Charging Lithium Direct from Alternator 78 series FTE (Part 3)

Hi Leigh

The alternator measured 14.11v on cold start up. Half hour at idle in our not so cold Darwin climate saw it at 13.95v.

So half the voltage drop you were expecting? Or do you think it would drop more if vehicle driven?

Has anyone put a thermal camera over their alternator under load?

Lots of different temperature figures getting quoted on the internet.

Regards

Lyndon

That would tend to indicate it is a temperature compensated unit, you really need to drive the car and get the engine bay hot and test at 1500RPM. I woul also turn the headlights on high beams to make sure you have a reasonable load on the alternator.

Temperature voltage modulation on older models won't be as great as on more recent models.
I'm also assuming you don't have an aux connected?

Hi

Yes, the leaf pack, OMG, what a headache. The like of which I have seldom encountered!

The pin only comes out 1 way, despite the guy at ARB just telling me to hit it harder.

The pin was the easy bit, airbags had to be completely pulled out. There is a preload on the springs. So for me, there is 600 kg of force on the springs whilst still in the hangars.
The rear sway bar that supports the diff had to be disconnected. ETC ETC ETC

Basically, the diff has to be floating in the air on both sides to do the job.

Then it has to go back in a certain order, as I found out, then pulled it apart again!

It's done, but I'm not keen on doing it again. Even though I do pretty much everything else myself.

Like everyone else, ARB have no staff, I inquired in June and was told the earliest they could do it was September. The vehicle literally could not be driven. So I did it.

Back to the Lithium batteries.

The only battery under the bonnet is the led acid starting battery.

The car does not have a "smart" alternator, so I don't have an under voltage issue.

No need to unplug it, I can see the model number and two dealers have looked at the exact alternator in their warehouse and told me it is 3 pin.

PS, re the leaf pack, the 78's are coil and leaf, so it was the rear.

Cheers

Lyndon

Yes, true, I cannot fully see into the alternator, but i can see the windings, not sure if that accounts for much.

Ross,

The later model 70’s have the start battery immediately behind the near side headlight. Don’t know when it was moved there, but my 2015 ute has it there. It also means, for most mortals, that the battery has to be removed just to change a headlight globe.

Bob

No worries Bob. I think that I have changed more batteries than headlight globes anyway. lol

What are some electrical vehicles now, about 20 minutes for a fast charge?

Yes, they have max and recommended charge rates.
In my case, 1 battery max charge 100A recommended 50A
2 batteries in parallel, recommended 75A
3 batteries 113A

Cheers

In all my experience, I have yet to see an electrical appliance whose life was shortened by being less stressed.

I have been using rechargeable NIHM AAA ,AA batteries in everything for over 15yrs. I started with a 1 hour fast charger the batteries last approx 2 to 3 yrs on average then we bought a slow 8 hour charger they definitely last longer now 5 plus yrs.

Kia say on their site fast charging reduces life by about 10% because it strains the battery go figure. There's a lot of info on the net from reputable companies Lyndon about the effects of fast charging electric vehicles.

Yep, and that's why I'll be charging them within the recommended charge rate.

Cheers

That will be the max rate won't it because you're going straight off the alternator with nothing to reduce the power just an isolator in between.

2 x lithium in parallel

Alternator seemed to settle down to around 105C with an output of around 60A @ 2000 RPM.

2 x AGM 110 A/hr @ 12.1v vehicle 2000 RPM

Note.
No noticeable difference was detected in Alternator output voltage. Voltage didn't really seem to drop with temperature, only with RPM.

At idle, output was around 37A and voltage had dropped into the 13's

It would seem the alternator will not drop below 14.1v regardless of temperature when traveling in the normal rev range.

I increased the RPM to 2400 with the AGM's connected, this didn't result in an increase in charge. Not sure if the same could be said for the lithiums. Increase in alternator temperature was quick with AGM's but did take a little time. With Lithium it was INSTANT.

Thoughts folks?

Cheers

Lyndon

I'm a tad confused you indicate the AGM's are fully charged yet they are putting a considerably load on the alternator looking at the temperature increase?

Flatten the AGM's down to 50% SOC and repeat test and see how the alternator handles them.

Also you wrote engine warm, what do you mean by that?

Is the car fitted with the OEM alternator?

Is it possible the regulator has been replaced at sometime?

It is not unusual to see alternator temperatures of 190C on some models with poor are flow on hot days.

Hi Leigh

I've had the car since new, same alternator. Car sat at idle at 2000 RPM for half hour in 35c.
Not sure if your indicating I need to get it hotter than that?

Please re read and the rest will make sense. If not let me know.

Thanks for the heads up on the 190c, I had no idea.

Cheers

Lyndon

Leigh, please see details on photos. Might make more sense.

What are you thoughts if I drive the vehicle for an extended period of time and the alternator is still >14v?

Cheers

Lyndon

Lyndon
If your alternator is running flippin' hot, it may be because it is sucking in the very HOT airflow from the radiator which is already running at 80+ degrees. Maybe try supplying the alt with a flex duct so the intake to alt airlfow is from an ambient source and not the fiery engine bay ambience. With the bay at 80 C There isn't much temp differential at all, to provide much cooling in the alternator internals.
COOLER IS BETTER FOR ALT HEALTH AND LIFE. Get away from temp pics because they only prove things aren't suitable for high output temps and high charge rates

Some aspects I don't understand:

In your intitial testing the alternators hot voltage was less than its cold voltage, in the latest info no change?

You indicate the AGM's are fully charged yet your thermal imaging would imply the altenators it is working very hard?

I would have thought your 3 agm's when down would draw a similar current to the two Lithiums, what size and length cable have you connecting the AGM's. Are you using the same setup for the Lithiums?

What isolator are you using for the AGM's.

When alternators are under a heavy load or at 100% output one would expect to the see the alternators output voltage dropping even if not temeprature compensated ie on a test bench setup yet that does not appear to be the case in your testing?

As for the voltage >14V, if it is only for a short duration and then the batteries are cycled ie charge during the days drive and discharging into a freezer orver night daily then it should not be a big issue. If your going to continue to charge them for hours on end daily when fully charged and thei not being drained after the drive then I wouldn't be happy with that setup. Personnaly when I'm not using the aux and just driving around town I disconnect the Lithium and only charge it when it needs it. which usually never needs to be done between trips.

Hi

There are details on the photos that are being overlooked.

Anyway.

In the car I had 3 tired old AGM's fully charged.

I ran a test to see what the alternator ambient temperature would be with these still in situ. i.e, under hood temperature.

I then removed these and installed the Lithium

Where upon start up the alternator put in around 60A under the load of the two lithium batteries at idle.
Temp jumped to the mid 120's. I didn't leave it run at this for long as unsure of what temperature alternator could run at.

I shut the motor off for half hour or so. Then ran the motor at 2000 RPM, output 90A, temp jumped into the mid 140's in seconds. I was very concerned, so shut motor down.

I then pulled out the lithium and put in two new AGM's. Details on photos above.

On idle, these pulled around 37 A. At around 13.4 V. Temp from camera was indicating around the mid 120's.

Ran motor up to 2000 RPM and left for around half hour. Initial input was around 68A with camera showing high 130's.
As amperage slowly dropped towards 60A the alternator temperature slowly fell to 105 or 110C
Voltage remained just over 14v.

Out of interest I increased RPM to 2400 as I think this is what it sits around when cruising. There was no noticeable increase in current flow.

Red arc isolator

Car is set up so I can flick a missile switch on dash to link AUX to start if required. New Lithium has a CCA of over 800A

2 B&S I believe. Same as battery cable throughout. Grounding to chassis done at each battery.

Now that I know that alternators run so hot I need to do some more testing.

I have previous towed a camper trailer with 2 AGM's in it also. So I guess the total capacity may have been 350 A/hr. I never tested A or V output on that set up.
I may flatten a couple of these not totally stuffed AGM's join them up to the other AGM and see what the alternator does then. As this will give me a rough comparison to a set up that I know has worked previously with this vehicle.

The Lithiums are going in the boat for an upcoming trip to the beautiful Roper River in a couple of months time.

I will then have to decide as to whether to put them back in the car. If I do, all 3 may be going in. I wonder if the draw will be greater again? Thoughts?

We are heading off to Litchfield in a couple of weeks with the AGM's in the car, so I will take my meters and do some testing to see if this alternator will ever output less than 14v unless at idle.

Cheers

Lyndon

Personally I would be using smaller cable to limit the charge current somewhat, in my setup I'm using around 4M of 13.5mm cable.

Lyndon.
I consider the stationary temps with either the bonnet up, or closed, to be causing different readings as it isn't the situation the alternator or batteries will be operating under. If travelling the hot airflow from the radiator will be flowing rearwards and some of that will be ingested along with it's temp, into the alternator in an attempt to keep it cool. If just stationary, the hot radiator airflow will be causing heat soak to all components and that airflow will sort of static, ie not changing much and be not moving away and the full radiator airflow temp will be the sucked into the alternator. Some tracing/tracking of travelling airflow temps at alt rear, compared to stationary/parked and running airflow might be needed before you can decide on a course of action. I would imagine a significant difference. all needed before you can really tell what temps the alt is running while charging lithium or AGM batteries.
What if what your pictures show, isn't really what happens while in actual use?

Depending on alt fitted, if the alt fan fins are external, are they close to case to ensure a full positive airflow extracted?
Have you ever been through muddy water and the alt stator windings are full of crap and mud and the fan airflow cannot cool it much at all no matter what the engine/alt revs are?
PS. If regulated, After a certain rpm an alternator won't keep increasing output after a designed rpm maximum no matter how fast you rotate it.

Lyndon,

What is the year and model of your car?

Idle voltages are not import, the alternator can't produce its maximum voltage at idle if heavily loaded you need to be testing with engine RPM's of 1500RPM or greater.

My main concern with your setup is there doesn't appear to be any temperature compensation taking place, if that is the case then the alternator will not be self protecting which is why I keep placing the importance of testing the voltages under driving conditions and not idling and ensuring temperature compensation is working. I'm assuming you have a diesel engine which take forever to warm up at idle. Load on the alternator though even at idle if great enough should heat up the alternator and cause it to back off back off but depends on load and ambient temperature.

For instance in my case with a light load on a cold day my alternator with a booster diode fitted will start of at around 14.4V and will gradually reduce to around 14.2V after a 20 minute drive or there abouts. If the Lithiums are down it will drop from 14.4V to around 13.8V within a short time and stay there to the load on the alternator drops and will then gradually creep back up to around 14.1V to 14.2V. Hot day voltage might drop to 13.5V before working it's way back up 13.9V or there abouts.

Model is in the initial heading

2004 Troopy FTE motor.

As I've been saying, and as as Toyota have said, I don't think the alternator is temperature compensated. But a certain few on here have insisted it is.

As for airflow when traveling, yes, yes, I get all that. But if the thing is going to cook itself just at idle with the bonnet up, the rest is kind of irrelevant.

The difference was AGM pulled 37 A at idle, Lithium pulled 60A. In hindsight, I should have run the idle test with the Lithium longer and seen what happened.

As for the alternator not being up to temp so it didn't drop the voltage. Anyone want to say how far above 143 C in needs to get before this function kicks in?

As said, I'll check the voltage output on our run to Litchfield in a couple of weeks (AGM'S) installed.

Cheers

Lyndon.

PS, not sure what you are putting into those batteries Leigh, but that 6 B&S is only rated to around 55A I think..........

Toyota specifies for Land cruisers built around the 2000's that the output voltage should be in the range of 13.2V - 14.8V, I haven't found a Toyota model that wasn't temperature compensated.

The temperature sensor will be in the brush assembly it will take a short time for it to heat and react. Once the temperature rises a few degrees you should see a drop in voltage, if this is not happening something is not right.

Leigh, is that form of compensation intended to protect the alternator or the battery? Or both?

An alternator putting 60amps into batteries at idle is very impressive do you have a smaller pulley on it.

Alan,

It is designed to protect the battery, the alternators main task is to charge the battery. In recent years car manufactures have also used the feature to reduce fuel consumption and emission though at the expense of battery life. To keep the design of the alternator simple when electronic regulators came along they decided to include the regultor in the brush assembly in most units one imagines for ease of assembly and replacement, to simply wiring within the alternator and to keep it away from the rectifers and their heat generation. With the alternator running under reasonable loads the location of the regulator this is not a problem. With very high alternator outputs though the heat load being shed from the alternator affects the sensor causing the voltage to drop, this is a design comprise but again doesn't cause much of an issue as when alternator output is approaching 100% of its output capacity it won't be able to produce anymore than its rated output which will around 13.8V - 14.2V anyway depending on the manufacturer concerned. It also comes in handy as a persudo form of overload protection but that was not the intention. I have seen alternator regulator chips that do have inbuilt overload protection which acts instantly but in the world of automotive manufacturing if it costs a few cents more their not interested hence why we they are still using incandescent bulbs. There were also more efficient alternator designs in the pipeline but with current developments and the move to towards EV's it would seem continued delevopment in those areas may be a waste of time and as more electonics is involved the higher cost will be a hinderence unless they have to use them for anti pollutions gains etc.

Good luck measuring the fuel econ you save through an alternator you might be able to do it in a lab but it would be very difficult in the real world unless you can monitor every milliliter the engine uses.

Not that hard to work out and it does make a difference, without idle speed correction ramping up the alternator to max output will slow and engine to the point it gets a rough idle and stumble. A 120A alternator under max load is drawing more than 1.4kW from the engine, at idle possibly 840W. Many smart charge systems reduce the alternator output to the point where the battery is either discharging or just being maintained. They then raise the charge rate during deceleration to put some charge back in the battery.

I haven't seen figures for cars but have seen it for a trucks, they estimated that for 2000 hours of operation the fuel cost to drive a conventional alternator at 100A would be around $1300. With a high compensation type alternator the difference in fuel cost would be around $263 a not insignificant amount and they based that on fuel costing 27C a litre!

Leigh
You mentioned the brush holder being apart from the hot rectifiers in automotive alternators. The alt in question is a Denso and all recent Denso designs have the brush holder screwed to the rectifier block and rear case. That is hardly apart or separated from the rectifier and it ensure the brush holder is heated by the rectifier. All the ones I have in my shed are like that, older Mitsubishi and many others also are similar.

Yep, there is little room in an alternator to mount things, they could have mounted the regulator directly to the rectifer plate if they wanted to heat it that way but they try to maintian as much thermal seperation as possible. The below is a 120 alternator diagram, there just isn't anywhere else to mount the regulator. The regulator itself will aslo generate heat that needs to be shed, note the cooling fins. An external regulator would have been better and in the case of the newer samrt charge setups the engine management system can control the alternator. Interestingly the alternators in such setups still in many cases have an internal voltage regulator and in the event engine management system loosing contact with the alternator regulator the regulator will switch to stand alone mode. This aspect has been used by a few to circumvent the smart charge systems in their cars.

Quite frankly, I cannot imagine that there would be ANY location inside an alternator housing that would be significantly cooler than any other location. It would be anywhere between 120c and 200c. The windings and diodes, being the source of heat, would be the hottest but the rest would not be far behind as the heat from those sources is dispersed.

You do have cooling air being dawn in, the air flows over the regulator etc, then across the windings in a compact alternator to shed the heat. If you look at the diagram above the regulator is not in the diode heatsink airflow. Below is the airflow path. I'll see if I can dig up a heat load versus output and post it.

Oh c'mon Leigh, all that diagram shows is that the air enters through the endplates and exits via the centre of the housing.
Inside the alternator would be considerable air turbulence with little temperature gradient.
Remember that I do have some form. I spent much of my life designing, installing and maintaining instrumentation to measure and control heat. I did learn stuff along the way. One being the difficulty of accurately gauging the temperature of specific points within a space of turbulent fluid.
Other than within the windings and right on the diode junctions it is going to be much the same everywhere.

Best i can dig up at short notice, regulator remains relatively cool compared to the rest:

Lyndon's idle test is flawed, because the alternator simply sucks in the heated air back into the inlet vents when the airflow is just milling around and not being changed. Also the background of his photos show the ambient components at around 25 to 30c, so for it to be hot quickly, it must be recirculating it's own air.
With background so cool the engine bay isn't anywhere realistic engine bay temps his battery will experience when all is hot.

Allan,
You are forgetting this is an internet forum, where no individule has any respect for any real life experience another individule has.
Many base their arguements on things they may have done once or twice and back it up by digging up diagrams and charts of the net that have no technical references, just invented by other inexperienced would be experts.
How many times have you seen the SOC voltage charts slapped on a thread to express superior knowledge of the subject without reference to temperature and settling periods?