RTK Express Kit / Battery Overcharging

GPS/GNSS Enclosed Products
1

Hi!

I just received my SparkFun RTK Express Kit and am really enjoying it. I have permanently mounted it and it’s always plugged in. I am using rfc2217 to telnet to the serial ports on it remotely. I can see that the battery is complaining and wondered if I should remove it to be safe.

Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
NTRIP Server 0 state: NTRIP_SERVER_CASTING
NTRIP Server 1 state: NTRIP_SERVER_CASTING
2024-10-22 16:14:19.653
    Tx0 RTCM: 2024-10-22 16:14:19.653, 7880 bytes sent
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
NTRIP Server 0 state: NTRIP_SERVER_CASTING
NTRIP Server 1 state: NTRIP_SERVER_CASTING
2024-10-22 16:14:34.633
    Tx0 RTCM: 2024-10-22 16:14:34.634, 7870 bytes sent
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
Batt (119%): Voltage: 4.34V Charging: 0.00%/hr No batt
2024-10-22 16:14:50.219
    Tx0 RTCM: 2024-10-22 16:14:50.219, 8422 bytes sent
NTRIP Server 0 state: NTRIP_SERVER_CASTING
NTRIP Server 1 state: NTRIP_SERVER_CASTING

It does discharge and charge but also ends up too full I believe. 4.34 is too much right? Should I remove the battery for safety or will it be okay? It would be nice to have the battery backup when necessary but I guess I could do without it. Do you think this is just a mis-read by the fuel gauge?

2

You are welcome to remove it. That’s what I did with my remote permanent install. If the power goes out, so does the base station, but it ensures a good boot when the power comes back.

I need to go digging in the code, but the system is saying ‘No batt’ because it believes no battery is attached. This is what’s seen when, well, no battery is attached. So something is indeed wrong. Perhaps there is a cold solder joint on the SMD JST connector.

I recommend pulling the batt if you don’t need it.

3

Can you remove the Li-Po and check the Voltage manually ?

While not impossible, it’s uncommon for a PMIC or Fuel Gauge to fail.

I’m guessing here - but it’s more likely that the Li-Po’s internal protection circuit has activated, disconnecting it, and you’re seeing the Open Circuit voltage of the PMIC output.

What temperature range is the RTK Express experiencing ?

4

Yep Ill pull it apart later today. It does go between saying No Batt and then normal status messages. Like said earlier - maybe a cold solder joint. I’ll check that first before just removing it completely.

2 Likes