Which will be better LM2576 or LM138?

Thread Starter


Joined Jun 5, 2019
Hi Everyone,

I want to make a 12 car battery charger circuit. I want to use an IC regulator for it.

I want to get opinion about which IC will be better? LM2576(switching regulator) or LM138 a linear regulator?

Input voltage is 18v(transformer) and current requirement is upto 3 Amps.

Actually, linear regulators heat quickly and a large heat sink will be required for 3 amps. Probably, a fan also.

what is your opinion?



Joined Mar 30, 2015
Why bother. You can buy one for $30 that will charge the battery properly.

If you design your own, you need to make sure you charge the battery hard enough and long enough to minimize sulfation. Then you need to lower the charge to trickle to keep the battery topped up. Not worth the bother IMO.

schmitt trigger

Joined Jul 12, 2010
What Dennis said.

Having said that, if you want the challenge and learning experience of designing and building one yourself, the answer is: it all depends.

--If you are not very proficient with electronic circuits and theory, then a linear regulator will be far easier to design and build.
--If you are confident enough with your technical skills, you should go the switchmode way. As you correctly mentioned, less heat will be produced.

Thread Starter


Joined Jun 5, 2019
I tried to make a low current battery charger with LM317. Now, I want to make a high current charger with current upto 3 Amps.

thats why I am asking which one will be better in terms of less heat generation.


Joined Jul 11, 2016
is mainly the condition at the beginning of the 1-st 20 minutes of charging the empty battery
if it's the Gel Battery - requires even more sophisticated charging . . .
you likely want to include an MCU in this project . . . for a multiple various reasons

some general know how compacted into a single document https://heliant.it/images/FV/battery-guide-battery101.pdf + minor more VRLA http://v4-upload.goalsites.com/52/editor_1478652896_17DM Technical Manual.pdf ...

random https://etd.ohiolink.edu/!etd.send_file?accession=osu1212002134&disposition=inline + VRLA Pg.241... https://epdf.pub/valve-regulated-lead-acid-batteries.html
Last edited: