Postcard RTK - Battery won’t charge to 100%

GPS/GNSS
1

Postcard RTK - Battery won’t charge to 100%

Hi everyone. After all the testing with PPP-HAS, I started having issues with the battery charge.
I have a Postcard and a Portability Shield with a 5000 mAh Lipo battery.
It was working fine and charged very well until two days ago. When I turned off the charging light, it remained at 101% and 4.21 volts, according to the information.
Now it charges very slowly and reaches 4.2 volts, says 58%, and the charging LED turns off.
What could it be?
Poor quality Chinese battery? Fault in the charging system?
I appreciate any ideas.
Regards
Angel

2

4.2V is the charge termination voltage, so the battery is fully charged. Most PMIC’s need a few cycles before the SOC (% charged) becomes accurate. The PMIC doesn’t know that you’ve installed a 5Ah li-po.

I can’t promise this is what’s happening for you, but it’s not uncommon for PMICs.

3

If you have a USB power meter, check if charging current actually drops to near zero when LED goes off. If it cuts early (e.g., still plenty of current flowing at ~4.1 V), then the charging circuit might be faulty.

4

Yea, I agree with rftop - 4.2 = 100%. The fuel gauge IC is just confused. I believe it will auto-correct if you run it down a few times.

5

The strange thing is that the battery already has 7 or 8 complete cycles and until the day before yesterday it was indicating 4.2 V and 100% correct.

Do you advise me to use it completely and recharge it a couple of times?

6

I don’t have a formal method to change the fuel cell profile. Personally, I would just use it knowing that you’ll get many hours of run time because the battery is full, and generally ignore the reported level knowing that it’s artificially low.

7

Go ahead, thanks.
I’ll test the lifespan under these conditions and let you know.
Regards
Angel

8

Hi everyone.
Update on the situation.
I charged the battery several times, and it still showed 4.2 volts and 58%.
And the yellow charging LED kept going off.
The battery life was still very good, lasting almost a full day.
So I left it on until it shut off due to low battery and charged it again.
It took a long time to charge the 5000 mAh battery, but it returned to the correct values: 4.2 volts and 100%.
We’ll see if it stays that way.
Regards
Angel

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