How to increase the current of LM2577 DC-DC regulator

Dear friends, is everything ok?

I have a little electronic problem that I would like to share with you all.

Well...At home I have some lead acid car batteries that I really want to charge but I haven't any good charger to do it.

Looking for a solution, I've thought in using a DC-DC step up regulator with an array of PNP or NPN transistor as current driver. At the first moment, it seems good, but I really don't know if it will work.

A friend of mine gives me a DC-DC step up regulator based on XL6009 (similitar to LM2577) and it can provide a voltage output between 5 and 35 volts (considering the input voltage: 3 to 32v) with 3A of current.

The main problem is: Can I use a 12v 15A power supply as XL6009 voltage input and some transistors as current driver to get an output of 14v 8A?

Many thanks and regards,

Pedro Rosa.

Transistor approach

**broken link removed**

XL6009 Datasheet

**broken link removed**

First of all, charging a lead-acid battery does not need a voltage regulator. Typical battery chargers utilize transformer-rectifier plus a 6V, 5A lamp in series to limit the current. The maximum recommended voltage from the charger is ~14 V.

Any of the above can be used; to achieve a larger output current you can add more power transistors in parallel. (2N3055).
780x series regulators need ~3V more input than output. As the output lines can be shorted, you need a fuse to prevent unprotected regulators from burnout. Exceedingly complex an unnecessary to charge a battery.

jiripolivka said:

First of all, charging a lead-acid battery does not need a voltage regulator. Typical battery chargers utilize transformer-rectifier plus a 6V, 5A lamp in series to limit the current. The maximum recommended voltage from the charger is ~14 V.

Any of the above can be used; to achieve a larger output current you can add more power transistors in parallel. (2N3055).
780x series regulators need ~3V more input than output. As the output lines can be shorted, you need a fuse to prevent unprotected regulators from burnout. Exceedingly complex an unnecessary to charge a battery.

Click to expand...

Dear, jiripolivka, how are you?

Thank you so much for having answered me too fast.

The bunch of lead acid batteries that I have need a voltage between 13.5 and 14.5v to be charged. So, I will use the XL6009 regulator to provide 14v from a 12v power supply and an array of 2 power transistors to drive more than 8A of current.

One more time, thank you so much.

Regards,

Pedro Rosa.

Plateau said:

Dear, jiripolivka, how are you?

Thank you so much for having answered me too fast.

The bunch of lead acid batteries that I have need a voltage between 13.5 and 14.5v to be charged. So, I will use the XL6009 regulator to provide 14v from a 12v power supply and an array of 2 power transistors to drive more than 8A of current.

One more time, thank you so much.

Regards,

Pedro Rosa.

Click to expand...

Dear Pedro,
you can do this if you like. Only please include a fuse in the output as a discharged battery can force a current surge and when connecting cables to charge batteries, shorts are common.
Regards, Jorge