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 Battery charging issue
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small4

Yugoslavia
7 Posts

Posted - 11/07/2022 :  14:40:38  Show Profile  Reply with Quote
Hi guys.

I have GMC-500+ and EMF-390 devices bought 2 years ago. Both of them act the same when it comes to battery charge:
- battery status is moving all time and never getting fully charged
- besides the visual graphics battery status being weird, the battery is not really charged more than let's say 30-40%, even if it stays on the charger for a lot of hours(6-7h)
- I used a phone charger(Samsung 2A), and maybe rarely sometimes computer USB port as a charger, but it seems like there is no difference
- I bought new batteries since I thought those broke, but it acts the same and the old batteries were fine
- I have an external charger, and when all those batteries are charged with it, everything is fine, but I wouldn't like to get outside&inside batteries all the time

Is anyone experiencing the same or similar issue with charging? Am I missing something or doing wrong? Would a firmware upgrade help?

Any help would be great.

Thanks

new year is comming!
Reply #1

EmfDev

1782 Posts

Posted - 11/08/2022 :  16:13:27  Show Profile  Reply with Quote
Hi small4, if you have a multimeter, can you try to measure the voltage of the batteries?
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Reply #2

small4

Yugoslavia
7 Posts

Posted - 11/13/2022 :  09:50:53  Show Profile  Reply with Quote
Hi EmfDev, yes.

The batteries in both devices are now empty and I made some images.


The 2 images below show the reading of empty battery voltage.










Following 2 images below are about voltages when the devices are plugged-in a computer USB.










And the last 2 images show displays during charging. Check the image with EMG-390, 100% and 30-something% are switching every couple of seconds. And now, after 30 minutes of charging, the display is showing 100% battery and it seems that the charging stopped.








And the last image is the battery from EMG-390 voltage reading, after 30 minutes of charging. The device on plug&unplug a cable shows 100% battery.




new year is comming!

Edited by - small4 on 11/13/2022 09:52:08
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Reply #3

small4

Yugoslavia
7 Posts

Posted - 11/13/2022 :  13:56:48  Show Profile  Reply with Quote
Now, after 4h:45m of charging, both devices are showing the charging process in progress, ~80% and ~92%.

new year is comming!
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Reply #4

small4

Yugoslavia
7 Posts

Posted - 11/13/2022 :  15:45:03  Show Profile  Reply with Quote
After full 6 hours and a bit over, bot devices showed 100% battery. Then, the devices were unplugged and left for 10 minutes, for the batteries measurement.

EMF 390:
3.87v on multimeter
3.99v on the device screen
100% battery in the device menu

GMC 500+:
3.96v on multimeter
3.96v on the device screen
77% battery in the device menu

From the previous experience, those batteries seem not to be full. As those won't last close the same as when charged on an external charger.

new year is comming!
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Reply #5

ullix

Germany
839 Posts

Posted - 11/14/2022 :  00:35:23  Show Profile  Reply with Quote
Voltage alone is a poor indicator for battery status. I am using charging and discharging via an USB meter like this:
https://smile.amazon.de/Multimeter-Digitaler-Spannungspr%C3%BCfer-Amperemeter-Verbesserte/dp/B07THZFDGH/

When charging it tells you the total charge in Watt-hours that has gone into the battery.

For discharging I plug in an electronic ballast like this: https://smile.amazon.de/ANGEEK-Einstellbare-Konstantstrom-Elektronische-Lastentlader/dp/B07WP1FP82

The USB meter then tells you the total charge that has come from the battery. Works beautifully.

And to top it off I measure the course of the voltage via GeigerLog. An example is shown in the GeigerLog manual v1.4.1, chapter "Manu Devices" with Fig. 47.
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Reply #6

Damien68

France
708 Posts

Posted - 11/14/2022 :  01:30:07  Show Profile  Reply with Quote
Hi Small4,
the voltages you measure are a bit low, the agreements are:
a charged battery: between 4v1 and 4v2
a discharged battery: 2v8 (never unload below).
There are three points that come to mind:

1. do you connect the USB cable directly to a Samsung charger or directly to a USB port on a PC?
you should not go through a hub, some have a protection diode which causes 0.5-0.6v to be lost on the 5v.

2. maybe your cable is defective, some have very thin conductors which become resistive and cause losses. maybe you should try another cable.

3. Maybe you should wait longer and see what happens, even if the GMC says 100% it may still be charging the battery. the battery charging current must be around 500mA, to charge a 2.6Ah battery under these conditions it will therefore theoretically take 5 or 6 hours, but I am not sure of the charging current it may be lower. also to have a fully charged battery, you could try while waiting for 10 hours for example and disregard the 100% charge indication which apparently is very approximate.

Mastery is acquired by studying, with it everything becomes simple

Edited by - Damien68 on 11/14/2022 04:02:34
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Reply #7

Timothy Love

USA
4 Posts

Posted - 11/15/2022 :  00:52:56  Show Profile  Reply with Quote
I have also faced almost similar issue#65292;but generally a new one will be fine.
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Reply #8

small4

Yugoslavia
7 Posts

Posted - 11/15/2022 :  13:39:22  Show Profile  Reply with Quote
Hi guys and thanks for your replays.

@Damien68
1 .During the last charging, when I did the pics, Samsung external battery was used. But, it is the same behavior on a charger or a computer USB port.
2. I have two original cables for the devices, both look fine and act the same. I can't say those cables are 100% fine, but I suppose. I don't have others to compare.
3. Yes, I see your point. But, charging of the same batteries on a 4eur external charger works perfectly, so I doubt that keeping the batteries longer on a charger will reach the missing 30%.

@ullix
Right, I was looking to get some of those handy USB current meters, it would be good to see the current when the devices show 100%. I might the thingies.

@Timothy Love
Oh, then it seems we got the weaker ones.

@EmfDev
I suspect the charging controllers are not so good on the devices. Do you have any advice? Would a firmware update help?

Regards.



new year is comming!
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Reply #9

Damien68

France
708 Posts

Posted - 11/16/2022 :  06:25:24  Show Profile  Reply with Quote
@small4
To know more, I quikly check my GMC-500+ (PCB version5.2). The battery charger controller IC is U8 marked "LTH7" while searching with google, I found that it's a "Analog-Devices/Linear Technology" LTC4054ES5-4.2 bellow his datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/405442xf.pdf

by checking on the PCB and with the specification on datasheet, the implementation of it is correcte and is configured with a RPROG (R36) of 2.7 Kohms, which according to the datasheet will limit the battery charging current to 370mA. this limitation was probably decided to keep the total current consumed by the GMC-500+ always below 500mA to remain compliant with basic USB standards.

the charge controller is completely autonomous and in no way depends on the measurements and indications made by the microcontroller who are apparently only sent back to the counter display and is may be used to make a shunt down in case of too low battery.

I checked the charging current on my counter with a half empty 3v62 battery, I measured 380mA it's a correct value.

a 4 euro charger can have a higher charging current but it only charges the battery, in the case of a GMC-500+ counter it must also supply the counter itself including the backlighting of the screen, the buzzer... (which justifies the limitation to 370mA to never drawing a current exceeding 500mA on the USB port). with a charger at 4 euros, we could therefore have a charging current of up to 500 mA or more, but if exceed 500mA it would no longer comply with USB standards but could be used powered by a Samsung 1A or 2A charger.

maybe there is a problem on your devices, but I think you should try while waiting longer. (10h or more)

Mastery is acquired by studying, with it everything becomes simple

Edited by - Damien68 on 11/16/2022 08:17:37
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Reply #10

small4

Yugoslavia
7 Posts

Posted - 11/18/2022 :  15:32:34  Show Profile  Reply with Quote
@Damien68
Wow :) Merci beaucoup for your investigation, conclusions, and advice.

Let me check the charging in a week and I'll share the results.



new year is comming!
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Reply #11

tumnahi232

1 Posts

Posted - 11/20/2022 :  21:33:31  Show Profile  Reply with Quote
Looks like the battery has a bad cell.

Do note that many of the newer models use an AGM battery instead of a lead acid battery and you should get a battery maintainer with an AGM mode. I believe many newer Mercedes recommend a minimum interval the vehicle should be driven to protect the battery.
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Reply #12

small4

Yugoslavia
7 Posts

Posted - 11/24/2022 :  14:47:00  Show Profile  Reply with Quote
@Damien68
Your finding showed to be right. I left both devices on charging for 10h30m. Both batteries(2600mAh and 3500mAh) showed 4.2v on the multimeter, after charging and taking a rest of a couple of hours.

It would be helpful for device owners to know how the battery readings and charging work.

Offtopic, I googled the account name from the post reply above and it is a spam bot. Interesting thing is that the post content was generated by an AI bot. It's some crappy AI bot since it couldn't get the proper context of the topic, but it shows what may happen to the web content in the very near future.

Thanks again and regards from Serbia.

new year is comming!
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