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Query Alternator issue
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userFiat Ducato
Posted: 7 January 2019 3:18 PM
Subject: Query Alternator issue
 


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Posts: 198
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Location: Dover, Kent


Hi forum members and Happy New Year. Not been on here for quite some time. So hoping there are still alot of familiar, helpful and contributive memebrs on here.

Just have a quick battery/alternator voltage question for Alan really but anyone else who is able to help. Just installed a new starter battery the Exide Premium 100AH 900 CCA to my van as last one packed in during December, and some time last year I replaced the LB for the Varta LFD 90 battery which Alan recommends.

Just had the van in for an MOT and my Mechanic informed me of the conduit with the main LB starter cable in as well as Alternator D+ signal wires and fridge cable had come loose and was rubbing on the Alternator, gone through the sleeve to the copper strands of the 16mm cable to charge LB. Also been having issues with the battery light coming on and going off, then finally staying on, when I investigated the terminal to the D+ on the alternator was a cheap one and had completely rusted and the wires had come away. Anyway cut out the damaged part of the 16mm cable and rejoined and heat shrank, replaced the D+ terminal with a good quality copper one, applied heat shrink to keep everything dry and taped the rest up inside conduit, cable tied everything up. And thought job would be a goodun, but testing the voltage at both SB and LB with the engine running (without 12V Fridge on) voltage is showing only 13.30V on LB and 13.38V on the SB

With the fridge switched on the voltage at the starter battery is 12.86V and the leisure battery is 12.69V surely this is not right is it?

Is my Alternator had it as well now? Haven't got round to checking the voltage at the Alternator yet, checked for voltage loss at the battery terminals and earth terminals and they are fine.

useraandncaravan
Posted: 7 January 2019 4:10 PM
Subject: RE: Query Alternator issue
 
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Posts: 2177
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Location: Conwy, North Wales


It is very unusual for the Alternator to only 'part work', they are usually putting out full charge or dead.
Therefore as you have 13.38v at the Starter battery the Alternator is almost certainly working.

There could be so many different issues causing the problems you see, but we would suggest the most likely and easiest to tackle first is poor Earth connectivity between the Alternator body and the Starter Battery negative clamp.

Have a read of the last part of this page where it covers 'Poor Earth connectivity trouble shooting' -
http://www.aandncaravanservices.co.uk/add-a-second-battery.php
Obviously rectify any problems that show up as per the web page.

Regardless of what you find, running a new 6 - 10 mm 'Black' cable from the Alternator body to the Starter battery negative ( and/or the Habitation battery negative).will reap rewards on a newish vehicle, but even more beneficial on an older 10+ years british motorhome.


If the original B+ cable is only 16mm, then running a new, additional 6 - 10mm 'positive' cable from the B+ just for the Fridge will also make a huge difference.
16 mm cable is rated around 100amps, so while it might be just about big enough to handle that amount of current, the voltage drop will be significant.
Having a new single run cable with no intermediate connections for the Fridge should also mean zero 'Charging voltage' drop at the habitation batteries, so benefits both Fridge efficiency and Battery charging..

Also check that every connection from Alternator to Starter battery and on to the Habitation battery plus Fridge is 100% perfect, often the connectors at the battery clamps are poor so benefit from dismantling and cleaning..
The slightest bit of corrosion will hamper things.




Edited by aandncaravan 2019-01-07 4:38 PM
usermikefitz
Posted: 7 January 2019 6:16 PM
Subject: RE: Query Alternator issue
 
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I recommend you remove the alternator from the vehicle and have the unit bench tested. The damage to the cable may have caused a short that could have damaged one or more of the rectification diodes, or voltage regulator, leading to a lower output than the 14v to 14.4v normally generated. If the voltage is 13.38 and drops to 12.86 with some load, (assuming the fridge is fed from the engine battery) it indicates that the alternator has partially failed.
Its also possible that the cable fault resulted in the failure of the batteries.
Although a specialist alternator repair shop could fix the alternator its often more economic to replace the complete unit. A motor factor like euro car parts can supply a replacement for less than £150.
Mike
useraandncaravan
Posted: 7 January 2019 7:36 PM
Subject: RE: Query Alternator issue
 
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Location: Conwy, North Wales


We spent years rebuilding Alternators and Richard and Arwel still do.
The Bosch originals are way superior to the very nasty budget copies, often from Lithuania, that are very poorly made, but cheap.

Not onty was the machining, bearings, and electronic components poor, but the quality of the Copper 'wire' used for the Stator of low quality.
When the copper wire is compared to a Bosch it was thinner, suggesting it's max rating wouldn't be what was on the label..

While their shortcomings might not become apparent in a Car, A motorhome with 3 batteries, triple the load, is a different matter.


I would suggest that if anyone suffers a failed Alternator on a Motorhome that the first course of action should be a repair (using quality parts not the cheap copies) and the next a new Bosch/OEM original.
While it is tricky on some motorhome models, the Alternator regulator and Diode pack can usually be replaced without removing the Alternator.
Testing is also a lot easier 'on the vehicle' than taking it off.

Most motorhome Alternator failures are Regulator or Diode related from being 'electrically overloaded', so usually cheap and easy to repair. But White van or truck Alternator failure, because they cover such huge mileages, tends to have mechanical related failures, like bearings/brushes, so can be a bit more expensive making a new Bosch unit a more cost effective option where high mileages are concerned.



.






Edited by aandncaravan 2019-01-07 7:42 PM
userFiat Ducato
Posted: 7 January 2019 8:23 PM
Subject: RE: Query Alternator issue
 


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Posts: 198
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Location: Dover, Kent


Hi Alan read alI your comments and as usual found them very interesting and informative. I'm affraid my Alternator isn't a Bosch after climbing underneath the van today to check it out. I found out it's a Magneti Marelli 70Amp rate alternator. I would say for a motorhome charging at least 2 batteries and also at times run a 12v fridge as well as run all your normal vehicle things like radio, lights, heater, sat nav, rear view camera, dash cam etc.
Ideally I'd like to upgrade the alternator to a much more powerful one but looking into it for me old 1997 fiat ducato there isn't much choice unlike the newer models with smart alternator up to 180Amps.

Also looking at the size of the main positive cable running from the alternator B+ to the starter battery it looks like 25mm to me. I run the length of fused 16mm cable from my LB to my starter battery. And also ran a 10mm cable via a relay and fuses to my starter battery from my fridge. But yes running the fridge directly from the B+ does make a lot of sense. Also when I fitted my new Leisure battery last year I moved it's location and added a brand new earth 16mm cable to the chassis from the negative.

Any ideas Alan?

Edited by Fiat Ducato 2019-01-07 8:32 PM
useraandncaravan
Posted: 7 January 2019 8:34 PM
Subject: RE: Query Alternator issue
 
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Posts: 2177
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Location: Conwy, North Wales


Fiat Ducato - 2019-01-07 8:23 PM

Hi Alan read alI your comments and as usual found them very interesting and informative. I'm affraid my Alternator isn't a Bosch after climbing underneath the van today to check it out. I found out it's a Magneti Marelli 70Amp rate alternator. I would say for a motorhome charging at least 2 batteries and also at times run a 12v fridge as well as run all your normal vehicle things like radio, lights, heater, sat nav, rear view camera, dash cam etc.
Ideally I'd like to upgrade the alternator to a much more powerful one but looking into it for me old 1997 fiat ducato there isn't much choice unlike the newer models with smart alternator up to 180Amps.

Any ideas Alan?


Magneti Marelli are quality units, I agree 70amp is puny, even for a Car, but I don't think a more powerful Alternator will solve your issues.
.

The new model motorhomes have really powerful serpentine belt drive systems that won't slip too much when a big Alternator is fitted, and you may find that the belt drive is the limitation on your vehicle?

I would imagine that 90a - 110a might be achievable, but I am not an expert on what can be fitted to your particular vehicle.
There is a very helpful man called Richard at ABC electrics who should be able to tell you.
He now runs his own 'shop', but used to rebuild Alternators for Lucas years ago, so he is not just a 'sales' person but knows his stuff.

Find out as much info as you can before you ring him -
Drive belt - is it a V belt or multi rib. If multi rib, how many groves.
Alternator - model number, etc

Richard - 01492 544533




Edited by aandncaravan 2019-01-07 8:57 PM
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