I was also thinking about converting mine to 12v. Then the alternator died on the first day of a holiday weekend trip in my dads 80. Since the 24v starter is happily working down to a voltage of 10,5V on both batteries, we just continued on with the trip for another two or three days, adressing the alternator problem when we got home.
And why in the world should you convert a car like this to an electrical fan? If it decides to give up on you while traveling, youre done. If your fan clutch dies, put a bolt through it and carry on.
Don't get me wrong, i really appreciate your build and enjoyed reading the associated thread, i just don't really get the benefits of called modifications.
Regards, Jona
@Ragnaroek
LONG!
Hi, I appreciate your comments however, if you had read through my thread (yeh I know a dozen or so years worth), you would have seen why the conversion was done on the 24 volt starter.
When I go off road I need a fridge (diabetic on insulin), so a fridge is not a luxury, it is essential. Running a fridge from a 24 volt parked 80 means the draw is on BOTH batteries as they are in parallel, they only go into series during cranking which means after a couple of days out in the desert there is a risk of the 80 not starting at all. On my vehicle and using decent quality equipment rated way above my 80's requirements the conversion was done. Once parked the fridge runs off of both batteries (both parallel), then a 500 amp Blue Seas VSR separates the batteries when it detects the starter battery has come down to a certain threshold. When this happens depends on weather, how often the fridge is opened and so forth, but generally it is some time during the night or early morning, remember the fridge is not on all the time. So, this leaves plenty of charge to work the 12 volt starter, note the starter battery after supporting the auxiliary battery for whatever hours, once separated the starter battery does just that, start the engine so, that means the starter battery is always protected.
So, to your 80 with the 24 volt system, your figures are quite frankly wrong, perhaps caused by a faulty meter or procedure in its use? At 10.5 volts your batteries are dead, there is absolutely no way they could crank the engine, 12 volts or 24 volts, they are dead. And to put that sentence into perspective. when the ignition on a diesel 80 is switched on, it immediately starts to heat the glow plugs, each one of the six drawling around 8+ amps, so a 48+ amp load on the batteries, the later versions with the manifold heater perhaps a similar draw, then there is the diesel pump solenoid, this is also circa 8 amps to operate, then there is the various ECU's that power up, dashboard check lights, although not a lot in the whole scheme of things but they are a draw all the same, now you start the engine and this takes a substantial amount of amperage, something around at a guess say 100 - 150 amps? So that will tell you that your reading of 10.5 volts (the pressure if your not electrical savvy?) is not sufficient to push that kind of amperage.
As an aside, my system allows me to press a button on the centre console and allow the two batteries to combine, in effect allowing me to jump start the engine without opening the bonnet, whereas jump starting the 24 volt 80 can lead to some expensive damage, in particular if the donor car battery is not connected to the correct battery on the 80.
So I hope that answers your first question?
Now to the electric engine cooling fan conversion.
This actually brought about a lot of controversy, and to be fair it is understandable, there are vendors who sell modified clutch kits for the 80, so taking that into consideration, the conclusion seems to be the stock fan clutch system is not sufficient to cool the engine.
So, a look at some of the advantages of an all electric system.
First economy, the 80 is not too bad in the diesel versions but pretty poor with the petrol or gasoline versions, fitting an electric fan without doubt does decrease the consumption of fuel, by how much not a lot for sure, but if it is 10% on a vehicle that only gives you say 15 miles to a gallon, then it is an extra 1.5 miles per gallon, that would seem to be obvious but it is not strictly true, there is the load to be considered on the alternator, I will put that aside just for a moment, just to slow down the mathematicians who will go on about using mechanical energy to create electric energy and then use that electricity to turn a fan, these are the people who have no idea about how DC motors work. One member on here quoting something like needing 400 BHP to make the conversion work!
Back to the electric fan, I know that on the typical vehicle moving at around 20 MPH there is sufficient air moving through the radiator to keep the engine cool, this assumes everything is working properly, a properly working fan coupling will be allowing the fan to idle over, so no load on the engine and the same for the alternator with the electric fan being off. The engine starts to heat up as the vehicle speed drops, this is where the engine driven fan starts to lose ground with the electric version. First the sensor controlling the electric fan is far more sensitive than a viscous coupling, so the fan come on earlier keeping under bonnet temperatures down, this does help prolong the life of under bonnet components. Eventually the VC starts to drive the mechanical fan and it will be driven quite hard to get the engine temperature down, this will be noted when the traffic starts to clear, you can hear the fan roaring, this is using more fuel than the electrical fan, manufacturers knew early on that the gains if any were negligible using the electric, just like the mechanical fan they were noisy and used more power from the alternator. The answer to this was to introduce two speed fans, the 4.6 V8 Lincoln fan for example, this was my first choice, it is a two speed fan with a controlled slow and fast speed settings, it needed less amperage from the alternator and was quieter, the second higher speed only needed in extreme conditions, which rarely happened because the engine was not allowed to get too hot. At this point the electric fan was taking the lead, being controlled by sensors which had become more precise now there was no need for the slow reaction of the VC mechanical fan to 'catch up' with cooling the engine.
Like pretty much everything these days modern technology moves on, and whilst some resent and reject it, there are others that will in many cases embrace it, I did exactly that, witness the amount of modern vehicles with electric cooling fans these days. So, I purchased the electric fan from a Mercedes Benz, now these use an entirely different system of control, this is called PWM, or Pulse Width Modulation, in other words as the engine starts to heat up the fan comes on very slowly, and if that amount of airflow is not enough it will increase incrementally to keep pace with engine temperatures, the result is minimal load on the alternator, in fact the load is incredibly small, but of course we have talked about energy here but it has proved there are fuel costs to be saved.
Now lets have a look at something else. Your car is outside your house, windows closed on a hot day and your fan is the typical VC unit. If you open the bonnet on a vehicle with a VC fan, you will find it it rotates with little or no resistance, in fact if you know what you are doing you can start the engine and stop the fan, I will not say how, but use some commonsense. So, back to our stinking hot car outside the house, you start the engine and put on the AC however, it is not working? This is because the fan power needed to draw air through the condenser is absent, the viscous clutch drive is not engaging so air is not being pulled through to cool the condenser, now we know this is not speculation it is fact. We also know that the AC condenser is in front of the engine cooling radiator, which at the moment is cold, so even if some of the warm air from the condenser does get drawn towards the engine it gets cooled by the engine radiator, and we already know for the viscous coupling to work it needs warm air, so until the viscous coupling heats up and engages the fan you can just sit in the car getting cooked, here is where the electric fan is a clear winner, the moment the AC is switched on, the PWM electric fan is switched on at around medium speed, so the cooling of the AC condenser is immediate, that is zero delay of getting cold air into your vehicle. It is only when the VC has had enough warm air over it to activate the silicone will the mechanical fan start to engage.
As an aside, people talk about the 'sweet spot' for driving with reasonable economy, in the modified dashboard display I designed and fitted I can say without a doubt that the cooling system on the 80 starts to struggle when approaching speeds of around 75....ish MPH, in particular when climbing hills, whilst I can see that as I have the temperature gauge modification designed by Raventai who I think is no longer a member? The modification shows the needle is starting to climb, I but I am going by the more accurate indication that the electric fan has come on. I am not saying the electric fan on my 80 which is the same size as the mechanical on the 80 is flowing more air than my car doing 70 MPH, but what I am saying is the fan will only run for a minute or so and then go off, if I maintain the speed it will come on and off if I continue over 75 MPH, I know nothing about aerodynamics, although the front of the 80 does resemble a breeze block, I think air is actually 'bouncing' off the front of the car, I would cite that members who have cut vents in the bonnet, or removed the rubber flaps on the chassis rails preventing mud or whatever enter the engine bay have seen decreased engine temperatures when their vehicle is worked hard.
And finally to finish this off and answer your final query about what happens if the electric fan fails, well first I would say I live in southern Spain, so 40* C in summer is not uncommon, so I know it works great, and in the unlikely event of it failing I would do what what anyone else would do, I would let the engine cool down (I do have an overheat warning system) and then continue my journey, but your question is spot on when it comes to being off road out in the desert, I take with me a spare starter, alternator, CV or Birf as they are often called, a drive flange......and yes the mechanical fan is part of my off road spares.
Sorry if there are any spelling or grammar errors.
Regards
Dave
(First car when I was 10 years old, mechanics apprenticeship completed in 1978, so approaching 54 years under a car, currently with my own garage business, which is pretty much dead now (brain surgery to remove cancer tumour), I would be happy to say I have a rough idea what I am talking about.
