Optimizing Battery Life and Signal Strength with Buck/Boost DC-DC Regulators

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    Battery Voltage
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Discussion Overview

The discussion revolves around the relationship between battery voltage and signal strength in transmitting devices, particularly focusing on the use of buck and boost DC-DC regulators to optimize performance. Participants explore how battery depletion affects signal output and the implications of using different regulator types.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the relationship between battery voltage and signal strength, suggesting that as battery power decreases, signal strength also diminishes.
  • Another participant notes that the transmit amplifier typically operates directly off the battery voltage, indicating that a drop in battery voltage leads to a comparable drop in output voltage swing to the antenna.
  • It is mentioned that the output of many Received Signal Strength Indicators (RSSIs) may be proportional to the logarithm of the input, raising questions about the relationship between RSSI and battery voltage.
  • A participant proposes that using a buck-mode switching DC-DC regulator can maintain constant received signal strength despite battery voltage changes, extending the operational time of the device.
  • Another participant suggests that employing a buck/boost DC-DC regulator could further enhance battery life and signal range, particularly in applications using standard battery configurations.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between battery voltage and signal strength, with some proposing that the use of specific DC-DC regulators can mitigate the effects of battery depletion on signal output. The discussion remains unresolved regarding the exact nature of these relationships.

Contextual Notes

There are assumptions regarding the operational characteristics of transmitters and the specific configurations of DC-DC regulators that are not fully explored. The discussion also lacks definitive sources to support claims about the logarithmic relationship of RSSI to battery voltage.

Who May Find This Useful

This discussion may be of interest to engineers and hobbyists working on battery-powered communication devices, particularly those looking to optimize signal strength and battery life through circuit design.

safdar
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Hi guys!
What is the link between the signal strength and the battery voltage?
Now I explain it in the following:
Consider a sending device that sends signals for example an anchor node. It sends signals of particular strength and it uses its battery power. As the time goes on and the battery becomes weaker and weaker the signal strength shall also be decreased. So what is the relationship between the signal strength and the voltage of the battery?
 
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safdar said:
Hi guys!
What is the link between the signal strength and the battery voltage?
Now I explain it in the following:
Consider a sending device that sends signals for example an anchor node. It sends signals of particular strength and it uses its battery power. As the time goes on and the battery becomes weaker and weaker the signal strength shall also be decreased. So what is the relationship between the signal strength and the voltage of the battery?

It depends on the situation, but usually the transmit amp will run directly off of the battery voltage to get max possible output voltage swing to the antenna. The output amp will be able to drive the antenna input voltage close to the rails (Vbatt and GND), but not quite. So as the battery voltage droops, the output voltage swing will droop by a comparable amount.
 
Also, on many RSSIs, the output can be proportional to the log of the input.
 
what said:
Also, on many RSSIs, the output can be proportional to the log of the input.

Does it mean, RSSI is directly proportional to the logrithm of battery voltage?
Any source that can provide further information?
 
If a buck-mode switching dc-dc regulator is used to reduce the battery voltage to a constant voltage for the transmitter, the received signal strength will remain constant, independent of battery voltage, for a longer time.
Bob S
 
Bob S said:
If a buck-mode switching dc-dc regulator is used to reduce the battery voltage to a constant voltage for the transmitter, the received signal strength will remain constant, independent of battery voltage, for a longer time.
Bob S

Good point Bob. And for even more battery life/range, use a buck/boost (National Semi calls it Sepic) DC-DC. That's pretty common in many 2xAA battery applications, IIRC.
 
Last edited:

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