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    Battery Tests, Homemade 3000mAh XL Battery & Q&A (POST #1) - New Layout

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    Estel | # 1321 | 2012-06-07, 18:40 | Report

    @zimon
    Interesting point - honestly, I have no idea if pascal's law is also applicable to voltage and batteries. Honestly, even if You're right, i would hesitate to connect different batteries, due to different internal resistance - as daniel_m said - and overall, subtle differences in chemistry (even if battery is of same type).

    Following Your logic, it would be like measuring drop of two different types of water - one very "hard", and one distiled. flow won't be identical.

    Still, i'mwaiting eagerly for dr_frost_dk's results, as real life can be different, from both Your (i.e. water comparison not applicable) or mine (differences too small, to impact real-life usage) theories.

    @stlpaul, awazix, thanks a lot, will investigate those.

    /Estel

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    dr_frost_dk | # 1322 | 2012-06-07, 19:20 | Report

    preliminary results show that the battery's i have chosen have been doing very good actually capacity wise

    1. Battery has 804mAh
    2. Battery has 1409mAh
    Totalling 2213mAh

    Discharge of both in parallel showed a capacity of 2260mAh.

    Now you might notice that the parallel capacity is higher but this is due to a miscalculation from my part.

    Process has been done like this for 1. test
    Discharge 1A to cutoff, then 0.2A to cutoff, this was also done for dual setup.

    Next test will be done with 0.5A and 0.1A for individual battery's and then 1A and 0.2A for parallel, this will also reflect a better capacity for the battery's as individual.
    1. battery has a total of 804mAh (tested) but this is not accurate as i have been discharging it at 1A (over 1C) so actual capacity will be higher.

    But for 1. conclusion on making a dual (or more) battery with different cells will work, but my testing was done under stable condition's, real world will fluctuate depending on usage and in case of getting close to empty the battery controller in the device will properly shut down when seeing a sudden voltage drop, that said this will happen close to the combined capacity anyway so you will get 90%+ of the combined capacity.

    Also note that the 1A drainage is higher then the N900 'should' use, and here we are talking about peaks, or your N900 will get VERY HOT.
    Also phone battery measurement (capacity left) will be a bit screwy, the voltage meter here under discharge was fluctuating quite a bit, where normally it would just go down in a normal pattern.

    So to sum up (yes i will shut up now ) using 2 different battery's will actually work, just please keep them kinda close (25% difference in capacity max).

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    The Following 6 Users Say Thank You to dr_frost_dk For This Useful Post:
    daniel_m, Estel, ILikeMaemo, qwazix, sEKI, zimon

     
    Firminator | # 1323 | 2012-06-08, 11:49 | Report

    Is http://www.avatardeals.com/SCUD-3-7V...le-Phones.html this the same as the Blue Dream ?

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    bsd1101 | # 1324 | 2012-06-08, 12:58 | Report

    Blue Dream has 1460 mah, and its label is the other way landscape wise. Could it be a fake SCUD ?

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    zimon | # 1325 | 2012-06-08, 17:44 | Report

    Originally Posted by dr_frost_dk View Post
    So to sum up (yes i will shut up now ) using 2 different battery's will actually work, just please keep them kinda close (25% difference in capacity max).
    Can you test somehow there is no current going from bigger to smaller battery when they are discharged in parallel?

    With some simple electronics that could be tested.

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    The Following User Says Thank You to zimon For This Useful Post:
    Estel

     
    dr_frost_dk | # 1326 | 2012-06-08, 18:31 | Report

    Originally Posted by zimon View Post
    Can you test somehow there is no current going from bigger to smaller battery when they are discharged in parallel?

    With some simple electronics that could be tested.
    Good idea, i will bring this to test 2, having problems finding the time, hence the late 1. test

    But as the combined discharged capacity is very much equal the capacity it should have i don't think there will be many problems here, even when there are so big difference between the battery's, but will be funny to actually see what's going on under discharge.

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    The Following User Says Thank You to dr_frost_dk For This Useful Post:
    Estel

     
    misterc | # 1327 | 2012-06-09, 12:18 | Report

    Originally Posted by misterc View Post
    modified bq27000.sh so that it displays VDQ when in LOOP mode...

    to install
    (copy & paste {path} to get it to the right directory)
    Code:
    find /usr -name i2cget
    {path}/i2cget
    cp bq27000_vqd2.txt {path}/bq27000_vdq2.sh
    chmod 755 {path}/bq27000_vdq2.sh
    to run & redirect output...
    Code:
    cd {path}
    bq27000_vdq2.sh >>/media/mmc/bq27000_vdq2.out
    bq27000_vdq2.sh 60 >>/media/mmc/bq27000_vdq2.out
    will generate a file with content similar to


    this way, it is easy to let the battery run empty & have all the values saved in a file automatically
    updated bq27000_vdq.sh
    now, called without loop, it will 1st display complete date
    2012-jun-09-08:08
    Code:
    echo "$(date +%Y-%b-%d-%H:%M)"
    same steps as previous version to setup / use.

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    Attached Files
    File Type: txt bq27200_vdq2.txt (6.7 KB, 85 views)

     
    daniel_m | # 1328 | 2012-06-09, 12:26 | Report

    Originally Posted by zimon View Post
    Can you test somehow there is no current going from bigger to smaller battery when they are discharged in parallel?

    With some simple electronics that could be tested.
    Theoretically both batteries should have the exact same voltage under charging and discharging. The bigger one will just draw or push out more power. As long as you stay under the limit of what the weaker of the batteries can take, there is no way that voltage could be different between them. And by "weaker" I am not talking about the smaller capacity battery but about the one that has higher internal resistance.

    A "real life" test would be nice though

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    The Following 3 Users Say Thank You to daniel_m For This Useful Post:
    dr_frost_dk, Estel, ILikeMaemo

     
    lall_manish | # 1329 | 2012-06-22, 16:39 | Report

    Whats its means ????


    Battery Tests, Homemade 3000mAh XL Battery & Q&A (GOTO POST #1) SCUD is BACK!!!

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    dr_frost_dk | # 1330 | 2012-06-22, 17:38 | Report

    Originally Posted by lall_manish View Post
    Whats its means ????


    Battery Tests, Homemade 3000mAh XL Battery & Q&A (GOTO POST #1) SCUD is BACK!!!
    Are you retar'ed?

    - Battery Tests
    - Homemade 3000mAh XL Battery
    - Q&A
    - Goto Post #1 for info
    - SCUD is Back (this needs to be changed since scud is hard to come by.

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