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I have a lot of LiPo packs, from 1000mAh to 20000mAh.

We are usually told that a "Normal" charge rate is 1C (IE 1A per 1000mAh capacity) and that fast charging (3, 4, 5c +) is bad for them.

But is slow / trickle charging (0.1c, 0.5c etc) BETTER for the pack than charging at 1C? is it worse? or a waste of time, IE the same.

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  • \$\begingroup\$ There do seem to be a good amount of other battery related questions though... \$\endgroup\$ Nov 5, 2015 at 15:02
  • \$\begingroup\$ not clear what is your definition of "better". Charge and discharge rates affect longevity (of every cell type, not only LiPo). If you worry about the battery in your phone use only 0.5A USB source and run your phone off of it as much as possible. If your battery is powering a motor then don't worry since advantage gained by slow charging will be lost many times during fast discharge. \$\endgroup\$ Nov 5, 2015 at 17:05
  • \$\begingroup\$ I believe the battery will last longer if you charge it and discharge it at lower rates, but I don't think it is necessary to go down to 0.1C. My reasoning is that in the real world, you usually don't get trend reversals unless you change your variable by a very large factor. In other words, if the cycle life is 300 cycles at 2C, and 500 cycles at 1C, I would not expect it to go back down to 300 cycles at C/2. I would suggest charging at C/2 or C/3 if you have time. I don't think there is much point in going all the way to C/10. Oleg's comment is also very good and I agree. \$\endgroup\$
    – user57037
    Nov 5, 2015 at 17:45
  • \$\begingroup\$ Charging each cell to a lower terminal voltage (e.g. 4.0V) will also help the pack last longer overall, but each individual runtime will of course be shorter. \$\endgroup\$ Nov 5, 2015 at 18:34

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The battery university does tend to suggest that, in genereal, lower charge rates lend to longer battery life.

However, it is also well known, as even pointed out in the comment by Ignacio Vazquez-Abrahms, charging the lithium ion to a lower voltage and therefore a lower capacity, helps to extend the battery's life.

Every lithium charger that I have seem charges on the CC-CV algorithm and terminates charge when the current in the CV stage gets to 1/10 the current of the CC stage. So if you start with a very low charge current, the charger won't terminate charge until the current is 1/10 of that small current. The result will be a very full battery! A very full battery may not have as long a life as described above!

I.E. if you charge your battery at 1000mA, it stops charging at 100ma. If you charge it at 100ma, it will continue charging until the battery is only accepting 10mA and very full.

Also, I don't have the paper now, but when I purchased a LiMn2O4 battery from a Nissan Leaf to rebuid for a different project, they gave me their research paper on charge/discharge of the battery. They found a faster charge rate of 15000 mA was better for battery life than slower or faster charge rates.

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  • \$\begingroup\$ What was the capacity of the Leaf battery? What I mean is, if you were charging it at 15A, what does that work out to, 1C? C/2? or what? \$\endgroup\$
    – user57037
    Nov 5, 2015 at 21:06
  • \$\begingroup\$ @mkeith - The battery I was working on was 30 Ah, but I am fairly certain that the paper was based on research done on their 60Ah version which is just 2P. So c/4. I guess calling that a 'faster' charge rate in my answer wasn't accurate. 15 amp charge rate just seems so high. \$\endgroup\$
    – Filek
    Nov 6, 2015 at 0:17
  • \$\begingroup\$ I know what you mean. 15 amps is a lot of current. Anyway, good information to know. Thanks! \$\endgroup\$
    – user57037
    Nov 6, 2015 at 0:29
  • \$\begingroup\$ I do not understand “They found a faster charge rate of 15000 mA was better for battery life than slower or faster charge rates.” | So faster charge is better than slower or faster charge rate? Please excuse me, but this phrase sounds illogical to me. But your answer is great. Please explain this to me, however. \$\endgroup\$
    – neverMind9
    Jul 2, 2018 at 20:54
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    \$\begingroup\$ @neverMind9 - just poor writing on my part. I was trying to say that the charge rate of 15000mA is faster than most people normally charge their lithium ion batteries. However, charging that particular battery at any charge rate faster or slower than 15000mA rate is NOT good for the battery. \$\endgroup\$
    – Filek
    Jul 4, 2018 at 3:37

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