Eflite 120mAh test done!

So a few days ago, the Jeenode stopped sending data. The beginning of this test can be found in this post. It stopped after sending 15,200 data points. That is pretty amazing.

It lasted from 2011-06-15 3:11 PM to 2011-06-26 2:59 PM. Just under 11 days on 120mAh LiPo.It shouldn’t take much solar juice to keep that small battery charged up, but now I know I get > 1 week on a full charge without adding any energy to the battery. That should cover some dark days….

Here is a graph of the entire time period:

You can see the battery held fairly linear until the end, the dropped off quickly. Final battery voltage when it stopped: 3.461V. Which is less than I expected as it should be something like 4V if the datasheet for the LDO regulator is right (or I’m reading it right). The datasheet says it should be the output + dropout, in this case 3.3V + 750mV or around 4.050V.

I tried to charge the LiPo back up using the Ladyada charger, but it wouldn’t take the charge since the Jeenode was trying to pull from the battery at the same time as the USB was trying to charge the LiPo. Got some really bouncy voltages. More investigation required here. I’m put together a circuit board which has the MOSFET/Diode that is in the reference circuit, but left off this charger. When I get that built we can see if it solves this issue.

EDIT

Here is a bit of the schematic to answer the below comment.

Just a simple voltage divider to get the voltage from the Lipo (~4.2V) to something less than 3.3V. Since the resistors are the same value, I’m just halving the voltage.

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