Hi everyone,
I need to ask for some help. I am a computer science Ph.D. student using an Arduino system to build a tangible user interface. I am by no means an expert and am really here to humbly ask for assistance.
I am busy with the power distribution. I have watched hours of tutorials and ended up building a rechargeable power bank using a LiON battery and the TP4056 USB-C charging unit. I next added an XL6009 buck-boost board and this is where things got a little weird. All the tutorials wire the out + to the in the + on the XL6009 board. I cannot do that, it fries the MOSFET in the USB charging unit. I have had to invert the wires... then it works fine?
I am really confused as to why that happens. I have attached a diagram of what I have working so far. There are likely a lot of things here that can be better and fixed. Any and all advice is welcome. I am mainly worried about swapping over the + and - wires from the USB C charging module to the XL6009 buck-boost converter.
Can you provide links to the charger module and XL6009 module you are using? It's a bit confusing because the datasheet for the XL6009 says the minimum input voltage is 5V, which the TP4056 could not provide.
That depends on how you intent to use it. The TP4056 does not allow for load-sharing !! Do not power the charger, with the battery connected and at the same time draw current from the system.
Also the unit that you have has it's charging current set at 1A, (by means of resistor R3 on your board) , what size battery do you intend to use ? And well, the input voltage isn't enough.
Ah I see what you mean, can you recommend a different board to convert voltages? (3v, 5v and 12v). This project is a smart activity quilt that uses a lot of sensors in order to help mom's in Africa with early childhood development for children. I am using a lot of touch, knock , and tilt sensors, some gyroscopes and magnetic sensors , a voice recorder and a speaker. The Arduino makes the quilt fully interactive and sends the sensor data to thingspeak for analysis. I am also using the ESP8266 Wifi module to create a wlan that sends stats on how the kids are progressing through activities to a mobile app for the moms. I need to power all of this, and make sure it can be charged since my research community is in rural South Africa where electricity is not always a given. Thank you again for your help !
Here is an example of what one piece of the quilt might look like. The electronics components is encased in a waterproof component , all the wires are covered in shrink , I have a hard shut off as well as a moisture sensor that will shut down the quilt if anything feels damp.
well yes in that case you are fine, still make sure No load sharing through the TP4056 !!
If you charge the battery while draining current from the system, the TP4056 won't be able to determine when the battery is full, and it won't stop charging even if it is full, which may cause your battery to eh.. Explode, now we don't want that. And you still haven't given indication of the size of the battery ?
With size i mean the actual capacity, which is defined in AmpHour, so for the 1st that is 2.6 Ah and for the 2nd 3.35Ah. Both are fine to charge with the maximum 1A that the TP4056 unit provides. You could increase the charging current without issue, but the TP4056 has a 1A maximum.
Standard charging time for a LiPo is the current that is required to fully charge the battery in 1 Hour, but as far as i know it is safe to double that (charging the battery in half an hour)
So the charging is safe, and as long as you can ensure that the circuit does not draw any current during the charging process, all is good. If you do want to use the circuit while it is plugged in you need to devise a 'load-sharing circuit, the simplest solution 2 diodes, but the voltage-drop may drop the battery voltage out of the range for the buck-booster's input voltage. There is a method that you could use that uses mosfets, but that is a little more complex. The simplest is not to use the circuit while it is plugged in,
Thank you so much for your reply! Based on your reply, can I ask another potentially not-so-enlightened question? I currently have a slide switch between the battery and the TP4056 and nothing between the TP4056 and the XL6009. Would it be better to add the on of the switch between the TP4056 and the XL6009 to ensure that there is no current being pulled while charging happens?
Yes !! this is required. In fact there should always be a switch between them, and the switch between the battery and the TP4056 is obsolete. The TP4056 does not draw current from the battery, but the buck converter (and whatever is beyond it) does.
