0

You can see in my crumby schematic that I am using a Non-latching relay to turn on a 3A circuit (one of them arc lighters), which is powered by a 25C (supposedly) lipo battery. That same battery also powers an Arduino through a TP4056. This works fine when I first turn it all on, but once the relay is activated by the Arduino, the lighter + Relay only turn on for a split second before stopping (when the Arduino is powered via USB, it works fine). I am thinking that the Arduino+Relay+Lighter is too much for the battery, even though it claims to be 25C. It is just strange because the Arduino+Activated Relay consume what, like 200 mA?

Notes: When I manually turn on the lighter, the light on the Arduino dims a fair bit, but stays on. The Arduino is running at logic level of 3.3V so that I didn't need a booster. enter image description here As for fixes, I was thinking about trying to use a transistor or SSR instead of the chunky relay I have now (which would be good, I need this to be compact). Or maybe the TP4056 is failing to provide enough output despite a decent input?

I am FAR from an electrical engineer so if anyone has any pro tips for improving this it would be much appreciated.

Improve this question
3
  • what is the voltage output of the battery when the lighter is energized?
    – jsotola
    Commented Aug 3, 2020 at 3:08
  • When you put power to the LED lighters the current is high for a short time. You can't compare this value to the continuous current that you can detect with a multimeter. The best way is to use another power supply for the Arduino. The relais I used hat two different circuits: logic and power.
    – harper
    Commented Aug 3, 2020 at 6:41
  • 1
    The TP4056 is a battery charger not a power supply.
    – Majenko
    Commented Aug 3, 2020 at 7:15

1 Answer 1

Reset to default
1

The TP4056 is a battery charger, not a voltage regulator. It cannot be used to supply power to a device like an Arduino. It is designed for charging the Lithium Ion battery from a 5V (e.g., USB) source.

By trying to use it as a power supply you're asking for trouble. It thinks it's trying to charge a battery (from a 3.7V nominal source) and will be doing things like:

  • Running constant current making the voltage fluctuate wildly as current demands change
  • Running constant voltage with limited current causing starving of power
  • Shutting off when it thinks it sees the non-existent battery being fully charged.

The TP4056 should be connected to a 5V USB power source and to the battery for charging it. The battery should be then through a (very) low-dropout regulator (ideally a switching regulator with zero dropout bypass ability) to power the Arduino at 3.3V.

Alternatively, if you don't need a (reasonably) precise 3.3V then you can power the Arduino directly from the battery.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.