X2100 loses bios settings if left unplugged

[jamesfawcett]

Hi everyone.

I'm on my third X2100/X210 now, 4th batch 10710u, I've got a strange issue where if I shut down the OS and leave the machine without the power cable plugged in, but main battery connected, it seems to lose all bios settings after e length of time (couple of days or so). When the bios clearing has happened, the only way to get the X2100 to boot up is to disconnect the battery and plug it back in.

It's not a big issue I seem to have memorised now where all the settings are copying the recommended XY-Tech settings, it's a bit annoying because it also clears the NVRam so my startup disk is reset back to default too.

If I leave it plugged into a mains charger, it's fine. I've replaced the bios battery with a brand new one.

I am thinking of selling this laptop soon and would like to make it perfect, so it would be good to fix this annoyance.

Any suggestions welcome, thank you.

Thanks
James

[RealBlackStuff]

How about replacing the CMOS battery?
Sounds like yours is dead.

[jamesfawcett]

I've tried two CMOS batteries from two different sellers, it does the same with both unfortunately. Sorry I should have mentioned that. It does sound like it's the CMOS battery though doesn't it! Especially as it's only after it's sat dormant. I'm just using standard X201 CMOS batteries from ebay.

[kfzhu1229]

I don't own these but I believe a more "silly" testing method is if you have a bench power supply go and supply 3V to the cmos battery connector and read the power draw. If what you're suggesting is that the CMOS battery runs empty after just a few days (and that the CMOS battery is actually depleted after that said few days with say like only 1V remaining), it could be a very bad omen being that the CMOS circuit inside the chipset is partially shorted, in which case the power draw would read a few hundred mA and up... Just pointing out that unfortunately from what I see online such kind of fault can have the potential to be very fatal faults...

[jamesfawcett]

Great idea - Do you happen to know what the voltage would be for a "good" cmos battery after a few days storage? I'll leave mine over the weekend then grab the multimeter and I'll start by seeing if I have a parasitic drain. I can compare to my original X201's CMOS battery too.

[kfzhu1229]

Great idea - Do you happen to know what the voltage would be for a "good" cmos battery after a few days storage? I'll leave mine over the weekend then grab the multimeter and I'll start by seeing if I have a parasitic drain. I can compare to my original X201's CMOS battery too.

A highly charged CMOS battery is 3V and up. On a typical laptop CMOS it will start to have difficulty with remembering things once your voltage is like significantly below 2V
Maybe it's an even better idea for you to have two identical rebuilt/replacement CMOS battery packs never used, plug one in that mobo and one inside a regular X2xx, and see 4 days later just how much more drain your mobo drew vs the thinkpad motherboard.

[jamesfawcett]

Great idea! It's so easy to swap that I will try the same battery in both my original standard X201 and my X2100.

I wanted to test the voltage today after leaving it unplugged all weekend, but unfortunately (or fortunately!?) it hadn't lost settings.

I use this X2100 a hackintosh machine running Mac OS Sonoma, and I'm wondering now if it's something to do with the shutdown procedure. Something I did differently on Friday was I booted into Windows before shutting down.

I'm going to try trigger the fault again and test the same battery in both machines, I'll post my findings when I never news, thanks for your help

[jamesfawcett]

I'm struggling to reproduce the issue now. I swapped the BIOS battery, and the old battery had 3.11v so I think that rules it out being flat? I learnt something new too, I didn't realise the BIOS batteries were not rechargeable, I thought the machine charges them whilst it was powered on, but infact they seem to have a life span of 5 years?

[kfzhu1229]

I'm struggling to reproduce the issue now. I swapped the BIOS battery, and the old battery had 3.11v so I think that rules it out being flat? I learnt something new too, I didn't realise the BIOS batteries were not rechargeable, I thought the machine charges them whilst it was powered on, but infact they seem to have a life span of 5 years?

The CR2032 is indeed not rechargeable. Most of the time tho the manufacturers will use those kind of coin cells optimised for long lifespan and also most laptops will not use the CMOS battery for date and time when the laptop has charger power or powered on, or in the case of Dell and HP laptops, also when there's a working battery attached.
If you want something that's rechargable there is the ML1220 rechargable cells (much smaller in size, often times found soldered on motherboards, Toshiba loves to use them)
Well, then I guess it is possible that the laptop's CMOS had some corrupted information from the previously bad CMOS battery that needed a full disconnect of power to fully reset?

[jamesfawcett]

Right so just to update this - I've figured out a bit more about what's happening.

If I leave the machine for a long period of time without the mains power connected, when I power it back on there is a 20 second wait before it starts up. When this happens, I have previously been then taking out the battery thinking that it needs resetting. I didn't realise that it would eventually turn on. I think it must be BIOS related, and my action of taking out the main battery whilst it's doing something in the background, has been possibly corrupting/wiping the bios?

I've not removed the main battery since and I've been waiting for it to complete whatever it's doing, and everything has been perfect.

I found this link https://www.xyte.ch/2021/12/14/x2100-me ... E%20issue. relating to a soldering fix for ME, but mine is a 4th batch motherboard so I don't think it applies to me - can anyone confirm? It does seem to match my symptoms!

[flyingfishfinger]

I've also often had the "long pause before BIOS" issue. When I was playing around with coreboot in particular it seemed to be the RAM retraining issue. I've had times where it did not happen, but I have no clue what those times corresponded to. I gave up chasing it after a while, since everything else seems to be fine.

[jamesfawcett]

I've also often had the "long pause before BIOS" issue. When I was playing around with coreboot in particular it seemed to be the RAM retraining issue. I've had times where it did not happen, but I have no clue what those times corresponded to. I gave up chasing it after a while, since everything else seems to be fine.

How do you feel about doing the solder mod? I have seen that you can achieve the same by modifying the sound board rather than soldering straight onto the motherboard. I have a spare X201 for parts, I am tempted to do it - but also like you say, now I know that everything works fine despite the occasional long wait, I'm tempted to leave it.