veletron Posted July 30 Share Posted July 30 2015 Fiat Ducato When I start the engine, there is only 11.8V on alternator D+. Step comes in and fridge switches to 12V. B2B is on D+ Sense mode (not voltage sense mode) so that will simply be pulling current from the battery regardless. Engine note is noticably higher due to no load from alternator I guess. 2-5 mins later, habitation panel beeps low engine battery voltage, battery light comes on on dash, no current through b2b. Switch off and restart and cycle repeats. I have disconnected B2B, set fridge to run on gas rather than AES and hooked solar up to only charge engine battery - all as a kind of get me home measure (im 250 miles away in the highlands). Anyway, guesses re the fault please! The alternator belt is good. Kind Regards Karen Quote Link to comment Share on other sites More sharing options...
Labby Posted July 30 Share Posted July 30 The problem could be a faulty engine to body earth cable connection the terminals can corrode internally . If you have jump leads try one as a temp. earth connection between the engine and body to see if it helps. Quote Link to comment Share on other sites More sharing options...
onecal Posted July 30 Share Posted July 30 (edited) Hi I would check you earths and all connections , It maybe also your alternator needs replacing .If you have a DC clamp meter see what Amps are at the battery when the engine is running Regards Edited July 30 by onecal Quote Link to comment Share on other sites More sharing options...
veletron Posted July 30 Author Share Posted July 30 Clamp meter is at home, but will try the jump lead trick - that said, if there was an issue with the engine earth strap, I suspect it would not even turn over! Quote Link to comment Share on other sites More sharing options...
Labby Posted July 30 Share Posted July 30 (edited) If the jump lead earth does not help , have a look at the connections at the positive terminal plate on the starter battery , under the cab floor, also , if you can get to it , the alternator main output connection at the starter motor (the same cable may be being used as a return/supply to/from the starter battery positive terminal . Is the charging light working on the dash display (coming on when ignition key on) or is it staying on when engine running ? Edited July 30 by Labby Quote Link to comment Share on other sites More sharing options...
veletron Posted July 30 Author Share Posted July 30 @Labby Light goes out initially for a 2-5 mins and then comes back on again. All fuses/connections on the main plate on top of battery positive seem good. I will get it up on some ramps later so I can get to starter motor and check those connections. I dont believe that the cable is shared directly, but prob goes back to a junction box somewhere. There is also a fuse box under bonet that ill take a look at. I have a 460AH leisure battery so intending to tie this in after engine start as a 'get me home' measure. I have spare cable hanging about in the van. Cheers for tips, all! Pain in the neck!! Quote Link to comment Share on other sites More sharing options...
Labby Posted July 30 Share Posted July 30 (edited) The main power cable connection at the starter is normally also the junction for the alternator output power , the cable at the starter goes to the starter battery for starter supply and also used for alternator feed into the starter battery.(although later Vans may use a separate 70amp Midi alternator fuse/supply cable at the battery plate) Regarding the possible earth problem have a look sometime at www.aandncaravanservices.co.uk , Fiat/Peugeot earth strap problems , as it may help in the future even if it is not the cause of the problem at this time. Edited July 30 by Labby 1 Quote Link to comment Share on other sites More sharing options...
rayc Posted July 30 Share Posted July 30 (edited) The battery connects to the B+ output of the alternator via the CAL4 fuse on the battery fuse board and the starter motor. With the engine running what is the voltage at the under bonnet jump start terminals? A020 is the starter and A010 the Alternator on the attached drawing. Edited July 30 by rayc Quote Link to comment Share on other sites More sharing options...
veletron Posted July 30 Author Share Posted July 30 Hi thanks. I'll check tomorrow, for obvious reasons I dont want to keep starting the engine! When i measured the D+ that does stuff like signal step in, start the B2B, switch fridge to 12V, tell nordelettronica pannel engine running etc it was 11.7V with engine running 0V engine off. Voltage at van battery did not rise with engine running (on either side of fuse). Ive pulled the DRL's just now, and will prob reverse my B2B and drop it to half power mode. That should get be home so long as headlights not needed. Weather is to go a bit rubbish after tomorrow anyway. Quote Link to comment Share on other sites More sharing options...
veletron Posted July 30 Author Share Posted July 30 Reverse charging van battery from hab battery. Will leave that on until the current drops off maybe the solar I get on the way down the road Tomorrow/Thursday is enough to get me home. Not sure what the ECU, pumps and essential electrical gubbins use wattage wise! Quote Link to comment Share on other sites More sharing options...
rayc Posted July 30 Share Posted July 30 2 hours ago, veletron said: Voltage at van battery did not rise with engine running (on either side of fuse). Sounds like the alternator is not working or the path from the alternator B+ terminal to the CAL4 fuse via the starter motor has a problem. Bread and butter stuff for a competent auto electrician to check - 15 minutes tops. Quote Link to comment Share on other sites More sharing options...
veletron Posted July 30 Author Share Posted July 30 Agreed, and if it was not such an utter ^£%#& to get at the alternator, I would be able to test it myself. What eejit decided to stuff it down the back of the bulkhead?!? Quote Link to comment Share on other sites More sharing options...
onecal Posted July 30 Share Posted July 30 Hi True. Makes you think why people keep buying them Regards Quote Link to comment Share on other sites More sharing options...
colin Posted July 31 Share Posted July 31 I've had a intermittent problem with the alternator not providing charge after starting after a long period of non use, so far revving engine fairly high has got it working. Quote Link to comment Share on other sites More sharing options...
MikeF Posted August 2 Share Posted August 2 On 30/07/2024 at 13:28, veletron said: guesses re the fault please! You may have killed the alternator. Your Sterling B2B will pull over 70 amps, 1000 watts from the alternator. The van electrical system can take around 50 amps with everything on, more if the starter battery is low. The standard alternator can deliver in the region of 100 amps at engine idle speed. A 9 year old alternator may be past its best. Unless the gearbox to chassis 'earth' strap has been changed recently it will be introducing a volt drop at high currents. This results in everything working harder and hotter. Quote Link to comment Share on other sites More sharing options...
veletron Posted August 6 Author Share Posted August 6 (edited) I made it home anyway without messing up my holiday too much. Hooked up leisure batteries to engine batteries via B2B reversal. Drew about 150AH from leisure batteries for the 250 mile journey home over a few days with various bike rides and walks done on the way south. Tested it out on driveway with a wee 12V light rigged up between battery +ve and alternator. Still cant say alternator or regulator fault, but no output from the alternator. Even changing the combined brush pack and regulator needs alternator removal due to its location so I just bought a 'nearly new' alternator off ebay and have booked it into garage for fitting. Thanks to folks who responded here. Ma 'new' van is getting old! In case its of-use, the alternator fitted to my van is a Bosch 504 385 134 rated at 150A Yes, I have always used it with a B2B, so its had a pretty hard life I suspect. Edited August 6 by veletron 1 Quote Link to comment Share on other sites More sharing options...
veletron Posted August 20 Author Share Posted August 20 Just to follow this up.... Bought me a second hand bosch alternator off ebay for £72 (identical unit). Looked at DIYing it - nightmare job. Was then away for a couple weeks, but got garage to fit it today. Cost me £270 just to have the thing fitted - they did comment that it 'was a right pig of a job' ! Suspect their hourly rate is £150... Kept the old alternator, prob get it sorted as a spare esp if I determine that its the brush pack/regulator thats failed. Quote Link to comment Share on other sites More sharing options...
arthur49 Posted August 21 Share Posted August 21 Glad you're sorted and back on the road. Even better when there is feedback re "cure" (rather than ask a question and disappear) Thank you Quote Link to comment Share on other sites More sharing options...
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