TheBeastie Posted January 4, 2014 Share Posted January 4, 2014 Just been to start The Beastie only to find flat battery. Switched on internal jump and still not enough so brought out my spare big battery and jump leads which did start it up. Now moved it to a better location for maintenance (bang goes today's walk!) and confess to being perplexed. My old charger failed just before Christmas - I had noticed the battery had got discharged thinking it was due to the earth fault on the sidelights (now fixed) - so got a brand new Ctek automatic multi-stage charger and charged up both batteries which passed with flying colours and a nice 12.6V. Did a run up to Angus for Hogmanay and then back again on New Years Day (about 85m each way) without any problem. Certainly it was windscreen wipers, headlights and heater all the way but a good decent speed run. Yesterday had to go out and she started but thinking back it was not "normal service". So something is knobbling the batteries. Once I had got her moved and the seat box open I found 11.85V on the main battery and 12.0V on the secondary battery. Had not been running any radios and find it hard to think that just trying one turn on engine using the internal jump would knock out the secondary battery. Is there any standard operating procedure to troubleshoot this sort of thing? Seems to me it must be inadequate charging from the alternator or else some sort of current drain running when ignition is off but not really sure where to start. Currently charging up the main battery. However I suspect this will just get me going rather than resolving the issue. Any suggestions would be most welcomed! Quote Link to comment Share on other sites More sharing options...
smallfry Posted January 4, 2014 Share Posted January 4, 2014 Measure the voltage on the batteries with the engine running. Should be around 14.4 volts. if its lower than this, the alternator is not charging properly. Try all the earths though..................... Does the secondary battery have some sort of changeover switch or blocking diode, or is it just wired in parallel with the primary ? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted January 4, 2014 Share Posted January 4, 2014 Have you any means of disconnecting the batteries - isolator? It could be the batteries are both dying, so if you isolate them from the vehicle and they still go flat look there. Likewise if they stay charged, look at the vehicle If you have a parasitic drain, leaving them connected and on charge will just mean the charger feeds the drain - this one I know from experience. I also have an ammeter that plugs in to a standard blade fuse holder, that will tell you if there's current flowing in that circuit, and you will know whether there should be or not. Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted January 4, 2014 Author Share Posted January 4, 2014 Thanks. The second battery is on an X-Eng split charge so should only be in parallel with the primary when the engine is running - so yes, if it is down too it looks more likely it is something happening whilst the engine is on rather than off. Cannot quite get my head around how I can diagnose the problem. Will check charge rate when engine running once main battery is charged enough to get the old girl started. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted January 4, 2014 Share Posted January 4, 2014 Short term I'd charge both, disconnect split charge, see what happens. 24 hours will probably be enough to show if there's a problem, and the disconnected battery should remain charged if it's healthy and disconnected. Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted January 4, 2014 Author Share Posted January 4, 2014 Thanks that sounds like a fair plan. Will see where I get to. May as well also just take all the connections off all four of the terminals since that isolates things completely back to the individual batteries. Preumably if the voltage drops by more than a few hundred mV from fully charged then it is the battery that is pooped? Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 4, 2014 Share Posted January 4, 2014 Have you got a multimeter with ammeter functionality? Put it in line with one of the battery leads with everything off to see if there's any draw. Don't turn any loads on though, you'll pop the fuse in the meter. Quote Link to comment Share on other sites More sharing options...
Steve King Posted January 4, 2014 Share Posted January 4, 2014 Have you got a multimeter with ammeter functionality? Put it in line with one of the battery leads with everything off to see if there's any draw. Don't turn any loads on though, you'll pop the fuse in the meter. That is the way I'd do it. If you then start pulling out fuses one by one, you can see where any current is going. Quote Link to comment Share on other sites More sharing options...
AMB Posted January 5, 2014 Share Posted January 5, 2014 I'd agree with the above. Suggest 1) check charging voltage on fast idle - should be around 14.5v depending on temperature 2) switch on a good load (headlights, wipers etc) and check charging voltage. Will drop, perhaps to 13.5 due to wiring losses. 3) fully charge the batteries then leave them disconnected (24-36 hours) to see whether they hold charge 4) Take an old fuse (or blow a new one!) and make up a test ammeter lead to plug into the fuse box to see where the current is going (engine on and off) Earths are always suspect. Doesn't take much to drop a volt or so. Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted January 5, 2014 Author Share Posted January 5, 2014 Well overnight charging has now got both batteries passing the Ctek charger test saying that they are both charged and holding charge. The voltage looks good on both batteries and I can certainly start the old girl now. When I run engine at tickover I am getting 14.4V on both batteries which suggests that alternator and split charge are both working OK. I did a quick ammeter check and that seemed to be OK but I need to double check the main lead off the battery since with the isolator switched on there was some current. I think it is the clock, but I need to make sure that it is just that. It was too damned cold to work out precisely what current it was that was running (need Nobel Prize to work it out on my multimeter - or perhaps I am just dim!). I will try checking the voltage on the batteries at 6 hourly intervals to see what is happening there. Trying to work out AMB's suggestion #4 - presumably drill through the plastic bit and connect a cable to each leg of the fuse?? Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 5, 2014 Share Posted January 5, 2014 You could make one by taking a fuse apart, or buy something like this. http://www.ebay.co.uk/itm/Sealey-TA123-Car-Fuse-Adaptor-Lead-Set-Standard-Fuse-/130668438537?pt=UK_Hand_Tools_Equipment&hash=item1e6c722409 Quote Link to comment Share on other sites More sharing options...
cackshifter Posted January 6, 2014 Share Posted January 6, 2014 Totally agree with AMB et al, I had a problem with a duff alt - charged fine till you put a lot of load on, so couldn't handle many short journeys. Car ran fine for weeks in good weather. With a full electrical load and the engine just off idle, you should be able to see 14.4v between the alt output terminal (the one with the thickest cable) and a handy earth eg the engine. Anything less than 14 and you have a duff alternator. If you measure voltages at the alt itself there are no voltage drops involved, so it should stay around the 14.4v mark (slow wipers are a sign of low voltage, as a rough and ready assessment). If you get to suggestion #4 , try just a small bulb across the fuse contacts, which will limit the current. If the bulb lights brightly you know that is not good, try the amp meter in series with the bulb(which will protect the meter). If you are getting more than about 20ma look for a problem, though some things like a radio with CD take a big current but just for a few seconds. Quote Link to comment Share on other sites More sharing options...
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