How to keep powersupply/step-up module citcuitry "awake"

Hello all. My next project is to power an arduino from solar with a li-ion battery.

So i have bought this little "5V Step-Up Power Module Lithium Battery Charging Protection Board Boost Converter LED Display USB For DIY Charger 134N3P"

I have attached an 18650 li-ion battery as the power supply.

Now, when connection the arduino uno the led on the step up module will light up and the arduino will power on and everything works.

However when i switch to the arduino nano nothing happens. It looks like the little nano is not pulling enough for the step-up module to recognize it has to deliver power. I have put a capacitor in between, this makes the nano led light up for a bit but then fade away and still nothing works.

Anybody got any idea how to get this thing to power the nano without to much trouble? The idea was to use the nano because it's small and doesn't use so much electricity, but the only idea i can come up with is to make the thing light up a led so it pulls enough to keep the step up module running, witch is waste of energy....

Read the number on the chip. Find the datasheet. Read the datasheet. Maybe the manufacturer though of your need.

Thank you for answering. I found this on the circuit board: t6845-c

If i google that i m able to find some pictures of it but no datasheet. Any suggestions what terms to use while searching for datasheets etc? This is the first time trying to dive into datasheets for me. :slight_smile:

Btw i found this:

Not sure if it is the right thing since searching for t6845-c in that document won't show any results

What is the output voltage of the step up module when the Nano is connected ?

What is the output voltage of the step up module when nothing is connected ?

@srnet

What is the output voltage of the step up module when nothing is connected ?
Nothing connected output is 3.5v (same as battery voltage)

What is the output voltage of the step up module when the Nano is connected ?
With arduino uno connected output is 5.08v

With arduino nano connected output is 5.08v, then after 3 seconds or so it drops for a fraction of a second below 4v and back to 5.08v rebooting the nano

So my first idea wat to put a big cap on the terminals to bridge that quarter of a second or so when the voltages drops down. However when the capacitor is in place the arduino won't boot up at all....

Bringamosa:
With arduino nano connected output is 5.08v, then after 3 seconds or so it drops for a fraction of a second below 4v and back to 5.08v rebooting the nano

So when this is happening, how much current is flowing into the nano ?

I will have a look tomorrow it is late in the evening now here, but not sure if my basic multimeter will be able to read those fast changes.

Those modules are made for powerbanks (the long slit is for a battery tab+).
Most powerbanks have an automatic shutdown when current drops below a certain value.

Nano on solar power?
Why don’t you run an 8Mhz Nano directly off the battery.
Leo…

It would help to see how you connected the two.
From your description the cap is connected wrong.

Did you connect the usb on the batteryboard to the usb on the nano?

What model is the board you have for the battery?

Daz

Wawa:
Those modules are made for powerbanks (the long slit is for a battery tab+).
Most powerbanks have an automatic shutdown when current drops below a certain value.

Nano on solar power?
Why don't you run an 8Mhz Nano directly off the battery.
Leo..

Yeah i read about powerbanks shutting down. Think this will be the case here sadly :frowning:

Yep on solar power. It will be installed on a difficult to reach place so not easy to change the battery. I know a barebone arduino will go for years on a battery but i won't be able to do that. I'll need a sonar module working and rf transmitter running to get the results back down.

Daz1712:
It would help to see how you connected the two.
From your description the cap is connected wrong.

Did you connect the usb on the batteryboard to the usb on the nano?

What model is the board you have for the battery?

Daz

The cap is installed right before the powerleads connect to the nano. So powerleads positive and negative -> cap -> nano. Polarity of the cap in the right way off course. This is connected to the VIN pin of the nano.

I did connect the usb from the board to the usb on the nano aswell als to the VIN on the nano.

For me it is hard to figure out what model that board is. what i can find on the circuit board is this:
T6845-C V1. and after the . it is unreadable.
20170511 A looks like manufactring date?

srnet:
So when this is happening, how much current is flowing into the nano ?

there is 15mA going true when it shuts down. The same with my regular powerbank but that one keeps running.

Looks like the SW2808S on the board you pictured is equivalent to the HOTCHIP HT4928S.
http://www.hotchip.com.cn/Uploads/goods/2017-11-03/59fc3d69cabf0.pdf

Unfortunately the datasheet is in Chinese, even on the “English” version of their website. Fortunately, some tables and illustrations are labeled in English. One table has a line that says “Iauto_off, BAT=3.6V Cout=20uF, mA, 60”. I think that means: ‘I’ (current) at which auto-off occurs, when the battery is at 3.6V and the capacitor across the output is 20 micro-Farads, is 60 mA. If you bring your current draw to over 60 mA you should prevent the power bank from turning off (until the battery drops to 2.95V).

johnwasser thank you for figuring that out. I'll try to meassure the power draw from the arduino uno and see if that is more than 60mA, if so, the problem is clear, just to figure out how to solve it then.

Any idea's for a constant 60mA draw? The solar panel provides more than 4 times that amount so would not be any problem i guess.

Bringamosa:
Any idea's for a constant 60mA draw? The solar panel provides more than 4 times that amount so would not be any problem i guess.

You can burn about 10mA in an LED. Add LEDs until your power supply stops shutting down. :slight_smile:

Was thinking about that too. Looks like my easiest solution.

Might attract all kinds of bugs during night :stuck_out_tongue: Maybe not the best combination with a water reservoir. Another option was using a little fan, might work as a vent for possible water vapors to minimize condensation (probably no condensation at all but hey) However this will have a lot of wear i guess from running fulltime.

I'll think about it a bit more.

What about a resistor?

If i put a 47ohm resistor on the load it pulls 90mah. So the thing will keep running.

However running this fulltime will make the resitor get very hot. There must be a way to run the power true on an interval using the arduino?

How about a 100 ohm resitor on one of the arduino pins? Make it go to high for 5 seconds and then back low for 5 seconds, avoiing heat?

Just measured, 5 volts on the 100 ohm resistor pulls about 47mah