# 13.8v dc to 9.5v dc

Discussion in 'General Electronics Chat' started by koenton, Feb 3, 2013.

1. ### koenton Thread Starter Member

Jan 9, 2011
18
0
I have a 12v battery with 7 amp and want to sepdown to 9.5 v for a moultree game camera, bought convertor that will step to 9.5 but need
something that will drop voltage as the 12v drops, the convertor holds
9.5 volts all the time so the camera reads 100% all the time, is their a
diode that would do this?

Thanks for any info.
Will

Jul 31, 2012
1
0
3. ### koenton Thread Starter Member

Jan 9, 2011
18
0
Will this converter drop voltage as the 13.8v drops, I have a convertor that will drop v to 9.5 but will not drop down as the 13.8v battery goes down, it holds 9.5v till the battery goes to low to regcharge, I need something like a diode in line for 10 amps. Do they make a 10amp diode that would drop v from 13.8 to like 9.5 v dc, maybe 3 in line to reduce voltage and then drop as the 13.8v drops.

Thanks for any info.

4. ### #12 Expert

Nov 30, 2010
18,093
9,682
Here's an idea. If you base the control pin of an LM317 on a voltage divider, the output of the regulator will fall as the battery voltage falls. The "how much" has not been defined as far as I can tell, but I just got out of surgery and I'm nutty as squirrel poop.

If you need more or less sensitivity to the failing battery voltage, you can add a zener diode in the top or bottom section of the voltage divider string on the left. Can you see the concept?

You have to declare at what battery voltage you want the output of the regulator to be which voltage so the low-batt indicator indicates properly. Then the math can be done for the voltage divider string.

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5. ### koenton Thread Starter Member

Jan 9, 2011
18
0
What I am trying to do is to use a 12v rechargeable battery to replace 6 c batteries that go in a deer game camery which equals about 9.5v, I bought a convertor to try it, it works but keeps the 9.5 volts all the time, my camera shows 100% all the time, the 12v battery would have to go to low before the camera would show in drop in 12 battery, that is the problem with convertor, can you help, was told I could get some zenith
diodes and put in line to reduce volts and they would drop as battery drops. Please help
Thanks for any info

6. ### #12 Expert

Nov 30, 2010
18,093
9,682
A 12 volt what kind of rechargable battery? From that we can find the "dead" voltage of the battery. What voltage produces a 50% drop in the camera's low battery indicator? What voltage shows 10% battery left on the camera's display? What voltage just barely shows "dead" on the camera's display? From one or two points on that curve we can calculate how to trick the camera into properly displaying how much of the 12 volt battery is left.

I'm saying that a single zener diode will not produce the results you want.

7. ### koenton Thread Starter Member

Jan 9, 2011
18
0
I have a 12v rechargable sealed lead acid battery, I am trying to find something that will reduce volts to 9.5 and drop as the input goes down, don't know how to figure the other stuff I was asked.
Thanks for any info

Last edited: Feb 6, 2013
8. ### koenton Thread Starter Member

Jan 9, 2011
18
0
The battery is a 12v sealed lead acid battery,
12 Volt Battery​
Voltage​
State Of Charge​
12.65V​
100%​
12.45V​
75%​
12.24V​
50%​
12.06V​
25%​
11.89V or Less​
Discharged​

This is the way the 12v battery breaks down, will this help on how to make the 9.5 go down as the 12v goes down, Thanks for any help.

9. ### koenton Thread Starter Member

Jan 9, 2011
18
0
12 Volt Battery​
Voltage​
State Of Charge​
12.65V​
100%​
12.45V​
75%​
12.24V​
50%​
12.06V​
25%​
11.89V or Less​
Discharged​