Renvu

• Charge Regulation - Pulse Width Modulation (PWM) is the most modern and common

• Pulsing charge allows for absorb, float and bulk charge stages, and can include MPPT!

• MPPT - important in cold climates since PV voltage will be high. It allows for longer solar panels strings

• Non-MPPT - PV Array must match battery voltage, and does not track peak power.

• Charge Controller Features

• Adjustability - Factory set or field adjustable settings, eg. battery type, timers, set points, ambient temp and battery temp

• Design Features - conduit knockouts, terminal block design, coated/sealed components for harsh environments, fan ventilation

• Metering and Remote Metering

• Auxiliary relay for fan, alarm, LVD (low voltage disconnect)

• Ground Fault Detection

• Load and Lighting Control

• Battery Temp. Sensors - BTS is critical in hot climates, consult manufacturer

• Attach BTS to side of battery, not top, and insulate with foam for protection and accuracy.

• Verify reading with inspection and manual temp measurement

• Meters - LED indicators are the minimum standard

• Types - Digital, remote, data logging (ports, good for checking expected battery life)

• Parameters -  Input volts, amps and watts; output volts, amps and watts; Battery SoC, load amps!

• SoC Meters - Battery voltage-based meters are only accurate when battery is at rest!

• Shunt-based - These measure amp-hours over time by checking directional voltage drop.

• Programmable (user error is possible) and some models use machine learning

Lithium Ion Charging:

• Benefits - Charging can be intermittent and incomplete without damaging batteries, efficient

• Challenges - Tighter voltage tolerance, must double check; Must not be overcharged!  (No float or equalization charging)

• Requires BMS  - Monitors each cell temp and V to prevent overcharging and over-discharging by shunting current around full cells to uncharged cells

• Usually comes preprogrammed and requires internet access for upgrades from manufacturer

• Verify compatibility with all other power electronics

• Charging Stages - Only 2 or 3 optional stages

• Constant Current (CC) -  Applied until voltage limit is reached

• Balancing - Reduction of current as max SoC approaches (optional)

• Constant Voltage (CV) - Equal to battery until SoC = 100%