Second Alternator

[Jock The Rock]

Gday

Just wondering if this is a good idea?

I was having a squiz through a thread the other day. From memory isuzurover wanted to fit a second AC compressor to his County. One for the Endless Air and one for the AC. Someone suggested fitting a second alternator and running one compressor off a 12V motor

Now I have been searching for a serpentine pulley for my York compressor, so far the cheapest I've found is $200. And I'm not too keen on turning the original pulley down to accomodate a serpentine belt.

I already have a spare alternator (standard Defender) and I can't imagine it would be too hard to mount that where the AC goes on my 300 Tdi

Then I can do as suggested above. This may also take some of the strain off my alternator; at the moment it will be running my headlights as well as 6 spotlights (Probably not all at once though). As well as the winch when thats going, and the worklights on the roof rack that aren't yet fitted, and the ARB Compressor as well as the 12V inverter.

See where I'm going :p

Then I could find a 12V motor and mount it under the Landy or even better here in this hatch with the York and the tank. I'll still be able to run the V-belt pulley on the York

https://www.aulro.com/afvb/images/imported/2009/08/23.jpg

So what are your thoughts?

And what sort of 12V motor should I be looking for?

Thanks

[Blknight.aus]

it'll work and youd want to be looking at something like a 6 preferabley 9 horse power 12v winch motor

the hardest part will be cooling the motor and the electrics

[Jock The Rock]

it'll work and youd want to be looking at something like a 6 preferabley 9 horse power 12v winch motor

the hardest part will be cooling the motor and the electrics

Was hoping you would reply Dave thanks

I might drop round a few Auto Electrical places this week and see what they have lying about

With the belt onto the alternator should I be looking at making the mount so it will be the AC belt that will run it or get a longer fan belt?

Didn't think about cooling, be nice if I could find something with an inbelt fan :)

When you say electrics do you mean wiring the alternator into the charging circuit?

With the 12V motor I'd be able to just wire it in like a winch wouldn't I?

Thanks mate

[Blknight.aus]

it'll wire up pretty much like a winch yes but then you have to worry about alternator excitation, remote excitation (in case the batteries are properly flat and wont do it for you) and if you retain the AC compressors clutch the fact that it wont hold up against much pressure in the delivery system once the battery voltage drops to about 10v.

the setup in fozzy (ask Redback for the VID which reminds me I still have to send steve my DVD's) is pretty much exactly what your after and thats running of a very primative 2 n70s wired in parallel charged by a 35a alternator.

If you were going to go that way unless you were planning on using the motor to drive the AC compressor Id forgo the second alternator and just put in a decent second battery and controller then wire it up winch style (obviously using a pressure switch to control the solenoids.)

[DeanoH]

Don't forget you'll need separate battery(s) with your second alternator.

Have you thought of making your second system 24 volt? half the currrent draw as 12 volts for the same power, a quarter of the cable power loss or you can use cheaper thinner cable for the same result.

Just a thought.

Deano

[DeanoH]

it'll work and youd want to be looking at something like a 6 preferabley 9 horse power 12v winch motor

the hardest part will be cooling the motor and the electrics

Hi Dave

Just done a bit of maths here, correct me if I'm wrong but 9HP @ 746Watts = 1HP, say 750 to make it easier in my head makes 6750 watts or 6.75 Kw. From a 12 volt source 6750 divided by 12 or 563 Amps. Thats one hell of a big alternator.

My small shed compressor, which I use mainly for pumping up car tyres has a 2HP motor and works fine. Why such a big one here ?

Deano

[Blknight.aus]

over head.

a 6hp motor working against a 2hp load will work easier and run cooler and generally have a nicer life for it compared to having a 2hp motor working flat out.

It will also deal with some minor line loss and lower battery voltages.

[Jock The Rock]

I was thinking 9 Horse was a bit much :)

I am currently runnning 2 Century N70s

So from what I gathering I can't run two alternators in one circuit? I'll have to split the batteries?

As with the clutch on the compressor; I'll have a switch to turn the electric motor on and one to engage the clutch. So if the clutch isn't working for me then I'll weld it up :D

[Blknight.aus]

you can but you wind up with the problem of if the regulators aren't set to exactly the same output voltage then one alternator winds up doing 90+% of the work which kind of defeats the purpose of having 2 alternators in so far as your reason for having 2 alternators goes. Same deal if you have a dicey electrical connection anywhere between any of the batteries and alternators if its all one box'o'tricks.

[Chucaro]

Why fit a second alternator?
Would not be better to fit an alternator with more capacity? :confused:

[roverrescue]

Jock,
put the York compressor on ebay,

Call a wrecker and buy a disco series1 aircon idler pulley, air con tensioner pulley, Sanden air compressor and dryer... or just go to your local auto leccy / AC joint and get above...

Bolt it up and you have air... so much less hassle and it will work and work well.

Unless you want to make it complicated!!!!

Steve

[DeanoH]

Why fit a second alternator?
Would not be better to fit an alternator with more capacity? :confused:

I just bought an alternator for Kayes TD5 it cost $1200, perhaps thats the reason if its similar for Jocks. But technically the best and simplest solution.

Whats the output of the existing alternator ? Kayes TD5 alternator is 120 Amps, if yours is around the same I would have thought it enough for all your extra lights and stuff. eg. you wouldn't have your driving lights and work lights on at the same time so you don't have to dimension for both at once or do you ?

Deano

[Blknight.aus]

doesnt he already have aircon and wants another one for endless air?

[Newbs-IIA]

Sorry for the hijack...
I was thinking of doing a similar thing for my Series IIA. As I have a military motor which is supposed to run dual fanbelts (I don't at the moment) I have a spare set of pullies to run something extra. I was thinking of running a second alternator on the other side of the engine to suppliment my current one when I install my shooting light. The current alternator (old bosch unit, probs 35-40amps max) whines a bit with just the regular lights + spotties so I am a bit worried as to what will happen once I switch the shooting light on.

Can I do this and just run the alternators in parallel? or as some have said - would the regulators have to be exactly setup? Don't particulary want to run dual batteries at the moment... surley there is some leeway with these old trucks

[paulthepilot_5]

Sorry for the hijack...
I was thinking of doing a similar thing for my Series IIA. As I have a military motor which is supposed to run dual fanbelts (I don't at the moment) I have a spare set of pullies to run something extra. I was thinking of running a second alternator on the other side of the engine to suppliment my current one when I install my shooting light. The current alternator (old bosch unit, probs 35-40amps max) whines a bit with just the regular lights + spotties so I am a bit worried as to what will happen once I switch the shooting light on.

Can I do this and just run the alternators in parallel? or as some have said - would the regulators have to be exactly setup? Don't particulary want to run dual batteries at the moment... surley there is some leeway with these old trucks

If you had alternators of the same type you could probably run them off the same regulator, but not a 100% sure if it would be possible. If this can't be done then you are stuck with the problem that Blknight.aus mentioned

Paul

[Blknight.aus]

the regulators and connections have to be matched and perfect.

lets assume that you have perfect connections between the alternators and the batteries but the regulators are .5v apart (13 and 13.5v). We'll call nominal fully charged voltage 13.5v again just to make the math easy

to start with with fully charged batteries (12v nominal) you crank the engine over it fires and your alternators start out putting while the engines spinning up and getting the alternators up to speed to start making output. Once the alternators are up to speed both alternators will be out putting until the 13v point is reached and then the alternator with the lower cutout will cut back its output and is essentially just along for the ride leaving the other alternator to do whats needed to get up to 13.5v Once at 13.5v the alternator will "throttle" its output to maintain the voltage

This is cool up until you get to the point where you start loading up everything.

lets say that you have a 35 amp alternator (which is the standard for an old series) and you put 40 amps worth of load onto it what will happen is that the first alternator will punch out everything its got to try and keep up with the load untill the battery voltage drops down to the point where the second alternator starts to sense that the battery voltage is low so it starts to ramp its power output up. Which is helpful but doesnt let the first alternator ease up at all.

when you get dodgy connections it just changes which alternator cops the abuse because it upsets the balance between the sense line and the charge line roughly speaking the alternator with the worst connection will do the most work but provide the least charge to the system.

Yes, I know that boats (and planes before anyone jumps on that bandwagon) with multiple engines run multiple alternators but theres a difference, each alternator is capable of dealing with the total load of the system and usually each has its own partial load (each engine and its ancillaries) to deal with so there is usually at least some rudimentary form of load sharing.

I'm not even going to look into what happens when you start getting noise and frequency stuff going on partly because its complicated to explain mostly because its ubergeek level stuff and it does me over on the best of days.

[DeanoH]

Can I do this and just run the alternators in parallel? or as some have said - would the regulators have to be exactly setup? Don't particulary want to run dual batteries at the moment... surley there is some leeway with these old trucks

No.

What Dave said.

Even if you got it exactly right when you set it up as the alternators age or you have a fault it will all turn pear shaped.

As Chucaro suggested earlier. The easiest solution is the best, installing a bigger alternator is the best solution.

Deano

[Newbs-IIA]

Thanks Dave... again :D

SO the best way to rectify my problem of possibly burning out the alternator while running my shooting light (remember you generally only idle around paddocks when shooting at night) could not be solved by running twin alternators unless I had a secondary isolated battery which was charged solely by the secondary alternator.

I could auctally see that working... just run a second car battery in the back which runs the shooting light and any other ancillary lights I might need. Then this battery is charged by the secondary alternator and is a completly isolated system form the rest of the car :) It all makes sense now

[Jock The Rock]

Jock,
put the York compressor on ebay,

Call a wrecker and buy a disco series1 aircon idler pulley, air con tensioner pulley, Sanden air compressor and dryer... or just go to your local auto leccy / AC joint and get above...

Bolt it up and you have air... so much less hassle and it will work and work well.

Unless you want to make it complicated!!!!

Steve

I had been trying to track down a AC idler and tensioner, not as easy as it sounds :(

And I like making things complicated :)


Why fit a second alternator?
Would not be better to fit an alternator with more capacity? :confused:

Why fit a second alternator? Because I have one spare already

My original alternator is already a higher capacity. 110 amps strikes a bell but I'm not 100% sure what size it is


I just bought an alternator for Kayes TD5 it cost $1200, perhaps thats the reason if its similar for Jocks. But technically the best and simplest solution.

Whats the output of the existing alternator ? Kayes TD5 alternator is 120 Amps, if yours is around the same I would have thought it enough for all your extra lights and stuff. eg. you wouldn't have your driving lights and work lights on at the same time so you don't have to dimension for both at once or do you ?

Deano

That is a fair point. How much can I run off an uprated alternator?


Reckon I might just go along with it and see what the outcome is. I have a spare deep cycle in the IIA so maybe if I mount that on a seperate circuit, run the charge from the second alternator through that circuit then hook a set of spotties up to that one as well as the compressor

Saves the hassle of stuffing round with wiring the 2 in together

That spare deep cycle is only going to go to waste if I don't use it :(

[TonyC]

the regulators and connections have to be matched and perfect.

lets assume that you have perfect connections between the alternators and the batteries but the regulators are .5v apart (13 and 13.5v). We'll call nominal fully charged voltage 13.5v again just to make the math easy


Dave,
Could it be done using a single external regulator driving both alternators?

Tony

[DeanoH]

Jock

Given your problem a bit of thought here to try and come up with a practical and simple (relative term) solution.

What you've outlined here is two problems. One is do you have enough electrical power to do what you want and the other is having a useful compressed air supply.

I reckon Chucaros suggestion of an uprated alternator along with Steves sugestion re compressor sounded like a good way to go.

If you've already got a 110 Amp alternator and Steves compressor alternative doesn't work for you have a think about this alternative.

Electrical

110 Amps @ 13.5 volts gives you 1485 watts of power to play with in theorey. In practice you can't run your alternator continuously at full output without it failing. So lets say you can get 75% of output continuously and more for short periods, which still gives you a constant 1100 watts to play with. This is a hell of a lot of power and should be sufficent. The big draw items here would be thermo fans if you have them and your lights. Thermo fans could use anything up to 500 watts but can turn on and off according to load, and your vehicle lights, taking a guess here, 55 watts each for the headlights and was it six driving lights ?, say 2 @ 100 watt and 4 @ 50 watt for a total of 510 watts plus whatever the car itself needs. Might seem that we're running close to the line here but havn't considered the battery(s) yet. Batterys hold power which can be used to even out the load thus decreasing alternator load at peak. For example your typical N70 4WD battery is rated around 90 amp/hour capacity. This translates to around 1100 watts of reserve power or, in theory, enough to run your headlights for about 10 hours. If you've got two batterys even better. Think of them as additional resorviors of power when your main supply (alternator) can't meet demand.

I reckon if you wire in your spare battery via a suitable solenoid you should have more than enough power to meet your needs.

Compressor.

Don't know how much air you need and what for but I'll give you a suggestion and see if it fits your needs.

The size of compressor and air tank you will need depends on what you intend to do with it. Heres what I'd do as I reckon its pretty good value.

I'd buy myself one of those 2 HP Chinese compressors from Bunnings, Super Cheap or whatever and a reasonably good 12 volt air compressor. My 2HP compressor with 40 litre tank hose and fittings cost me $90 and my KCI 12 volt air compressor came with my 4WD Action Subscription and is probably worth no more than $150. I'd ditch the 240 volt motor/compressor unit off the tank and connect the 12 volt one in its place. Stick it in the back and away you go. Draws a max of 30 Amps when the motors running which I'd have via a relay off the tank pressure switch so it turns itself on and off. If I thought this was all too much for the electrical system I'd put in an interlock so it couldn't run when say high beam was on or when the aircon was running or something. But really are you going to need 6 spottys, 2 headlights, aircon, thermo fans and a partridge in a pair tree all going at the same time as the compressor? So the interlock is probably just idiot proofing.

Don't know if this helps or not, just trying to think of another way around the problem.

Deano

[Blknight.aus]

short version, no not easily and not without going to a lot of effort/expense
long version (Only by request because It means I have to go have a dig through my power generation books again)

realistically gentlemen the easiest solution is a bigger alternator with suitableu uprated wiring and the best solution involves a decent dual battery system with a big second battery

also read http://www.aulro.com/afvb/discovery-1/86470-electrical-woes-96-disco-v8.html

Imagine that at twice the frequency.

[scottvdw]

Jock,
I got my AC belt idler and tensioner off a dead 300TDI at Triumph Rover Spares (can't remember the cost but It couldn't have been more than $30). I bought them for an endless air setup using an old sanden 508 AC compressor.After seeing the price of serpentine belt pulleys, I have decided to machine one up from scratch myself. I have all the bits sitting on the bench in the shed, I just have to get around to doing it!

Scott

[d2dave]

Jock



I reckon Chucaros suggestion of an uprated alternator along with Steves sugestion re compressor sounded like a good way to go.

If you've already got a 110 Amp alternator and Steves compressor alternative doesn't work for you have a think about this alternative.

Electrical

110 Amps @ 13.5 volts gives you 1485 watts of power to play with in theorey. In practice you can't run your alternator continuously at full output without it failing. So lets say you can get 75% of output continuously and more for short periods, which still gives you a constant 1100 watts to play with. This is a hell of a lot of power and should be sufficent. The big draw items here would be thermo fans if you have them and your lights. Thermo fans could use anything up to 500 watts but can turn on and off according to load, and your vehicle lights, taking a guess here, 55 watts each for the headlights and was it six driving lights ?, say 2 @ 100 watt and 4 @ 50 watt for a total of 510 watts plus whatever the car itself needs. Might seem that we're running close to the line here but havn't considered the battery(s) yet. Batterys hold power which can be used to even out the load thus decreasing alternator load at peak. For example your typical N70 4WD battery is rated around 90 amp/hour capacity. This translates to around 1100 watts of reserve power or, in theory, enough to run your headlights for about 10 hours. If you've got two batterys even better. Think of them as additional resorviors of power when your main supply (alternator) can't meet demand.

I reckon if you wire in your spare battery via a suitable solenoid you should have more than enough power to meet your needs.


Deano

Deano,
What I make from the above is that if you have a large battery capacity you can draw more than alternator capacity for a short time by drawing power from battery. Yes?

Dave.

[Jock The Rock]

Jock

Given your problem a bit of thought here to try and come up with a practical and simple (relative term) solution.

What you've outlined here is two problems. One is do you have enough electrical power to do what you want and the other is having a useful compressed air supply.

I reckon Chucaros suggestion of an uprated alternator along with Steves sugestion re compressor sounded like a good way to go.

If you've already got a 110 Amp alternator and Steves compressor alternative doesn't work for you have a think about this alternative.

Electrical

110 Amps @ 13.5 volts gives you 1485 watts of power to play with in theorey. In practice you can't run your alternator continuously at full output without it failing. So lets say you can get 75% of output continuously and more for short periods, which still gives you a constant 1100 watts to play with. This is a hell of a lot of power and should be sufficent. The big draw items here would be thermo fans if you have them and your lights. Thermo fans could use anything up to 500 watts but can turn on and off according to load, and your vehicle lights, taking a guess here, 55 watts each for the headlights and was it six driving lights ?, say 2 @ 100 watt and 4 @ 50 watt for a total of 510 watts plus whatever the car itself needs. Might seem that we're running close to the line here but havn't considered the battery(s) yet. Batterys hold power which can be used to even out the load thus decreasing alternator load at peak. For example your typical N70 4WD battery is rated around 90 amp/hour capacity. This translates to around 1100 watts of reserve power or, in theory, enough to run your headlights for about 10 hours. If you've got two batterys even better. Think of them as additional resorviors of power when your main supply (alternator) can't meet demand.

I reckon if you wire in your spare battery via a suitable solenoid you should have more than enough power to meet your needs.

Compressor.

Don't know how much air you need and what for but I'll give you a suggestion and see if it fits your needs.

The size of compressor and air tank you will need depends on what you intend to do with it. Heres what I'd do as I reckon its pretty good value.

I'd buy myself one of those 2 HP Chinese compressors from Bunnings, Super Cheap or whatever and a reasonably good 12 volt air compressor. My 2HP compressor with 40 litre tank hose and fittings cost me $90 and my KCI 12 volt air compressor came with my 4WD Action Subscription and is probably worth no more than $150. I'd ditch the 240 volt motor/compressor unit off the tank and connect the 12 volt one in its place. Stick it in the back and away you go. Draws a max of 30 Amps when the motors running which I'd have via a relay off the tank pressure switch so it turns itself on and off. If I thought this was all too much for the electrical system I'd put in an interlock so it couldn't run when say high beam was on or when the aircon was running or something. But really are you going to need 6 spottys, 2 headlights, aircon, thermo fans and a partridge in a pair tree all going at the same time as the compressor? So the interlock is probably just idiot proofing.

Don't know if this helps or not, just trying to think of another way around the problem.

Deano

No worries

Thanks for doing the thinking :)

I never knew the electrical facts, seems I don't need the extra alternator

Only trouble is my headlights are 100w and so are the driving lights so thats 800w which is still within the limit

Maybe I was just making it all to complicated, I'll just wire the thing up like a winch and be done with it :p

I have an air tank that a mate gave me off a truck, and the compressor. I'll just find the motor bolt it to a piece of plate wack it in the back and hook up wiring similar to a winch. With a few solenoids thrown in to for good measure :)

[Blknight.aus]

Thats the basic concept.

in the automotive world the alternator is your electrical source and the battery is just a bank if you can borrow from in times of need. What you take out you have to repay erventually or just like a real bank when you need it most it wont be there for you.

[Jock The Rock]

Was your York run off a starter motor Dave?

I remember seeing a pic of it once a while ago

[Blknight.aus]

yep a 2.25 petrol series starter.

[Jock The Rock]

Hows it holding up?

Do you reckon that would suit my setup?

Thanks

[Blknight.aus]

http://www.aulro.com/afvb/projects-tutorials/76829-12v-compressors-2.html
theres the thread, oneday I'll run up the video
yeah itd work for you but as suggested in the thread youd really want a motor with real bearings ass opposed to sintered bush bearings like whats normally in a starter motor.

[DeanoH]

We got two Daves here ? I'm getting confused. Blknight.aus covered that pretty well.

Jock with 800 watt of headlights; crikey, you'll be BBQing possums at 100 paces, I reckon I'd definitely put in that interlock for the compressor. One thing I didn't factor in is a sound system. If you've got one of those high power amps connected to your head unit you'll need to consider that too.

Deano.

[loanrangie]

Seems like a way over complicated way of getting an onboard air setup, just use any rotary compressor and adapt a single V pulley to your existing ac pulley or buy a small air compressor - really ,how often do you think you will use it ?

[Jock The Rock]

We got two Daves here ? I'm getting confused. Blknight.aus covered that pretty well.

Jock with 800 watt of headlights; crikey, you'll be BBQing possums at 100 paces, I reckon I'd definitely put in that interlock for the compressor. One thing I didn't factor in is a sound system. If you've got one of those high power amps connected to your head unit you'll need to consider that too.

Deano.

I reckon I'll just wire it in like a winch, I doubt I'll be pumping up tyres with all the spotties running :p

I only have a couple of extra speakers no amp or anything like that


Seems like a way over complicated way of getting an onboard air setup, just use any rotary compressor and adapt a single V pulley to your existing ac pulley or buy a small air compressor - really ,how often do you think you will use it ?

Often enough mate

I have a small wheezy ARB at the moment and it's not up to the job. I also like the convenience of running a compressor that can handle air tools.

I don't beleive it is much more complicated, if anything it would be just as complicated as fitting a rotary

[loanrangie]

I reckon I'll just wire it in like a winch, I doubt I'll be pumping up tyres with all the spotties running :p

I only have a couple of extra speakers no amp or anything like that



Often enough mate

I have a small wheezy ARB at the moment and it's not up to the job. I also like the convenience of running a compressor that can handle air tools.

I don't beleive it is much more complicated, if anything it would be just as complicated as fitting a rotary

I have a small jap rotary pump that is no bigger than an alternator, it would sit beside the ac pump in the same location as your 2nd alt would fit, surely that is a much simpler method than fitting a 2nd alt to power another battery to run another in efficient bulky electric compressor ?