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Old 06-15-2021, 10:26 AM   #1
ReplayGem
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Default Acer E5-571 RTC battery - alternate solder point

I have an Acer E15 (E5-571) that is loosing all settings whenever unplugged. I got a replacement battery however the original battery broke off from the motherboard and the positive lead broke away completely. I tried scrapping the board and soldering the new battery to it however it still looses all settings when unplugged. Is there an alternate point on the board where I can solder the positive lead of the battery? I found schematics of the board on the forums however I have no clue how to read it.

Thanks.
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Old 06-15-2021, 10:43 AM   #2
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Default Re: Acer E5-571 RTC battery - alternate solder point

Yes, you should have some options. Post clear and zoomed up pix of the battery region so we can review the parts in that area. Specifically looking for the presence of a very small surface mount resistor (often the body is black in color for the insulator) and the silk screen on the logic board should offer the text

R446
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File Type: png rtc_battery.png (73.0 KB, 10 views)
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Old 06-15-2021, 11:05 AM   #3
ReplayGem
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Default Re: Acer E5-571 RTC battery - alternate solder point

Thanks for the quick response. I've uploaded two pictures of the motherboard battery area (ignore my bad solder work), I hope one of them will provide you with what you asked for.

Thank you.
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File Type: jpg Acer E5 Pic2.jpg (329.7 KB, 14 views)
File Type: jpg Acer E5 Pic1.jpg (339.8 KB, 13 views)
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Old 06-15-2021, 11:24 AM   #4
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Default Re: Acer E5-571 RTC battery - alternate solder point

Hi. Yes the pics help. The large white base is the original coin cell battery that is used to retain your real-time clock (RTC). Ideally, you should search out the CR2032 (?) or whatever the computer manual recommends for this coin cell battery holder.

Coin cells do vary in diameter; the thickness and mAH (milliamps per hour) rating. The coin cell battery is NOT rechargeable but often last a few years if a good brand and original.

You have the soldered on battery pack which should be fine but be 100% sure that it is the same voltage as the original +3v0 value or close to this. Otherwise, can cause damage.

Aside from the above blabbing, see the attached.

Solder as noted and see if that works for you.

PS: My brother spoke very highly on the quality of food he at when he was in Barbados. Hope one day to come and visit. Stay safe.
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File Type: png battery.png (1.12 MB, 16 views)

Last edited by mon2; 06-15-2021 at 11:26 AM..
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Old 06-15-2021, 11:59 AM   #5
ReplayGem
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Default Re: Acer E5-571 RTC battery - alternate solder point

Thanks,
This motherboard battery is actually rechargeable (ML1220 Rechargeable Coin Cell... go figure). I am guessing the motherboard keeps it charged once on power or on battery but this is the first time I've dealt with a laptop with this type of battery although it appears to be common. I was wondering if there is some way to know if the cell was providing power to the motherboard once there is no power or, if it is actually being charged once on power; also I can't seem to measure the voltage of the battery once connected to the board, well at least I don't know how. Makes me wonder if there is another component on the board that is not working and stopping the battery from saving the settings.

re PS: That's funny, I thought the food in Canada was fantastic (still miss Burrito Boyz); and I hope you can visit someday.
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Old 06-15-2021, 12:52 PM   #6
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Default Re: Acer E5-571 RTC battery - alternate solder point

Ok - check the voltages:

1) on your external battery. What is the voltage from this external battery pack? Meter in volts mode. Red lead to red on the battery; black lead to black on the pack.

Value in volts ?

2) Then place the meter in ohms mode. Remove all power.

Check the continuity from the + battery connector to the pin # 1 of the 3 legged dual diode (SOT-23 package).

You should see the voltage from the battery reach pin # 1.

The voltage should flow in the direction shown in the red hand drawing

Then the diode inside D23 should allow for the voltage to travel to pin # 3.

Confirm these details. If D23 is working, the voltages should reach pin # 3 which then powers your RTC IC.

PS: You are making me hungry. We have a few good places but my brother tells me it is just not the same. Locally have Mumma Burrito and Quesada. Both are decent quality and always fresh but the best is in Mexican Village in Detroit. However, the border has been closed since covid started
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File Type: png battery.png (1.00 MB, 14 views)
File Type: png rtc_battery2.png (93.7 KB, 9 views)
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Old 06-15-2021, 01:44 PM   #7
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Default Re: Acer E5-571 RTC battery - alternate solder point

Thanks,
Here are the results,
1- got a 2.07 reading with battery detached from the board.
2- when battery connected, there is no continuity to D23 at least not from the battery lead but from the plus side of the 2032 battery image.

Don't understand, the original battery was soldered exactly where the new one is soldered but I get no reading once attached to the board. Should I solder the battery to the plus and minus (2032 battery image) as you suggested even though it is not the original location not sure if it would damage the board once plugged in??
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Old 06-15-2021, 01:50 PM   #8
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Default Re: Acer E5-571 RTC battery - alternate solder point

Quote:
Originally Posted by ReplayGem View Post
Thanks,
Here are the results,
1- got a 2.07 reading with battery detached from the board.
2- when battery connected, there is no continuity to D23 at least not from the battery lead but from the plus side of the 2032 battery image.

Don't understand, the original battery was soldered exactly where the new one is soldered but I get no reading once attached to the board. Should I solder the battery to the plus and minus (2032 battery image) as you suggested even though it is not the original location not sure if it would damage the board once plugged in??
Maybe the 2032 image space allows you to install a regular 2032 battery and remove the rechargable original battery? I get a continuity reading from the adapter power lead to the minus lead of the 2032 image space, nothing to the plus side.
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Old 06-15-2021, 03:04 PM   #9
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Default Re: Acer E5-571 RTC battery - alternate solder point

Is the white cap battery holder with a lid that can be removed? From which side do you install a fresh coin cell battery? Is there an opening on the other side of the logic board? Looking for 2 of compression fit contacts for the coin cell.
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Old 06-15-2021, 03:14 PM   #10
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Default Re: Acer E5-571 RTC battery - alternate solder point

it might be like this under the cover .. https://media.digikey.com/photos/San...ML1220-TT2.JPG
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Old 06-15-2021, 04:17 PM   #11
ReplayGem
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Default Re: Acer E5-571 RTC battery - alternate solder point

The original battery is very small,as seen in the motherboard pics posted (badly solder battery). There is nothing on the other side of the board that would lead me to believe it fits a 2032 battery... I can rig up a 2032 battery to fit but not sure what issues might arise from installing a battery that doesn't, like the original, charge.

Thanks.
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Old 06-15-2021, 04:26 PM   #12
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Default Re: Acer E5-571 RTC battery - alternate solder point

Quote:
Originally Posted by ReplayGem View Post
The original battery is very small,as seen in the motherboard pics posted (badly solder battery). There is nothing on the other side of the board that would lead me to believe it fits a 2032 battery... I can rig up a 2032 battery to fit but not sure what issues might arise from installing a battery that doesn't, like the original, charge.

Thanks.
Should I just try soldering the original battery to the board as suggested earlier; will it cause any issues with the board and will it charge?

Thanks.
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File Type: png battery (1).png (1.12 MB, 13 views)
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Old 06-15-2021, 06:37 PM   #13
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Default Re: Acer E5-571 RTC battery - alternate solder point

DOH .i see now the white is just silkscreen . there are a few variations of the ML1220 battery .just choose the easiest one for you .
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Old 06-16-2021, 07:48 PM   #14
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Default Re: Acer E5-571 RTC battery - alternate solder point

Hi, to me, the board looks like it was designed to accept either a rechargeable ML1220 battery, or a standard, non rechargeable CR2032, depending of the components fitted to the board

From the looks of it, D32 and R446 are not fitted (for using a regular CR2032), instead you have D23 installed on your board
Brief explanation of the circuit:
- From +3VLP goes to PR111 (may be fitted with a jumper trace instead), and it becomes +CHGRTC (RTC voltage with charger plugged in)
-+CHGRTC goes from pin 2 to pin 1 of D23 (+RTCBATT), then it goes 2 ways:
-+RTCBATT goes to PR113 and PR112 (2x 560R in series) to charge the ML1220 battery (PBJ101)
-+RTCBATT goes from pin 1 to pin 3 of D23, then it becomes +RTCVCC (to system)

At pin 2 of D23, with charger connected you should get +3V, charger unplugged 0v (green line on the attached pictures)

Pin 1 of D23 (red line), you should get voltage from the RTC battery
Pin 3 of D23 (purple), you should get voltage from the RTC battery (minus diode drop), with charger unplugged
Also check continuity from the - terminal of the battery to GND (marked with black line), you can use the screw hole as GND for measurement

Don't connect the ML1220 battery directly to the + of the CR2032 pads, instead it should go to PR112 (yellow line on the pictures)
The trace marked with "Maybe?" in yellow near those 2 resistors on the attached pictures, is where i think the + of the battery should go, please measure voltage there with charged plugged in, and RTC battery not installed (should give around 3v minus the diode voltage drop)

Also, you can scratch a bit of the solder mask on the trace marked in yellow near the battery, and measure continuity from there to PR112 (the other part I marked with yellow, near 2 resistors), if i'm right should measure 0 ohm

The circuit may be modified to use a regular CR2032 battery, by removing D23, and installing D32 and R446 instead, I also marked the possible location of R446 on the pictures

Hope I explained well

EDIT:
Quote:
Originally Posted by ReplayGem View Post
Should I just try soldering the original battery to the board as suggested earlier; will it cause any issues with the board and will it charge?

Thanks.
Not a good idea, may damage the battery by overcharging it
From there it should go to PR113 and PR112 (2x560R), as explained before
Attached Images
File Type: jpg Acer E5 Pic2 RTC.jpg (265.9 KB, 11 views)
File Type: png acer e5 RTC battery sch.png (37.4 KB, 13 views)

Last edited by m1ch43lzm; 06-16-2021 at 07:56 PM..
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Old 06-17-2021, 01:59 AM   #15
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Default Re: Acer E5-571 RTC battery - alternate solder point

Personally, I have solved problems like this by taking CR2032 battery holder from scrap board, solder it on the damaged motherboard and just install new CR2032 battery. The board has the option to manage it like that. Very simple problem and easy solution.
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Old 06-17-2021, 09:37 AM   #16
ReplayGem
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Default Re: Acer E5-571 RTC battery - alternate solder point

I followed m1ch43lzm suggestions and ended up soldering the battery as shown, and the settings are now being saved. Using what m1ch43lzm suggested I couldn't understand why I was getting a voltage at the yellow line close to the resistors but not where I had originally soldered the + end of the battery so I scrapped a little more and got a voltage. Not sure if there was a break along the line somewhere but now with the battery soldered, I get a voltage (about 2.67v) to D23.
DanielDacko, your solution is interesting but I am curious about something, when the board is powered from the adapter, i get a 3v reading to the + side of the space; would that damage a 2032 battery?

Thanks everyone for your input, there is still soooo much I have to learn.
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File Type: jpg Acwe E5 - 20210617_100151.jpg (207.3 KB, 12 views)
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