DPRG mailing list archives: [DPRG] Batteries in parallel

Mon Mar 26 15:07:53 CDT 2007

Rick,
  So?  Just call it "charging".  Are the 9V batteries you plan on using rechargable or primary cells?
If they are primary cells (i. e. non-rechargeable) just live with the slight differences in cell voltage and they will all balance out in a very short amount of time and the batteries would enter the operational mode of life. Eventually the first one runs out of chemical activity and starts to drag the pack down.  A low voltage alarm would sound (like a smoke detector) and you would replace all the batteries, since they are all nearing death.

  However if you plan on re-charging the 9V batteries insitu and not replacing them you will need isolation devices as you are  planning on right now.

Regards,
John Drummond

-----Original Message-----
From: rbickle at intconsys.com
To: dprglist at dprg.org
Sent: Mon, 26 Mar 2007 10:45 AM
Subject: [DPRG] (no subject)

Hello all, 
I've got an application where I want to put a number of 9v batteries in parallel to increase the current capacity. I need to prevent the higher voltage cells from discharging into lower voltage ones, but I don't want to have the 0.7 volt diode drop. (Germanium diodes don't have enough current capacity.) Doe anyone have a circuit to do the same job as diode isolation without the voltage drop?

Rick 
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