Hello, I am trying to charge a lipo battery. My battery is able to charge at up to 500ma, but it currently is only drawing 0.02A (20ma). Any ideas or solutions will be much appreciated. Thanks for your time.
You might have a problem with the unidentified battery, the unidentified charger, the circuit, the power supply, or the method of current measurement.
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Yes, it is almost charged, hence low current
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@TomGeorge, my battery is 500mAh and am using a 4.2 voltage regulator with 500mAh current output.
@killzone_kid, my battery is at 3.6v, I don't think it's almost charged.
Hi,
Can you please post an image(s) of your setup.
A circuit diagram will be helpful too, just a hand drawn schematic with component labels and pin names will ge good.
What is your power supply for the regulator?
Tom... 
No, that regulator is 1000mA max output.
Can your battery handle that safely ?
It would be a much better (and far safer) idea to charge the battery with a device that is actually designed to be a battery charger ............
What does it mean? Could you post your set up and diagram with all the measure instruments?
My battery has a protection circuit on it, so I think it should be fine.
I tried is the STC4054GR, but it's not working right. When it's connected up just like the schematic on the datasheet, it is outputting 2.5v - 2.9v. It is supposed to output 4.2v with 800mA max (the 800mA can be adjusted with a resister, I used a 2k for 500mA).
My battery voltage when I measured it is 3.6v, that is probably like 50% charge capacity.
Its outputting 2.5V with a battery connected, sounds like the battery is flat ?
No, it's outputting 2.5v without a battery connected. Is it normal for it to be at that voltage without a battery connected, then when a battery is connected it goes to 4.2v?
Lipo chargers are constant current in the first phase. Checking the voltage with nothing connected is pointless.
If the battery voltage is at 4.2V then it's fully charged or very close i.e. it's moved to the constant voltage phase, which explains why there's almost no current going into it.
Steve
My battery is at 3.6v, still 0.6v away from 4.2v and very little current is going into it. It should still be in the "constant current phase" at 3.6v, right?
If the battery is fully charged, then yes.
What happened when you connected a partially charged battery ?
Then it is broken. Data sheet says 4.2v
Hi, @JeremyOne
PLEASE post a circuit diagram of your project?
PLEASE post a image(s) of you project?
PLEASE show your power supply, the regulator and the battery.
What is the power supply you are charging from?
Thanks.. Tom...
Fixed!!! Connecting the 4.2v voltage regulator to 5v on the Arduino Uno charges the battery at 4.2v 400mAh. I was trying to turn on and off the charger with the digital IO pin, perhaps I should try to turn on and off the 5v going to the 4.2v voltage regulator with a MOSFET so I can control charging.
This is what I was trying to do before with the digital IO pin:
This is what I am doing now:
Sorry for wasting your guys time...
well you are lucky Arduino has many pins so once you burn one you can switch to the next and then the next… you are exceeding pin current at least 10x
Edit just noticed second picture, much better, no wonder it didn’t work
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I have one more question, I want to use a MOSFET to turn the charger on and off, but the battery is now only drawing 0.15mA. This is the MOSFET I'm using. Here is the schematic:
Thanks.
If you want to turn of charging because you think you are going to damage battery by overcharging it, you won’t, charged battery takes minimal current and your circuit cannot exceed 4.2v so cant overcharge