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posted on April 16th, 2003 at 07:20 AM
bigger Alternator/Generator
I have a 2ltr motor and was wondering if a bigger output alternator/generator is availablefor it and how bigger can you go.
mainly to run larger spotlights ,fridge and other accessories for night trips
MIKE.
VW'S DON'T LEAK OIL, THEY JUST LEAVE THEIR MARK !!!
Robo
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posted on April 16th, 2003 at 07:48 AM
Hi sand kombi
I too wanted a bigger output alternator, and found someone who was modifying watercooled alternators (75 Amp) to fit the old aircooled TIV motors,
they stopped doing this because it was frying other componants, that were not designed to carry the extra load.
I was running 100-65W H4 globes in the headlights, I have dumped these for Xenon globes 55-60W with a small loss in illumination but I have saved
some of the total output, as for the fridge and other accessorys, you should have a seperate fused circut, running off a second battery in a dual
battery system, hooked up with a solenoid (isolator) that charges the second (deep cycle) battery, all these componants should be matched for optimum
performance, you cant just chuck any old stuff together and have it work, well it may but not properly. A lot of the four wheel drive accessory mobs,
or battery centers will sell a package system, or try an auto electrician, the problem with Kombi's is the battery's are a long way apart,
on opposite side of the body.
Some one on the fourm will have specialist knowlage I am sure.
I have tried to find a higher output alternator system for quite a while now and have found nothing that will work, you just have to manage the
output that came from the factory.
Rob.....
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Member of DMLRK.....Die Mittler Lebuns Resto Komeradschaft
sand kombi
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posted on April 16th, 2003 at 04:14 PM
Thanks for the information, it's not going to be as straight forward as I thought.:beer:beer
MIKE.
VW'S DON'T LEAK OIL, THEY JUST LEAVE THEIR MARK !!!
KruizinKombi
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posted on April 16th, 2003 at 04:53 PM
It never is mate!! :o
I haven't actually done it yet, but I see no reason why putting in a higher output alternator should be a problem. Every alternator in my shed is
approximately the same size, so space shouldn't be a problem. I've just compared my VW alternator with one on a Chrysler V8 and they look
quite similar in dimensions - the pulley seemed to line up correctly, the mounting points were very close to the same, and I think that the cooling
tin on the rear of the VW alternator could even be adapted to the Chrysler alternator by moving a few holes in the tin. I expect that a similer
alternator could be found with a higher output.
The question is, why do you need a higher output?
Deep cycle batteries like Robo mentioned, are a good idea because you can run them completely flat without damage, and they provide a heavier constant
current than a standard lead-acid battery. Lead-acid batteries can provide higher current, but only for short periods, such as starting a car. They do
not work so well for constant long term power draws such as fridges or thumping stereos though. The Deep cycle is a good idea. :thumb
I would suggest that you:
(1) ensure that all accessories are running of a seperate Deep Cycle battery, so as not to run the main (starting) battery flat. Any accessory that
you use while the car is not running (stereo, heater fan, cigarette lighter, even headlights) can be run off the Deep Cycle battery.
(2) fit an automatic isolator that charges the main battery first, then charges the extra battery(s) automatically once the main is adequately
charged.
This way your starting battery is kept charged as per usual with no ill effect caused by your accessories. If you haven't driven enough to charge
your batteries, your fridge may stop running in the middle of the night, but your engine will still start in the morning!! :thumb
It's only when you try to charge both (or all) your batteries at once that the alternator would not be able to cope with the load. A bigger
alternator would charge them faster, but it won't stop the battery running flat when you're stopped for the night anyway. A good 2nd battery
setup is a much better investment.
Kruizin Kol
mnsKmobi
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posted on April 17th, 2003 at 11:19 AM
A minor point of clarification. A deep cycle battery is "damaged" (i.e. its lifespan is reduced) by running it completely flat. The
difference is that they can be run flat a lot more times than a standard car battery. However, the less times you run them flat, the more life you
will get out of your deep cycle battery.
aussiebug
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posted on April 22nd, 2003 at 03:24 PM
I feel the need to put my 2 cents worth in here too.
It's not JUST the ampere output of the alternator, it's how far (how long) you drive too.
If you have a set of spot lights, a big stereo, fridge, you have to add up the amps to check if it's under the alternator's output.
For example - the igntion system is about 5 amps, the tail lights about 1 amp, the headlights about 8 amps and the fridge - what - 10 amps?? And add a
set of 2 x 100 watt spots for another 16+ amps.
That's about 40 amps, so a 50 amp alternator is still just fine - the battery(s) will not go flat whilst the engine is running.
But lets say you've tried to run the fidge overnight on the extra battery and you flattened the thing. So when you start up and the fridge is
still on 12v, you still need those 40 amps (if the spot lights are on) just to keep things running and even assuming the normal starter battery
doesn't need much charging, you have to "refill" the other battery. If it is say 50 amp-hours capacity (about right for a normal sized
battery - the amp-hour rating - Reserve Capacity - relates roughly to the physical size of the battery- to how much acid and metal plate there is in
the casing), you'd need to run for more than 5 hours for the remaining 10amps from the alternator to completely charge the second battery.
In fact it will take a little longer than that because you have to put about 140% into a lead acid battery to get 100% out - they are not very
efficient in converting electrical current into chemicals and back again.
So 140% of 5 hours is about 7 hours rdriving before the second battery is fully charged again.
If you use a higher output alternator, the batteries get charged faster, but then it's also an issue as to how much charging current a battery
can accept - the normal auto battery is designed for fast-in, fast-out current flows, but a camper (deep cycle) battery prefers a lower current in
either direction, so JUST putting a larger alternator in may not solve the problem if the battery can't accept all the extra amps available.
As others have said, to get the best performace out of the electrical system with added components and extra batteries, you should seek the advice of
the offroad or caravan places - they should be able to recommend a system which will work for your intended uses.
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic http://www.vw-resource.com
Andy
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posted on April 23rd, 2003 at 02:39 PM
For camping and extended stays don't forget there are good solar panels available these days, and very compact and quiet generators to re-charge
batteries if your not driving far or at all the next day.
I'm only just looking into this at the moment so don't have any details yet.
sand kombi
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posted on April 23rd, 2003 at 08:33 PM
yeah I have thought of that option as a standby charge for the inverter battery ( for the lights in the tent and tarp ) but it was mainly for driving
/ travelling at nights
MIKE.
VW'S DON'T LEAK OIL, THEY JUST LEAVE THEIR MARK !!!
