Alternator bypass & engine preheater mod

[paulgato]

Having discovered that my mpg rises by almost half a mile per gallon for each amp I reduce my electrical consumption by, I just thought of another mod to reduce electrical consumption.

In most cars I have owned, when the headlight main beam comes on the dipped beam goes off. It's only when pulling on the light control stalk that both come on together momentarily - for signalling.

In my present VW Golf Mk4 TDi (PD) estate car, the dipped headlights stay on all the time the headlight switch is on, even when the high beam (HiD) lights are being used. This uses 110w (or nearly ten amps) that I don't think needs to be used at all. It would be a simple matter to fit a relay in line with the dipped headlight bulbs so that when the high beam is on (2x35=70w) the dipped beam goes off.

Admittedly, I more often use dipped beam than main beam, but it's such a simple and cheap mod, and when I do use main beam it will make about 4mpg improvement to f/e.

Whilst in this vein (and right now this is about extending my driving range without an alternator) I have just ordered some low energy bulbs. So I'll be fitting LED's in place of the regular front side lights and tail lights, as well as rear number plate lights. These are all nominally 5w bulbs at an 80% saving in energy so will save me 40w. (There are two pairs of tail light bulbs.) I also ordered a pair of energy saving H7 headlight bulbs (Phillips Eco Vision) which claim a 20% saving on energy, as well as a doubled lifespan. A guy on t'interweb somewhere has tested the current draw of these and sure enough they put out as much or more light than standard bulbs but use 44w as opposed to the standard 55w. So those should save me another 20w, making a total of 60w saved. I also think it's worth changing all the interior bulbs for LED's, but I'll do that another time.

Frankly, this is small potatoes as far as fuel saved per pound spent goes, but there is the added benefit of vastly improved reliability (and therefore safety) of these low energy bulbs over conventional ones. In the context of designing an alternator-free system, I can expect to save about five amps using these new bulbs, and even more by turning off the dipped beams while the main beams are lit, and that should extend my night-time driving range by about 20%.

I'm so glad I did all that current measurement though as I can now improve fuel efficiency by about 3mpg simply by not using the blower. I was in the habit of using it on speed 2 all the time, which I realise now was using a massive 6.8A. There'll be times I have to use it of course but I've been experimenting with not using it and so far it's been fine almost all the time.

[paulgato]

Engine pre-heaters are as rare as hen's teeth here in the UK. You can get them but they're really expensive, and there is approximately one manufacturer and one model of heater to choose from. I can get them from the US but they are mostly 110v, and also there can be import tax problems when buying stuff from the US.

But today I found a company in Germany...

AutoteileOst (look for 'motorvorwärmer')

...who sell a range of cheap engine pre-heaters. There is a bit of a language barrier but I think I have found my supplier. UK cars almost never have engine pre-heaters fitted, but I guess winters in Eastern Germany are a bit colder.

Has anyone had any experience with Autoteile Ost?

[California98Civic]

Subscribed.

Nice thread. I'd point out that Brucepick did something similar--as far as the charging system and "leisure battery"--with his Civic HX before the engine blew. He called it an "externally powered electrical system."
http://ecomodder.com/forum/showthrea...tml#post287705

[RedDevil]

Subscribed!

I can only recommend replacing the low beams with HIDs. That should save you about 3 Amp on their use (assuming 35W HIDs versus 55W Halogens). And as the HIDs have their own power regulators, a drop in voltage to 12V will have no effect on their brightness.

You would need to use the high beam less often when you have HIDs too. They are about 3 times as bright despite their lower power consumption. You can see the road about 50% further ahead in the dark.

The ecovisions are about 35% more effective than standard. Nice and well.
HIDs are about 400% more effective though. They beat anything, even LEDs and CFLs.

Need to add that my Insight has low beam lenses with produce very little stray light, so at night other road users seemed to overlook it coming from aside (no running lights in European Insights too...!).
My cheap aftermarket HIDs solved that problem, helped by the now very brightly lit area on the road ahead of my car of course.

[paulgato]

A good plan RedDevil.

I did look into getting after-market HiD's for the dipped beam lights but balked at the cost. How much did yours cost? If I could get them cheapish then yes, that should negate the need to bump up the voltage to the standard H7 headlight bulbs.

I measured the voltage at the H7 terminals today. At 12.2v battery voltage the headlights were getting 11.0v. With the engine on (and alternator on) the battery voltage was 14.5v and the headlights were getting 13.2v. So upgrading the wiring and fitting a relay would bring the headlight voltage up by at least a volt. With alternator off, the headlights would be getting at least 12v, which should help a lot. And a couple of relays will only cost a couple of quid. But, as you say, HiD's have therir own voltage regulators so they would be much better.

Maybe I should look again at the aftermarket HiD's, but it's costing quite a bit to get the engine pre-heater system and the new battery/charger system sorted out, so the HiD's might have to wait.

...

Hmmm... Just been reading about aftermarket HiD's. It seems they sometimes don't work well in a reflector designed for halogens. It also seems it's an illegal modification in the UK, unless you also have self-levelling headlights or self-levelling suspension, ...which I don't. (Well, LED's as tail lights and side lights - anything except interior lights in fact - are technically illegal too, but they're not as obvious, so you would be very unlucky to be challenged on them. Dipped headlights can potentially dazzle other drivers so will attract more legal attention if they're not standard.

I'm not too keen on spending a lot of money on something that may get me into trouble, and may have to be taken off the vehicle anyway to pass an MoT test. HiD's make perfect sense technically, and congratulations on fitting them successfully on your car, but I think I'll file that under 'to be done later, maybe'. More light, that's true, but only an 18w total power saving over the Phillips Eco Vision (35w per bulb rather than 44w per bulb). If I can't see where I'm going, I do have the HiD main beam lights at my disposal.

Oh, and I just read something about UK law saying that HiD's must be configured so that the dipped beams stay on when the HiD's are on, so it looks like my 'main beam on: dipped beam off' mod would be illegal too. Ah well, like I say, I don't use the main beam that much. (An advantage of driving everywhere slowly!)

[RedDevil]

Hi Paul.

Google is your friend. I've seen complete HID sets for less that $25 on alibaba.com, yet shied away from that because of delivery time and customs and shipping issues.
Also I do not use PayPal (yet, maybe later).

Several shops over here sell those kits for < 50€; I got me one of those.
It had the wrong plugs, after a hassle with the shop I got the right plugs with a free set of lamps.
They were the wrong color, but still nice as spares. If I ever need them; HIDs typically last for 6000 to 8000 hrs burning time.

Yes, HIDs take a few seconds to get as bright as the halogens they replaced and a few more to get near their full strength. Also you need to clear the lamp units more often; condense does not evaporate and snow does not melt because it hardly emits any heat at all, bright as it may be.

The HIDs draw less power so the voltage drop in the wiring should be less. and the regulating units that come with the set will do the rest. There is no drop in intensity when I key off, despite a 2V drop in voltage.

Over here cars sold with HIDs need beam heigth auto-adjust and automated lamp unit spray cleaners and typically have a double sized window spray tank because of that.
Aftermarket HIDs are exempt from that ruling, as it is almost impossible to retrofit those extra measures on cars that were not designed for it while HIDs do increase visibility.
You need to check your law on that, what makes sense over here might well do so in the UK too.
It might even be one of those European laws bestowed on us.

With HIDs you can choose the color 'temperature'. I chose 5000K which appears chalk white. I already had LEDs for running lights that were 6000K (slightly blueish) that were a big color mismatch with the halogens, but the HIDs look almost right.
I thought the color difference would not matter much, but once you see it it itches.
If I had to do it again I would buy both HIDs and LEDs with a lower temp color (4300K, sunlike white)

Cheers, Bart

[paulgato]

Update...

Work has been super-busy lately and I haven't had a chance to do much on this. I've researched various options, and made a few preparatory purchases, but not actually done much. Also, nights are getting longer and I've not had much daylight for working on the car.

I have managed to replace all interior bulbs with LED's. Small potatoes, but just about worthwhile I guess. That cost £25. Well, frankly, if I'd known how much hassle it was going to be I probably wouldn't have bothered. But now it's done I guess it's kind of worthwhile.

I replaced the two front sidelight bulbs with Osram LED's and fitted those Phillips EcoVision H7 dipped headlight bulbs. That saves me 20w. I'll get some LED's for the tail and brake lights, which will save me another 15w. It doesn't sound much but that's probably adding at least 1mpg.

These little electrical savings will save me fuel now and will extend my alternator-free range once I start plugging the car in every night.

I did get a battery to replace my standard starter battery. In the end I went with a 90Ahr AGM battery which was slightly smaller than the 110Ah flooded leisure battery I was originally looking at. The 90Ah AGM is heavier than the original but fits straight into the existing battery box without modification, and it seems AGM batteries are a good choice for this 50% daily discharge regime. It cost £90 delivered and has a four-year warranty. They claim it will be good for 1000 discharge cycles to 50%.

I've just ordered a 10A charger to install in the engine bay and a remote (keyfob activated) relay switch to turn on the engine heater from indoors in the mornings. So the battery charger (and possibly a small, 100w sump heater?) will be active all the time the 230VAC lead is plugged into the car's inlet socket, and the coolant pre-heater (3kw?) will be switched on a half hour before drive-time.


Two further thoughts...

1. Having discovered how much electrical power the heater blower motor uses, I've been experimenting with using windows instead. Once the car is warm I can just about keep the screen clear using the windows, but as the weather has got colder I'm finding I can't heat the car properly without the blower.

I've done some calculations and realised that the blower at lower speeds is incredibly inefficient due to the use of resistors to slow it down (That's Stone Age technology VW!) If I could fit a Pulse Width Modulation speed controller in place of those pesky resistors (resistance is useless!) then I'd save a HUGE amount of power...

At present, the blower motor uses...

Full speed... 217w (including 0w wasted in resistor)
Speed 3/4... 154w (including 46w wasted in resistor)
Speed 2/4... 106w (including 53w wasted in resistor)
Speed 1/4... 75w (including 50w wasted in resistor)

...so on the lowest speed I could cut the power consumption from 76w to about 25w using a PWM controller. In fact, on any speed but the maximum speed (which I almost never use) I would save a similar amount of power: about 50w. That's 4A (!) and will improve gas mileage by almost 2mpg in my car. Given that in the winter I really do need that blower motor, and tend to also use it all year round, this would be a real saving. I can't believe that no one is making after-market PWM modules to replace the resistor pack modules in these cars. (Maybe no one realises just how much fuel is being wasted by these stupid resistors?!) The resistor packs are pretty unreliable too, as they rely for cooling on the motor blowing cold air over them.

(Perhaps an easy, though slightly inelegant solution is to leave the existing set-up as it is and add the PWM in between the blower motor and the max speed contact of the blower speed selector switch, mounting the potentiometer knob of the PWM on the dash somewhere. I can then leave the original switch on the max setting and control the speed with the new potentiometer knob.)

I can't believe VW are forcing me to make this blower motor mod by their continued use of 19th Century technology, but I stand to make more gains by doing this than by all the lightbulb LED replacements combined. A blower motor PWM controller should save me about 50w under nearly all driving conditions, whereas the LED's will only be saving me fuel when it's dark.


2. Now what was that other thought...? Oh yes, a slight problem. If I drive with the alternator field wire (IGnition wire) disconnected from the alternator, then after about ten minutes a warning light comes on. It's actually the 'ESP' warning light (yellow triangle) that normally indicates that I have switched off traction control, but reading up on it reveals that it will also come on if there is a break in the field wire from the ignition switch.

I haven't tried yet but I think I can stop that warning light coming on if I connect a 12v +ve supply to the disconnected Ignition wire so the ECU sees a proper voltage on that wire and 'assumes' the alternator is working and is supplying '12v' to its own rotor field. I'll experiment, but I don't like having warning lights on the dash, even if I know they don't mean anything. I guess if the experiment 'works' then my alternator ON/OFF switch will have to be a changeover switch that disconnects the IGnition wire from the alternator field and connects it to a 12v +ve supply.

(I'd thought about including an 'alternator kill switch' which drains the field current down to ground in an already excited alternator, but it's also very easy to momentarily stop the engine if I ever need to kill the alternator while driving, so I won't bother with that one.)

So that's the update. Mostly thoughts rather than actions, but it's all coming together gradually.

[echo-francis]

how did you calculate the watts wasted at the resistor? because my car also use a resistor to control the speed of the blower motor.

[paulgato]

echofrancis, I had already measured the current used by the blower motor at different speeds. (There's a post in this thread with all that data laid out.) I then simply applied Ohm's Law to work out the rest.

In my case (VW Mk4 Golf) that works out like this...

Current draw of blower motor...

Speed 4/4... 17.5A
Speed 3/4... 12.4A
Speed 2/4.... 8.5A
Speed 1/4.... 6.0A

At full speed (4/4) there is no resistor in series so I can calculate the equivalent resistance of the blower motor from Ohm's Law (R=V/I) 12.4V / 17.5A = 0.7ohms.

So then for a 6.0A current passing, there would be a 4.2v drop across that 0.7ohm 'resistor' (Ohm's Law again: V=IR). Therefore the remainder (8.4v) of the total 12.4v is seen across the resistor, and at 6.0A that is 6.0A x 8.4v = 53.76w dissipated (wasted) by the resistor and only 25.2w used by the blower.

There are other ways of calculating but it's basically Ohm's Law.

I find it quite shocking how much energy I'm wasting by having the blower on all the time, and yet, in the winter especially, I can't do without it, so that's a constant 50w being totally wasted whether at night or in daylight.

Now I'm trying to maximise mpg and I've measured the difference in mpg (at 30mpg) at different levels of electrical load. At that speed I'm getting around 90mpg (Imperial) and the difference made by using an extra 1A of electrical power is just under 0.5mpg at 30mph. So that 50w, being equivalent to roughly 4A, is robbing me of just under 2mpg. Your mileage may vary, but the absolute amount of fuel wasted by having 4A of unnecessary electrical load is going to be about the same no matter what vehicle you have. (Well, an efficient diesel will waste about the same as mine and a less effiecient petrol engine will waste much more to produce those 4A.)

(I can't believe car manufacturers still use this old technology. Well, I guess it took them long enough to start using LED's. I well remember cursing them for using tiny incandescant light bulbs in the dash illumination when I had to take the whole dash apart to change a blown bulb (!) This was years ago but LED illumination was already well-established technology for low level lighting. LED's would have been so so easy to incorporate onto the instrument circuit board and would have lasted for the life of the vehicle.)

So, the short answer is, I just used standard Ohm's Law. But I would never have known how much was being wasted there if I hadn't measured the actual current being used on my car. I really recommend doing that. Borrow a DC clamp meter if you haven't got one. That makes it really easy, and you only have to do the measurement once. Once you know what each item of equipment is using you can refer to the list and you'll know how many amps you're using depending on what equipment you have on at any one time.

Oh, and by the way, I've been calculating and measuring based on 12.5v, because I'm planning to drive around without the alternator, but if your alternator is running and producing 14.5v then the power being wasted will be even higher.

And just for the record, I know I measured the effect on mpg of electrical load with the alternator running (of course!) so the voltage will have been 14.4v and not 12.4v. That will skew the figures a bit.

[echo-francis]

I just did the calculation and my resistor dissipate about 25-26w of power
does a PWM controller look like this HOSSEN® NEW 6V-90V 15A DC Motor Pump Speed Controller: Amazon.com: Industrial & Scientific ?