9v alkaline charger

279

03:08:15

Can you help?  I need help solving a few issues between this simulation, and the breadboard tests.  This circuit charges a 9 volt Alkaline battery at about 7mA rate.  Adjust 9v load voltage to simulate charging between 8v and 9.78v.  In the  simulation, LED starts to light at 9.7v, fully bright at 9.8, thus increasing amperage beyond supplied 7mA.  9v Alkalines can charge at 100mA without heating up.  I would like help getting the charge up to about 40mA.

The breadboard version comes much closer to expected.  Frequency of 555 is 112Hz.  Adjust load voltage with 9v battery removed to 9.8v (Amperage is always under 7mA at load, 12.5mA at 13.5v source).  Connect 9v battery, charge time is expected to be 4 hours.  No heating of battery at this low amp rate.  (I use a voltage and current controlled source.)

Questions:  Everycircuit shows the frequency at about 6Hz, this is wrong.  It is also hard to configure the transistors to real world, as I can't find any information on how to convert 2SC3199 )NPN transistors to configuration adjustable in everycircuit.  

Please help me fix the frequency to show 112Hz in this simulation?  Help solve when the LED turns on?

published 10 years ago

Karsten

10 years ago

First of all, charging a battery isn't a good idea. Second try changing the sim speed.

opticell

10 years ago

Thanks. Changed the sim speed to 50ms/s. Whereas the Sim fluctuates 133 to 200 Hz, the breadboard is constant at 112 Hz.

opticell

10 years ago

I have the breadboard version ready to change with your suggestions.

opticell

10 years ago

Sim speed now 1mS and displayed frequency is steady. Changed 3 transistor output resistor from 68 ohms to 10 ohms, charging at 9mA vs 7mA. Amperage reduces as voltage rises. (manually changing the output 9v source in the simulator).

Karsten

10 years ago

Maybe someone like hurz can help you. Currently I don't know that much about electronics (at school we're learning about inductance right now) to help you.

thebugger

10 years ago

Why do you need a switching power supply to charge it? Just use a linear PSU.

opticell

10 years ago

Linear/Switching PSU: I'm not sure why this is, but the straight DC PSU charges up fine, but it settles to about 0.5 to 1 volt down from ending charge voltage. I am open to ideas, and only have some theory and practice with this method. The switching psu I am using is for protection from shorts during tests, and had a few.

thebugger

10 years ago

Use a linear one. For such power levels it can be done with only one transistor, and the current limiting can be a simple resistor. No need for such complexities such as a switching PSU.

opticell

10 years ago

Thanks, will try simpler.

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