Why does a new car battery test bad-replace?
Digital testers like the Ancel often read a new battery as "bad-replace" even after hours on a charger that fails to show a full charge light. This leaves owners wondering if they can return the battery while avoiding dangerous multimeter testing methods that can fry the meter on high-amperage circuits.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Hooking up to a trickle charger
- 2Taking the battery to an auto parts store that has resistive load testers
- 3Using the voltage drop approach across fuses instead of measuring amperage in series
- 4Using an expensive DC amp clamp for current measurement
- 5Making the car think all doors and the hood are closed and the car is locked
- 6Placing key fobs far away or in a Faraday cage to prevent waking modules
- 7Using multimeters with a MAX memory function to catch intermittent spikes overnight
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Have a new Walmart battery, everstart maxx 78 for the 3 year replacement.”source ↗
“Hooked up my Napa charger for large vehicles and let it sit on the standard setting for hours, all it did is eventually quit humming but no full charge light.”source ↗
“Ancel tester always showed bad-replace.”source ↗
“What should I do with this damn battery? I'm sure I can't go back and return can I and start fresh?”source ↗
“Putting a multimeter in series is the dumbest approach available. Why? Look at your fuse box. See all those 20A, 30A, 50A, and larger fuses? Now look at your multimeter. What's its amperage rating? Yeah, 10A. If you wake up all the modules at once, open a door, or do anything else that powers up those double-digit-amp circuits, your multimeter is toast. Either you'll blow its fuse or you'll fry the meter itself.”source ↗
Where this came up
People with this problem also raised
- 2Do I actually need to register a new car battery?
- 3Is my car battery dead or is it the alternator?
- 13Car battery keeps dying even after replacing battery and alternator
- 3Car battery leaking acid with no warning lights
- 2Why is my check engine light on after changing the car battery?
- 4When should I preemptively replace a car battery?