Would this setup work?

I want to power my Electron with two parallel LiSOCl2-batteries on a PCB. As these batteries don’t really meet the voltage requirements of the Electron (3.0-3.6V, each with max. 2A current), I want to use a booster like this, which has a 2.0-5.0V input, and a 5V 2A output. I then want to connect this booster to the VIN pin.

If I read the documentation on it correctly, since it will deliver a steady 10W (5V, 2A) it should be able to power through the VIN pin. I guess I’d like to make sure however, since I’d be waiting quite some time for my components probably :slight_smile: Is there anything I need to be aware of?

Be aware of this, at 3v the boost converter will only supply 1A of current.

You also need a converter with extremely low idle current to prevent from continually draining your batteries.

Feeding your Electron 5v is less efficient than feeding it via the battery Li input. Sleep current is lower when powering via the Li input.

What’s the reason for needing 5v? A 5v sensor addon?

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Yeah, it’s for some 5V sensors…technically, they could be fed 3.3V but their performance is pretty bad at lower voltages. I want the setup that requires the least amount of additional components; preferably that would mean supplying 5.0V to the Electron, and outputting 5.0V to sensors.

I’ll look at a better converter, truth be told the one I linked is a really cheap unit… is it fine if the setup is capable of supplying more than 10W on the VIN (e.g. 5.0V and 3A)? I shouldn’t ever drawn such an amount though.

I know about the Li+ pin, but it only accepts up to 4.4VDC input, which means I have to use another converter in my setup to power my sensors… Powering by USB isn’t an option as due to space constraints the USB port is inaccessible on my Electron. The JST-port also only accepts up to 3.7VDC. So powering from the VIN is the only option for me if I don’t want to add extra converters in my setup I believe.

I guess in theory I could put my batteries in series for a 6.0V-7.2V supply and not require any additional components, but it does cut the capacity in half…

How much power does your 5v device consume?

All together, probably only around 100mA or so

Your probably better off with a 3 to 5v boost regulator that has a 200-500mA ouput range with really low stand by current like the 3v regulator your using with the batteries now. This way you will not be eating up your battery capacity while the regulator is not being used.

Some Boost regulators have Enable pins that you could use so the Electron only turns the 5v regulator ON when the Electron wakes up and puts the regulator into OFF mode when the electron is sleeping.

This unit would work without costing too much.

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I’m assuming you’re talking of placing this regulator in between the VIN and the sensors? However, the batteries themselves still don’t supply sufficient voltage for the Electron, so I would need a regulator for that either way.

If the Pololu regulator is placed in between the batteries and VIN, how would that satisfy the 10W requirement and supply enough power for the 3G Modem?

I’m recommending that you keep the current 3.7v regulator your using now because it’s super low power and it’s proven to work for you in your present application.

Then I would use the second 5v boost regulator with an enable pin to only turn ON when the Electron wakes up and pull that enable pin LOW when it’s not being used, so it stays in the low power mode and only consumes microamps of power vs. mA of power from your battery bank.

The 5v Regulator I linked to consumes 100 Microamps when in the Enable pin is held LOW. Ideally, you want a regulator with a lower sleep current to keep the standby current to an absolute minimum.

Here is another regulator board with 1uA sleep current which is 100 times less power during sleep than the first unit. The key will be finding out if the supplier can sell you 50 or 100 of these if you need them.

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Thanks, make sense. Adding two regulators in my setup is totally fine - I was just wondering if there was a way to make things do with one regulator (between power source + VIN) but I understand now that there would be implications with that - Deep Sleep current indeed is very important to me, as the whole point of going with the LiSOCl2-batteries is to achieve a lifespan of a few years

Just wondering; what will happen to the quiescent current of sensors that I place after the regulator board if I pull the Enable pin low?

All my sensors combined would have a quiescent current of about 12mA; would the power be cut off to them completely if Enable is low, so there’s no drain?

After running the math, an extra 100-200uA wouldn’t matter so much to me; it’s mostly those mA that are going to cause issues in the long run.

@Vitesze, when you disable the switcher all power will be cut “downstream” meaning your sensors will no longer be powered. This may or may not be an issue if the sensors need warm-up or settling time when they are powered again.

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Thanks for the reply. They don’t require a warm-up time.

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If you go with this regulator then it has:

image

Other versions of this regulator do just pass through the battery voltage when the regulator is disabled which is important to know and check when you’re looking at different regulator options.

Below you can see other versions of this chip do not actually disconnect the battery from the load.

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Thanks to you and @peekay123 for the detailed explanation, it’s all clear now :slight_smile: I will go with my original 3.6V booster, and probably the Polulu U1V11F5.

You don’t want the Poluou booster because it’s 100X’s less efficient in shut down mode as this one:

A silly question, but is it okay to use the 3V3 pin to feed this regulator, but connect it to the GND on the other side of the Electron? Anything internally in the Electron that would not like the power source and GND to be on opposite sides?

That would be inefficient to hook the 5v regulator to the 3.3v pin since your taking the battery voltage input an then regulating that to 3.3v which causes some loss, although it’s little.

Power the regulator from the battery for the most efficient setup. Connect the 5v reg + input from the Li+ pin on the Electron which is a direct connection from the battery.

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Testing this board right now, but it seems to not be supplying sufficient power to my ultrasonic sensor(s).

I have this firmware to test with. When the ultrasonic sensor is directly connected to VIN, I can clearly hear the ‘clicks’ of the sensor. When it’s connected to VOUT of the regulator, quite often I hear it “trickle” (i.e. only a few clicks) or no clicks at all. I do get measurements every now and then, but overall it’s way too unreliable.

Anything firmware-related that may be causing this? the ENABLE pin is connected to C2.

Can you diagram the 2 different hookup options or post a picture of your setup so we have a better idea of what exactly you’re doing as far as powering the Ultrasonic sensor?

What are the power input and current draw specs on the Sensor your powering?

Which exact 5v regulator are you using?

Using the one you linked before (MCP1640T).

Current draw is about 15mA. Power input is 3.0 - 5.5V, though 5V is recommended (which is why I use this regulator)

When I power the sensor directly from the VIN or 3V3 pin (bypassing the regulator) it seems to work fine. Since the regulator should easily be able to support 15mA and output the correct voltage, I was thinking it would be firmware-related. Is setting C2 to input and then pulling it high, the right way to Enable the Regulator?