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Date: Fri, 9 May 2003 08:11:46 +0100
From: "Andy Hookins" <andrew.hookinsnopsamamnopsamodata.co.uk>
Subject: Re: Charging  and othe voltages


"Copernicus" <arpicnopsammail.com> wrote in message news:qadlbvors5vf5rcs8jrmrem2b7oignple2nopsamcom... > On Thu, 08 May 2003 15:02:05 GMT, "Fred W." <arpicnopsammail.com> wrote in message > >news:oosjbvopr1jii1kuh7gqeedqbutv0b6oopnopsamcom... > >> i do not know how accurate the voltmeter is in the edu (Saab 9000S > >> 1992) but the voltage displayed immediately after starting is about > >> 9.2 to 9.4. Isn't this very low? > >> > > > > >the displays and come around back to the voltage that it will then show the > >realtime display which should be around 13.8 volts. > > > >-Fred > > > why, then did it used to show 14.5 or even 14.7 and now I do not get > to 14.0? > > Malcolm Disclaimer: I have only ever had the misfortune to deal with primary cells and have never been involved with re-chargeable cells or chargers, but... AFAIK the EDU voltage display is not particulary accurate in an absolute sennse, but it shouldn't jump around The EDU will show the lowest voltage measured during cranking. If you have a 'weak' battery with a relatively high internal resistance then for a given load current the voltage measured at the battery's terminals will be lower than a 'good' battery. Similarly when charging, if the battery has a high internal resistance then for a given charging current the voltage measured at the terminals will be higher than a good battery. Maybe what happened when you fully discharged your car's battery and then charged it from this depleted condition was a kind of renewing effect, like memory effect in NiCad cells - but there are a lot of fallacies and mistruths about memory effect so please don't quote me on this :-) If so I would imagine the phenomenon will be rather short lived. Of course, just cleaning and re-seating the battery terminals will have a similar effect if there was poor contact there, but you didn't say anything about messing with the battery terminals. AndyH '94 9000 CDE

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