Unless your city has a 24/7 perfectly reliable power grid, you’re likely familiar with backup power solutions like diesel generators or energy storage systems. Many users assume that connecting batteries in parallel is simple — just hook them up and double the capacity. But even small mistakes during the process can cause serious problems, from system failures to safety risks.
Below are 7 field-tested tips derived from real installation experience — not theory.
1. Same Brand ≠ Same Batch — Internal Resistance Matters
Even batteries of the same model may vary internally by batch. Uneven internal resistance leads to current imbalance, overheating, or aging.
- Select batteries from the same batch when possible;
- If mixed, ensure internal resistance differs by ≤ ±3mΩ;
- Voltage difference should be ≤ ±0.05V;
- Parallel new batteries from the beginning.
2. Respect Your BMS Limits
Every BMS has limits — on parallel count, voltage, and comms. Overloading it can crash the system or burn the MOSFETs.
- Check datasheet for max parallel support;
- e.g., Lithtech wall-mounted batteries support up to 15 units;
- Some batteries are for series use only — read the manual.
3. Loose Terminals Are a Hidden Killer
Loose screws or mismatched cable lengths can create resistance, causing heat spots, voltage drops, and damage over time.
4. Inverter Shouldn’t Connect to Just One Battery
Connecting both terminals to one battery overloads it, leaving others idle. This causes imbalance.
Best practice: Connect inverter’s positive to the first battery, and negative to the last one.
5. Use Circuit Breakers — Always
Install at least one main DC breaker, and ideally, one per battery. This protects the system if a unit fails.
- Main breaker near inverter;
- Use 125V/250V DC-rated breakers;
- Delay-type breakers help prevent false trips.
6. Mind the Spacing — Batteries Need to Breathe
Placing batteries too close limits heat dissipation, especially in summer or under load.
- Keep 10 cm gap between units;
- Avoid enclosed, unventilated spaces;
- Add HVAC if ambient temp >35°C.
7. Monthly Checks Prevent Surprises
Issues may arise silently over time. Regular inspection helps catch imbalances early.
- Terminal temperature;
- Voltage/current consistency;
- Cable wear or heat marks;
- BMS warnings or logs.
Parallel connection may seem routine — but every wire, breaker, and limit matters. Always follow the manual or consult a professional to ensure safe, efficient scaling.
Need help with parallel installation?
Please contact the Lithtech technical team — we’re here to help.
