Looking for a good battery solution.

Discussion in 'General Electronics Chat' started by Ally Cat, Mar 31, 2016.

  1. Ally Cat

    Thread Starter Member

    Mar 28, 2016
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    I need a battery that is rechargeable that I could use with a digital multimeter. I don't have a current budget yet but I believe it will need to be 1 at least 1 amp hour. This is because I plan on using a graphical LCD and it will draw more than the average DMM. I don't much care what the voltage is as long as I can charge it through a USB port. I would also like it to be widely available on the market.
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    So far any AA or similar rechargable battery fits the requirements..
     
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  3. Ally Cat

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    Mar 28, 2016
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    Just never heard of some using a USB to charge a 4 pack of AA's. Can this be done?
     
  4. Lestraveled

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  5. mcgyvr

    AAC Fanatic!

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    As Lestraveled has already shown you yes..
    USB is just a 5V power source in addition to the data lines.. slap that with the correct charger IC and voila..

    And you never stated 4 (or any other number of batteries) either in your original post..
    (hint..hint.. Details man.. details.. that where the Devil hides :) )
     
  6. Ally Cat

    Thread Starter Member

    Mar 28, 2016
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    Sorry, I assumed it would take 4 AA to equal an Ah. Thanks for the help. That's typically how they do it. Now I just need to find the circuit that can charge these batteries. Out there some where.
     
  7. jpanhalt

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    Jan 18, 2008
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    I have used Li-chemistry for a current hogging GLCD. What voltage do you need? A single Li with booster or two in series with regulator could work. Sparkfun makes a nice booster based on the NCP1402, which you could use piggyback or incorporate on your main board. Its circuit is quite simple. And, if you use a single cell, charging is simplified.

    John
     
  8. Ally Cat

    Thread Starter Member

    Mar 28, 2016
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    I haven't looked too closely on the LCD requirements on voltage level. May be I do to get this answered. Jpanhalt I don't know too much on li batteries. Most of my design(including LCD) is around 5/3.3 Voltage range. Their will be a small +- 16 V for some comparators work but the current is really low. I plan on using switching regulators on the 16 V. Is there a lithium battery that you recommend with this in mind. If there is a solution to 4 AA batteries id rather use that because of availability.
     
  9. #12

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  10. jpanhalt

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    Jan 18, 2008
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    I have been using the Tenergy LiFePO4 123A size ( about 400 mAh). Tenergy also makes the 18650 size that is 1.45 Ah (http://www.tenergy.com/Site/LiFe-Cylindrical). There are also flat batteries in similar sizes. There are other brands to consider. I have had great luck with the smaller Tenergy 123A batteries and poor luck with another brand of 18650 batteries. My point is, whether in series or parallel, rechargeable batteries present additional, perhaps only small hurdles that single cells do not present.

    Check out that boost regulator at Sparkfun. For a recent project with a XBee, I used two of the 123A batteries in series to give me the capacity I needed with a 5-V regulator and the Microchip charger MCP73x23 (http://ww1.microchip.com/downloads/en/DeviceDoc/22191E.pdf). Have had no failure of the smaller Tenergy cells in 2 years.

    John
     
  11. mcgyvr

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    Is product size an issue? aka is 4 x AA an issue?
    Is the ability for a user to get replacements at the local grocery store a need or just be able to pick them up on amazon?
    You want to be able to charge the batteries inside this unit (via the USB) an not have to take them out right?
    A charging solution needs to fit the battery chemistry NiMH/Li,etc.. being used
     
  12. Ally Cat

    Thread Starter Member

    Mar 28, 2016
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    It is going to be a large PCB so size of th 4xAA is not an issue. The need to go down to a local store and find replacements for the secondary cells is a plus. I think I found a solution that will allow me to do that. The charger bq2000 seem to do that for NiMH. It supposedly works for NiMH chemistry with an added bonus on working with Li. My only concern is that people will put primary cells(zinic carbon) instead of secondary(NiMH) to use the USB charger that it is part of the system. I guess it will be ok if I have a message on the LCD reminding users of the requirement.
     
  13. jpanhalt

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    Four AA zinc batteries will be >6V. Can you put a pre-regulator voltage detector, so the meter will not work with Zn batteries?

    John
     
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  14. Ally Cat

    Thread Starter Member

    Mar 28, 2016
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    I have plenty of SAR ADC's on the processor that I am not using, that could work. I did not think of that. That would probably be the best solution. That is the point of this DMM anyway. I would like to have a bit of brains to it.
     
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