<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=us-ascii">
<META content="MSHTML 6.00.6000.16414" name=GENERATOR></HEAD>
<BODY>
<DIV dir=ltr align=left><SPAN class=554040815-27032007><FONT
face='"Verdana"'>John,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=554040815-27032007></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=554040815-27032007><FONT
face='"Verdana"'>The batteries are primary cells, not
rechargeable.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=554040815-27032007>I understand that 9v
batteries have a high internal resistance and will balance out, but my customers
will inevitably replace only one battery and leave an old low voltage battery
installed. This will drain the new battery into the old one and shorten the life
of the unit. The end result will be that the customer will blame the
machine.</SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=554040815-27032007></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=554040815-27032007><FONT face='"Verdana"'>I
think that either the PNP or P channel MOSFET solution will work pretty well.
I'll have to prototype it and try it out.</FONT></SPAN></DIV>
<DIV><SPAN lang=en-us><FONT face="Arial Black"
color=#800000></FONT></SPAN> </DIV>
<DIV><SPAN lang=en-us><FONT face="Arial Black"
color=#800000>Rick</FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma><B>From:</B> jdrumm9015@aol.com [mailto:jdrumm9015@aol.com]
<BR><B>Sent:</B> Monday, March 26, 2007 3:08 PM<BR><B>To:</B> Rick
Bickle<BR><B>Cc:</B> dprglist@dprg.org<BR><B>Subject:</B> Re: [DPRG] Batteries
in parallel<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV><SPAN contentEditable=false
style="DISPLAY: inline-block"></SPAN>Rick,</DIV>
<DIV> So? Just call it "charging". Are the 9V batteries you
plan on using rechargable or primary cells?</DIV>
<DIV>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.</DIV>
<DIV> </DIV>
<DIV> 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.</DIV>
<DIV> </DIV>
<DIV>Regards,</DIV>
<DIV>John Drummond</DIV> <BR>-----Original Message-----<BR>From:
rbickle@intconsys.com<BR>To: dprglist@dprg.org<BR>Sent: Mon, 26 Mar 2007 10:45
AM<BR>Subject: [DPRG] (no subject)<BR><BR>
<STYLE>.AOLPlainTextBody {
FONT-SIZE: 12px; MARGIN: 0px; COLOR: #000; FONT-FAMILY: Tahoma, Verdana, Arial, Sans-Serif; BACKGROUND-COLOR: #fff
}
.AOLPlainTextBody PRE {
FONT-SIZE: 9pt
}
.AOLInlineAttachment {
MARGIN: 10px
}
.AOLAttachmentHeader {
BORDER-RIGHT: #7da8d4 1px solid; BORDER-TOP: #7da8d4 1px solid; BACKGROUND: #f9f9f9; FONT: 11px arial; BORDER-LEFT: #7da8d4 1px solid; BORDER-BOTTOM: #7da8d4 1px solid
}
.AOLAttachmentHeader .Title {
PADDING-RIGHT: 3px; PADDING-LEFT: 3px; BACKGROUND: #b5ddfa; PADDING-BOTTOM: 3px; FONT: 11px arial; PADDING-TOP: 3px
}
.AOLAttachmentHeader .FieldLabel {
PADDING-RIGHT: 10px; PADDING-LEFT: 9px; BACKGROUND: #f9f9f9; PADDING-BOTTOM: 1px; FONT: 11px arial; COLOR: #000000; PADDING-TOP: 1px
}
.AOLAttachmentHeader .FieldValue {
BACKGROUND: #f9f9f9; FONT: 11px arial; COLOR: #000000
}
.AOLAttachmentHeader A {
COLOR: #2864b4; TEXT-DECORATION: none
}
.AOLImage A {
COLOR: #2864b4; TEXT-DECORATION: none
}
.AOLAttachmentHeader A:hover {
COLOR: #2864b4; TEXT-DECORATION: underline
}
.AOLImage A:hover {
COLOR: #2864b4; TEXT-DECORATION: underline
}
.AOLWebSuiteCompose .AOLPicturesFullSizeLink {
OVERFLOW: hidden; WIDTH: 1px; HEIGHT: 1px
}
.AOLWebSuite .AOLPicturesFullSizeLink {
OVERFLOW: hidden; WIDTH: 1px; HEIGHT: 1px
}
BODY {
BORDER-RIGHT: 0px; BORDER-TOP: 0px; FONT-SIZE: 10pt; BORDER-LEFT: 0px; BORDER-BOTTOM: 0px; FONT-FAMILY: "Verdana"; BACKGROUND-COLOR: white
}
.AOLWebSuiteCompose P {
PADDING-RIGHT: 0px; PADDING-LEFT: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-TOP: 0px
}
IMG.managedImg {
WIDTH: 0px; HEIGHT: 0px
}
IMG.placeholder {
BORDER-RIGHT: #dadad6 1px solid; BORDER-TOP: #dadad6 1px solid; BACKGROUND: #f4f4f4 no-repeat center center; BORDER-LEFT: #dadad6 1px solid; WIDTH: 275px; BORDER-BOTTOM: #dadad6 1px solid; HEIGHT: 206px
}
</STYLE>
<DIV id=AOLMsgPart_3_6377f6ff-6a31-4623-9597-6c453343e296>
<DIV><FONT face=Arial>Hello all,</FONT> </DIV>
<DIV><FONT face=Arial>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?</FONT></DIV><BR><BR>
<DIV><FONT face="Arial Black" color=#800000>Rick</FONT> </DIV></DIV><!-- end of AOLMsgPart_3_6377f6ff-6a31-4623-9597-6c453343e296 -->
<DIV class=AOLPlainTextBody
id=AOLMsgPart_4_6377f6ff-6a31-4623-9597-6c453343e296><PRE><TT>_______________________________________________
DPRGlist mailing list
<A href='javascript:parent.ComposeTo("DPRGlist%40dprg.org", "");'>DPRGlist@dprg.org</A>
<A href="http://list.dprg.org/mailman/listinfo/dprglist" target=_blank>http://list.dprg.org/mailman/listinfo/dprglist</A>
</TT></PRE></DIV><!-- end of AOLMsgPart_4_6377f6ff-6a31-4623-9597-6c453343e296 -->
<DIV class=AOLPromoFooter>
<HR style="MARGIN-TOP: 10px">
AOL now offers free email to everyone. Find out more about what's free from AOL
at <A
href="http://pr.atwola.com/promoclk/1615326657x4311227241x4298082137/aol?redir=http://www.aol.com"
target=_blank><B>AOL.com</B></A>.<BR></DIV></BODY></HTML>