monitoring solar power module's li-ion battery

Hi

I am testing out Libelium's solar power module for Arduino: http://www.sensor-networks.org/index.php?page=0828028040

I need to monitor the li-ion battery and take action when it reaches the low-voltage threshold. Two problems + associated questions:

a.) the battery manufacturer does not state what the low-voltage threshold is on their data sheet. Is there a standard way for calculating this?

b.) the board converts the battery's 3.7V to 5V, meaning that what is coming off the board is not a true reflection of the battery's current voltage. Is the best approach monitor the battery voltage before it enters the board to get a 'true' reading, or is there some way to use what is coming off the board?

thanks in advance

Is there a standard way for calculating this?

No you will have to measure it. The criteria is when it can no longer supply the 5V to the arduino.

Is the best approach monitor the battery voltage before it enters the board to get a 'true' reading

Yes this is the best approach. Measuring the output voltage will not be as informative as it will tend to hold up as the battery discharges and then drop rapidly.

Thanks for the advice Grumpy Mike. I’ll give it a go and report any issues.