I hope it's okay to ask this here

My e-bike has a Lithium Ion battery (32 Volts, 15 Amps), and it has a USB-A output, marked as 5V and 1A,

I have 3 questions:

  1. How long will this battery last while charging a USB device at the full 1A output? (I'm assuming the reduction in Voltage causes this 15A pack to run longer than my 25A USB power bank?)

  2. If my USB device tries to draw more than 1A (like 2.4A), will it put pressure and damage the e-bike battery? (I know less/more Ampers can't damage my device as long as the Voltage is 5V, but not sure if the e-bike battery will be damaged)

  3. If I use a converter directly connected to battery's 32V output (not the USB output) can I have 220V at maybe 60-100 Watts? or will this damage the battery?

  • 1
    \$\begingroup\$ How many hours using 5W from 500Wh (?) \$\endgroup\$ – Tony Stewart EE75 Feb 11 '20 at 0:52
  • \$\begingroup\$ Do you mean a Li-Ion Battery with 32V and 15Ah? \$\endgroup\$ – someonr Feb 11 '20 at 0:53
  • \$\begingroup\$ @TonyStewartSunnyskyguyEE75 I wasn't sure if it's that simple... I had doubts because my 25000mAh power bank does not charge my 5000mAh phone 5 times, only like 3.5 times. \$\endgroup\$ – J. Doe Feb 11 '20 at 0:58
  • \$\begingroup\$ Capacity will degrade going from C/20 to 5C rates batteryuniversity.com/index.php/learn/article/… It's called Peukert's law \$\endgroup\$ – Tony Stewart EE75 Feb 11 '20 at 1:03
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    \$\begingroup\$ That's mainly because power banks cheat and report capacity at the battery voltage (3.some) instead of the output voltage (5.0). \$\endgroup\$ – Brian Drummond Feb 11 '20 at 12:34

1) Around but less than 4 days (500 Wh / 5 W = 100 hours = 4 days). Because the conversion efficiency is less than 100%, you will not get the full time.

2) it won't hurt the battery itself but who knows what the 5V circuit will do? In any event it is not adviseable to exceed the limits of the stuff you buy unless you are willing to take risk. Most likely outcome is that the 5V output will be shut off by the battery pack.

3) This should not damage the battery. It may be difficult to find such a circuit. Basically you are looking for a 32V inverter. Maybe a 48V inverter will work.

  • \$\begingroup\$ Thank you very much for the time you put in answering this. \$\endgroup\$ – J. Doe Feb 11 '20 at 0:59
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    \$\begingroup\$ Check back in a bit to see if anyone gives a better answer. Often people wait at least 24 hours before selecting an answer. I focused on answering quickly but someone else may explain more. \$\endgroup\$ – mkeith Feb 11 '20 at 1:03

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