB 12/24-20 |
|---|---|
| Battery Voltage | 12/24 V with automatic system voltage detection [for LiFePO4 no automatic system voltage detection] |
| Rated charge current | 20A |
| Second battery output | Yes |
| Load output | 2 USB ports 5V/2A |
| Automatic load disconnect | 10.5V/21V |
| Maximum solar voltage | 28V / 55V |
| Self-consumption | 10 mA |
| Protections | Battery reverse polarity (fuse), Over temperature |
| Grounding | Common negative |
| Operating temp. range | -35 to +55°C (full load) |
| Humidity (non-condensing) | Max 95% |
| Default Settings | |
| Charge voltage 'absorption' | 14.4V / 28.8V |
| Charge voltage 'float' | 13.7V / 27.4V |
| Battery temperature sensor | Yes, remote sensor [included] |
| Temperature compensation | -30mV/ºC / -60mV/ºC |
| Enclosure | |
| Protection class | IP20 |
| Terminal size | 16 mm² / AWG6 |
| Weight | 0.3 kg |
| Dimensions (h x w x d) | 101.5 x 184.0 x 47.1 mm [4.0 x 7.4 x 1.8 inch] |
