usb fast charger question

I routinely charge at 2.5C (20% SOC) and 1C (60% SOC) for most 2Ahr cells. They hardly get warm at all, as long as the total charge time is short (15 minutes). With USB (5V) supply, you can hardly drive it over 1.5C (3A for 2Ahr cell). If the cell does not get warm, then most of the energy is stored instead of heating up due to "Internal Chemical Resistance to Charging". Heat is the biggest problem.

Reply to
Ed Lee
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Here you are showing you don't understand the difference between power and energy. Damage to the cells happen from the overcurrent regardless of the temperature. By your reasoning you should be able to pump the cell with 100C if you do it for a short enough time.

One wear mechanism is plating of lithium on the graphite anode instead of lithium being intercalated. Intercalation is a reversible reaction while plating is not. Lithium is preferentially plated at higher currents. It doesn't matter that the current is short enough the battery temperature doesn't rise a lot.

Reply to
Rick C

On a sunny day (Fri, 19 Nov 2021 00:48:44 -0800 (PST)) it happened Ed Lee snipped-for-privacy@gmail.com wrote in snipped-for-privacy@googlegroups.com:

I try avoiding charging more than 1C to extend battery life (I hope). I have a bunch of 2 cell and 3 cell lipos for my drones. Those also need individual cell monitoring when charging, and I have a special charger for those.

Those batteries do not last very long, discharge is high, >10A for a 2700mAh 7.4V 10C cell:

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does not matyter if charging takes a while, I have several so I can keep flying.

Reply to
Jan Panteltje

But we are not talking about 100C, just 2C.

Highlights Harvested electrodes are tested at high discharge and charge rates. Several limiting processes were observed within a single 10 s pulse. In 10s pulses, the cathodes could be charged at 10C and stay below the 4.2 V limit. The anodes voltages went negative at 5C, but the limiting process was diffusion. Repeated pulsing with 20C, 10s pulses lead to lithium plating on the anodes.

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Reply to
Ed Lee

Ok, I give up. No point in talking when no one is listening.

Reply to
Rick C

I listen to facts. They tested 5000 cycles of 20C for 10s and find lithium plating on the anode. I don't know how much it would degrade, but sound like it would take a while to cause problem. Anyway, i am not even getting close to 20C and even if i cycle it everyday, it would last 10 years.

Reply to
Ed Lee

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