Timeline for Limiting battery input current to avoid voltage drop when activating LoRa radio
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Sep 15, 2020 at 19:05 | comment | added | Criticizing Israel not allowed | @AlexC Then use a bigger supercap. Also measure the voltage across the supercap and see whether it finishes recharging up to the battery voltage. If it doesn't finish charging before it starts discharging again, then you need a bigger battery. If it does, but it still drops too far, then you need a bigger supercap. | |
| Sep 15, 2020 at 19:05 | comment | added | Chris Stratton | @AlexC when a battery fails high-impedance, energy would be mostly pulled from the capacitor, not the battery. In reality you're probably draining the capacitor, which is why I suggested observing the capacitor voltage with a scope during the long transmit operation. If you really wanted to, you could rig up something with a silicon power switch (or even on the bench, a relay) to disconnect the battery and attempt the transmission entirely on the capacitor; you'll probably find you didn't store enough energy. | |
| Sep 15, 2020 at 18:58 | comment | added | Kevin White | @AlexC - "it should take it from the supercap in priority" - how would that help? If both sources together can't power the transmitter, using only the capacitor would be even worse. Putting the capacitor before the converter would allow more of the energy in the capacitor to be extracted. | |
| Sep 15, 2020 at 18:55 | comment | added | Alex C | The point is not to get energy out of nowhere. The point is to reduce peak demand from the battery and place it on the supercap. The problem is that when it is transmitting, it drains both the supercap and the battery, when it should take it from the supercap in priority. | |
| Sep 15, 2020 at 18:21 | comment | added | Chris Stratton | @AlexC then thermodynamics is against you; there is no "free energy". Your only option is to find a power source which can deliver the needed power for the desired radio output power, or get the capacitor idea to actually work. Try watching the capacitor voltage with a scope during an actual transmit attempt. | |
| Sep 15, 2020 at 18:21 | history | edited | Chris Stratton | CC BY-SA 4.0 |
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| Sep 15, 2020 at 18:20 | comment | added | Alex C | Using a lower transmit power is not an option. We absolutely need the maximum power output for our application. | |
| Sep 15, 2020 at 18:19 | history | answered | Chris Stratton | CC BY-SA 4.0 |