Low Battery LED Indicator Board [OSHPark]

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Low Battery LED Indicator Board [OSHPark]

Post by Helder » Thu Jul 28, 2016 8:06 pm

Hey guys I have this board I whipped up that I have tested on breadboard and it works good but you need to adjust the value of when the LED turns on with the Potentiometer. I ordered 3 to come in so I can test it and get some proper values but I know some people have been looking for something like this for their builds.

SMD Version:
https://oshpark.com/shared_projects/Q2XKys7X

Image

Parts list for this project:
Transistors:
http://www.taydaelectronics.com/t-trans ... b-215.html

33K Resistors:
http://www.taydaelectronics.com/resisto ... -0805.html

10K Resistor:
http://www.taydaelectronics.com/resisto ... -0805.html

47k Potentiometer (Variable Resistor):
http://www.taydaelectronics.com/potenti ... r-6mm.html

Red LED:
http://www.taydaelectronics.com/leds/ro ... m-red.html





Through Hole Version:
https://oshpark.com/shared_projects/btIHScY7

Image

Parts list for this project:
Transistors:
http://www.taydaelectronics.com/t-trans ... istor.html

33K Resistors:
http://www.taydaelectronics.com/resisto ... istor.html

10K Resistor:
http://www.taydaelectronics.com/resisto ... istor.html

47k Potentiometer (Variable Resistor):
http://www.taydaelectronics.com/potenti ... r-6mm.html

Red LED:
http://www.taydaelectronics.com/leds/ro ... m-red.html




Now the way this circuit works is the two transistors are configured as voltage sensor and inverter.

The first transistor on the left senses the threshold voltage level as per the setting of the 47K preset. As long as this transistor conducts, the second transistor on the right is held switched OFF, which also keeps the LED switched OFF.

As soon as the battery voltage falls below the set threshold level, the left transistor is no longer able to conduct.

This situation instantly triggers the right hand side transistor, switching ON the LED.

The LED switches ON and provides the required indications of a low battery warning.





-----------------------------------------------------------------------------------------------------------------------------------------------------


I got some solid values to make the board a little more low profile without the pot and it comes on at 3.26V so no need to tweak the pot.

SMD Version:
https://oshpark.com/shared_projects/KtfWqSdE
Image





Through Hole Version:

https://oshpark.com/shared_projects/N6qwkU4V
Image
Last edited by Helder on Sat Aug 13, 2016 4:45 pm, edited 3 times in total.
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Re: Low Battery LED Indicator Board [OSHPark]

Post by Lanceomni » Thu Jul 28, 2016 8:18 pm

You are awesome. Ordered.

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Re: Low Battery LED Indicator Board [OSHPark]

Post by username 123 » Thu Jul 28, 2016 10:21 pm

So we buy the board from there and then populate it ourselves?

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Re: Low Battery LED Indicator Board [OSHPark]

Post by Lanceomni » Thu Jul 28, 2016 10:25 pm

Yep

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Re: Low Battery LED Indicator Board [OSHPark]

Post by Helder » Fri Jul 29, 2016 2:08 am

Updated first post with a friendlier through hole version and explain what and how the circuit works plus added parts links. This can be built for less than $4 for 3 boards.
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Re: Low Battery LED Indicator Board [OSHPark]

Post by Ganreizu » Fri Jul 29, 2016 8:30 am

Where do the bat+ and - lead from? Something from the pwrboost?

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Re: Low Battery LED Indicator Board [OSHPark]

Post by Helder » Fri Jul 29, 2016 9:08 am

Ganreizu wrote:Where do the bat+ and - lead from? Something from the pwrboost?
You connect the battery leads to this and obviously you need to add the battery leads to the charge/boost board.

This isn't for the powerboost1000c since it has a low battery LED, this is more for the cheap alternative that costs $3 since it lacks this feature.
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Re: Low Battery LED Indicator Board [OSHPark]

Post by Ganreizu » Fri Jul 29, 2016 9:23 am

Helder wrote:You connect the battery leads to this and obviously you need to add the battery leads to the charge/boost board.

This isn't for the powerboost1000c since it has a low battery LED, this is more for the cheap alternative that costs $3 since it lacks this feature.
Ahhh i see. Good stuff! I got a batt_dmg from kitsch-bent and was going to hook that up to the LBO, hoping that will give me a good battery indicator.

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Re: Low Battery LED Indicator Board [OSHPark]

Post by Helder » Fri Jul 29, 2016 11:32 am

Ganreizu wrote:
Helder wrote:You connect the battery leads to this and obviously you need to add the battery leads to the charge/boost board.

This isn't for the powerboost1000c since it has a low battery LED, this is more for the cheap alternative that costs $3 since it lacks this feature.
Ahhh i see. Good stuff! I got a batt_dmg from kitsch-bent and was going to hook that up to the LBO, hoping that will give me a good battery indicator.
That's a bit pricey and not sure what the IC draws but I know this circuit (the boards in first post) draws 1.5mA to function and go as low as 1.4v for the threshold sensor but obviously we don't need that as that is way too low.
My Sale Threads:

Retro PSU, 3.5A output!


Chat with me and other members


Don't contact me about obtaining my board files (as you will not get them). Don't contact me about any of my boards if they are sold out, they will be restocked as soon as I can get them.


Don't support thieves like ckliang who copied my AIO to resell and is now cloning the mintyPi, support the original creators and not the thieves!

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Re: Low Battery LED Indicator Board [OSHPark]

Post by Ganreizu » Fri Jul 29, 2016 12:25 pm

Helder wrote:That's a bit pricey and not sure what the IC draws but I know this circuit (the boards in first post) draws 1.5mA to function and go as low as 1.4v for the threshold sensor but obviously we don't need that as that is way too low.
Yeah i'm not sure if batt_dmg is appropriate for GBZ build. Just kind of bought it for the hell of it so if it worked great if not oh well. Looking like it won't work at all since it's connected to the original circuitry and is based on the batteries it's supposed to run from. Got this quote from the installation doc:
if you replace the LED with your own, assume the forward voltage to be 4.6V @ 20mA (the IC will not connect the circuit until engaged at 4.6V). use this for your calculations. the resistor is 0603 package. the included red LED is rated at 2.5V @ 20mA
the light will illuminate when the batteries can only supply 4.6V. the DMG is designed to run at 5V, with a voltage input tolerance of +/- 10%. meaning, (some of) these ICs are suggested to operate at 4.5V – 5.5V. this low-power indicator will alert you when the batteries can only supply 4.6V, so that you may extend the life of your equipment and are not surprised by a weak battery when it matters most (like a performance)

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