Powerbank for Bicycle: Charging a Li Ion Battery with Varying Current

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Discussion Overview

The discussion revolves around the feasibility of charging a lithium-ion battery for a bicycle power bank using a generator that produces varying current. Participants explore the implications of charging with less than 1 amp and the complexities of charging protocols for devices like cell phones.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the possibility of charging a 4400 mAh Li-ion battery with less than 1 amp and with a variable current from a bicycle generator producing 3W.
  • Another participant mentions the complexity of cell phone charging protocols, suggesting that improper charging could lead to damage, and notes that details may depend on the specific make and model of the phone.
  • A different participant argues that as long as 1 amp at 5V is provided, the specific model of the phone may not be crucial, emphasizing the constant voltage but variable current in their setup.
  • One participant suggests looking for inexpensive charging modules that can handle a wider range of input voltages, recommending further research into buck and boost voltage regulators for compatibility with human-powered generators.

Areas of Agreement / Disagreement

Participants express differing views on the importance of the phone model in relation to charging protocols, and there is no consensus on the best approach to charging the battery with variable current from the generator.

Contextual Notes

There are limitations regarding the assumptions about charging protocols and the specific requirements for the generator's output voltage and current. The discussion does not resolve the technical challenges of charging with varying current.

Who May Find This Useful

Individuals interested in DIY electronics, bicycle power solutions, and those exploring battery charging methods in variable power scenarios may find this discussion relevant.

Akmalidin
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Hello,
I made powerbank for my bicycle to charge my phone while I ride it.
I am using one 4400 mah Li Ion battery. I was wandering If it is possible to charge the battery with less than 1 amp and not constant current? Because, generator I have on my bike produces 3W and it varies as I change pedaling speed.
Thank you in advance !
 
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In a previous post here on PF, I read that cell phone charging protocols are complex. They must prevent damage because of improper charging.

Hopefully someone else can provide details, but they will need to know the make and model of your phone.
 
I think the model of the phone does not matter as long as 1amp 5 V is provided. But in my case, I have 5 V constant but variable current.
 
I have been looking at these really cheap modules on ebay, search on "LI-ion charger module" or battery charger board or similar terms. Many of these regulators are for 5V input but I found one with this title "LiPo Charger Step Down 5A 5V-32V to 0.8V-30V Power Supply Buck Module" that would cope with a wider range of input voltage typical of a human powered generator, you just need to ensure that the generator output is at least 5V after rectification most of the time.

A deeper search of more sites may find an even better suited module with lower min input voltage, this can't be a new problem, someone must have solved it previously, keep digging. Expand the search to buck and boost voltage regulators. These are generally inexpensive component modules. You don't need really pure power for charging.
 
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