Short answer: Usually, you should not solder directly to a bare NiMH or NiCd cell. For an RC transmitter, receiver, car, boat, or aircraft battery pack, the preferred approach is to buy factory-tabbed cells or have the pack assembled with the proper spot-welded tabs. Solder the wire to the approved tab or terminal lead, not to the cell case or bare terminal. If the cell manufacturer gives different instructions for a specific model, follow that documentation.
Adapted from Radical RC’s original cell-soldering guide, with technical guidance updated September 14, 2026.
Battery cells are not ordinary pieces of metal. Heat at the terminal can damage insulation, the separator, or the gas-release and safety parts inside the cell. FDK’s NiMH precautions warn against soldering lead wires directly to NiMH batteries because the heat can cause leakage, heating, bursting, or fire. Panasonic’s NiMH handbook describes the safer production method: spot-weld a nickel or nickel-plated steel tab to the terminal strip, then solder the lead to that tab as quickly as possible.
Choose the right RC battery pack before soldering
Before building or repairing a pack, confirm the chemistry, cell size, capacity, cell count, connector, and physical layout required by the model. A transmitter pack, receiver pack, electric-flight pack, and RC car pack may have very different current, space, and connector requirements. Use the RC battery configuration chart to check the available shapes, and compare the connector and wire requirements with the RC connector and wire chart.
For a new pack, factory-tabbed cells are the best choice for most hobby builders. If the cells are un-tabbed, have a qualified battery technician build the pack with the manufacturer-approved welding process. Do not sand the ends, scrape the plating, tin a bare terminal, or try to attach a tab directly with a soldering iron. Cell construction, terminal design, and permitted heat exposure vary, so the cell manufacturer’s instructions control the method.
How to solder an approved tab or lead
These steps apply only after a tab has been properly welded to the cell, or when the cell is supplied with a solderable terminal lead. They do not authorize soldering to the cell body.
- Remove the pack from the RC model and disconnect every charger, ESC, receiver, switch, and accessory. Work on a nonflammable surface with eye protection and good ventilation. Prevent loose tools, wire, and solder from bridging the positive and negative terminals.
- Read the cell or pack manufacturer’s instructions first. Confirm that the tab and wire are suitable for soldering, and use the specified soldering temperature and maximum contact time. A hot, properly sized electronics iron can transfer heat quickly; wattage alone is not a safe limit.
- Use thin rosin-core electronics solder and clean, tinned wire. Tin the wire and the exposed tab separately, keeping the iron on the tab or wire rather than on the battery body.
- Join the tinned wire and tab with one short, controlled application of heat. If the solder does not flow promptly, stop and let the joint and pack cool. Do not keep increasing heat or hold the iron against the cell to force the joint.
- Let the connection cool naturally. Inspect it for a smooth joint, loose strands, sharp edges, damaged insulation, or movement at the welded tab. Add insulation and strain relief so vibration in an RC model cannot flex the connection.
- After the joint has cooled, inspect polarity and connections with the pack disconnected from every device and charger. Use continuity mode only on isolated, unpowered leads or connector paths; never use continuity mode across a connected cell or energized pack. To measure pack voltage, use DC-voltage mode with the correct range and polarity, and keep the probes from bridging the terminals. Never use current or amp mode directly across a battery. Check that the connector matches the model and charger. A short or reversed connection can damage the radio system, speed controller, charger, or aircraft.
When to stop and replace or outsource the pack
Stop if a cell becomes hot, vents, leaks, swells, smells unusual, loses its insulation, or shows physical damage. Do not charge or install a questionable cell. Set it aside away from combustible material and follow local battery-recycling or hazardous-material guidance.
Do not attempt to solder a cell that has no factory tab, a damaged terminal, or an unclear data sheet. The safest practical option is a factory-tabbed replacement or a professionally welded pack. This is especially important when the pack will power a model in flight or a high-current RC vehicle, where a failed connection can cause loss of control.
NiMH and NiCd packs also require a charger and charge method suited to their chemistry. For charging and first-use checks, see our NiMH and NiCd battery charging guide. Energizer’s NiMH handbook explains that charging produces heat and that overcharge can raise battery temperature and pressure, so never use a generic charging rule in place of the cell and charger instructions.
This guide covers NiMH and NiCd RC packs only. Do not apply it to lithium-ion, LiPo, LiFe, or other lithium cells. Those chemistries require their own cell-specific charging, protection, tab, and assembly instructions.
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