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battery protection

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URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=115999
Printed Date: May 03, 2025 at 3:35 AM


Topic: battery protection

Posted By: vmail
Subject: battery protection
Date Posted: August 30, 2009 at 3:12 PM

I have 2 2.8Ah 12V batteries connected in parallel.

I am after a circuit that will kill the supply to the load when the voltage drops to approx 10-ish volts



Replies:

Posted By: KPierson
Date Posted: August 30, 2009 at 5:57 PM

How much current is your load pulling?

A general approach would be to use a 5vdc voltage regulator to create a solid reference point.  Then, use a voltage divider circuit to cut your battery voltage by ~1/3. 

Use an op amp set up as a comparator to compare your 1/3 battery voltage value and an adj voltage fed off the 5vdc regulator (this adj voltage would be your cut off and would equal (cut off voltage / 3) or 3.33vdc. 

Your op amp would then feed a transistor that will power your load.  When the battery voltage is higher then the cut off the output will be on, when it drops lower then the output shuts off.



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Kevin Pierson


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