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Powering system using battery

Discussion in 'General Electronics Discussion' started by bobdxcool, Jun 14, 2020.

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  1. bobdxcool

    bobdxcool

    98
    0
    Mar 9, 2012
    I made an arduino nano IR sensor based auto liquid dispenser. Currently it is being powered by a 12V 2 amps adapter. The 12v adapter is connected to a LM2596 DC to DC buck converter which converts the 12V to 5V and powers the arduino, IR sensor and a regular green LED. Also I am using a RO valve solenoid (rated upto 24V DC) which is being powered by the 12V adapter. So whenever the IR sensor is triggered, the DC motor (5V 200mA) and solenoid (12V 300-500mA) are turned on for 3 seconds.

    Now, I intend to power this system via batteries. I am considering the following 3 options.

    a.) Lithium batteries in series (4 of 3.7V batteries). But again here I believe things would be complex as I have to make a BMS and charger for this. Is anything available off the shelf so that I can directly integrate the battery and charger with my existing system ?

    b.) Connect 8 AAA batteries in series to get 12V. But how long would these batteries last for my application ?

    c.) Connect 2 9V batteries in series. Again, can you guys please tell me how long these may last in the system.

    Arduino nano I believe consumes 20mA and the IR sensor probably around another 10- 20mA.
    If it wasnt for the solenoid, I was considering connecting a mobile power bank to power the system.
     
  2. bertus

    bertus Moderator

    683
    237
    Nov 8, 2019
    Hello,

    The AAA look a little bit small for the application.
    The 2 X 9 Volts will even be worse, as some are made of 6 X AAAA batteries inside or have a couple of button cells inside.
    https://www.rfcafe.com/references/electrical/aaaa-cells-inside-a-9volt-battery.htm
    Or watch this video from EEVblog:



    The run time all depends on the battery capacity.
    On this page of the wiki, you will find a list:
    https://en.wikipedia.org/wiki/List_of_battery_sizes
    Also the dimentions and capacities are given on the page for all types.

    Bertus
     
  3. bobdxcool

    bobdxcool

    98
    0
    Mar 9, 2012
    Since AAA wont work, I was thinking of the following 2 solutions:

    1.) Use a protection circuit board like one of these (https://aws.robu.in/wp-content/uploads/2017/09/DATASHEET_ROBU.IN_.pdf) and connect 3 18650 batteries (3S1P) with this board. I would able to charge the battery using a dc adapter (13.5 volts) and also simultaneously power the load. Whenever battery is fully charged, I can remove the adpater.

    2.) Or use one of these battery packs with BMS (https://robokits.co.in/batteries-ch...1v-2200mah-2c-with-inbuilt-charger-protection). And recharge these batteries at the end of the day for 1.5 hours with a 12V 1 amp adapter.

    What do you think ?

    Either solution 1 or 2 would give me upto 4 amps of current I believe , which is much more than what I needed.
     
  4. Bluejets

    Bluejets

    4,054
    847
    Oct 5, 2014
    One can get ready made bms boards relatively cheap so one could make the battery(3s would suffice) from single cells.
    Bms boards available in a variety of current ratings, 3A I believe the smallest.
    Arduino can take 12v at the raw terminal without any other converter.
    Lipo cells require dedicated charger to maintain absolute max @4.2v per cell so just any old charger simply will not do.
    18650 etc. normally charge @1c.

    How do you plan running a 24v (and why 24v) solenoid from just 12v or near.
    Don't forget filtering for the Arduino and freewheeling diode in the coil.
    Drive the coil with a logic level mosfet, Arduino can only supply 20mA on outputs.
    Use a 1k pull down resistor on the gate and a 100R series from the Arduino output.
     
  5. bobdxcool

    bobdxcool

    98
    0
    Mar 9, 2012
    My solenoid works with 12V as well. So using 12V. I am using the buck booster (LM2596) to power my arduino, small dc motor and the sensors. The solenoid is already being driven with a mosfet and diode has been added along with the resistors. thanks for your inputs.
    https://robokits.co.in/batteries-ch...1v-2200mah-2c-with-inbuilt-charger-protection

    As per the claim in the link above, do you think it is not possible to charge a lithium ion battery pack with a regular 12V 1A adapter ?
     
  6. Bluejets

    Bluejets

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    847
    Oct 5, 2014
    That's what I said, yes.
     
  7. bobdxcool

    bobdxcool

    98
    0
    Mar 9, 2012
  8. Bluejets

    Bluejets

    4,054
    847
    Oct 5, 2014
    I would not put too much credence in a POC such as that.
    Balance charging is not the issue, the way it charges and the cut off levels, is.
    The charger I use comes in at around $80.00 odd but there are cheaper, just as there are more expensive.
    One could try the cheap versions but no guarantees and the outcome can be disastrous if the charger is unattended.

    If one could believe the specs, (towards the bottom of the page) the following would be the bottom of the pile.....
    https://www.ebay.com.au/itm/3S-11-1...797804?hash=item1a4c45e16c:g:CrcAAOSwQ~ha0B9f

    Mid-range would be something like this......
    https://www.banggood.com/HTRC-C150-...html?rmmds=category&ID=47184&cur_warehouse=CN

    Or you may go with a module arrangement and supply your own power unit for an el-cheapo system.
    I've used similar on attended charging system and they work ok.
    https://www.ebay.com.au/itm/Multi-C...m215d3d1c2a:g:1KMAAOSwT5RdB0xz&frcectupt=true

    Again, specs are lower down on the page.
    I would still include a bms board on the pack itself if you are making your own battery from cells.
     
  9. Bluejets

    Bluejets

    4,054
    847
    Oct 5, 2014
    Second thoughts also, you could run the Arduino into the Vcc terminal straight from one of the 3.7v cells ( they don't draw much) and forget about the converter.
     
  10. bobdxcool

    bobdxcool

    98
    0
    Mar 9, 2012
    I plan to get (https://www.ebay.com.au/itm/Multi-C...m215d3d1c2a:g:1KMAAOSwT5RdB0xz&frcectupt=true).
    And also use a battery pack with BMS as suggested by you. Now my question is if I have the load connected to my 3S lithium pack (11.1 - 12.6v) , if I connect the DC adapter input to the ebay based board, will the battery charge and simultaneously power the load ?
     
  11. Harald Kapp

    Harald Kapp Moderator Moderator

    10,025
    2,138
    Nov 17, 2011
    Use a 5 V power bank for arduino co plus a step-up regulator for the solenoid?
    Use a step-up regulator with enable input (example). This will allow you to shut down the step-up while not needed (I think you may need it only for short intervals when liquid is dispensed).
    You may even discard the solenoid driver, connect the solenoid directly to the step-up converter and instead of driving the solenoid drive the enable input of the converter.
     
    bertus likes this.
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