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HermannSW
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Powering Pi from 3S lipo with LM2596 step-down converter

Wed Sep 12, 2018 7:56 pm

Until recently I did run several Pi Zero[W]s from 1S lipo (nominal 3.7V, fully loaded 4.2V) by directly connecting to Pi GND/5V pins.

This stopped to work (steady reboots, directly when LCD gets initialized) for my first mobile Pi ZeroW. It seems that Pi CPU, Pi Wifi, 320x240 SPI LCD and wireless keyboard USB dongle were just too much for a 1S 600mAh 25C lipo. I don't understand that because the lipo should be able to deliver 3.7V at 25*0.6=15A?!?!?

I replaced the 1S lipo with a 3S 1000mAh 25C lipo and now have 12.6V fully loaded.
And use LM2596 step-down converter with voltage LCD to step down to 5V:
https://www.aliexpress.com/wholesale?Se ... wn+display

There is a switch on the step-down module that decides whether input or output voltage gets displayed.
Output voltage is interesting for calibrating the module to deliver 5V, input voltage to see when lipo needs to be recharged:
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

Brandon92
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Wed Sep 12, 2018 8:57 pm

I'm not 100% what you are asking.
HermannSW wrote:
Wed Sep 12, 2018 7:56 pm
Output voltage is interesting for calibrating the module to deliver 5V, input voltage to see when lipo needs to be recharged:
But if you are using a LM2596, the output voltage should not change much if the voltage at the input is changing.

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Thu Sep 13, 2018 12:07 am

Hi,

as I said output voltage is only needed to adjust to 5V once, LM2596 output voltage range is 1.25V ~ 37V.

My question is why the potential 15A for 1S lipo directly connected to GND/5V Pi pins do not sufffice driving ZeroW+Wifi+LCD+wireless dongle.
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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Imperf3kt
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Thu Sep 13, 2018 1:10 am

How thick are the wires coming off the lipo cell?
Most lipo cells only come with wiring rated to 1A
55:55:44:44:4C
52:4C:52:42:41

Rose tinted glasses are difficult to see through.

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Thu Sep 13, 2018 8:04 am

Thanks, that is a good point.

I don't want to look inside the 2mm(?) cables.
But I assume the 25C lipo rating would not make sense if the lipo cables could not do 25*0.6=15A.
But you pointed to the problem, I used small breadboard cables to connect the lipo connector to Pi ZeroW GND/5V pins.
I will have to retest with attaching lipo connector directly on Pi pins 4+6 (5V+GND).

Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Thu Sep 13, 2018 8:17 am

Thanks again, I did the test, disconnected the cables coming from LM2596 and directly plugged the 600mAh 25C 1S lipo onto pins 4+6 -- works perfectly, and reliably. Did some tests, graphics on screen, accessing internet, ... no problems. Now I need to find cables that can deliver >1A which the breadboard cables obviously were not able to -- because I don't want to loose the power switch functionality of my mobile Pi by having to open the box and connect/disconnect the lipo to pins 4+6.
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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Imperf3kt
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Thu Sep 13, 2018 8:37 am

It is how those Lipo are made. Many wholesale manufacturers where I live stress this point.

For example, I recently purchased a 10,000mAh cell directly from the Chinese manufacturer. It came with a datasheet which claims the cell is capable of 1C (10A) but the wiring is rated for 1A@3.7v
55:55:44:44:4C
52:4C:52:42:41

Rose tinted glasses are difficult to see through.

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Mon Apr 13, 2020 12:17 pm

I did use 4S 1300mAh 95C(!) lipo to power Pi3B+ plus Mipi camera plus 9" HDMI monitor, see bottom photo.
The lipo C rating says that lipo can provide up to 123.5A.

It happened seldom, but sometimes I saw undervoltage symbol.
Lipo cables to XT60 connector are very thick.
I used cables extracted from 3 line mains adapter cable from XT60 to LM2592.
The output side was likely too thin, I used 1S lipo charger cables, male soldered to LM2596, female to USB male Pi connector.
4S.XT60.png
4S.XT60.png
4S.XT60.png (120.01 KiB) Viewed 3500 times
Perhaps I should use cables extracted from mains cable on output side as well.
I have no idea how to solder that big cable onto a micro USB connector.
Perhaps solder on a female 2x1 header pins and power Pi via pin4(5V) and pin6(GND)?


viewtopic.php?f=43&t=267563&p=1642029#p1642029
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Tue Apr 14, 2020 10:15 am

> Perhaps solder on a female 2x1 header pins and power Pi via pin4(5V) and pin6(GND)?
>
I did cut plastic of two female headers in the middle with a knife.
Then I soldered thick cables to them (bottom center).
Then I moved the headers back into the front halves of cut plastic with superglue.
Finally I taped the connection.

Now Pi plus 9" HDMI display plus camera plus whatever should not show undervoltage again:
(the white mains power cable is not connected to mains)
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Wed Sep 02, 2020 11:35 pm

I just tested 13000mAh Anker power bank of my son, and that can deliver 5V/3A.
No problems, no undervoltage indicator, powers Pi4B plus 9" HDMI LCD easily!
And is plug-and-play:
https://twitter.com/HermannSW/status/13 ... 9927973896
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Thu Oct 29, 2020 5:04 pm

I got reminded that I wanted to buy that Anker power bank last Friday:
viewtopic.php?f=63&t=288899&p=1746946#p1746958

I now have it since some days, did Power Pi4B with HDMI display, wireless keyboard USB dongle and 400Msps logic analyzer from it without issues, no power warning symbol. Last night I powered a Pi2B with DPMI display this time and HQ camera from it and no issues either:
viewtopic.php?f=43&t=279752&p=1750312#p1750312

So all I can say is, that I now have a reliable 5V/3A 13000mAh/46.8Wh power supply to power all my PIs with add-ons whereever I need.
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Mon Nov 02, 2020 3:12 pm

Yesterday I powered Pi2B from fully loaded Anker 13000mAh power bank the whole day during my core1 not under Linux control timer off experiments.
viewtopic.php?f=72&t=245561&p=1751985#p1751985

There was nothing connected to the Pi2B (besided wireless keyboard USB dongle), but the power bank powered it for more than 8 hours.
And I just looked at the power bank, it shows 3 lights of 4, so has 75% power left ...
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Fri Nov 20, 2020 10:43 pm

I did replace Pi4B and wireless keyboard with my newly arrived Pi400 -- now this is my "easy to move anywhere" Pi400 laptop:
viewtopic.php?f=63&t=290622&p=1764745#p1764745
20201120_231711.15%.jpg
20201120_231711.15%.jpg
20201120_231711.15%.jpg (38.99 KiB) Viewed 2049 times
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

emma1997
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Sat Nov 21, 2020 1:12 am

HermannSW wrote:
Mon Apr 13, 2020 12:17 pm
Lipo cables to XT60 connector are very thick.
I used cables extracted from 3 line mains adapter cable from XT60 to LM2592.
The output side was likely too thin, I used 1S lipo charger cables, male soldered to LM2596, female to USB male Pi connector.
You had it backwards. It is important to know the input of the DC module runs at much lower current than the output due to power conversion. Should use thin wires from the lipo and thick wires to the Pi.

And the xt60 (which I like and use a lot for RC and ebikes) is serious overkill. Would have made much more sense on the Pi side but don't fit USBC that well. They are for amps not milliamps like coming from the lipo.

Also note that not all lm2596 are the same. 90% of the ones I buy off Ebay use a fake chip and cannot always be relied upon to power a Pi4. Generally if you pay a lot more for them there is higher probability it's genuine. However even then not guaranteed. This is why I stopped using them for important setups and switched to either lm2596hv or xl4015 type. A few pennies more but chips not cloned yet.

Glad you found success with the Anker bank. I have one for other use but prefer more like your first setup for Pi because they cost almost 15x more to do the same job.

PS You must have very powerful airsoft gun to penetrate plywood like that. lol

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Sat Dec 12, 2020 11:42 am

emma1997 wrote:
Sat Nov 21, 2020 1:12 am
HermannSW wrote:
Mon Apr 13, 2020 12:17 pm
Lipo cables to XT60 connector are very thick.
I used cables extracted from 3 line mains adapter cable from XT60 to LM2592.
The output side was likely too thin, I used 1S lipo charger cables, male soldered to LM2596, female to USB male Pi connector.
You had it backwards. It is important to know the input of the DC module runs at much lower current than the output due to power conversion. Should use thin wires from the lipo and thick wires to the Pi.
Using thick wires on both side does not hurt ...
And the xt60 (which I like and use a lot for RC and ebikes) is serious overkill. Would have made much more sense on the Pi side but don't fit USBC that well. They are for amps not milliamps like coming from the lipo.
I don't get that, the 4S 1300mAh 95C lipo came with male XT60 connector.
So I had to use XT60 female connector to connect to LM2596 input:
(that lipo is a power monster, can deliver 95*1.3=123A continuously -- I bought lipo safety bag for charging those)
https://www.conrad.de/de/p/droneart-mod ... 84866.html
4S.1300mAh.95C.lipo.jpg
4S.1300mAh.95C.lipo.jpg
4S.1300mAh.95C.lipo.jpg (18.46 KiB) Viewed 1811 times
Glad you found success with the Anker bank. I have one for other use but prefer more like your first setup for Pi because they cost almost 15x more to do the same job.
Yes, but powering over USB-C is more convenient. And the powerbank has two connectors, allowing to power eg. HDMI display driver and Pi400 of my Pi400 laptop directly from powerbank, not costing a USB port of the Pi400:
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

LTolledo
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Sat Dec 12, 2020 1:04 pm

at "average use"...how long does your battery last powering your setup.... before needing a re-charge... ?
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

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HermannSW
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Re: Powering Pi from 3S lipo with LM2596 step-down converter

Sat Dec 12, 2020 1:47 pm

LTolledo wrote:
Sat Dec 12, 2020 1:04 pm
at "average use"...how long does your battery last powering your setup.... before needing a re-charge... ?
The 4S lipo with my raspcatbot while continously doing one run after the other in room (it powered Pi3A+, L298N, three 9V leds and two 1500rpm 12V gear motors; robot weight was 879g, speeds up to 2.5m/s, full speed direction reversal braking):
More than 60 minutes, less than 90 minutes.

I used the 13000mAh Anker powerbank once for 4 hours with Pi4B, HDMI display and logic analyzer (and Raspberry mouse).

After superglueing CStoC adapter onto eyepieces of my cheap telescope, I am able to screw HQ camera onto the eyepieces. Once I did run Pi2B with 7" display of my LightStandPi and HQ camera at telescope for more than 8 hours while doing magnification experiments with "eyepiece projection" by inserting different number of additional CStoC adapter rings between telescope eyepiece and HQ camera:
viewtopic.php?f=43&t=290331#p1759139
Image
https://stamm-wilbrandt.de/2wheel_balancing_robot
https://stamm-wilbrandt.de/en#raspcatbot
https://github.com/Hermann-SW/Raspberry_v1_camera_global_external_shutter
https://github.com/Hermann-SW/raspiraw
https://stamm-wilbrandt.de/en/Raspberry_camera.html

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