You removed the RTC battery from an industrial PC, waited 24 hours, and the BIOS settings are untouched — including the one that switched the USB controllers off, so no keyboard or mouse responds. On this class of machine that is normal behavior, not a fault: the settings sit in EEPROM and never needed the battery. This guide covers why the wait cannot work, what the cell actually powers, and the recovery route that does work — a BIOS update that loads factory defaults — plus setting the clock and keeping a vision station out of this corner for good.
Why didn't the BIOS settings reset after 24 hours without the battery?
Because the settings are not in battery-backed memory: modern industrial PCs keep BIOS configuration in nonvolatile EEPROM, so no battery-out time — 24 hours or 24 days — clears a single option.
The desktop trick of pulling the coin cell and waiting comes from boards whose setup data sits in CMOS RAM that the cell holds up. Industrial PC makers moved the settings into EEPROM so a battery service stop never wipes a configured production machine. One panel-PC manual says it in a single line: "any BIOS settings made are retained (stored in voltage-safe EEPROM)" when the battery is changed with the machine voltage-free — only the date and time must be entered again.
There is a second tell in what you saw. If even the date and time survived the battery-out period, the board never went voltage-free: a real-time clock runs from the board rails whenever any power is present, and only falls back to the cell when every rail is down. A standby feed or a live DC input kept it ticking.
What does the RTC battery actually back up?
On an EEPROM-backed industrial PC, only the real-time clock: a 3 V lithium cell — usually a CR2032 in a holder, or a soldered rechargeable equivalent — keeps the date and time alive while power is off.
Three separate memories live in these machines, and only one of them needs the cell:
- Firmware and setup options sit in flash and EEPROM on the board, kept with no power at all.
- The real-time clock runs from the 3 V cell whenever the machine is off.
- Controller-style units may add a second backup cell on a plug-in card for retentive memory; the front coin cell never touches that store.
How long the cell lasts is simple arithmetic. A CR2032 stores about 220 mAh, and an RTC on backup draws on the order of 1 µA:
Pure clock draw would stretch a cell to decades; self-discharge and a warm cabinet cut real life to five to ten years. Put the cell on the five-year service list, not the fault list. The early warning is the clock falling behind or resetting on cold boots — the signs to catch, and what to save first, are covered in a CMOS battery running low on a vision or industrial PC.
Is there a CMOS reset jumper on these machines?
Rarely: sealed panel PCs and box PCs expose the battery but not a clear-settings header, so the desktop jumper shortcut simply is not there — the hardware chapter of the manual would list one if the board had it.
Desktop boards run a two- or three-pin clear header beside the coin cell because their settings live in battery-held RAM. Industrial boards skip it for two reasons: the enclosure is sealed, and on an EEPROM machine a jumper would do nothing anyway. Clearing RAM does not touch EEPROM; only a deliberate firmware write changes those bytes. Do not hunt for an undocumented pad with a screwdriver — a slip to the wrong rail finishes the board.
How do you get back into the BIOS with USB disabled?
Try the inputs the USB setting does not govern: a PS/2 keyboard if the machine has the port, then every USB port on the machine, because controller options often disable only some of them.
PS/2 input comes from the keyboard controller and works regardless of USB options in setup — it is the reason industrial machines kept the port. Work through front ports, rear ports and any internal-header port before concluding all controllers are off. On a vision station the disabled controllers take any USB cameras down with them: the camera cables and cameras are fine, the ports behind them are switched off.
If no input works, the recovery route is the BIOS update in the next section. And if a setup password is the real blocker, the way through is the vendor's own password-clear process, not the battery — resetting an industrial computer BIOS password without a CMOS battery covers those routes.
How does a BIOS update restore the factory defaults?
Because the update rewrites the firmware and loads factory defaults into the settings area as it finishes, which switches the USB controllers back on — on EEPROM-backed machines the reflash is the reset.
Work it as a procedure:
- On another computer, download the BIOS update for the exact model from the vendor's official site. Firmware from anywhere else is how boards stop booting.
- Build the boot media the package asks for — on panel PCs commonly a USB stick or a CFast card.
- Power the machine down fully, fit the media, then power up and let it boot from that media.
- Let the flash run to the end. If the package stops at a confirmation prompt you cannot answer, run it with the package's unattended option, or ask the vendor for a silent build.
- On the first boot, enter setup, confirm the defaults loaded, then re-enter your station's settings.
If the machine will not boot from media at all, the remaining route is the vendor's service — the same destination the manual's battery chapter points to for anything beyond a cell swap.
How do you set the clock after the battery change?
Enter the date and time in setup once, or let the operating system sync it: after any battery loss, set the clock by hand in BIOS or let NTP correct it on first network contact — one of the two, every time.
If you have another cell to fit, do it with the board voltage-free: unplug AC and break the DC feed at the machine's input. If that feed comes from an enclosed 48 V unit such as the LRS-75-48, open its output breaker or lift the conductor at the terminal block.
- Type
- Power cords and supplies
After the swap, a machine that refuses to start is usually a seating problem, not a settings one — work through an industrial PC with no power after a CMOS battery swap before anything else.
Then decide how much you trust the clock. The onboard timekeeper is a 32.768 kHz crystal held to about ±20 ppm at room temperature. A 30-day month is 30 × 24 × 3,600 = 2,592,000 seconds, so 20 ppm of that is 2,592,000 × 0.00002 ≈ 52 seconds of drift per month — before cabinet temperature swings. Good enough for a file stamp; wrong for inspection records. Sync the station's system time over NTP and stamp images from the synced clock, not the bare RTC.
When does removing the battery actually clear settings?
On battery-backed CMOS boards — most desktop motherboards and older machine-tool and PLC controllers — settings clear within about five to ten minutes of the cell being out with all power removed.
| EEPROM-backed industrial PC | Battery-backed CMOS board | |
|---|---|---|
| Where settings live | Nonvolatile EEPROM on the board | CMOS RAM held up by the cell |
| Battery out, power off | Settings survive indefinitely; clock stops | Settings clear in five to ten minutes; clock stops |
| Reset route | BIOS update or vendor service | Battery out, or the clear jumper |
| Main risk | An option turned off by mistake, like USB | A dead cell wiping settings in service |
The manual settles which one you have in a minute of reading: a battery chapter that names nonvolatile storage for the setup data leaves the cell with only the clock to keep, while one that names battery-held CMOS, or lists a clear jumper, confirms the pull-and-wait method works. The 24-hour figure itself was always margin: the discharge behind a CMOS clear takes minutes, and the extra hours never added anything. On the battery-backed side the failure runs the other way — a dying cell takes the machine's parameters with it, and lost CMOS settings on a machine-tool controller walks that repair.
How do you keep this from happening again?
Record before you change, and never switch off the last enabled USB controller: those two habits prevent nearly every BIOS lockout on an industrial PC.
- Photograph every setup page before changing an option, and after. Cameras hold their own configuration through power cycles once written — keeping camera bitrate settings after a power cycle is the same discipline on the camera side — but a BIOS page you have left has no undo.
- Disable individual ports if policy demands it, never every controller. One enabled controller is your recovery path.
- Keep a PS/2 keyboard in the cabinet spares; it ignores USB options entirely.
- Replace the RTC cell on a five-year schedule instead of waiting for symptoms.
- File the BIOS update media and the settings photos with the machine's documents.
- Set the power-loss option so the machine restarts after an outage, and a tripped breaker does not leave a headless station dark.
When the machine is back in service, give its feed one look: the power supplies range and the accessories finder cover the enclosed supplies and cords behind a station's DC rails.
Enclosed 12 / 24 / 48 V supplies for cameras, lights and controllers
4 models · from $29.00If the reflash looks risky on a live production line, contact us before you start — expert support is free with every order, and five minutes of planning beats a board that will not boot.
問題
Will removing the battery erase the operating system or stored inspection images?
No. The RTC cell backs the clock, and on older boards the setup data; the operating system, programs and image archives live on the storage drive and never see the battery. The only write risk in this whole procedure is the BIOS update itself — cut power during the flash and it is the firmware, not your files, that gets damaged.
How can I tell whether my machine stores BIOS settings in EEPROM or in battery-backed CMOS?
Read the battery chapter of the manual. Wording such as settings retained in a voltage-safe EEPROM means the cell backs the clock only; wording such as battery-backed CMOS, or a listed clear jumper, means the pull-and-wait method works. A ten-minute battery-out test with all power removed confirms it: settings that survive are in EEPROM.
How often should the RTC battery be changed in an industrial PC?
Schedule it at five-year service intervals. The arithmetic gives about 25 years of pure clock draw from a 220 mAh cell at 1 µA, but self-discharge and cabinet heat cut real life to five to ten years. A clock that falls back to a factory date on every cold boot, or drifts quickly, is telling you the cell is finished.
Can I keep running the vision station while the clock is wrong?
You can acquire images, but do not trust the timestamps. Inspection records ordered by time will sort wrongly, and correlation with PLC or line-controller logs breaks by exactly the clock error. Set the date in setup or let NTP sync the system clock at the next network contact before you log another result.
Do I need a newer BIOS version, or will the current one reflash and reset?
The current version is enough. The reset comes from the update tool rewriting the settings area with factory defaults as it completes, not from the version number, and most vendors' flash tools accept reflashing the version already installed. Download it from the vendor's own site either way — a mismatched image is what stops boards booting.