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[HW-FIX] losing time/date on battery swap? Replace bupbat
some of you might never have known: N900 is not supposed to lose cmos-clock time and date ([edit] and alarms) on every battery swap. It's a tiny rechargable coin LiIon cell backup-battery (next to vibrator and power button) that's supposed to keep RTC aka cmos-clock running during months of main battery removed. Alas all those components break during a 12..24 months of usage, some even leak.
Now for the "bright" side of this story: the battery is easily replaceable when you got some moderate soldering skills (and tools), and using a YUDEN, PAS414HR-VA5R, capacitor, 0.06F, 3.3V, STAKED COIN Coin Type Polyacene Capacitor https://hbe-shop.de/Art-2112777-TAIY...3V-STAKED-COIN will avoid having it broken again in another 12 months of time. (datasheet) [edit]my local stock of those ran out, so the following doesn't apply anymore[/edit] For your convenience I got some of those components as of above, and I'm willing to ship them worldwide via simple letter, for a 3EUR donation per unit to maemo donation paypal account. Contact me via IRC(freenode.net):#maemo or by mail to techstaff at maemo.org, or simply donate and give FULL addr plus your online contact (mail or IRC) in "message to account owner" some macro-shots (taken with N900): http://maemo.cloud-7.de/share-service/20130727_001.jpg pointing to coin cell with a red balltip fine pen http://maemo.cloud-7.de/share-service/20130727_002.jpg left black switch is camera trigger, right one (white head) is power button. The huge silver thing below the coin is vibrator http://maemo.cloud-7.de/share-service/20130727_003.jpg also see http://maemo.cloud-7.de/Gallery-N900-exploded/ cheers jOERG |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Thanx for finding and bringing to us/community.
-- unfortunately my soldering skills are weak weaker ... last time it was cmos batt on 486 and I dropped a bit of tin into RAM blocks :(, but hey it still ran :) otherwise I would immediately go for one from you |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
could swap that with a capacitor?
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
i mean a smd one , not battery , just one smd capacitor or
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
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/j |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Funny, I got so used to setting date/time after swapping batteries that I assumed this had always be the case.
However, since the n900 is still my main phone (I'd like to keep it like this for the next couple of years to come) and I don't trust my soldering skills, I'm not going to attempt a hardware fix. But thanks for sharing this information with the community. |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
good post.
For those considering doing the soldering themself, you should be aware of RoHS. (http://en.m.wikipedia.org/wiki/Restr...nces_Directive) Shortly, you need higher temperature when soldering this, than with usual lead. going to ask a good friend myself :) |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
reserve one for me as i cant find one . Long story ...
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
is there a limit per person? I'd like three...
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/j |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
i want one as i stated beforehand but cannot donate:)
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
:) donated 20€
Need one :) rest is donation for maemo.org maintanenece PayPal #: 9W437295L11051929 |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
I'm sending out 3 standard letters with n+1 PAS414 (+1 for practicing ;-D "Dispose of properly! Please do not litter!")
N.N. By 116 3xxx F. Denmark 2 K.L. z.d.E. 21 4xxxx D. Germany 2 P.P. 1 S.E. O.14 n xx U.K. 4 /j |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
so far I hope I handled all requests. If you "ordered" and haven't heard from me for 4 weeks and not received the batteries already, please ping me joerg at openmoko org.
S.N. Il.gr. T:304 SE-2xxx L. is in the pipeline feedback in here when letter arrived, in which condition, and how the rework panned out... all HIGHLY welcome ;-) /j |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
I don't mind using my hour/date on battery changes, but I would mind if the battery leaks. Is the hour and date backup the only function of the battery? If so, how easy is it to just remove the battery?
Then again, if I remove the battery I might just as well solder in that capacitor. No soldering experience, though. What soldering equipment would I need to at least remove the battery? And thanks for providing this information and the capacitors! |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Is it possible for paying using other form of donation than paypal, for those that religiously doesn't use it? IDK, moneybookers, or whatever?
/Estel |
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The battery is not needed for anything relevant except RTC. Proof: N900 with broken bupbat work "flawlessly", except for losing date&time on battery swap. [edit] Note that the RTC also stores an alarm that boots up the device from power down when set. Of course this will also get lost when bupbat is defect and you swap main battery! I hope I managed to process all orders and you all received your bupbat. If somebody didn't, please holler! This is not a planned scam cheers jOERG |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
I've managed to rip off the positive soldering pad (the bottom side of the bupbat) while replacing it on one of my spares. Clumsy me. I am not too hart-broken about that: it was the phone with non-working telephony that I use only for testing. The old battery was dead anyway, so I have not actually lost any functionality.
Still, does anyone know if there is an alternative pad somewhere else on the board? |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
4 Attachment(s)
Ideally you use TWO soldering irons (or so called soldering tweezers) to unsolder the coin.
C4257 position M8 http://wstaw.org/m/2014/04/15/plasma-desktopTS1775.png it's parallel to bupbat. It's the only alternative pad. /j |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
A bit of feedback, nearly 2 years on. I replaced the bupbat on four of my N900s and it worked fine for a while, but I noticed a few months ago that the RTC time is lost again once the main battery is taken out for more than a few seconds. That would suggest that the bupbat has ran out and is not being recharged. Wasn't there supposed to be a fix in the power kernel for that?
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
hmm, the charging *should* be enabled per default, afaik. You might want to check the registers, and/or probe voltage on bupbat during and after inserting main battery and attaching wallcharger
maybe useful:http://wstaw.org/m/2015/10/15/plasma-desktopiM9051.png http://www.ti.com/lit/an/swca025/swca025.pdf actually seems it's not on per default: http://wstaw.org/m/2015/10/15/plasma-desktoppb9051.png http://www.datasheetarchive.com/SWCU050G-datasheet.html Quote:
I would have expected this getting done by NOLO |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
OK, I made a few tests. Please note that I have the package, whatever it is called, that puts up the "enter date" dialog on boot up removed. My phone boots up straight to desktop every time.
Test 1: Remove main battery for 5 minutes. Put it back, power up. System tme is preserved. Test 2: Remove main battery for 2 hours. Put it back, power up. System time is reset. So it looks like the bupbat keeps some charge but not for very long. |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
which bupbat you are using? The polyacene capacitor type is not supposed to provide nearly as long a backup as the original LiMg cell. Anyway I'll try to find the data and do the math how long actually
to start with: http://wstaw.org/m/2015/10/15/plasma-desktopAq9051.png PAS414 CAP PAS COIN-TYPE 3.3V 0.07F 0.07 As/V * 3 V * 3 V = 0.63 VAs; aka Ws aka J (actually * 0.5 since voltage drops linear with discharge) 0.63 Ws / 7.2E-6 W = 87.5E3 s = 24 h (* 0.5; assuming the capacitor could power the VBRTC domain until voltage = 0, so actually probably another time half of that, ~6h in the end) Anyway BB_CFG register reset default is 0b00000000, for polyacene cap PAS414 (!!!) I suggest setting it to 0b00011111 as soon as possible during boot |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
I am using the ones from you. If this is as expected then fine. I think my test proves that the bupbat does get recharged, otherwise the time would be lost right away and not after two hours. I was under a misconception that an RTC backup battery should last for days, if not years. We used some RTC chips back in mid-1990's, can't remember the type number, that had the battery built in. So clearly not vety big. IIRC, the catalogue page claimed the battery should last 10 years.
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Looking for new bup, Tayo Yuiden part is out of production. Could be ELNA DSK-414-HL a suitable replacement?
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Thanks for the pointer /j |
The N900 has a clock backup battery? All these years of ignorance I assumed it was just s lost technology and reseting date/time when changing battery wss a feature. Thanks to this recent activity in this thread I'll see if I can find that potential replacement.
The things one learns every day here! And digikey stocks the Elna part. Makes it easy to get just one. |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
It's probably realted to broken firmware in mine case, but does Nokia N9 got similar RTC battery?
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Hi guys
My N900 dont save the time and date anymore after of remove the battery for few seconds adn suppose i need replace the bupbat capacitor coin. Do you know any store on internet where i would buy it?? I could not find nothing on stock with the info give by @joerg_rw |
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Looking for a replacement backup battery available today.
Seems to me that there is enough room around the battery to replace it by something slightly bigger. Did some/one of you replace it recently? With what? Finally, after some years experience, li-ion battery or capacitor? |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Hah, is there anothner battery? Loosing time and date while removing battery - I thought it as a device character. Are there some other problems if it's dead?
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Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Yes, another battery. You can see it on the first page of the thread.
There aren't any other problems if it is dead. They all seem to die after one or two years. |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
I guess no answer means nobody knows but just to be sure, I bump this:
Do someone know with what we could, today, replace the backup battery? Capacitor, li-ion? Bigger size? thanks |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
Any battery that has the same voltage?
If you can fit it in there nicely (no stray contacts to other components), I don't see how this could break your machine. |
Re: [HW-FIX] losing time/date on battery swap? Replace bupbat
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The only negative effect is that, if you let your main battery discharge (or take it out), then the first thing the phone does the next time you switch it on is ask you to enter the current date and time. Quote:
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EDIT: oops, instruction in post 33, just above. On the orher hand, I often remove the battery and am a bit bored to Code:
ntpd -s |
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