2013.08.20, 09:13 AM
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#46
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Location: Southern NH
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Please forgive my ignorance if this is already said quazster, but does your prototype discharger unit measure Internal Resistance, either actual or real-time? This is something I fooled with using my MuchMore CellMaster Platinum SP ED. and found the IR data told a lot about how a cell could handle high amp draw while maintaining maximum voltage (Good for Mod guys)
Thanks for all the info and pics! Very interesting! Great job
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2013.08.21, 02:47 AM
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#47
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Join Date: Jun 2012
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Forgot to add it to features, yes it has a function to measure internal resistance. For now it is a separate test, I haven't had time to code a function that does IR measurement during discharging for example every 5 seconds or every 30 seconds or whatever I want. It is easily done, only needs some coding work, and it is also in my todo-list.
Best way to match batteries quickly so far (without Excel work) has been a function that discharges 300mAh at 3A and calculates how many mWh battery gives out.
IR reading is very much dependant on the battery temperature and state of charge. This is why I have to finish the constant discharge function with repeated IR measurements.
Last edited by quazster; 2013.08.21 at 03:49 AM.
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2013.08.23, 01:20 AM
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#48
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2013.08.23, 01:24 PM
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#49
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No plans to sell now but we will most likely do a second, bit more sophisticated version just for fun. And maybe do a small batch of devices for sale, who knows.
This has so far been a nice research project to the world of AAA Nimh batteries :-)
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2013.08.24, 10:11 PM
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#50
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Location: Southern NH
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Excellent job on this device and thank you for the info. I for one am looking forward to possible additional updates, thanks again!
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2013.11.06, 07:21 AM
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#51
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Coded a new function some weeks back. Was sick at home and off work for few days so had time to make this work.
Functions:
- discharge at constant 3A current
- two GUI configurable mAh limits that control the result points
- three IR measurements during the discharge, first at start before the discharge begins, second at first mAh limit and third at second mAh limit
- results are displayed on the screen real time during discharge
- function gives out 7 different results from the battery, 3x IR readings, the average voltages between 0 - first mAh limit, first mAh limit - second mAh limit, second mAh limit - discharge to 0.9v, and total mAh discharged
This works really good and the batteries are easily tested and it is fast to write the results to Excel to sort the batteries with the reading of choice.
Here is a photo of some of my matched batteries and the results screen, first mAh limit is 50, second 300mAh:
https://drive.google.com/file/d/0Byz...it?usp=sharing
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2014.12.30, 09:18 AM
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#52
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Join Date: Dec 2014
Posts: 215
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Like the concept here. How far did the design go? Did it provide any marked improvement on cell life, charge cycles, or charge/discharge performance?
Sounds like you are just trying to duplicate the discharge profile of cells running in an RC on a track. I'd like to know how you were able to capture that information so as to duplicate it, while running on a track.
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2015.03.24, 06:16 AM
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#53
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Join Date: Jun 2012
Posts: 48
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Quote:
Originally Posted by Jshwaa
Like the concept here. How far did the design go? Did it provide any marked improvement on cell life, charge cycles, or charge/discharge performance?
Sounds like you are just trying to duplicate the discharge profile of cells running in an RC on a track. I'd like to know how you were able to capture that information so as to duplicate it, while running on a track.
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No improvement on cell life, charge cycles or charge/discharge performance at cell level.
But huge improvement on the visibility on single cell performance, capability to choose the best of the best cells for the big A-mains, ability to detect in real time when one cell starts to go bad, also we have learned the right way to charge, discharge and store cells.
Overall we just get the most out of our batteries and get the edge over our competitors here
No new developments on the device, the two prototypes we made 3 years ago are working too well still, and because they just have been too good we haven't had the motivation to design any new hardware
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2015.03.24, 07:17 AM
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#54
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Join Date: Dec 2014
Posts: 215
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Quote:
Originally Posted by quazster
No improvement on cell life, charge cycles or charge/discharge performance at cell level.
But huge improvement on the visibility on single cell performance, capability to choose the best of the best cells for the big A-mains, ability to detect in real time when one cell starts to go bad, also we have learned the right way to charge, discharge and store cells.
Overall we just get the most out of our batteries and get the edge over our competitors here
No new developments on the device, the two prototypes we made 3 years ago are working too well still, and because they just have been too good we haven't had the motivation to design any new hardware
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That's interesting. Something I've wondered about.... If you were to keep a group of 4 cells 'together' through all charge/discharge cycles, do you think that each cell would degrade at different rates?
Do you believe any variations you experience between cells would be due to manufacturing variations, or is it due to mixing your cells between one charge/discharge cycle and the next?
It may be interesting to see if, in a 4 cell series configuration, whether or not the most positive cell or the most negative cell experiences any different loading conditions, where it may be prudent to rotate the individual placement of each cell in the 4 cell series configuration between each cycle, so that the cells would wear in evenly so to speak.
At any rate, your charge/discharge datalogger sounds like it has some interesting potential, however I'm glad you're getting the most out of it in your club. It really does all start with the cells...
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