2 Alternators?

[DR Frankenstine]

can it be done and how to wire if it can?
My auto elec says no

[-Scott-]

Some variants of the Ford F Trucks come with two alternators. I'm guessing you'd need a regulator designed to handle the two inputs.

Or you could run the second for a 24V system, and get some big mofo lights!

Scott

[chimpboy]

Put two alternators on, hook them up in parallel. Identical alternators would be better, but it doesn't really matter.

This is just my opinion, it could go bang (However, I can't think of any reason there'd be a major problem.)

What is it that you want? Just more current output?

Jason

[kranked_dirt]

I am also considering doing this, or a bigger alternator. There was a writeup of a bloke that did it in 4x4 monthly a while ago... i think he's on here somewhere... cant think of his name at the moment...

[mechtech]

well in

[mechtech]

well with two altonators, hooked up stright to batt, they can both sense the batt v and they should hold voltage at 13.5 - 14v and any drain/workload amps wise would be shared by the two. just get the self reg type (e.g. it got B+ batt, F feild, (and sometimes R reference voltage)

[chimpboy]

well with two altonators, hooked up stright to batt, they can both sense the batt v and they should hold voltage at 13.5 - 14v and any drain/workload amps wise would be shared by the two. just get the self reg type (e.g. it got B+ batt, F feild, (and sometimes R reference voltage)

I agree it will work, but there are two things that people say could stuff up. Firstly, if one stops eg a broken belt, the other could send current into its field coil - not good. But this is wrong because the diode set up will protect it, so no problem.

Second claimed problem is that if they each have a separate regulator, then one will end up doing all the work, with the second only kicking in when the first can't manage the current output. This is because the regulators are never going to be 100% identical.

I think this one is probably correct, but I don't think it matters. Sure, one alternator is doing most of the work, but big deal, it's still good to have a second one there to pick up the extra load.

Jason

[Spike_Sierra]

just get another battery and hook the other alternator up to that, then only connect you starter motor to the main battery and all the accesories to the other one, simple dual batterys.

[DR Frankenstine]

Ok to clarify things.. I run 2x 650 cca batterys for running everything. Starting, winching, driving lights etc.
I am about to fit 4 more driving lights as i do a lot of night runs with a lot of winching. so that will be

6 x 100 watt lights. 600 watts devided by 12 volts = 50 amps
2 x 100 watt headlights = 17.7 amps
Plus maybe wipers, heater fan, taillights, brake lights etc.
Then Batterys need to recover after winching.
A 50 amp alternator won't cope.

I need definate info by someone who knows for sure what will work. Im not adding extra batterys, 24v for acc. (to much weight).
An idea I had was to run a commodore 100 amper and just run the original alternator disconected(to retain the vaccum pump).

WHAT U THINK

[spazbot]

im sure if an auot elec (whos job it is to know this shit) says it cant be done it prolly cant be done without sme serious booty fab

[chimpboy]

I can't think of a single reason not to do this, and I've really tried. I've also searched a fair bit on the web and can't find any convincing argument against it. I would try it.

However, I am not an auto electrician so you might want to consider that when you decide whether to believe me.

But: lots of boats already do this. They have single battery banks but two engines, and each engine has its own alternator, and they are simply hooked up in parallel.

So it's up to you, but I think it might not hurt to talk to someone who has done a bit of electrical work on boats and see what he has to say.

The only problem I can see is that one alternator gets "lazy"; that is, the load doesn't split evenly, it just all goes on one alternator until that one is overloaded, then the "lazy" one picks up the slack. There's no way around this unless you get a special regulator, but it's no big deal because it's still better than just having one alternator that's not strong enough.

Again, you have to weigh my advice against your auto elec's, and he's a pro, and I'm not. So you'd be kind of stupid to listen to me

Jason

[RoldIT]

I'd say give http://www.redarc.com.au/ a call and see if they have a do hickey or a thingamy-bob to regulate or equalize the load between the 2 alternators.

[spazbot]

i was wrong , here is some info

http://www.adverc.co.uk/technical/technical-twin.asp

seems you need to use thier managment system got get it to work .....

[chimpboy]

i was wrong , here is some info

http://www.adverc.co.uk/technical/technical-twin.asp

seems you need to use thier managment system got get it to work .....

I read that also. Their unit controls how much charge goes where, but it isn't actually necessary - although they don't mention this presumably because it's not good for sales.

Another site I found was this one: http://www.amplepower.com/primer/twoeng/

It says, "However, if two alternators, each with their own regulator, are connected in parallel, the regulator with the lowest setpoint will quit charging when the other alternator can supply all the current required by the battery and load. The lazy alternator is a problem when the tachometer signal for the engine is derived from the alternator.

By using a single regulator to drive both alternators, both alternators share the load and deliver according to their rating and their RPM. Thus both tachometers continue to operate correctly."

So you don't *need* a special regulator unless you are concerned about one alternator working harder than the other, which is not really anything to be concerned about.

But I don't mind if nobody tries this.

Jason

[MQ SWB]

First thing is the vehicle 12v or 24v, if 12v say have one battery for everyday car use(ignition, wipers and so on) and maybe have a couple of driving lights set up to run of that one, Then have the other battery to run winch and other driving lights.
Or if 24v system having 2 alternators to charge batteries or just having one big alternator to charge system.

If 12v system then I'm currently running 2 Alternators on mine one for each battery, the vehicle originally had a winch plus all this other crap attached but not anymore.

If 24v system I've heard of people getting their alternator re-wound to say 120 amps or even bigger, but don't know what is involved in doing this.

Your probably saying what drugs is this bloke on, just offering some help

Dixie

[chimpboy]

Last thing I'll say is, I was looking over the Bosch Australia website and found this:

"Operation of alternators in parallel

If demanded by power requirements, alternators with the same power rating can be connected in parallel. Special balancing is not necessary, although the voltage regulators concerned must have the same characteristics, and their characteristic curves must be identical."

http://apps.bosch.com.au/products/saa/a ... arters.pdf

Again, though, as far as I can tell the only reason it's important that they be matched is that otherwise one will do the majority of the work.

Jason

[DCTECHO]

After reading all the info in the links posted earlier I decided to try this out ,I am an auto sparky so I just hooked up two internally regulated mitsubishi units on our test bench wired in parallel but with the two positive output terminals feed through blocking diodes to one battery . This works fine and no special regulator required.
As I get more spare time I will try some other type alternators and regulator set ups and let you all know the outcomes.

[chimpboy]

After reading all the info in the links posted earlier I decided to try this out ,I am an auto sparky so I just hooked up two internally regulated mitsubishi units on our test bench wired in parallel but with the two positive output terminals feed through blocking diodes to one battery . This works fine and no special regulator required.
As I get more spare time I will try some other type alternators and regulator set ups and let you all know the outcomes.

Cool, keep us posted.

[mechtech]

I know you may not have time, but would be very interesting to see what the load share is between them would be ie. when in par, what the amp output difference between them is/ if any, also same hooked in series.. weather or not one just picks up where the other lags or if the complement eachother.
just a though, btw hows the weather

[MissDrew]

Daz used to run 2, I thought you would have known this pete

[chimpboy]

ie. when in par, what the amp output difference between them is/ if any, also same hooked in series.. weather or not one just picks up where the other lags or if the complement eachother.

I was thinking about having them in series also, because in theory that would be a really good 24V setup - you could steal 12V from either battery and not worry about it, because each battery would have a dedicated alternator - best of both worlds, run whatever voltage accessories you can get your hands on.

But I don't think this would be possible in practice because the alternator bodies would both go to ground when mounted to the engine. If you tried to put them in series you'd get a big bang... unless there's some make of alternator that gets its ground through a cable, but I've never seen one.

Jason

[pongo]

this sounds as though its getting complicated.

When you jump start a car you have two alternators feeding into one bank of batteries. Nothing blows up !

When does an alternator actually run at full draw?
When there is the demand for it.

Comclusion.

The fact that one alternator may become lazy, is whats they are designed for. You start a car. alt works hard to recharge and then goes into trickle mode. trun light s on load varies. turn on spotties,etc and alt works harder to meet the demand.


This is about as simple/hard as it gets. set up the exviter wire for the second alt ( int reg, most new ones are) and it'll self regulate as their ment to. Only drama is fitting it in engine bay and belts ( as well as pulley speed) . I plan to do this mod on my MQ . When i can get my toymota pos out of my shed.


Cheers

[DR Frankenstine]

After reading all the info in the links posted earlier I decided to try this out ,I am an auto sparky so I just hooked up two internally regulated mitsubishi units on our test bench wired in parallel but with the two positive output terminals feed through blocking diodes to one battery . This works fine and no special regulator required.
As I get more spare time I will try some other type alternators and regulator set ups and let you all know the outcomes.

Thanks for that looking forward to the outcome.

[DR Frankenstine]

Daz used to run 2, I thought you would have known this pete

Hi dave
I thought he had 2 compressors.
By the way the system is 12 volt and an auto elec said even if you run 2- 55 amp alternators in parralell they will only charge 55 amps not the 80+ I need.

[chimpboy]

By the way the system is 12 volt and an auto elec said even if you run 2- 55 amp alternators in parralell they will only charge 55 amps not the 80+ I need.

Well, that's wrong.

Jason

[-Scott-]

By the way the system is 12 volt and an auto elec said even if you run 2- 55 amp alternators in parralell they will only charge 55 amps not the 80+ I need.

Well, that's wrong.

Jason

Yeah, we already saw earlier in this thread that auto-elecs don't necessarily know what they're saying.

If you only need 80 amps, what's wrong with finding an alternator which generates more than 80 amps? There are plenty out there running 100+ amps. If alternator speed is an issue, put a smaller pulley on it so it runs faster at lower engine revs.

Scott

[DR Frankenstine]

By the way the system is 12 volt and an auto elec said even if you run 2- 55 amp alternators in parralell they will only charge 55 amps not the 80+ I need.

Well, that's wrong.

Jason

Yeah, we already saw earlier in this thread that auto-elecs don't necessarily know what they're saying.

If you only need 80 amps, what's wrong with finding an alternator which generates more than 80 amps? There are plenty out there running 100+ amps. If alternator speed is an issue, put a smaller pulley on it so it runs faster at lower engine revs.

Scott

The issue is retaining the vaccum pump for the brakes. And exactly this auto elec obviously hasn't had anything to do with things out of the ordinary

[-Scott-]

By the way the system is 12 volt and an auto elec said even if you run 2- 55 amp alternators in parralell they will only charge 55 amps not the 80+ I need.

Well, that's wrong.

Jason

Yeah, we already saw earlier in this thread that auto-elecs don't necessarily know what they're saying.

If you only need 80 amps, what's wrong with finding an alternator which generates more than 80 amps? There are plenty out there running 100+ amps. If alternator speed is an issue, put a smaller pulley on it so it runs faster at lower engine revs.

Scott

The issue is retaining the vaccum pump for the brakes. And exactly this auto elec obviously hasn't had anything to do with things out of the ordinary

Ahh! I see!

Sorry - never owned a diesel, so these things don't occur to me...