Matador
100 kW
- Joined
- Jun 29, 2016
- Messages
- 1,045
[youtube]qFSfx5Pf6GE[/youtube]
I could'nt find any specification of this R&D product that Grin is deveopping on their website yet.
It can discharge you battery at different discharge rate and give capacity at different loads.
You can datalog the [CA-Grinspector] unit complex to a computer and plot all the data.
AND !!!! Calculate DC internal resistance.
Now that's very interesting.... DCIR measurement can be complex too. Hence i'm intrigued how they do it.
Can you measure DC-IR in function of State of Charge and get a cruve of the DC-IR evolution through whole the discharge cycle ??? (DCIR on y-axis versus SOC on x-axis) ?
Very intrigued... And enthousiast!!!
I'd like to do discharge cycles with different resistor values, and Justin say you can interchange the big resistors (or parrallel or serie them) to have different loads.
If there is many different values of resistors, you can plot a graph that's :
V = - r I + E in the y = mx + b form (the slope m = - r)
where
V = voltage (V)
r = DC internal resistance (Ohms)
I = current (A)
E = electomotive force (aka float voltage of battery with zero load)
The more points you have on the graph, the more refined the DCIR measurement becomes.
A graph with 5 or more points and you can get some very accurate DCIR measurement.
I did it on a smaller scale here (on one 18650 cell) : https://endless-sphere.com/forums/viewtopic.php?f=14&t=87173&p=1276187&hilit=LTO#p1276187
Image if for each measurement of the discharge curve you get a set of 5 measures like this to get the precise "r" value. Than plot "r" against the state of chare/voltage.
As you may notice, I took measurement precise given voltage (state of charge). DCIR can vary with SOC... And my method has a flaw : you have to take into considaration that voltage drop is actually voltage drop + a bit of voltage loss from normal discharge.
Now if the Grinspector does a multipoints (multiresistance values) testing not just at one discrete SOC but for the whole SOC range/curve. This tool is what I have been looking for a long time now and did not find before.
I'd like to understand this product in more details...
I imagin myself running a battery for 10 cycles, with 10 different loads(10 different external resistors). I coud obtain 10 dicharge curves that sag differently.
Then for that graph with 10 curves, I get 10 datapoint for every discrete SOC value plotted on x-axis.
I then get a very precise DC-IR value at any given SOC....
I could'nt find any specification of this R&D product that Grin is deveopping on their website yet.
It can discharge you battery at different discharge rate and give capacity at different loads.
You can datalog the [CA-Grinspector] unit complex to a computer and plot all the data.
AND !!!! Calculate DC internal resistance.
Now that's very interesting.... DCIR measurement can be complex too. Hence i'm intrigued how they do it.
Can you measure DC-IR in function of State of Charge and get a cruve of the DC-IR evolution through whole the discharge cycle ??? (DCIR on y-axis versus SOC on x-axis) ?
Very intrigued... And enthousiast!!!
I'd like to do discharge cycles with different resistor values, and Justin say you can interchange the big resistors (or parrallel or serie them) to have different loads.
If there is many different values of resistors, you can plot a graph that's :
V = - r I + E in the y = mx + b form (the slope m = - r)
where
V = voltage (V)
r = DC internal resistance (Ohms)
I = current (A)
E = electomotive force (aka float voltage of battery with zero load)
The more points you have on the graph, the more refined the DCIR measurement becomes.
A graph with 5 or more points and you can get some very accurate DCIR measurement.
I did it on a smaller scale here (on one 18650 cell) : https://endless-sphere.com/forums/viewtopic.php?f=14&t=87173&p=1276187&hilit=LTO#p1276187
Image if for each measurement of the discharge curve you get a set of 5 measures like this to get the precise "r" value. Than plot "r" against the state of chare/voltage.
As you may notice, I took measurement precise given voltage (state of charge). DCIR can vary with SOC... And my method has a flaw : you have to take into considaration that voltage drop is actually voltage drop + a bit of voltage loss from normal discharge.
Now if the Grinspector does a multipoints (multiresistance values) testing not just at one discrete SOC but for the whole SOC range/curve. This tool is what I have been looking for a long time now and did not find before.
I'd like to understand this product in more details...
I imagin myself running a battery for 10 cycles, with 10 different loads(10 different external resistors). I coud obtain 10 dicharge curves that sag differently.
Then for that graph with 10 curves, I get 10 datapoint for every discrete SOC value plotted on x-axis.
I then get a very precise DC-IR value at any given SOC....