Alternator bypass & engine preheater mod

[paulgato]

Originally Posted by redpoint5

I feel like I'm on dial-up whenever I visit this thread and the pictures begin loading line by line.

Yeah, I know. I'm not very clever with images. I've tried to resize them now so it should be a bit better. I've also removed most of the pictures of the bumper connector as they're not really necesary. Next time I'll remember to take low-res pics!

[serialk11r]

Originally Posted by fearone

Thinking out aloud here...

How about using a cloth iron as a budget, powerful, adjustable temp, sump heater?

After all, this is what ecomodding is all about!

Hmmm that's actually a good idea, especially if you have an aluminum oil pan (aftermarket baffled pans for example). I got to drive a Porsche 981 Cayman, and I had never seen a real water temp and oil temp gauge before; I noticed that the coolant temp went up very fast, but the oil took forever. I feel like you would get better results if you preheated both coolant and oil a little bit rather than just having the coolant heated significantly, but barring that maybe just heating the oil isn't so bad given how fast coolant tends to come up to temperature.

[brucepick]

Paul,

Nice project!

Before I ask for your help, one comment/suggestion:
Maybe you've already done this. Your starter doesn't need boosted 13.5 or 14.0 volts. I think you can connect it directly to a lead acid battery, and also connect your boost converter to the same battery and run the rest of the car off that. Higher voltage going to the starter might not be good for it.


I did a similar project but not as evolved, on my '97 Civic HX. That was before the engine blew (as mentioned here in this thread) by California98Civic. RIP my Civic HX.

I still have the two batteries I used for the Civic, and am now driving the '96 Accord. I expect to drive it another 12-18 months. I'm considering doing a similar project again. I hope I can get some input from you (pun??).

Overall plan:
I'm considering powering all the electrical from the two deep cycle (aka deep discharge) batteries, plus the regular starting battery which will only be used to start the car.

I found the car itself ran just fine on my 12.8V 40AH lithium battery. Over the course of a day's driving, about 2.5-3 hours, it would drop to somewhere around 11.8-12V while in use, which was OK.

The headlights didn't do as well, running on a 12V lead acid deep cycle battery. For these, I now want to use some of those Chinese 10A DC-DC boost converters you mentioned. The 2 headlight fuses are under the hood (bonnet); it will be easy to provide power there. I plan to set them at about 13.5 or 13.8V. I don't think I need a full 14V, and any slightly lower voltage will extend both battery and bulb life.

My lead acid battery for headlights was nominally rated about 100AH but really only good for about 40-50AH if you don't want to destroy the battery. After about 1 hour's drive the headlights were getting less than 12V and so were not very bright. If I needed headlights for both to and from work I was out of luck; I would need to hook up the alternator.

Question 1:
How many of those 10A DC-DC booster converters would I need, supporting only the headlights? The car uses 2-20A fuses for headlights, one each left and right. So theoretically 4x10A converters should provide 40A. However I think maybe it's better to provide 50-60A of capacity so as not to overtax the boosters. What do you think? The car uses separate high beam and low beam (dip) bulbs. At approx 10A each, when all four are lit that's 40A. This car lights all four bulbs when using the high beams. I don't think it's practical to reconfigure the circuit to use only one bulb set at a time - even on cars built to do that, there's always an instant when all bulbs are lit, when switching between high/low beams.

Question 2:
What do those boosters do when they get less than the specified 10V required input? Damage to the boosters? Or do they just not provide your specified output voltage briefly, and then go back to normal when the input voltage goes over the 10V minimum? Do you know?

I'm considering also using the boosted battery to power the wipers. The wipers never were very happy on the 12.x volts provided by the lithium pack. Just a matter of routing power to the wiper fuse patching it in.

Again, great project, and thanks in advance for any advice you can give.

[oldtamiyaphile]

Originally Posted by paulgato

As for the PWM controller idea, that 10A PWM unit should be suitable for the heater blower but you might need to bypass it with a switch for the highest speed. At 12.5v my blower motor takes about 16A at full speed, 8A at speed 3, 4A at speed 2 and 2A at speed 1, and at 14.5v those motor loads will be proportionately higher of course, so 19A at full speed and 9.5A at speed 3. I got a 15A PWM so I would have to do the same thing and bypass it for speed 4.

...but why are you using a PWM for controlling DRL's? Are the DRL's on your car just the headlights fed via a resistor?

I suspect 10A will be fine in the real world as the 3-4 settings are a bit too much really. Ideally, I want to buy a spare blower assembly to convert to brushless power.

I have a set of Phillips DRL8's. They use a PWM controller to improve effciency/life and dim them when the main beams are on. Problem is they are automatic so they switch off after ten seconds of EOC. A basic PWM controller will mean they're always on in the ACC position, with the option for dimming with main beam/ park light still there. I also like the idea of gradual dimming via an Arduino when the vehicle is stationary to further save power.

[paulgato]

Your starter doesn't need boosted 13.5 or 14.0 volts. I think you can connect it directly to a lead acid battery, and also connect your boost converter to the same battery and run the rest of the car off that. Higher voltage going to the starter might not be good for it.

The starter motor will be drawing 100+Amps. Any DC/DC step-up converter I might use to get the battery voltage up to the alternator output voltage of 14.5v is only going to output 30 Amps at the very most, more likely between 10 and 20 Amps, so I don't think the starter motor will 'see' a significantly increased voltage. If you start a car with the headlights on, they often dim as the starter turns, right? That's because the starter is drawing so much current that the battery voltage is pulled right down, even though the starter motor has its own dedicated cable.

The headlights didn't do as well, running on a 12V lead acid deep cycle battery. For these, I now want to use some of those Chinese 10A DC-DC boost converters you mentioned.

As far as the headlight dimming goes, have you measured the actual voltage drop between the battery and the headlights? Both positive and negative? It's common to find a significant drop there which can be removed by feeding the headlights direct from the battery via thick cable and a relay triggered by the existing wiring to them. (The stock wiring is usually too thin and runs a long way to the headlight switches on the dash and back again, hence the voltage drop.) I'm going to try that first. My headlights get at least a volt less than the battery puts out, so when the battery is at 12v, the headlights are getting less than 11v. If they were truly getting at least 12v at all times my hunch is that they would be fine. The same MAY be true of the wiper motor, although I haven't measured that yet.

Question 1:
How many of those 10A DC-DC booster converters would I need, supporting only the headlights? The car uses 2-20A fuses for headlights, one each left and right. So theoretically 4x10A converters should provide 40A. However I think maybe it's better to provide 50-60A of capacity so as not to overtax the boosters. What do you think? The car uses separate high beam and low beam (dip) bulbs. At approx 10A each, when all four are lit that's 40A. This car lights all four bulbs when using the high beams. I don't think it's practical to reconfigure the circuit to use only one bulb set at a time - even on cars built to do that, there's always an instant when all bulbs are lit, when switching between high/low beams.

I would forget the fuse ratings. Headlight bulbs use about 55w, or about 5Amps. One 10Amp converter should be adequate for each bulb.

Question 2:
What do those boosters do when they get less than the specified 10V required input? Damage to the boosters? Or do they just not provide your specified output voltage briefly, and then go back to normal when the input voltage goes over the 10V minimum? Do you know?

No, sorry, I don't know. I have never actually used a DC/DC converter, and I expect they vary in design and performance.

One thing to watch out for is that they usually don't have a common ground or common negative. That means that you have to isolate both the positive AND the negative outputs from the vehicle's chassis and from the rest of the car's wiring. Car wiring is not usually designed that way and almost always uses the car body as the negative return path, so unless you can find a converter that uses a common negative ground (input negative terminal connected directly to the output negative terminal) then that does potentially make it tricky to use them in a car for individual components. (I bought a 30Amp PWM for my blower motor that turned out to use a common positive rather than common negative, so that was a waste of money! My fault: I should have asked before buying.)

Using DC/DC converters to feed power into the WHOLE of the car's electrical circuit however is not so complicated as the only place where you have to carefully isolate a negative from the chassis is between the donor battery's negative terminal and the DC/DC converter. The output negative from the converter can be connected direct to the chassis as long as the input negative is not. I hope that makes sense. As I say I have not yet used one of these converters so take anything I say for what it's worth!

I'm considering also using the boosted battery to power the wipers. The wipers never were very happy on the 12.x volts provided by the lithium pack. Just a matter of routing power to the wiper fuse patching it in.

Again, that MAY be all that is required, provided you can find a converter with a common negative ground.

I have found just ONE such converter so far...

E914 12A 12v-12v Battery Charger (12V Turn On)

It is designed as a charger for an auxilliary battery to charge it from the vehicle's main cranking battery, so I'm not sure it will really be suitable as far as shut-off/switch-on voltage levels go, and the output seems to be a fixed 14.0v, which may be half a volt too low for my purposes, but at least it has a common negative!

[brucepick]

Thanks Paul!

Originally Posted by paulgato

The starter motor will be drawing 100+Amps. Any DC/DC step-up converter I might use to get the battery voltage up to the alternator output voltage of 14.5v is only going to output 30 Amps at the very most, more likely between 10 and 20 Amps, so I don't think the starter motor will 'see' a significantly increased voltage. If you start a car with the headlights on, they often dim as the starter turns...

Agreed. I didn't account for the fact that a booster of approx 30-40A capacity couldn't possibly power a starter.

As far as the headlight dimming goes, ... It's common to find a significant drop there which can be removed by feeding the headlights direct from the battery via thick cable and a relay triggered by the existing wiring to them. (The stock wiring is usually too thin ... The same MAY be true of the wiper motor, although I haven't measured that yet.

My experience, in which the 12V lead acid deep cycle really only could power headlights for about 1-1.5 hours effectively, was based on my experience in the Civic. Originally it had too-thin headlight wiring, with too long of a run also. Early in my ownership of it, I remedied that with heavy gauge leads directly from the battery to relays, and more heavy gauge leads to the bulbs. I used the deep cycle battery with that improved wiring configuration.

I would forget the fuse ratings. Headlight bulbs use about 55w, or about 5Amps. One 10Amp converter should be adequate for each bulb.

Good point. I like that.

... One thing to watch out for is that they usually don't have a common ground or common negative. That means that you have to isolate both the positive AND the negative outputs from the vehicle's chassis and from the rest of the car's wiring...

Using DC/DC converters to feed power into the WHOLE of the car's electrical circuit however is not so complicated as the only place where you have to carefully isolate a negative from the chassis is between the donor battery's negative terminal and the DC/DC converter. The output negative from the converter can be connected direct to the chassis as long as the input negative is not. I hope that makes sense. As I say I have not yet used one of these converters so take anything I say for what it's worth!

Thanks - I wasn't aware of this. My past setup used a chassis ground for the battery. I'll need one additional wire for battery - to booster -, but that is very doable.

[paulgato]

Originally Posted by brucepick

My experience, in which the 12V lead acid deep cycle really only could power headlights for about 1-1.5 hours effectively, was based on my experience in the Civic. Originally it had too-thin headlight wiring, with too long of a run also. Early in my ownership of it, I remedied that with heavy gauge leads directly from the battery to relays, and more heavy gauge leads to the bulbs. I used the deep cycle battery with that improved wiring configuration.

Ah, so you're ahead of me on the wiring.

I am surprised then that you only got 1 - 1.5 hours headlight use out of the deep cycle battery or batteries. I currently have a single 90Ahr AGM battery in the engine bay and I get 5 hours daylight use out of it or about 2 - 2.5 hours night-time use with headlights on. If it's also raining and I'm using wipers then that will drop to 1 - 1.5 hours, especially if also using the blower. The point at which I give up and plug the alternator back in is when I THINK the RESTING voltage has dropped to 12.2v, which should correspond to about 50% charge. I gauge this by monitoring a little volt meter plugged in to the cigarette lighter, although that of course measures the voltage under load, which at 50% charge could be 12.0v or 11.5v or even 11v, depending on the load being drawn at the time. Just to run the engine, ECU, etc. - ie, with no lights on or other 'optional' equipment - takes 6.4A @ 12.5v. Adding sidelights makes practically no difference as all 6 bulbs involved are LED's now, so I often use those as daylight running lights, or even urban (under street lights) night-time lights, as they are quite bright.

I experimented with different headlight bulbs. I ended up using Phillips EcoVision bulbs as they do use about 20% less power than standard (44w as opposed to 55w) but still output a better-than-standard light, and seem to do OK-ish at lowish voltage. Also, keeping the speed right down means the headlight brightness is not so critical, and saves fuel of course.

[CORRECTION: I made a mistake here. I had originally fitted the Phillips Ecovision bulbs, but I found they didn't give out enough light at 12.x volts so I re-fitted a pair of Osram Nightbreaker bulbs, which are marketed as being brighter and whiter at a standard 55w power rating. (I had forgotten I had gone back to the Osrams.) Obviously, you don't get enything for nothing and the brighter bulbs don't seem (anecdotal evidence from the web) to last very long and people seem to have to replace them every year or so. I find that the Osram Nightbreakers) do give out adequate light at the lower, alternator-free voltage, and I believe that at this lower voltage they should also last much longer than at 14.4v. At some point, when I get around to it, I will upgrade the wiring to the headlights - and perhaps then I'll be able to use the 20% lower-wattage Phillips bulbs and still get a good light output - but in practice the Nightbreakers work well already.]

But a battery's Ahr rating changes depending on what load you put on it. You get many more Ahr's out of it if you can keep the load less than 1/10 of it's nominal Ahr rating, so if you have your two deep discharge batteries plus your starter battery (you don't say what Ahr rating they are) then your load should be nice and low compared to the Ahr rating, and you should get WAY more than 1.5 hours out of the set-up, I would have thought. If you had 200Ahr in total then in theory you could draw 20A for 5 hours to get down to 50% charge. 20A on my car would represent engine (6.4A), headlights (10A), and wipers (3.3A). My single 90Ahr battery gives no more than 1.5 hours under that kind of load, but actually less because at that load the battery voltage is pulled right down, and at 50% charge under high load the voltage is too low to light the headlights as I would want (...and under dark and rainy road conditions, I DO want good headlights!) But if I had more/larger batteries - something closer to 200Ahr total - AND if the load were spread between the batteries, the terminal voltage under such a load at 50% charge would be higher - closer to 12v - and the headlights would therefore be brighter.

Just thinking aloud here for my own situation. I had thought that the higher the current capacity of the DC/DC converter the better, but if the aux battery were taking the entire load of the system until its voltage was so low that the DC/DC cut out, leaving the starter battery to take over from there, then each battery would be drained more quickly than 1/10 its nominal Ahr rating. (Unless I had 200Ahr+ of aux batteries!) So maybe it's actually better to have a modestly rated DC/DC converter that will provide something like 10 or 12A, so it will provide ALL the power under low-load conditions and about HALF the power under high-load conditions, thereby spreading the load between the two batteries and keeping the load on any one battery at or below 1/10 of its nominal Ahr rating.

I was even thinking of using one (or two) of these 8.5A laptop adapters, set to 15v output...

15 24V Laptop Car Adapter 8.5A 9 Charging Tips | Maplin

I was thinking of trying one of those out to see if it worked as a DC/DC converter/charger. In theory 15v would be enough to fool an alternator into closing down without having to disconnect it, and 15v would not be too much for the starter battery for an hour or two at a time, given that it would be under partial/occasional load and would have been drained a bit by cranking the engine. And if it doesn't work for any reason then I will have a good car adapter for my laptop, which I am sure to use from time to time.

[Edit: Another consideration is that the larger the batteries in relation to the load, the longer they will last before needing to be replaced. I can't afford the real deep-discharge traction batteries (that can be regularly discharged to 20% without ill effect and will last 10-15 years) and also they tend to be too physically tall to fit anywhere sensible in the vehicle, so I'm going for some AGM 'leisure' batteries that cost just under £100 and come with a four-year warranty. I got a 90Ahr one as that was the largest I could fit in the battery tray in the engine bay, and I shall get a slightly larger (110Ahr?) battery to fit in the spare wheel well. Larger would be better, but it needs to be low-profile to fit nicely in the wheel well. I could fit two of the 110Ahr batteries in the wheel well, but weight is also a consideration, and since 80% of my driving is local and well within the range afforded by the single 90Ahr battery, I think I can only justify the weight and cost of one auxilliary battery of about 110Ahr.]

[paulgato]

Originally Posted by fearone

Thinking out aloud here...

How about using a cloth iron as a budget, powerful, adjustable temp, sump heater?

After all, this is what ecomodding is all about!

That's actually a really good idea. An electric flat iron is about 1kw or 1.5kw I believe, but closely controls the temperature of it's plate. (A silk shirt is WAY more fussy about temperature than an engine sump!) And the temperature range of a flat iron is perfect for a sump heater. You could bond it onto a flat area of the sump with heat transfer epoxy adhesive - the stuff they use on heat sinks - or just ordinary epoxy works quite well if the two surfaces are nice and flat.

The main problem is that there is VERY limited space between an oil sump pan and the road, and having a hard lumpy item right on the bottom could spell disaster if you hit a rock: rather than having a slightly bent sump pan you'd be liable to crack a hole in it. Also you would have to waterproof the iron's electrics very effectively.

But I really like it! You might have to 'hack' the iron. I've never taken one apart (I threw one out a few weeks ago - drat!) but you might find the element is also quite flat and close to the plate, so you can seal that part off, bond it to the bottom of the sump, so that whole part has a nice low profile, ...and then extend the wires (?) to the heat setting knob and mount that in a little box somewhere higher up where you can get to it easily to adjust it. Or mount it on the dash! But you'd probably find that one particular setting is ideal and you can then seal the temperature control in a waterproof box in the engine bay somewhere and forget it.

I reckon a 1kw iron would get the oil up to full temperature in about half an hour. Modern synthetic oil doesn't begin to break down below 150 degrees C, so setting the iron to a 'wool' setting of about 150 degrees C should be perfectly safe, given that there's always going to be a temperature drop between the iron and the oil across the oil pan's wall.

Do it! And let us know how you get on.

[nemo]

Originally Posted by paulgato

The main problem is that there is VERY limited space between an oil sump pan and the road, and having a hard lumpy item right on the bottom could spell disaster if you hit a rock: rather than having a slightly bent sump pan you'd be liable to crack a hole in it.

Why must it be mounted on the bottom. The bottom may be the most efficient placement but you may be able to mount it low on the side.

Originally Posted by paulgato

...and then extend the wires (?) to the heat setting knob and mount that in a little box somewhere higher up where you can get to it easily to adjust it. Or mount it on the dash!

Interesting.

[paulgato]

Originally Posted by nemo

Why must it be mounted on the bottom. The bottom may be the most efficient placement but you may be able to mount it low on the side.

True, true. You'd need a flat area to mount it though. But yes, because the iron has a very effective built-in thermostat you could safely mount it anywhere on the sump, even if it's not in perfectly flat, intimate contact. An aluminium sump pan (such as the one on my Golf) should transfer heat very effectively from ANY position on its surface to the whole area of the sump. It wouldn't even have to be mounted below the oil level. I should get under there and check the actual geometry of my sump pan.

[Edit: This kind of travel iron might be ideal as it is small and you can fold away or remove the handle...

http://www.amazon.co.uk/Kenwood-Disc.../dp/B0000ZGZRM

...and they can be found even cheaper or second hand on ebay for almost nothing.]