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The Vallon VMH3CS, and no doubt other detectors, use boost regulators successfully to increase and regulate low battery voltages to higher voltages required by the detector circuit. I, for one, would like to use these readily available and low cost modules, together with high capacity Li-ion batteries to power any future PI detector designs.
This looks like it could develop into a discussion and design topic outside of the Vallon thread; hence this new thread.
Still on a learning curve, one question that I am pondering at the moment is whether there is any advantage (or disadvantage) in using a single high capacity pack of three) paralleled cells i.e. 3.7V at 7800mAh as against 11.1V 2600mAh series connected cells. The MT3608 converter output is adjusted to give 15V output with a detector load of 200mA. The published input voltage range is 2 - 28V
It appeared to me that the conducted noise level, viewed on a scope at the output, was higher when running at 3.7V input. Would this be expected?
One thing I learned yesterday is that series connected cells need battery protection circuits. I inadvertently left a detector switched on and while away the batteries died, or at least one of the two did. They were obviously not equally charged with one cell still reading 2V and the other 0V. The MT3608 will continue running to 2V with the other cell dead and SC. All attempts to wake up the dead cell have failed. The other is OK although running it down to 2V is 0.5V too low. Parallel cells equalise themselves presumably, so at the end voltage of battery life, all cell voltages are the same if you disconnect them. I plan on using protected batteries for forthcoming experiments and suitable candidates are Ansmann 3.7V 7800mAh or 11.1V 2600mAh battery packs. Both are three cells and available from RS Components. The interesting thing is that the 3.7V pack is very much cheaper, which takes me back to my question - which to use.
Eric.
This looks like it could develop into a discussion and design topic outside of the Vallon thread; hence this new thread.
Still on a learning curve, one question that I am pondering at the moment is whether there is any advantage (or disadvantage) in using a single high capacity pack of three) paralleled cells i.e. 3.7V at 7800mAh as against 11.1V 2600mAh series connected cells. The MT3608 converter output is adjusted to give 15V output with a detector load of 200mA. The published input voltage range is 2 - 28V
It appeared to me that the conducted noise level, viewed on a scope at the output, was higher when running at 3.7V input. Would this be expected?
One thing I learned yesterday is that series connected cells need battery protection circuits. I inadvertently left a detector switched on and while away the batteries died, or at least one of the two did. They were obviously not equally charged with one cell still reading 2V and the other 0V. The MT3608 will continue running to 2V with the other cell dead and SC. All attempts to wake up the dead cell have failed. The other is OK although running it down to 2V is 0.5V too low. Parallel cells equalise themselves presumably, so at the end voltage of battery life, all cell voltages are the same if you disconnect them. I plan on using protected batteries for forthcoming experiments and suitable candidates are Ansmann 3.7V 7800mAh or 11.1V 2600mAh battery packs. Both are three cells and available from RS Components. The interesting thing is that the 3.7V pack is very much cheaper, which takes me back to my question - which to use.
Eric.
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