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Old 06-01-2016, 08:57 PM   #21 (permalink)
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Although I was able to obtain amp levels each time I charged each stick during the refurb process, and noted the voltages, I was not sure how to calculate the internal resistance of each stick. Would such information be useful? Can I still do it since I have the data all written down? Is there a formula I can use to do such?
I did contact BumbleBee today and I am looking at a purchase, but if calculating internal resistance for each stick tested can lead to a reconfiguration of my sticks (I have so many to choose from) then I will try that before making the purchase.

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Old 06-01-2016, 08:57 PM   #22 (permalink)
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Although I was able to obtain amp levels each time I charged each stick during the refurb process, and noted the voltages, I was not sure how to calculate the internal resistance of each stick. Would such information be useful? Can I still do it since I have the data all written down? Is there a formula I can use to do such?
I did contact BumbleBee today and I am looking at a purchase, but if calculating internal resistance for each stick tested can lead to a reconfiguration of my sticks (I have so many to choose from) then I will try that before making the purchase.
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Old 06-01-2016, 09:42 PM   #23 (permalink)
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Calculating a meaningful IR is difficult. Verifying performance at high current is a validation of acceptable IR.

You've given no details as to what you did or what equipment you have available.

Sticks need to be evaluated for total capacity, IR and self-discharge. There will be top performers, and all others are outliers to some degree or another. You select the best of the bunch, preferably all in the top-performer group and drive with glee.
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Old 06-02-2016, 02:46 AM   #24 (permalink)
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I had done a lot of reading (at least I thought I did) and followed a procedure that was outlined by 99mpg (http://99mpg.com/projectcars/mimapackwhack/ There were several posts on Ecomodder that corresponded to the procedure and so read that material as well. I set up a chart and then used five Superbrain 977's and one superbrain 989 to test each stick. The tests involved discharging and changing each stick. I discharged at 4 amps and charged at 5 amps. The 989 would allow higher amperage but I thought it would be good to keep the amps all the same. The 977 can only do 4 amp discharge and 5 amp charge. I am now down to 3 of the 977's due to silly mistakes during the procedure.
I did 3 cycles on each stick. If the numbers looked good to me, I did not do additional cycles. Typically, if the charging produced consistent numbers between 6700mA and 7100mA while charging, and within 20% of that during discharge I considered it good. So the discharges were typically around 6000mA.
After the last charge of each stick, I sat them on a shelf for a week. Once the week was up I topped off each stick and note the additional mA as a percent. This was the discharge capacity. Typical sticks put into the pack had charge rates above 6700mA and discharge rates after a week of 13-16 percent.
Since I do not have knowledge on measuring internal resistance I can not do that test. If it is just math I think I can do it but would need a formula.
At one point in the process I became concerned about the bending of the PTC strip tabs because I was doing numerous assembly and disassembles of the sticks into a battery. Now I am not so worried since the PTC strips are out of the loop. It appears if the tabs break off it is of no concern.
The only other piece of equipment I have is a multimeter.

So looking at the numbers above and the procedure I followed, is there anything you would suggest I try prior to or instead of ordering a new battery.; in order to locate 20 usable sticks out of my 60?
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Old 06-02-2016, 08:39 PM   #25 (permalink)
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That's the original and likely still the best guide. Can I see your data?

Are you saying your 989 is no longer operational? Bummer.
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Old 06-03-2016, 07:00 AM   #26 (permalink)
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The 989 works fine although I must state I have not used it on higher amp settings. I will assume it can go 10 amps.

I took a photo of the data sheet but it is not very clear. I will redo the sheet and then attach it later today to another reply. Looks like there is a tool for easy image attachments...
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Old 06-03-2016, 03:34 PM   #27 (permalink)
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S Keith:
I am sending the photos as a private message since I can not figure out how to upload them here.
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Old 06-03-2016, 03:37 PM   #28 (permalink)
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S Keith:

Apparently I can not make a simple attachment of images. Can I send the two photos of the data to you by way of email?


Last edited by retired paul; 06-04-2016 at 03:09 PM..
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