maemo.org - Talk - Battery Tests, Homemade 3000mAh XL Battery & Q&A (POST #1)

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- - Battery Tests, Homemade 3000mAh XL Battery & Q&A (POST #1) - New Layout (https://talk.maemo.org/showthread.php?t=65568)

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

@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

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

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 :p) using 2 different battery's will actually work, just please keep them kinda close (25% difference in capacity max).

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

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

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

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

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

Quote:

Originally Posted by dr_frost_dk (Post 1219116)

So to sum up (yes i will shut up now :p) 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.

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

Quote:

Originally Posted by zimon (Post 1219576)

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.

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

Quote:

Originally Posted by misterc (Post 1218149)

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.

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

Quote:

Originally Posted by zimon (Post 1219576)

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 :D

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

Whats its means ????

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

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

Quote:

Originally Posted by lall_manish (Post 1225820)

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.