I have a setup of a 3.7V LiPo charged by a LiPo charger from a solar cell. The setup works fine and charges the battery up to 3.62V. To power my Arduino I would need to boost it to 5V and I have a booster (0.9V-5V) which works fine and outputs about 5.11V from my 3.7V LiPo.
My issue is that when testing my battery-charger-booster setup, I noticed that the battery would basically lose all its charge at night, without being connected to anything. Its a 800mAH battery but nothing was drawing power from it. Well, nothing except the booster. After removing the booster I noticed the battery held on to its charged perfectly.
I want to run my Arduino UNO from this LiPo and monitor the battery voltage. But if the battery is drained by the booster, it wont be much of a project, will it?
I do have another 3.7V & 4000mAH battery. I would still need the booster. So I want to set up a way to measure its SOC as it powers an arduino with nothing else. I recently posted about how to monitor a 7.4V LiPo as it powers an arduino and I learned alot about voltage dividers. Now that Im using a 3.7V I wont need a divider. So can I monitor the LiPo & power the Arduino like this:
3.62V is barely charged. 4.1V or 4.2V is charged. Can you get it higher during the day?
So for a 3.7V battery, 3.7V is barely charged?
Ok I have 3 batteries as follows. Ive marked on them their voltage as of today:
So Im guessing the 3.62V is probably missing some charge and the other 2 are fine.
A/ So with any of these I would still need to use the 0.9-5V booster to have it power the Arduino board, right?
B/ And would the diagram from post #0 be the correct way of monitoring the battery as it powers the board itself?
C/ Finally, I should really use the 4000 mAH because the 800 would be a waste of time seeing as how the board itself uses about 45mA, which means that it would draw more than 900mAH in a 20 hr day.
what is the rating of your solar cell in full sunlight?
the rating of your battery will dictate how long your arduino will last but can the solar cell recharge it with available light
Well the panel states 6V but today I clocked it at 5V. It was sunlight at a normal angle but it was 20 minutes before sunset.
I'll measure it again tomorrow morning.
the voltage is not that material, its the AMP HOUR ratings that count.
If your arduino uses 45 mah then for each 24 hours you need storage for 0.9 mah hours of battery storage.
Your solar cell has to be big enough to recharge your battery when there is light available.
The Arduino consumes 45ma. This is 45 x 24 = 1,080 mAh. The battery stores 4,000 mAh.
Marciokoko:
The Arduino consumes 45ma. This is 45 x 24 = 1,080 mAh. The battery stores 4,000 mAh.
OK how much does the solar cell generate when there is light.
sorry for the sums eerror
That's what I'll measure tomorrow 
But is my wiring diagram right for monitoring battery soc?
