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Old Oct 26, 2009, 11:34 AM
mrforsyth is online now
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So. Cal.
Joined Oct 2004
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I understand Junior's concerns and I had the same light bulb go off when I started parallel charging several years ago. I decided to perform some tests to satisfy my own curiosity and verify the safety of parallel charging packs of different age and internal resistance. I simply hooked a wattmeter inline with each pack and monitored current while charging at 1C and found that while the current was not absolutely equal, it was so marginally different that it was inconsequential and not worth mentioning.

I recently repeated the tests with a 4 year old 3S 2100mAh pack with cumulative IR of ~90 mOhms and charged it in parallel at 1C rate with a brand new 3S pack of the same capacity but with cumulative IR of ~16 mOhms. Once again, while current was not identical it was well within safe margins for each pack, telling me that no matching for IR is necessary when charging at 1C rate. If charging at 5C rate, one will obviously need to exercise some care in pack matching.

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