Alternator question

[dth17]

Just had auto etectricain round, as we were having problems with leisure battery blowing fuses he has recommended upgrading alternator, as the one on our van is old, standard
he has advised upgrade of bigger better unit,

what should I be looking for?
what would fit straight on?
do I need to buy new ? or can one be sourced throught a scrap yard / trader
Van is 89 JX 1600cc Turbo Diesel

Any advise would be appreiciated, thanks

[bigherb]

You should have a 65A alternator on there already. if it is working correctly it should be good enough.

[Red Westie]

What is his rational/reason for diagnosing the alternator? is he suggesting that it is overcharging? if so that could be cured by fitting a new alternator/brush pack for under a tenner.
Contact details for the regulator/bush pack supplier:
Mine was £9.70 posted!
Vehicle Electrics (Birmingham Ltd) The aftermarket number for MY alternator (yours may be different) was VERG 1009 but they have a list to cross reference your particular aternator number against so you can order the correct item.
CONTACT VEHICLE ELECTRICS, 166 STOCKFIELD ROAD, ACOCKS GREEN, BIRMINGHAM, B27 6AU. TEL : 0121 706 0688 EMAIL: VEHICLEELECTRICS@AOL.COM

[Plasticman]

Agree with Red W, today unfortunately with labour costs as they are it is not worth diagnosing and stripping and repairing an alt' as the fitting time is the same but they bung a recon/new unit on and dont go stripping down adding labour rates.

Nowadays most of them are fitters as opposed to mechanics and prob' wouldnt know how to do the job.

That said there are enough mechanics about (inc some that post on here) that are switched on enough to diagnose a prob and rectify quick enough to be more cost effective than a swop out.
Mike

[VWCamperfan]

Ok, there's something not quite right here!
If a fuse blows in your plug to your toaster, do they knock down the power station and build a new one because it's been there a few years?
Nope!
What the 'electrician' is saying then, is something along the lines of 'Feed it with more power, see if that cures it'.
I can tell you now, you will be buying a whole load more fuses!
What you need to look at is what rating is the fuse? Is it enough to charge a battery from flat, which can draw many amps (almost as many as the alternator can produce).
Is your wiring heavy enough to upgrade the fuse or will you need to upgrade the wiring to the leisure battery as well?
Always allow extra ampeage in the wiring if unsure but remember to keep the fuse ampeage below that of the ampeage rating of the cable.

[Cafnod]

I dont quite understand.
Fuses are rated on current not voltage.
voltage is whatever the alternator is putting out; default regulator setting if OK, under or over if not.
Current is drawn by whatever load is requiring it, irrespective of regulator condition or performance.
Therefore how is the alternator causing the leisure battery to blow a fuse?
If the leisure battery is drawing more current than the system is capable of delivering without blowing fuses then either;
1 The leisure battery is knackered and constantly trying to recharge above the designed sytem ratings and blowing fuses OR
2 The battery is flat because of high demand due to the amount of 12vdc power you are consuming.
If 1 replace u/s battery. if 2 Your system needs to be uprated, not necessarily with a bigger alternator but with a higher ampage relay and heavier cables.
did the 'auto electrician' drop test the l/battery? Did he do a current /voltage output test on the alternator? Did he test the split charging system for servicability?
I would have thought the first call would be to get the opinion of another auto electrician, perhaps one with a working knowledge of physics.

[Red Westie]

VW camperfan.....I initially thought along those same lines quote 'What the 'electrician' is saying then, is something along the lines of 'Feed it with more power, see if that cures it'.
But then you are making assumptions the new one would put out more power? when infact the old alternator could be over charging.
Cafnod I also understand your interpretation but a regulator charging at 16volts instead of 14 will overheat and boil a battery dry because it isn't regulating charge voltage and current output correctly and yes I do know the difference.
My gut feeling is the leisure battery itself is the most likely culprit here but then we really do need some figures and explainations of the checks the electrician made and why did those checks lead him to recommend a replacement (higher output) alternator?
What fuse is currently blowing? it should be at least 30amps or higher depending on leisure battery size/alternator output.
If you trust the electricians judgement then it does sound like his recommendation is based on an over charge senario and the suggestion to fit a larger higher powered unit is a 'whilst you are at it! you might as well go bigger suggestion' which in itself has nothing to do with the issue to hand.
Rating the split charge circuit, relay and fuse a little higher is a good suggestion as is ensuring the fuse used is rated lower than the current carrying capability of the wiring.
We just don't know enough about this setup to be sure....blind guesswork me thinks.
Martin

[kevtherev]

Agree with Red W, today unfortunately with labour costs as they are it is not worth diagnosing and stripping and repairing an alt' as the fitting time is the same but they bung a recon/new unit on and dont go stripping down adding labour rates.

once removed...

fitting a brush pack is a 10 min job.
Red westie's recommendation is a very very good one as most alternator/starter refurbishers will diagnose for free..
Alternators rarely conk out, it's usually the brush pack or the bearings