Siting
- Temperature. Sweet spot is 15–25°C. Not the attic. Not the sun-facing garage wall in Phoenix. Not an unheated shed in Minnesota unless the battery is heated.
- Clearances. The manufacturer's install manual gives working clearances and separation between units. Energy storage in dwellings is also governed by NEC 706 and NFPA 855 — including limits on aggregate kWh per room and required separation.
- Egress. Never mount a battery where it blocks the path out of the room it is in.
- Structure. A wall-mount LFP unit runs 200–350 lb. Two lags into drywall is not a mounting method. Find studs, use the manufacturer's bracket, and confirm the wall can carry it.
Sequence
- Receive and inspectCheck SOC on arrival. Most ship at 30–50%. A unit that arrives at 0% has been sitting and may already be damaged. Photograph the packaging before you cut it.
- Mount before you wireBracket, level, torque the anchors. Then and only then bring conductors in.
- Bond first, DC lastChassis ground before anything else. Then comms cable. DC positive and negative last, with the battery disconnect open.
- Match parallel unitsSame model, same firmware, and within a few percent SOC of each other before you close the disconnect. Charge them individually if you have to.
- Set the DIP switches / addressMaster and slave addressing, and the correct termination resistor on the last unit in the CAN chain. This is the number one reason nothing communicates.
- Configure the inverterSelect the exact battery model in the inverter menu. Set charge current, absorption, and low-voltage cutoff to the battery manufacturer's spec, not the inverter's defaults.
- Commission and logFull charge, verify SOC reporting matches, pull a load and watch cell voltages spread. Record firmware versions on both ends before you leave.
Do not do thisNever work a live DC battery circuit with a wrench and no plan. There is no breaker between you and thousands of amps of short-circuit current — a dropped tool across the terminals vaporizes and takes your hand with it. Open the disconnect, verify zero volts, insulate the wrench, and take the ring off your finger.
Terminal torqueBattery lugs are usually specified in in-lb, not ft-lb. A loose lug is a resistive heater; an over-torqued one strips a soft post. Use a calibrated torque wrench, then re-check every lug after the first full charge cycle — connections settle.
Comms troubleshooting order
- ProtocolWrong protocol selected in the inverter is the most common fault. Check the pairing chart.
- PinoutAn RJ45 that fits is not an RJ45 that is wired right. CAN-H and CAN-L pins differ by brand. Verify against both manuals.
- TerminationResistor on the last unit only. Not on every unit. Not on none.
- AddressingOne master. Unique addresses. Power-cycle the whole stack after changing DIP switches.