Tyrone Posted June 1, 2006 Share Posted June 1, 2006 My 8 month old battery will not hold charge and I have had to use jump leads to start the car since it came back from its latest visit to the engine hospital. I guess I have a short somewhere which is draining the battery. Can someone explain the best way of finding it for a person terrified of electrics? Link to comment Share on other sites More sharing options...
shn7 Posted June 1, 2006 Share Posted June 1, 2006 First thing is probably to put an ammeter in series witht he battery and measure the drain. That way you'll know if the drain is more than just the immobiliser of if the battery is simply kaput. Steve. Not forgetting Percy the Polar Bear Link to comment Share on other sites More sharing options...
DaveMorris Posted June 1, 2006 Share Posted June 1, 2006 How far back do we have to go. 🤔 If you understood the words "ammeter" and "in series" in the above post I think we can get you sorted remotely 😬 Now - do you have an ammeter, or multimeter of any sort ? If so, and if connected in series with the battery, what current is flowing OUT of the battery when nothing is turned on ? (if you havea cut-off switch see if there's any flow when this is turned off). Dave. ps - would say to call me but I'm knacked and off up the wooden hill. Not on site tomorrow but will check this thread p.m. Friday to check on your progress. pps - surprised if the battery is goosed after only 8 months. Edited by - DaveMorris on 1 Jun 2006 22:47:49 Link to comment Share on other sites More sharing options...
LazerBrain Posted June 2, 2006 Share Posted June 2, 2006 Tyrone - which engine do you have? Once the battery has been freshly charged, and the car driven, is there enough charge to start the engine? cheers, Darren. Edited by - LazerBrain on 2 Jun 2006 15:48:10 Link to comment Share on other sites More sharing options...
Tyrone Posted June 2, 2006 Author Share Posted June 2, 2006 It's a 1700 crossflow with wasted spark ignition and a recently installed megajolt. The battery was flat on Wednesday night so I used the jump leads, drove the car for 30+ miles to the Club meeting and the car wouldn't restart immediately after switching off. It still wouldn't start after it had cooled down so I had to jump it again before driving home. I have a multimeter and I know the difference between parallel and in series so I'll try it out tonight. Incidentally, the alternator belt snapped recently, could this have damaged the alternator? The warning light comes on at idle but goes out under normal driving Link to comment Share on other sites More sharing options...
shn7 Posted June 2, 2006 Share Posted June 2, 2006 Tyrone, Sounds like it may not be charging properly from that description. Check the voltage across the battery at idle. You should be getting 14.2 - 14.4ish volts. Has the car been left for long periods with the battery connected on a regular basis? Even with that treatment I would have thought the battery should last more than 8 months. Also have you chekced the battery fluid level? Steve. Not forgetting Percy the Polar Bear Link to comment Share on other sites More sharing options...
duffym Posted June 2, 2006 Share Posted June 2, 2006 Bri , try the in series bit If there is a drain try taking out one fuse at a time to see if one of them stops the drain happening. IYSWIM At least it will be narrowed down a bit. Also check battery voltage when doing nowt and when the engine is running. Off the top of my head somewhere around 14 volts when the engine is running should confirm that the alternator is charging . Sure this has been covered before. Let me know if you want assistance as I have some free time tomorrow. wheels and tyres done what upgrade next? power or handling Link to comment Share on other sites More sharing options...
Tyrone Posted June 2, 2006 Author Share Posted June 2, 2006 The car has sat around for too long! But like Steve, I would have expected it to last a little longer. I have checked the battery fluid levels and all the plates are covered. Mark, we've got guests coming for the weekend for Evie's birthday so protracted spannering is out of the question, I'll be too busy shopping, tidying up and cooking. Link to comment Share on other sites More sharing options...
duffym Posted June 2, 2006 Share Posted June 2, 2006 Ok no worries , let me know if/when you get some free time Enjoy the weekend! Link to comment Share on other sites More sharing options...
cskip Posted June 2, 2006 Share Posted June 2, 2006 It is worth checking that the connectors on the back of the alternator haven't come loss when the belt broke. I had a similar issue when the forth cable on the back of the alternator (the one by itself. I can remember off hand what it does) was not making contact. They only way I could stop the battery drain was to us the kill switch. Probably not this, but it would be easy to check. Skip. West Hants Luddite See CSKIP here Link to comment Share on other sites More sharing options...
DaveMorris Posted June 2, 2006 Share Posted June 2, 2006 Bri, you're having about the same amount of luck as I am. Just had to wip the engine back out (again) to re-modify the partially shortened footwell 🙆🏻 Was being a bit greedy with how much footwell I wanted to keep and found that I couldn't route the d/s pipe thru the gap that I'd left. Also managed to get it into my head that engine mounting bolts are 7/16UNF and order some special cap-heads. Now find that they're NOT 7/16. 🙆🏻again. If/when I ever get the car running again I'll run it in by visiting you - by which time you'll need to be roadworth too. Good luck, Dave Link to comment Share on other sites More sharing options...
Tyrone Posted June 5, 2006 Author Share Posted June 5, 2006 OK, Multimeter on the battery without the engine on showed 13+ volts. Thought I'd try starting the car without jump leads, lo and behold, 'He's alive!'. So what's the craic there With the car at idle the multimeter shows 12 volts. I then disconnected the +ve connection to the battery on the theory that if the car still ran then the alternator was working ish. Anyway, it stopped, conclusion, the alternator is goosed, am I right? The other thought was loose or dirty connections to the alternator but the exhaust was too hot by the time I remembered Clive's suggestion. If it isn't just dodgy connections, where do I get a new alternator from, local motor factors? Do I need to specify it's for a crossflow? Link to comment Share on other sites More sharing options...
Paul Formston Posted June 5, 2006 Share Posted June 5, 2006 Hi Tyrone You don't seem to have a lot of luck with your seven do you, take the Alternater off and take it to a repair specialist much cheeper than buying a new one, I had mine overhauled about a month ago for £10, where abouts do you live there is a good alternater repair specialist between Pen-Y-fford and Wrexham Regards Paul Link to comment Share on other sites More sharing options...
Petrolhead Posted June 5, 2006 Share Posted June 5, 2006 If the voltage at the battery is only 12 volts with the engine running it sounds like the alternator NE7Club Web Site R5 no 65 😬 Link to comment Share on other sites More sharing options...
Tyrone Posted June 5, 2006 Author Share Posted June 5, 2006 I doubt if I have any more troubles than most Paul, it's just that I tend to need more help in sorting them out 😬 This has all been down to a terminal engine failure a year ago coupled with the fact that the car is 20 years old this year. I'm in Darlington so Wrexham is a little far but I may buy aa new one for the weekend and have the existing one repaired in time for Le Mans Classic. Link to comment Share on other sites More sharing options...
Chris W Posted June 5, 2006 Share Posted June 5, 2006 With the car at idle the multimeter shows 12 volts. I then disconnected the +ve connection to the battery on the theory that if the car still ran then the alternator was working ish. Anyway, it stopped, conclusion, the alternator is goosed, am I right? If you undo the positive battery lead while the engine is running you WILL goose the alternator because the regulator detects the battery voltage has fallen (because there's no battery) and raises the alternator voltage to compensate. The alternator output can reach 200v instantaneously then the regulator diodes burn out. Never disconnect the battery while the engine is running. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Tyrone Posted June 6, 2006 Author Share Posted June 6, 2006 So, even if it wasn't, it probably is now, or is that a definite. I disconnected the +ve on advice ☹️ I'm sorry, I promise I won't do it again. Link to comment Share on other sites More sharing options...
Chris W Posted June 6, 2006 Share Posted June 6, 2006 Tyrone I can't say for certain that it will have blown the alternator but I would be surprised if it hadn't. Chris 2003 1.8K SV 140hp see it here Link to comment Share on other sites More sharing options...
Tyrone Posted June 6, 2006 Author Share Posted June 6, 2006 My local Partco has a 29 amp alternator in stock and also list 35 and 55 amp alternators for crossflows. Can someone confirm which is right or better still give me a part number. I'm at work so I can't check it out. Link to comment Share on other sites More sharing options...
Paul Formston Posted June 6, 2006 Share Posted June 6, 2006 Hi again Tyrone yes I remember the engine drama last year, 😳 I think if I was buying a Alternater for a Seven I would pick the 35amp one at fear of being ridiculed by some one on this forum 😬 Regards Paul Link to comment Share on other sites More sharing options...
Tyrone Posted June 6, 2006 Author Share Posted June 6, 2006 On the strength of the post above (which will be below now) I ordered a 55 amp alternator from Partco. It's half the cost of the same one from Caterham. Link to comment Share on other sites More sharing options...
Petrolhead Posted June 6, 2006 Share Posted June 6, 2006 see this here third post NE7Club Web Site R5 no 65 😬 Link to comment Share on other sites More sharing options...
Tyrone Posted June 6, 2006 Author Share Posted June 6, 2006 That's the post I was referring to Pietro. Link to comment Share on other sites More sharing options...
Paul Formston Posted June 7, 2006 Share Posted June 7, 2006 Hi Tyron I told you didn't I, Ok get the 55 amp but theres not a lot of Electrics on a Caterham so I didn't think you would need that much but I stand corrected 😬 Regards Paul Link to comment Share on other sites More sharing options...
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