Rechargeable Lithium Ion Sensor Custom PCB
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I have some thoughts about voltage.
A LiPo is 4.2 volt when it is 100% charged or when you have charged it for a few minutes, power will come from charger TP4056.
Do you use the regulator on Arduino board?
Can I use your files and modify it?
@flopp said:
Can I use your files and modify it?
Yes, absolutely.
But I don't think you need a voltage regulator. At least on the arduino I ordered there's already an onboard regulator which is rated for up to 12V DC input. -
I'm thinking of building the same kind of board for protyping sensors, also powered by Li-Ion or LiPo cells as I have plenty lying around :)
The TP4056 board will protect the cell if voltage drops bellow 2.8v. The arduino and nrf24 module should be fine at those values. This might not be the case for all sensors...
However when charging or at 4.2V the nrf24 module will exceed its 3.6V max input power. Did you manage to get your board working ? -
I'm thinking of building the same kind of board for protyping sensors, also powered by Li-Ion or LiPo cells as I have plenty lying around :)
The TP4056 board will protect the cell if voltage drops bellow 2.8v. The arduino and nrf24 module should be fine at those values. This might not be the case for all sensors...
However when charging or at 4.2V the nrf24 module will exceed its 3.6V max input power. Did you manage to get your board working ?@akumar said:
The TP4056 board will protect the cell if voltage drops bellow 2.8v. The arduino and nrf24 module should be fine at those values. This might not be the case for all sensors...
That's right, but for this case (which will only happen once a year or less (depending on configuration and used lipo battery) you have the battery measurement supported through mysensors onboard, which can tell you if the voltage drops below a certain level.
Also make sure to get the new tp4056 because the old and common one does not have a battery protection circuit!
@akumar said:
However when charging or at 4.2V the nrf24 module will exceed its 3.6V max input power.
No, the nRF24 is hooked up to VCC of the arduino, which has an internal voltage regulator. So the VCC output of the arduino should always be max. 3.3V, as long as the input is below 12V.
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If the arduino is outputing 3.3v that means that you are powering the arduino with the RAW pin, isn't it ?
If so make sure the linear voltage regulator on the arduino will be able to provide the 3.3v if battery voltage drops below 3.3v (so from 3.3v to 2.8v). I don't think they can boost the voltage from 2.8v back to 3.3v :( -
If the arduino is outputing 3.3v that means that you are powering the arduino with the RAW pin, isn't it ?
If so make sure the linear voltage regulator on the arduino will be able to provide the 3.3v if battery voltage drops below 3.3v (so from 3.3v to 2.8v). I don't think they can boost the voltage from 2.8v back to 3.3v :(@akumar said:
make sure the linear voltage regulator on the arduino will be able to provide the 3.3v if battery voltage drops below 3.3v (so from 3.3v to 2.8v).
That's not necessary - for this case you have the battery measurement circuit as mentioned in my previous post.
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@akumar said:
make sure the linear voltage regulator on the arduino will be able to provide the 3.3v if battery voltage drops below 3.3v (so from 3.3v to 2.8v).
That's not necessary - for this case you have the battery measurement circuit as mentioned in my previous post.
@HenryWhite said:
That's not correct. You are mixing up something. The RAW pin is for unregulated power input. With this you can bypass the internal voltage regulator. When you use the normal VCC input, the voltage will be regulated to 3.3V, if the input is (depending on arduino model) between 3.3V and 12V.
It is actually the other way around. From https://www.arduino.cc/en/Main/ArduinoBoardProMin :
If you're supplying unregulated power to the board, be sure to connect to the "RAW" pin on not VCC.
Power on RAW pin results in the regulator being in use.
Power on Vcc bypasses the regulator. -
@akumar said:
make sure the linear voltage regulator on the arduino will be able to provide the 3.3v if battery voltage drops below 3.3v (so from 3.3v to 2.8v).
That's not necessary - for this case you have the battery measurement circuit as mentioned in my previous post.
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@HenryWhite said:
That's not correct. You are mixing up something. The RAW pin is for unregulated power input. With this you can bypass the internal voltage regulator. When you use the normal VCC input, the voltage will be regulated to 3.3V, if the input is (depending on arduino model) between 3.3V and 12V.
It is actually the other way around. From https://www.arduino.cc/en/Main/ArduinoBoardProMin :
If you're supplying unregulated power to the board, be sure to connect to the "RAW" pin on not VCC.
Power on RAW pin results in the regulator being in use.
Power on Vcc bypasses the regulator.@mfalkvidd said:
Power on RAW pin results in the regulator being in use.
Power on Vcc bypasses the regulator.indeed. seems like I mixed up something there :D
I will update the eagle files when i have time to. -
So if I sum up, powering this node with a single Lipo cell will work by connecting the Lipo to the raw pin on the arduino. This will work from 4.2v to 3.4v. This is not that good for the battery life.
Using 2*AA batteries with a boost converter seems a lot easier...
I'm almost giving up on this idea : I liked the flat form factor of the lipos and they were solar pannel friendly. Is there a way to use a voltage regulator from 4.2v to 3.4v and then switch the circuit to a boost converter from 3.3v to 2.8v ? -
So if I sum up, powering this node with a single Lipo cell will work by connecting the Lipo to the raw pin on the arduino. This will work from 4.2v to 3.4v. This is not that good for the battery life.
Using 2*AA batteries with a boost converter seems a lot easier...
I'm almost giving up on this idea : I liked the flat form factor of the lipos and they were solar pannel friendly. Is there a way to use a voltage regulator from 4.2v to 3.4v and then switch the circuit to a boost converter from 3.3v to 2.8v ?@akumar It's the same problem as with all lipos. But you have to consider that it will take a really long time until the battery hits 3.4V or less. There are even smartphone batteries with 3000+ mAh which are very small.
Also it seems to be good for battery lifetime when the voltage does not drop that much compared to using a step-up converter below 3.4V.
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So if I sum up, powering this node with a single Lipo cell will work by connecting the Lipo to the raw pin on the arduino. This will work from 4.2v to 3.4v. This is not that good for the battery life.
Using 2*AA batteries with a boost converter seems a lot easier...
I'm almost giving up on this idea : I liked the flat form factor of the lipos and they were solar pannel friendly. Is there a way to use a voltage regulator from 4.2v to 3.4v and then switch the circuit to a boost converter from 3.3v to 2.8v ? -
Looking at discharge curves I can see that I should be able to squeeze 75% of the battery capacity if I charge it back when it reaches 3.3v. On a low power node this could work.
@flopp The reason I was mentionning 2.8v is because the battery protection module will kick in at this voltage. But you're right, no reason to go this far.Thanks !
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Looking at discharge curves I can see that I should be able to squeeze 75% of the battery capacity if I charge it back when it reaches 3.3v. On a low power node this could work.
@flopp The reason I was mentionning 2.8v is because the battery protection module will kick in at this voltage. But you're right, no reason to go this far.Thanks !
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Sure ! The newer ones have a battery protection chip. I've tested it and it kicks in at 2.8v.
http://www.aliexpress.com/item/Free-Shipping-10pcs-lot-1a-lithium-battery-charging-18650-with-protection-one-plate-protec-2-in/1876166772.html -
@flopp said:
Now I see, there are pads for battery and pads for out. Looks good
Correct. The old Tp4056 modules do not have the OUT terminals (and therefore won't fit on the pcb I designed in this thread)
@akumar said:
On a low power node this could work.
Why should it only work on a low power node?
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hi.
"Why should it only work on a low power node?"
with time we will have more and more things to charge every week/day (phone, watch, iot...), so I would say : for less maintenance ? lol
more seriously, it is a nice project I will follow it ;) I have one board to order (not ordered yet) with a li charger but mine is definitely not diy (too small chip so it is for stencil use).
Mobile phone batt is a very nice idea :smiley: I am a more confident than cheap lipo..and I have some old cheap galaxy s2 batt..How do you plan to hook the battery to your board? -
hi.
"Why should it only work on a low power node?"
with time we will have more and more things to charge every week/day (phone, watch, iot...), so I would say : for less maintenance ? lol
more seriously, it is a nice project I will follow it ;) I have one board to order (not ordered yet) with a li charger but mine is definitely not diy (too small chip so it is for stencil use).
Mobile phone batt is a very nice idea :smiley: I am a more confident than cheap lipo..and I have some old cheap galaxy s2 batt..How do you plan to hook the battery to your board?@scalz said:
How do you plan to hook the battery to your board?
As smartphone batteries are usually fully enclosed, I will just stick the battery (I will use the galaxy s4 batteries) under the pcb.
The whole package should fit nicely in a 75x75x40 distribution box, which will only cost a few cents in your local hardware store.
Only downside of the boxes is that they are a bit ugly :D
But since I don't have a 3D printer yet i will go with that solution and maybe paint the boxes black or white.
