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Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

X200, X201, X220 (including equivalent tablet models) and X300, X301 series specific matters only.
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rhlee
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Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

#1 Post by rhlee » Thu Oct 17, 2019 3:20 pm

I had to replace the CMOS battery on my x220 a few weeks ago. Unfortunately the battery came with the terminals back to front. I only realised when the laptop went into a non-bootable state.

When I say non-bootable state, I mean that pushing the power button does not turn it on. In this state I have to disconnect the power supply, main battery and CMOS battery and wait for whatever residual charge lingering in the system to discharge. This takes roughly 12 or so hours.

Swapping the terminals around to the correct polarity, the machine worked fine for a week. Then returned to the non-booting state.

Got a new cmos battery, just to be safe. This time the termials came the right way round. Working for a week, back to non-booting. Has to do the discharge trick again.

Have I damaged my mainboard in someway by connectinting the CMOS battery in reverse?

I mean it's only 3.3v. Doesn't seem as it if could do much damage.

Also is there a faster way to discharge the x220?

If I haven't discharged it properly, the very act of attaching power via the lead or battery or CMOS battery, charged up the system. And then I have to wait for another 12 hours.

I mean the charge must be held somewhere on the board components. I tried shorting out vcc and gnd on the cmos chip itself, but it had no effect.

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Re: Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

#2 Post by TPFanatic » Thu Oct 17, 2019 11:10 pm

To discharge power have you tried disconnecting power,battery and holding the power button on the keyboard?
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rhlee
Posts: 15
Joined: Sat Oct 09, 2010 12:45 pm
Location: London, England

Re: Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

#3 Post by rhlee » Fri Oct 18, 2019 3:31 am

Yeah, 1 second down then release for 1 second ten times. Then hold down for 30 secs. Tried that many a time.

rhlee
Posts: 15
Joined: Sat Oct 09, 2010 12:45 pm
Location: London, England

Re: Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

#4 Post by rhlee » Fri Oct 18, 2019 3:35 am

I was just about to order another board. Though I'd give it one more try. Pushed the power button, turned on again. Not sure how long it will be for. Swear to god the machine is toying with me.

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Re: Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

#5 Post by RealBlackStuff » Fri Oct 18, 2019 3:57 am

Next time (without charger and battery, leave CMOS in), just hold down the power button once for ~20 seconds, that's enough.
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rhlee
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Joined: Sat Oct 09, 2010 12:45 pm
Location: London, England

Re: Put in CMOS battery in reverse polarity. Possible damage? / Discharging residual charge

#6 Post by rhlee » Fri Oct 18, 2019 2:29 pm

Thanks will give that a shot next time that happens.

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