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60A to 100+A alternator

Sorry site running a little slow so will add this.

To take your winch analogy you are right......to a degree.

Engine is idling, alternator putting out say 10 amps, you apply a winch load of 500 amps, initially the alternator will supply the maximum current it can given it's idle speed, this may climb to say 30 amps, now the battery needs to supply the remaining 470 however, if the alternator could supply 500 amps at idle, then nothing would come from the battery.

Regards

Dave
 
Well I think that's largely academic if you'll forgive me Dave. With either an 80amp or 100 amp unit, when you're winching the the pull is so huge that the alternator is barely a factor. You'd literally need a 600 amp alternator. If you tried to pull 600 straight from an 80 amp alternator I think you'd hit problems. Therefore the main working current is pulled from the battery. So to say that you're getting 100 from the alternator and 500 from the battery is probably electrical fantasy.

Engine idling, battery charged, you light up your main beams, engine note will alter as the load on the alternator increases

Well we all experience that of course, but genuine question, how you you know that the output from the alternator is feeding the lights directly and is not being directed to the battery to replace the lost capacity? I would dare bet that if you fitted let's say a ridiculous 1000 amp hour battery, you wouldn't experience that same alternator kick in.

It also depends on what current the alternator is capable of kicking out at tickover without having to make it work audibly harder. I'm not enough of an expert to be able to answer that but I can't say my current daily drive does that at all.
 
Dave I think we crossed in the ether there. But I'm still not convinced. Not completely.
I get your theory, but as the alternator and winch are connected to the same posts of the battery, I don't know how you can say that the load somehow differentiates as to where it gets it current from. Yes the alternator might be able to generate 100 amps or whatever, but in terms of capacity the battery is sitting there with 700 cold cranking amps ready to burst out. The alternator has no capacity does it; it merely generates on demand. Quite what its ability to generate say 120 amps is in terms of duty cycle I can't say. But I know my winch cabling is at the very least 35mm but my alternator supply cable to the battery post is something like 16mm. I'd not want to be be pulling 120 amps for very long down a 1 meter long drinking straw.
 
The battery post is simply a connection point. Your right Chris as I said earlier, if you pull a 600 amp load the battery would be the supplier as an 80 alternator cannot cover that draw but would contribute, even increasing engine speed to say 2000 rpm the alternator would simply max out.

Flashing the headlights as you say we all experience that so to clarify.

DC electricity cannot flow out of the battery and in at the same time. So consider the battery terminal connection as a one lane + junction, vehicles are to be our current flow.

One leg of the + comes from the battery, another from the alternator, the third to the load the winch for example and the fourth runs the engine electrics.

So let us assume the engine is off, you apply power to the winch, the 'car's flow up one leg of the + (battery) into the winch cable and the winch turns, cars are being used up. Now we start the engine, the alternator sends cars to one leg of the + to run the engine, and also some to the battery, the alternator is sharing its cars with two legs of the +. Now apply the winch load, the alternator and battery are now both supplying cars to the winch and engine running needs, in effect the battery is supplementing the alternator as it simply cannot manufacture enough cars.

If you had a 500 amp alternator and you applied a 500 amp load, the 'car's would not come out of the battery, the battery just sits there, they would all come from the alternator.

Re fitting a 1000 amp alternator, this will make no difference to the headlight flash test, the alternator responds to load , so a full battery would mean the 1000 alternator output would be just a couple of amps, flash the lights and demand increases, the engine note changes as load on the drive belts is applied. The alternator does not send out 1000 amps unless it is called on, one the downsides of a DC 2 DC charger but that is for another discussion.

FWIW modern vehicle electrics increase idle speed in a fraction of a second in response to this headlamp flash load, so the engine speed increases slightly to compensate as opposed to slowing.

Off to bed now, waaaay past my bed time.

Regards

Dave
 
I can understand but at the same time still not necessarily agree fully Dave.
You have to address the cable capacity of the alternator. All of your theory only works if you can get sufficient current to flow out of the alternator doesn't it. If you have 10mm cable and a fictitious 600 amp alternator, the cable will melt in a heartbeat.

I know you can't draw and charge at the same time by the way. I do get that, but correct winching technique is to winch little and often as it were not pull as hard as you can until the battery is flat then wait for it to recharge - hopefully people do know that! So of course when winching, some of the current comes from the battery and some from the alternator. You correct of course. But the draw on the system when you winch is instantaneous (rope under load) so there's an immediate maxing out of the alternator's capacity isn't there. It's not as though it slowly ramps up and then the battery starts to discharge also. The draw from both is immediate. So to say that it doesn't draw from the battery until the alternator is maxed out it technically true but at the same time purely theoretical as over-demand is instant. When just freespooling this is not the case, sure. The double jeopardy too is that as you say you can't put in at the same time as drawing out and I know that some people believe that when winching, the alternator is putting charge into the discharging battery. Which as you say, it can't.


I do understand how the load on the alternator increases resistance in the belts. Thanks - I didn't need that bit explaining actually. Not after 1000 miles of squealing belts in Russia every time I ran something in the truck.

All of my services are connected to a different battery which is not fed directly by the alternator. I run 12v start with a split charge so it's perfectly possible for me to be running the engine, flash the lights and it not come from the alternator at all. Not until the split charge is connected. But that's genuinely semantics and a quirk of my system. Which incidentally is why I junked the crap Nat Luna split charge because it was on a timer and not VSR. I could drive for 10 mins with lights, wipers etc all running from the battery until the stupid thing clicked in.

Anyhoo - the upshot here is that I think people fit bigger alternators, mistakenly, especially when it comes to winching. Regardless of being 80 or 120 amps, the contribution to winching made by the alternator is comparatively small. It might contribute to putting lost capacity back in - in between pulls a bit faster, sure, but the key is to drain less from your battery between recovery charges. If you do decide to fit a larger unit - cool, but I would do two things. Firstly, up rate the charge cable from the alternator and secondly, fit an additional earth from the alternator bracket area to the vehicle body. Just to supplement to one single earth strap fitted down by the PS pump.

Interested in the additional discussion of the DC 2 DC set up though Dave. I have two and to my way of looking at them, they are performing superbly. But I'd like to know if I'm doing something wrong. I'm not noticing any oddities at all. Maybe it's a new thread? When I am pulling the trailer effectively I have two running.
 
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I cannot see your point Chris, of course the cable capacity would be in excess of the alternator capacity. If you fit a 600 amp alternator then the cable would represent that and more.

Correct the load is applied to both sources at the same time, which is not per your post earlier which I was contesting.

With the conversation moving to other batteries ect is just muddying the waters, so to keep it clear they can be put aside.

At the end of the day I was addressing your statement "I'm not the best person to advise on all of this Stu. But really when winching, you aren't pulling from your alternator are you. Draw can be up in the region of 500 - 600 amps so you're pulling from the battery" Chris that is not correct.

So to be clear, if when you flash your headlights the engine note changes, it is because the alternator responds to the load.

If you apply a winch load then again the alternator responds, it will simply put out it's maximum capability at whatever revolutions it is being driven at.

So now change the alternator to the theoretical 600 amp unit and of course the cable. Now when you flash your headlights the alternator responds in the same way, now apply winch load, again the alternator does exactly the same, but this time nothing needs to be drawn from the battery.

Another example would be a winch load of 600 amps, but now the alternator is a 500 amp unit in this case the alternator would max out again assuming sufficient revolutions, but now the battery would supplement the alternator.

Apologies for the 'load on belt' analogy, I was not trying to be clever, just not very good at getting my point over, and given my experience I can get a little frustrated when trying to explain something that I have been working with for over 40 years.

To the DC 2 DC charger, if you have a specific need to have one then that is great, I agree they have their place, but they are not for me.

As an aside, I fitted a Blue sea VSR and a separate NL monitor around 6 - 7 years back and no issues.

I am not a lover of the 'all in one" units, they can disguise faults, only found out by chance, or worse when you really need their performance.

Regards

Dave
 
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Morning Dave, hey no apology needed for the 'how an alternator works' bit. It's always dangerous to assume that the other person knows what you're talking about. We're hugely off topic here but sometimes these conversations are useful in the archives for others to follow.

This bit here seem to be the crux of the debate.
At the end of the day I was addressing your statement "But really when winching, you aren't pulling from your alternator are you."
I've been working on vehicles for 37 years myself Dave so I'm not new at this either.

What I was trying to say is that Stu has some winch issues and by going from a 60 amp to a 100 amp alternator he's not going to find an immediate solution. You have to agree with that surely? OK I concede that taken literally, when I said you're not pulling from your alternator in reality you are - but I did address that Dave. I really didn't mean it quite that literally. I should have been clearer - I just didn't think I needed to be.

You are not though at any point ONLY pulling From the alternator. If you pull 500 amps when you hit the button, it's coming from the alternator and the battery simultaneously. And the proportion that comes from the 60 amp alternator is close to only 10% with everything else that it has to do, so I can't really understand why you're debating that.

It's semantics I guess, but it was not my intention at any point to suggest that the alternator somehow did NOT contribute to the current, it was a turn of phrase that I used without intending to turn it into a key debating point. I mean to push a point, if your engine was running and your alternator had packed up completely and you tried to winch - would the winch turn? Of course it would and you're actually winch for a bit. If it had no battery and the alternator was good, would the winch turn, it would - until the rope went tight!!

Which is contributing more in a winch situation - the alternator or the battery?
 
Guys, I think you’re both singing from the same song sheet but nobody has mentioned the key factor which is voltage.

That which delivers (not produces) the highest voltage to a given point will take the greatest share of the current, (and current is shared) limited by chemistry (battery) resistance (battery, alternator windings, and conductors) electronic limitation, engine speed and magnetic flux density (alternator). The cars analogy is good but tanks of water at heights corresponding to the voltage and linked by pipes corresponding to the conductors is more usual. The lower the voltage of a connected item (winch, lights, battery, alternator) the more current they will draw. Correspondingly the greater their voltage, the more current they will supply. All governed by the limits above.

As said, current draw for leisure purposes is now so low as to not need so much capacity. The factor being time on leisure battery alone between charges and speed of charging when needed.

Winching is the only area I can see which would benefit by a larger alternator but as said, not by much in the grand scheme of things. With the winch running the draw will be shared unequally between the battery and the alternator. With the engine stopped, it will of course be from the battery alone, which is why the engine needs to be running, both to ensure it can be started and to allow some recovery of batteries. Winching current will ramp up, not come on suddenly except on starting, as tension is applied to the rope and will vary from it’s no load running current all the way to it’s stalled or ‘locked rotor’ current. Hopefully this will be in short bursts when load is on to allow battery recovery as well as cooling for motor(s) and cables. I often think a load meter would be beneficial but ones ears should suffice. Winch motors are only short time rated as they lack cooling.

It may not be necessary to add an engine strap as the one provided from factory has to deliver starting current, albeit for short duration, so should be of sufficient size, worth checking though. The one to increase, depending on the earth connection of a leisure or auxiliary battery, is the one between battery -ve and body. If the auxiliary or leisure battery is ever used to supplement a failed starter battery and utilises the body as it’s earth, this cable will take its share of starting current and could get a bit warm and restrict the applied voltage from the auxiliary battery (albeit only slightly).

While we’re here, never fit a winch isolator in the negative cable. The return current will find a way back through all sorts of things you really don’t want high currents passing through. Bearings, straps, braided brake hoses that sort of thing.

DC DC chargers ensure that battery voltage is kept correct for charging (including setup for different battery designs) which ensures maximum charging current (up to the unit rating) at the auxiliary battery terminals. They also allow for multi stage charging to help keep the auxiliary battery in optimum condition and in the case of the Intervolt, provide solar charging for both leisure and vehicle batteries subject to certain conditions.

Any increase in current either supply (alternator) or demand (winch etc) will require assessment for increasing cable size and fusible link (or fuse) size to exceed the expected current.

Let me know if I’ve missed anything.
 
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Always good stuff Rich. The additional earth strap thing came from an equally protracted conversation some years back when an alternator specialist jointed the discussion. It's not needed to increase capacity as such, it's there as a back up due to the relatively common state of deterioration of the original especially on the 80 where the earth goes via the change over relay post IIRC and is exposed on the block where the crudd collects. Sticking an extra cable on just gives some more reliability if I can call it that. Redundancy it's called isn't it?

Look at how many times we've advised people to use a jump lead from the block to the body when they get the click click. I know I did and it fired up immediately. I pulled the earth strap and there was significant burning on one end at the terminal post thing. At that point I went 12v.
 
That’s more reason to increase the size of the earth strap Chris, the 12v start will take slightly more current.
We are now talking about fault situations rather than general running but it’s no bad thing. Earth straps suffer generally. The earth goes direct, not through the start changeover relay, that will be the negative from the left hand side battery that does that on the 24v start.
 
Ahh well it's been a few years Rich and so I can't pop outside to have a look at what doesn't exist anymore. I do recall and earth on the relay though and that was burnt and loose. It had to go.
 
Like I say that’s be the negative from the left hand battery which is connected to earth at all times other than start. So a cable to Battery - and a negative to Body or earth. My bad for not being clearer. :)
 
Always remember the first rule V=IR. Also there must be a ratchet that stops the alternator from effectively shorting and destruction when a large load is applied.
 
I pushed the issue Chris as you have stated on other occasions that the alternator is not involved during the winching process. And given what I understood of your vehicle knowledge, I guessed it was simply an oversight, hence did not respond. Having seen the statement repeated, I thought I would be right in offering some clarification.

The long and short of it is a battery is for storage, it is to supply current when demand from wherever, whether it be lights or a winch outstrips that available from the alternator.

If the alternator could carry the load the battery in essence need not exist.

I cannot at this time think of another way of explaining however, Starcruiser would be right about the higher voltage, which will always be from the alternator over that available from the battery.

BTW, I completely agree that Stu has a problem. :thumbup:

So, glad that's sorted. :thumbup:

Re the DC chargers, not having any experience with them but read plenty, I do see their potential in battery maintenance.

So call me a learner at this point.

Having looked at the installations and hardware that is supplied, it appears the cabling at best could carry perhaps 30.....ish amps?

So if a leisure battery is very low after a couple of days fridge use for example, and I wish to drive an hour to my next campsite, my alternators ability to supply say 100 amps to the low battery will be stemmed by the DC charger, perhaps reduced to 30 amps? The low battery will take as much amperage as it can get within a certain voltage range so, hypothetically my direct alternator to battery supply would have put back more than a DC 2 DC charger in that one hour of travelling, perhaps a longer journey would favour a DC charger?

No I am not rushing out to purchase one regardless of the answer, I just see these chargers are addressing a problem that did not exist in the first place. I would certainly agree with the use of the technology in a mains charger, after arrivng home after a trip and giving the battery a good maintenance charge, BTW, I use solar when parked :happy-sunshine:

Regards

Dave
 
Your scenario would be correct Dave if there were no losses and your starter battery that provides volt sensing for the alternator is sitting at less than a full charge (14.4v).

The Intervolt will push 25A all day long into an AGM leisure battery in a boot or in a trailer or caravan at 14.7v which is where they score and are most probably aimed. Most caravans arent capable of drawing much more than 20-25A through the grey socket. It’s only an on board battery that could be charged at a higher rate (which is of course what we are talking about here). The Cteks have their ‘smart pass’ unit which effectively allows heavier charging up to I think 100A.

I agree, I believe Stu has a problem with either batteries, cabling, winch or any combination of.
 
So I have over the time changed everything but the alternator and the problem is still there.

The other thing is the master switch.

I feel the alternator has a problem. Under load
 
Eliminate the master switch first. You could either move the wire and bolt the two on one bolt or measure voltage across the switch with the winch running.
 
I'd agree. from my years of experience in winch recovery, the number one cause of problems by a country mile has been isolators. I've tried several myself and never found one that was any good. Inside they're rubbish. I did toy with using a second TG Thompson winch relay as an isolator. It's the only thing I'd trust.
 
Ok will bolt the cables together and try it.
 
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