How old is the laptop ? The CMOS backup battery can get drained if you remove the main laptop battery between uses. Charging the laptop and leaving the battery in may do the trick.
I've only seen one machine where backup battery replacement was properly catered for and that was an old Dell. In most cases I reckon the makers rely on the fact that lithiums have a life of about ten years which is much longer than most people keep a computer so replacement usually involves disassembly.
1. CMOS batteres DO NOT recharge so sticking the main battery in will not do jack
2. 10 years is shelf life. How long the battery last depends on current drain and physical size of battery (ie a D cell vs a AA Cell)
I had to replace the CMOS battery in my Compaq laptop - PAIN IN THE A2S
What I did was google "Laptop repair" and/or "Laptop disassembly" might try "dissasemble Gateway M-Series"
Normally the computer will not keep the correct time is a good indicator, but not always.
CMOS batteries normally last 3 -> 5 years.
for filart -
There are a VERY few computers that use a rechargeable CMOS battery system and have a trickle charger circuit built in. The vast majority uses a non-rechargeable battery and as such do not incorporate a recharging circuit - no connection to a source voltage.
To recharge the battery there must be a connection to a source voltage. In the case where a NONRECHARGABE battery is used why would you go to the expense of adding a charging circuit - not cost effective. There is also the safety aspect as nonrechargable “Watch” batteries have a tendency to overheat and explode. You can recharge them with limited success – but it is just not worth it.
Requirement for attempting to recharge a nonrecharable battery.
Basically you would need a regulate source, voltage regulated to approx 10 to 20 percent greater than the battery no load voltage that decreases as the battery reaches no load voltage. The current must also be limited, normally 1/10th of stated amp hours (in this case milliamps. You could also apply a greater voltage, when it gets hot remove voltage be for it explodes - Just kidding.
The CMOS battery is a non-rechargeable Lithium cell which powers the chipset when the machine is off. This prevents your mainboard's system time and BIOs settings from resetting each time the power is switched off. In other words, leaving the PC switched on will not charge the CMOS battery, neither will it damage the cell.
PS I've seen "how to recharge "watch" batteries - But as I said It's just not worth it.
Retired Chief: I'm fully aware of what you say.
I can only tell you that we had a girl at work who was in the habit of removing the main battery from her laptop and leaving it over weekends like that. She then complained that it kept losing the time/date.
I advised her to stop removing the main battery and the problem went away.
I don't know or care why, but it worked and thus I passed on that info to the OP.