usb fast charger question

T · 2021-11-17T07:58:29+00:00

Hi All,I asked about the voltage of a USB fast charger. I got back:5V-3A, 9V-3A, 12V-3A, 15V-3A, 20V-3AMy Android tablet wants 5.2V, 2.0 AUhhhh. Is there something about the USB cable thattell the charger not to fry what I plug it into? thanks,-T

Nov 17, 2021 Last reply: 4 years ago 46 Replies

Rate this thread:

Rick C 4 years ago

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.

Vote

Jan Panteltje 4 years ago

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:

formatting link

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

Vote

Ed Lee 4 years ago

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.

formatting link

Vote

Rick C 4 years ago

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

Vote

Ed Lee 4 years ago

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.

Vote