Battery Testers for the Bench
The test gear that's worth having for cordless battery work, from a basic multimeter to capacity testers.
You don't need a full lab to look after cordless batteries. A few pieces of test gear tell you whether a pack is healthy, tired or unsafe. Here's what each one does and when it's worth buying.
1. Digital multimeter
The first tool to buy. It measures pack and cell voltage, which tells you whether a pack is charged, flat or out of balance.
- Look for an auto-ranging meter with a clear display and good probes.
- A category rating (CAT III or similar) shows it's built with safety in mind.
Revival Academy 101 has a full lesson on multimeter basics.
2. Capacity tester
Voltage alone doesn't tell you how much energy a pack can still hold. A capacity tester (or a hobby charger with a discharge function) charges and discharges cells and measures the capacity in mAh. Comparing it with the rated capacity shows how worn the cells are.
3. Internal resistance meter
As cells age, their internal resistance rises. A pack with high resistance sags under load and runs hot, even when the voltage looks fine. An internal resistance meter shows this quickly. Compare cells against each other and against the cell's datasheet.
4. Infrared thermometer or thermal camera
Heat is an early warning sign. A cheap infrared thermometer lets you check a pack, charger or terminals for hot spots without touching them.
5. Safe storage and a safe surface
- A non-flammable work surface, such as a metal bench or ceramic tile.
- A metal container or fire-resistant battery bag for charging and storing questionable packs.
- A suitable fire extinguisher nearby, and know when to get out and call 000.
6. Spot welder (only for rebuilds)
Pack rebuilds need cells joined with nickel strip by spot welding, not soldering. Only buy one if you're doing rebuilds regularly. See Is a Battery Pack Rebuild Worth It?
Where to start
A multimeter and an infrared thermometer cover most everyday checks. Add a capacity tester when you want to know exactly how much life is left in a pack.
Handy gear
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