idling Mind - Battety Box Mod

hippy

Senior Member
It may be &quot;blindingly obvious&quot;, but here's a convenient battery box mod for those times when you don't have enough batteries to hand ...<code><pre><font size=2 face='Courier'> .-------------------.------------------.---&gt; +V = 2V5 / 4V / 6V
| | |
| .--|&gt;|--' .--------------|---&gt; 0V
| | | |
.-----|-----------|-----------|-----. |
| | .---^---. | | |
| | | | | | |
| _ _____ _ _____ | |
| _|_|_ | | _|_|_ | | | |
| | | | | | | | | | |
| | | | | | | | | | |
| | | |_____| | | |_____| | |
| |_____| |_| |_____| |_| | |
| | |
| `---.---' `-------' | |
`---------|-------------------------' |
| |
`----------------|&gt;|---------------' </font></pre></code>
 

premelec

Senior Member
Ok I'll agree that Hippy's a genius but I'm at a loss as what this circuit does... 4 cells in series with two diodes tapped to the upper part of the string + 'output' - what's the problem that this is a solution to? Thanks...
 

Ralpht

New Member
Correct me if I'm wrong but, assuming you have fresh batteries, you will always have 6V output. The higher voltage will always overide the lower voltage taps supplied thru the diodes. To get the various output voltages, you'll need a switch to select between batteries.
As the batteries slowly lose capacity, yes the voltage will drop and the next highest voltage will become available but isn't this what will happen on a battery supply anyway? The corresponding drop in voltage will be accompanied by a loss in current capacity. You will not be able to get multiple outputs from this circuit at the same time, if that is what Hippy was alluding to.

Or have I missed something blindingly obvious?


 
 

hippy

Senior Member
Maybe not so obvious :)

Yes, it's always 6V output ... unless you're one battery short. With an unmodified battery box you're stuck until you can find another or have to wire-link over the missing battery. With this the linking is automatically done.
 

leftyretro

New Member
Don't to forget to take into consideration the voltage drop (loss) across the diodes, as Hippy showed in the valuse avalible. Different diode type have different voltage drops.

Lefty



Edited by - retrolefty on 28/08/2007 01:41:58
 

Ralpht

New Member
Ahhh.. yes Hippy.

That makes sense. I never thought of the &quot; I'm one or two battery(s) short &quot; scenario.

 
 

premelec

Senior Member
OK - my 'solution' has been to keep some old shorted NiCds on hand which I put in when I need a bridge.... whatever works!
 

Dippy

Moderator
I'm definitely &quot;one battery short&quot;.

And don't forget that the Vdrop across a diode varies with load/temp too.


Edited by - dippy on 28/08/2007 08:55:52
 
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