Monitoring

Voltage is not fuel

LFP voltage stays flat over much of its charge range and changes with load/charge, so voltage alone is a poor state-of-charge gauge. A shunt integrates current over time and must be configured to the bank.

What to watch

State of charge, net amps, watts, consumed Ah/Wh, lowest voltage under load, charger power, solar yield and daily history. Reset/synchronize only under the monitor maker's defined full-charge conditions.

Find faults

Normal solar volts with zero current suggests controller state, battery full, wiring or fuse issue. Large battery voltage sag suggests low SOC, undersized path, weak battery/BMS or resistance. Unexpected overnight draw can be isolated circuit by circuit.

Calibration

Enter exact capacity, charged voltage, tail current and efficiency parameters. Confirm all loads and chargers pass through the shunt. Compare monitor current with a trusted clamp meter.

Use the data

Build a seven-day energy budget from actual use. If demand repeatedly exceeds replenishment, change behavior, add charging, or reduce loads - not the state-of-charge display.

Rule of thumb

If you cannot state the expected current, full conductor length, protection rating and manufacturer limit for a circuit, the circuit is not ready to build.

CHAPTER CHECK

• I can explain the purpose of every component covered here. • I can identify the exact manufacturer limit that controls my design. • I have added the decision, rating or measurement to my schematic/worksheet.