Menno van Rij Posted January 22, 2010 Report Share Posted January 22, 2010 (edited) Since my TR is back on the road, there was always something about starting the engine that got my attention: the battery didn't turn the starter motor over that quickly. Mind you, I have a modern style starter in my car. There was always a slight hesitation, always the feeling that the starter motor wasn't as quick as I would have expected from a modern style starter. The last few months, the car has been standing in a fully heated showroom.. Last week, the guys at the workshop decided that it was time to refresh the oil in my car etc and they wanted to start the TR. The battery was flat! The recharged it and a few days later it was flat again! So, they took the multimeter from the shelf and started a fault finding expedition. They discovered that something was drawing a current from the battery of 0,8 Amp, with all electrics switched off! To make a long story short: is was the diode bridge inside the Denso alternator!! That was drawing a current all the time. The problem was easily cured: I went to the workshop earlier this afternoon, took the alternator off and took it to a specialised firm. They replaced the diode in a few minutes and I returned to the workshop and reinstalled the alternator. No current loss after reinstalling! Mind you, this is the second time that modern parts are playing havoc with my car. The first time, last year was a modern style Bosch relay (brand new!) that failed; as a result, the cooling fan didn't work. And now the Denso alternator (fail proof Japanese for g*d sake!) didn't work properly... There will be a moment in the future that I will confess: low tech rulezzz! Menno Edited January 22, 2010 by Menno van Rij Quote Link to post Share on other sites
GUY BENNETT Posted January 23, 2010 Report Share Posted January 23, 2010 Not all Denso parts are made in Japan! Quote Link to post Share on other sites
angelfj Posted January 23, 2010 Report Share Posted January 23, 2010 Since my TR is back on the road, there was always something about starting the engine that got my attention: the battery didn't turn the starter motor over that quickly. Mind you, I have a modern style starter in my car. There was always a slight hesitation, always the feeling that the starter motor wasn't as quick as I would have expected from a modern style starter. The last few months, the car has been standing in a fully heated showroom.. Last week, the guys at the workshop decided that it was time to refresh the oil in my car etc and they wanted to start the TR. The battery was flat! The recharged it and a few days later it was flat again! So, they took the multimeter from the shelf and started a fault finding expedition. They discovered that something was drawing a current from the battery of 0,8 Amp, with all electrics switched off! To make a long story short: is was the diode bridge inside the Denso alternator!! That was drawing a current all the time. The problem was easily cured: I went to the workshop earlier this afternoon, took the alternator off and took it to a specialised firm. They replaced the diode in a few minutes and I returned to the workshop and reinstalled the alternator. No current loss after reinstalling! Mind you, this is the second time that modern parts are playing havoc with my car. The first time, last year was a modern style Bosch relay (brand new!) that failed; as a result, the cooling fan didn't work. And now the Denso alternator (fail proof Japanese for g*d sake!) didn't work properly... There will be a moment in the future that I will confess: low tech rulezzz! Menno Menno: I am very happy that you solved this problem. By chance, did this peoccupy your mind whilst enjoying that warm Florida sun. Seriously, the problem you encountered is quite common. These modern alternators in essence include a small 3-phase, a-c generator and 3-phase, full-wave bridge rectifier. The bridge has 6 diodes. Three of the diodes conduct during the positive half of each phase-cycle and the other three during the negative half of each phase-cycle. Of course the positive conducting diodes block current from flowing whilst the negative are conducting and vice versa. If one of the 6 diodes fails with a short, it will conduct current in the forward and reverse direction. Unless the battery is completely isolated from the car electrical circuitry whilst not in use, there can be this continuous small leakage current. You say 0.80 amps, so a 60 amp-hour battery would be flat in 70 - 80 hours. The repair firm probably replaced the diode bridge. So, you should be good to go. However, this is not a guarentee that it will not happen again. There are some things that you can do to minimize a future incident. 1. install a battery cutt-out switch and use it. Granted this requires discipline, but if you isolate the battery during extended periods when you are not driving the car, there is no way for the battery to drain through the cars wiring. Lucas Battery Cut-Out 2. check your battery voltage once a week. This should be done at tick-over and you should expect between 13 - 14 volts. The higher the better, up to perhaps 14.1. 3. maintain battery with a good quality float charger. But, beware of cheap units. Be sure to buy one that is self-regulating. An over-charged battery is no better than a flat battery. Battery Tender Good luck, Frank Quote Link to post Share on other sites
Menno van Rij Posted January 23, 2010 Author Report Share Posted January 23, 2010 (edited) Frank, You lost me after the first paragraph I don't know a thing or two about electrickery (for the Brits: here's the wizard Catweazle again!). But then again, I'm sure that others will benefit from the technical explanation!! Anyway, I must confess that it didn't cross my mind when I was in Florida! Man, Sanibel was great! In fact, you know the place: Sanibel and Captive are not unknown to you! Henk and Alan found the problem. And last Friday I was in the shop (again, you know the place!) where I took off the alternator and too it to an specialised workshop. They replaced the faulty diode. All things you've pointed out (1,2 and 3) are now under control now. I installed the cut-out and I just replaced the Ctek battery charger for a new one: the old one died earlier this month; my Saab is hooked to the Ctek every night and that car starts every morning without hesitation! The thing is, Henk and Alan stored my TR in their showroom, mirror to mirror with a Rolls Royce and a BMW Batmobile (a real one, not a fake) without hooking it to a battery charger. Wich in fact, is a blessing! Now we had to address a problem we wouldn't have encountered when the car had been on a charger all the time. I hooked the car to a spare Ctek and we're monitoring what will happen in the next couple of weeks. Thanks for the input! Menno For those of you that don't know what a BMW batmobile is: EDIT: somehow, the pic of the BATmobile went AWOL. Stangely enough, I can see the URL on the line above the one I writing now, but there's nothing in the posting. So, a retry... Menno Edited January 23, 2010 by Menno van Rij Quote Link to post Share on other sites
ianc Posted January 23, 2010 Report Share Posted January 23, 2010 I have a battery isolator mounted on the lower edge of the left side of the dashboard on my TR4, and I use it whenever I leave the car (including when purchasing petrol). After all this prolonged snow, ice, salt & grit, I decided this morning that the recent heavy rain should have cleared the salt from the roads, so the beast needed a run after a month sitting in the dry, but cold, garage. I hand-primed the carburettors and there was no problem starting because the battery hadn't lost charge. A simple modification, as the isolator cost me £10 at the Triumph Spares Day (Stoneleigh) in 2008, and I bought a spare at the NEC in 2009 for £17.50. Ian Cornish Quote Link to post Share on other sites
dykins Posted January 23, 2010 Report Share Posted January 23, 2010 For those of you that don't know what a BMW batmobile is: Regards Peter Quote Link to post Share on other sites
angelfj Posted January 25, 2010 Report Share Posted January 25, 2010 Frank, You lost me after the first paragraph I don't know a thing or two about electrickery (for the Brits: here's the wizard Catweazle again!). But then again, I'm sure that others will benefit from the technical explanation!! Anyway, I must confess that it didn't cross my mind when I was in Florida! Man, Sanibel was great! In fact, you know the place: Sanibel and Captive are not unknown to you! Henk and Alan found the problem. And last Friday I was in the shop (again, you know the place!) where I took off the alternator and too it to an specialised workshop. They replaced the faulty diode. All things you've pointed out (1,2 and 3) are now under control now. I installed the cut-out and I just replaced the Ctek battery charger for a new one: the old one died earlier this month; my Saab is hooked to the Ctek every night and that car starts every morning without hesitation! The thing is, Henk and Alan stored my TR in their showroom, mirror to mirror with a Rolls Royce and a BMW Batmobile (a real one, not a fake) without hooking it to a battery charger. Wich in fact, is a blessing! Now we had to address a problem we wouldn't have encountered when the car had been on a charger all the time. I hooked the car to a spare Ctek and we're monitoring what will happen in the next couple of weeks. Thanks for the input! Menno For those of you that don't know what a BMW batmobile is: EDIT: somehow, the pic of the BATmobile went AWOL. Stangely enough, I can see the URL on the line above the one I writing now, but there's nothing in the posting. So, a retry... Menno Menno: Please say hello to Henk and Alan, I am happy for you that they sorted out the problem All the best, Frank Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.