Newsgroups: sci.electronics From: tchannon@black.demon.co.uk (Tim Channon) Path: cantaloupe.srv.cs.cmu.edu!magnesium.club.cc.cmu.edu!news.sei.cmu.edu!fs7.ece.cmu.edu!europa.eng.gtefsd.com!gatech!howland.reston.ans.net!noc.near.net!uunet!pipex!demon!black.demon.co.uk!tchannon Subject: Re: Lead Acid batteries & Concrete? Reply-To: tchannon@black.demon.co.uk Distribution: world X-Mailer: cppnews $Revision: 1.20 $ Organization: null Lines: 29 Date: Fri, 23 Apr 1993 22:03:16 +0000 Message-ID: <735627796snx@black.demon.co.uk> Sender: usenet@demon.co.uk > Why does a lead acid battery discharge and become dead (totally unuseable) > when stored on a concrete floor? When will people learn! The trouble is the ballast in the concrete and as every fool knows Ballast resistors are used to discharge batteries. Furthermore it is very silly to store the battery with the terminals downwards as you must have done to contact the ballast. Seriously: self discharge (the actual problem, as stated by others) does vary greatly with certain types and freaks show low self discharge. I have in fact seen ordinary automotive batteries which have effectively held full charge for > 2 years so it must be possible. If your garage is heated, store the batteries somewhere cooler but above freezing (flat batteries freeze more easily). Occasionally charge it (once a month?) or even leave it on 'float' charge permanently (special charger, DON'T do this unless you know what you are doing, seriously dangerous). Anouther point is the unsuitability of automotive batteries for things like electric mowers -- they are not generally designed to be repeatedly deep discharged and their life may be greatly shorted. Some early zero maintenance automotive batteries in fact responded to a full discharge with total failure shortly afterwards but modern ones are superb. (6yrs, 95000 miles and counting) TC. E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk