12v Battery charging

Hello, I have used a dc motor as a generator using human physical motion to rotate the motor. My voltage goes from 0volts all the way up to 30+ volts.. How can I control the voltage to 14volts dc. A usable voltage to charge a car battery.

by Reodo
September 23, 2018
Add comment...

Please sign in or create an account to comment.


2 Answers

Answer by mikerogerswsm

Use an LM317 https://www.onsemi.com/pub/Collateral/LM317-D.PDF

Or, if you're really fussy about efficiency, a boost/buck SMPS of sufficient power.

+1 vote
by mikerogerswsm
September 24, 2018

Hello, I'm really curious about your buck/boost suggestion. If I understand correctly, this would have power output regardless of speed rotation and would buck or boost as speed changes. Is this what they use for wind turbines? And would it be easier to build my own or just buy one made for wind turbine?

by Reodo
September 25, 2018
Add comment...

Please sign in or create an account to comment.


Answer by Reodo

Hello, I'm really curious about your buck/boost suggestion. If I understand correctly, this would have power output regardless of speed rotation and would buck or boost as speed changes. Is this what they use for wind turbines? And would it be easier to build my own or just buy one made for wind turbine?

+1 vote
by Reodo
September 25, 2018

Yes, buck boost smps is the best way to go, see:

https://en.wikipedia.org/wiki/Buck%E2%80%93boost_converter

If you want to build your own you could use the AD recommmendations:

http://www.analog.com/en/products/power-management/switching-regulators/buck-boost-regulators/external-power-switch-buck-boost.html?gclid=EAIaIQobChMIweuNsuLa3QIViLTtCh0C2g7GEAAYASAAEgKv__D_BwE

But it would save a lot of time to buy a ready-made item with the right range of input and output voltages, and of course power. The difference is cost, if you go for overkill it may get very expensive.

by mikerogerswsm
September 27, 2018
Add comment...

Please sign in or create an account to comment.


Your Answer

You must log in or create an account (free!) to answer a question.

Log in Create an account


Go Ad-Free. Activate your CircuitLab membership. No more ads. Save unlimited circuits. Run unlimited simulations.

Search Questions & Answers


Ask a Question

Anyone can ask a question.

Did you already search (see above) to see if a similar question has already been answered? If you can't find the answer, you may ask a question.


About This Site

CircuitLab's Q&A site is a FREE questions and answers forum for electronics and electrical engineering students, hobbyists, and professionals.

We encourage you to use our built-in schematic & simulation software to add more detail to your questions and answers.

Acceptable Questions:

  • Concept or theory questions
  • Practical engineering questions
  • “Homework” questions
  • Software/hardware intersection
  • Best practices
  • Design choices & component selection
  • Troubleshooting

Unacceptable Questions:

  • Non-English language content
  • Non-question discussion
  • Non-electronics questions
  • Vendor-specific topics
  • Pure software questions
  • CircuitLab software support

Please respect that there are both seasoned experts and total newbies here: please be nice, be constructive, and be specific!

About CircuitLab

CircuitLab is an in-browser schematic capture and circuit simulation software tool to help you rapidly design and analyze analog and digital electronics systems.