virden Posted July 16, 2014 Share Posted July 16, 2014 When not in use I always connect the car to a trickle charger, and the charging light always comes on for a minute or two. Yesterday I returned from a100+ mile run (headlights off) and after connecting found the charge light stayed on for more than ten minutes. Is this a sign of impending battery/ alternator failure? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 16, 2014 Member Share Posted July 16, 2014 Trickle charger or conditioning charger? Jonathan PS: Probably nothing to worry about. Link to comment Share on other sites More sharing options...
Mort Posted July 16, 2014 Share Posted July 16, 2014 Probably nothing. I suspect there would be other symptoms if you had a problem. Question: why do you habitually put your battery on charge? Do you have a battery drain problem, or do you only use your Seven very occasionally? I ask because mine will happily sit for a month or more if needs be without issue, and there is a train of thought that it's better if the battery is not put on permanent charge, but is only put on charge at regular intervals if left unused for long periods of time. Not being critical, just curious. Link to comment Share on other sites More sharing options...
FramerateUK Posted July 16, 2014 Share Posted July 16, 2014 I tend to put mine on if I know the car is going to be left for more than a few weeks. I've never experience a flat battery though, it's just a precaution... Link to comment Share on other sites More sharing options...
virden Posted July 16, 2014 Author Share Posted July 16, 2014 Mort, It has become a habit after experiencing a flat battery. As I live close to the sea, it is very damp and I never know from one day to the next what the weather will be like, also I am away a lot of weekends, so a fortnight or more can pass between engine start ups. I have taken on board your comments and shall leave it off charge to see what happens. Thanks all Link to comment Share on other sites More sharing options...
Mort Posted July 16, 2014 Share Posted July 16, 2014 Jonathan asked whether your charger was a trickle charger or a conditioning (float) charger. If it's the former then leaving it on charge for long periods can damage the battery. If it's a conditioning charger then it will sense when the battery is fully charged and stop charging. When it senses that the battery is below a given threshold and requires charging it will automatically do so, and so on. A conditioning charger can theoretically be left on all the time, although I wouldn't choose to do that myself. Edited by - Mort on 16 Jul 2014 15:10:38 Link to comment Share on other sites More sharing options...
shn7 Posted July 16, 2014 Share Posted July 16, 2014 And of course assuming it's not a sealed battery do check the fluid levels. Link to comment Share on other sites More sharing options...
sjmmarsh Posted July 16, 2014 Share Posted July 16, 2014 Virden Most conditioning chargers work by detecting the voltage AND the rate at which it is rising. To do this it needs to put the battery on charge for a few minutes before it can decide that the battery is already fully charged. Steve Link to comment Share on other sites More sharing options...
virden Posted July 16, 2014 Author Share Posted July 16, 2014 Thanks all, I now know the difference and guess it is a conditioning charger, which has now been disconnected. We shall see... Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 16, 2014 Member Share Posted July 16, 2014 Lots of us leave 7s on conditioning chargers all the time they're unused. Good advice on checking the fluid. I suggest measuring the battery voltage at rest, during cranking and at 3,000 rpm if you're worried it's on the way out, or you've got a charging problem. Jonathan Link to comment Share on other sites More sharing options...
sjmmarsh Posted July 17, 2014 Share Posted July 17, 2014 JK - what readings would indicate a battery is on the way out? I understand it should be 12.8v at rest and 14+v at 3000 rpm for a good battery, but other than the 'at rest' voltages, don't know what the danger signs are. Steve Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 17, 2014 Member Share Posted July 17, 2014 In everyday language, and as a crude approximation my working guide for typical car systems with ordinary batteries is that you should observe : Rest, fully charged, no load: Voltage > 12.6V. This is not a sensitive early sign of battery failure. But if the voltage is lower there is a problem. Cranking: Voltage > 9.5V. Low voltage while cranking can be the first sign of battery failure. The voltage at the starter is sensitive to high resistance from poor connections etc regardless of the condition of the battery. Charging (say 3,000 rpm to allow for unusual pulleys): Voltage > 13.8V, and usually > 14.2V. This is a test of the charging system, but don't try it without a battery. Electronic systems eg ignition can't be relied on to work below 9.5V. I'm happy to be corrected by the experts. From my experience and the archives: 1 Most problems can be quickly localised with these three tests, which need a multimeter, and sometimes some good jump leads and another car alongside. But in many threads it's hard to extract this information. If you're asking for advice adding the observed voltages is going to save you time. 2 Inspecting, checking and cleaning feeds and earths as early as possible also saves time in the long run. Jonathan Edited by - Jonathan Kay on 17 Jul 2014 08:00:45 Link to comment Share on other sites More sharing options...
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