LiFePO4 solar charger shield

jvoermans / Vibration_Logger

Logger to measure sea ice vibrations

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LiFePO4 solar charger shield #28

Closed jerabaul29 closed 3 years ago

jerabaul29 commented 3 years ago

@jvoermans would you be able to test the LiFePO4 solar charger shield? As there is really quite a lot of electronics on this box, I wonder if you should use the largest solar panel available:

https://www.adafruit.com/product/2747

Should check that:

it effectively chargers (i.e. measure intensity delivered to the battery)
it does not overcharge

Anything more you can think about?

jvoermans commented 3 years ago

I think that is it.

Sorry how do I measure intensity? I initially though just measuring the battery voltage continuously, see if it increases to 3.5/3.6V and then stops?

jerabaul29 commented 3 years ago

No worries. You should use 2 multimeters at the same time: 1 in series to measure intensity, 1 in parallel to measure voltage. Yes, that should be it more or less for the voltage: check that it rises until the specified maximum and then stops increasing.

Regarding intensity, I think you should try with one of the big solar panels, put it right under the sun, and check that for a relatively non full battery (for example, anything under 3.35 V or something like this, so that the battery has a level of charge "low enough" that it will take in all the amps you throw at it), the charging power is a full several Amps as specified by the solar panel (you can calculate the typical max number of amps as the datasheet max power / the voltage of the battery). Does that make sense?

jvoermans commented 3 years ago

Ok I think I get it, thanks for the details! Luckily it is getting more sunny each day now here ;)

jerabaul29 commented 3 years ago

😊👌👍☀️ Enjoy summer time!

jvoermans commented 3 years ago

Solar panel charges the battery and current becomes zero after about 3.4V is reached.

I have problems though in making the shield work with the Arduino. The load pins give the correct voltage but I don't think they provide current. I attached a Due to it, but it won't start. If I attach the Due to the battery directly, it starts as we would expect. I tried a second shield, just adding a 10K resistor at the thermistor terminal and a 120K resistor at the MPP spot. Again, there is 3.3-3.4V at the load terminal, but not starting the arduino. I've send a message to the shield developer...

jerabaul29 commented 3 years ago

Mmh, ok, strange. Will be curious what he answers. We're you able to measure how much current the shield provided?

jvoermans commented 3 years ago

Ok my mistake. Apparently there was something with the settings of my multimeter. Everything seems good now :)

jerabaul29 commented 3 years ago

Good that it works now :)