First, let's cover some of the important characteristics of common Charge Controllers and Lithium Ion Batteries. Once you understand these options, RENVU Sales Engineers will be happy to help select a specific model number based on your preferences.
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%
Lithium Voltage - Higher than Lead Acid Batteries, 3.7-4.2 Vpc
If you already read the other Battery-based systems articles, then you covered everything from battery-based system load analysis to system sizing and battery technology product selection. All that remains is to integrate all these moving parts and install the system! I recommend reading Battery-based System Electrical Integration next.