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I have a 3S 1.3MAH Lithium Polymer battery with a 25C discharge rate, and a 5C charge rate.From what i know, the discharge rate is the rate at which the battery can be safely ischarged( i.e how many amps it can provide saafely) while the charge rate is simply the rate at which it can be charge. Therefore for my battery, it can provide 25 x 1.3A -> 32.5A and can be charged at 5 x 1.3A -> 6.5A.

However, if the battery can be discharged at 25C, shouldn't it also be able to be charged at 25C? Why does it have different charge rates for discharging and charging when i should be able to pump in "energy" as fast as i can draw it out?

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  • \$\begingroup\$ Consider the voltage dropped across the cell's internal resistance. Charging at 25C, would that expose part of the cell to an overvoltage condition? Which is not good for LiPo cells... \$\endgroup\$ – Brian Drummond Oct 19 '14 at 17:07
  • \$\begingroup\$ A 3 cell battery may have some charge-balancing circuitry built in and this circuit could have a limit to its current handling capability. Just a guess though. \$\endgroup\$ – brhans Oct 20 '14 at 2:15
  • \$\begingroup\$ Can you provide the data sheet of the battery? \$\endgroup\$ – Adithya Oct 27 '14 at 4:12
  • \$\begingroup\$ You'd have a better time asking this on a Chemistry site. \$\endgroup\$ – Scott Seidman Jun 1 '15 at 12:12
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My best "educated guess" is that if you are discharging a battery, the "heating effect" is decreasing with time, whereas when you are charging the battery, the heating effect is increasing with time. So, as time passes, nothing happens to the battery when discharging. But in the second case, most likely the battery would explode, or at the very least, burn up! This still can happen, even at the lower charging rate if the battery can't dissipate the heat generated at this current.

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    \$\begingroup\$ In both cases the heat is building up with time. The difference is that during charging it becomes hottest at maximum voltage, when it is most vulnerable to damage by elevated temperature. I have seen a fully charged lipo puff up after it was taken off the charger, simply due to being left out on a hot sunny day for a few minutes. Another identical battery that was charged at the same time and kept in the shade was fine. \$\endgroup\$ – Bruce Abbott Oct 27 '14 at 4:38

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