GPS Modul Backup Battery load

[Nicolai]

Hello,
I have two GPS modules, as shown in the picture (I got this picture from the forum). The batteries each have 1.5 volts. My idea is to charge them to see if they're still OK or if they need to be replaced. The module's voltage is 5V. You could take a standard USB charger from a cell phone, remove a plug from the cable, solder it to a suitable socket, and connect it to the module, thus charging it externally and not in the Typhoon H. Has anyone tried this before?

 

[h-elsner]

This will work.

 

[Nicolai]

Then I'll test it

 

[Nicolai]

I tested the external charging of the batteries of the 2 GPS modules, before charging the batteries had 1.5V. After 10 hours of charging the voltage was 2.7V. After a 10 hour break 2.5V. Charged again for 6 hours again 2.7V.
After 3 days the voltage had fallen back to 1.5V. I charged yesterday for 9 hours, then the voltage was back to 2.7V, today it was 2.5V.
I assume that the voltage will continue to fall in the next few days and that the batteries will need to be replaced, as they probably won't hold the voltage before you build one of the GPS modules into a copter. There is a red LED on the GPS module that started flashing after 1 minute 20 seconds after the module was connected to the 5V. Does anyone know what this LED shows?

 

[h-elsner]

The LED on the GPS Module is called PPS-LED. PPS means pulse-per-second. It indicates that the GPS chip has synchronized clock. You can use it as very precise clock signal.
PPS LED not bright when GPS not fixed, flashing when fixed.