California98Civ

As many of you will know, an alternator kill switch would cut power to the field windings in the alt on demand. Keeping them from powering-up would reduce parasitic drag on the engine from the alt and "create" power that some might use for MPH or for MPG (as I do). I need a tip on the best way to do this mod.

WARNING! MUCH INFO FOLLOWING: Below is the wiring diagram for the alt for the 1998 Civic I drive. The "wht/grn" wire in the diagram is the ALTC ("Alternator Control") wire that connects the voltage regulator to pin A19 in the ECU. It is the #2 wire in the alt's 4P connector. The service manual says the ALTC "sends alternator control signal" from the ECU. The "wht/red" wire in the diagram is the #4 pin in the 4P connector. It's the ALTF ("Alternator FR Signal") wire that the manual says "detects the alternator FR signal." But it seems like the best idea might be to cut into the blk/yel wire where it comes into the cabin and run my switch from there. What do you think would be safest for the alt and most reliable as an on-demand switch? (The blk/yel wire, by the way, is the #1 wire in the 4P connector on the alternator.) So if I cut the blk/yel wire for my switch, I will have in effect an on/off switch that will not damage the alt because I'm denying the field windings the power they need to fire up as well as the power needed to send/receive signals to the ECU?

grumblemarc

iTrader: (4)

Maybe you should have posted this in the thread you got this info out of. For one thing no one can see any wiring diagram that is being referenced.

owneyboy

iTrader: (1)

i think this wouldnt work IMO. the belt would still be on rotating (mechanicly) is rotational mass same ammount of drag would be created there still causiing "strain" on your motor and will still have that extra rotational mas to move.

wires have to be pretty thick i would assume and switch has to be able to sustain the "power" other wise it would just overheat and melt.

owneyboy

iTrader: (1)

I get the concept but dont see it working. do you plan on running a relay

grumblemarc

iTrader: (4)

I've heard this idea circulated around and I always wondered how much power people think they actually save. I agree with the above, not a well thought through idea.

California98Civ

I added the diagram on this site. Didn't know you wouldn't see it when I linked it. To answer one question: this is not a high current line. That's the white wire (see diagram). The blk/yel is a low current wire, and a small gauge. It works for some guys. I just need help with the Honda set up. On the rotational mass: that's not the big issue. The real parasitic resistance comes when electrical load is added to the alt's generator. Without that the alt mostly free-wheels. That's drag too, but the tiny minority of the total drag the alt creates.

Do you think the blk/yel is the best wire for the mod? It seems to be in line with the key switch so... any risk of damage you can see?

EDIT: no, I was not planning a relay, just a switch mounted on the dash.

EJ8_Man

I agree with the consensus the rest have provided to you. Why waste time doing this? I saw "kill switch" and my brain classified this as "anti theft". I see little or no functional benefit from your proposed modification.

I encourage you to use this creative aspiration to develop a real kill switch that will work against someone trying to steal your car. Might I suggest you focus this thought at the distributor and fuel pump leads at the ECU. If you need some guidance I'd be happy to offer some ideas. Feel free to PM me if your interested in making your wiring interesting.

94EG8

When you put a load on an alternator the force required to turn it increases, a lot.

That said this is really all kind of useless when you realize that these things will only run for 15 - 20 minutes off the battery.

lostforawhile

you are correct in interrupting that wire, ignore the trolls, the ecu even reduces the field current to unload the alternator when the voltage is high enough, that's the reason for the load detector Honda has used for years, when there is a light load on the electrical system the field current is reduced, the inertial drag on the alternator is very small, what causes the load are magnetic forces, when the alternator is charging and producing heavy current, it's essentially a magnetic brake that is being spun by the engine, when you turn off the field current, this load goes away, and you are simply spinning the weight of the armature and it's fan on bearings.

owneyboy

iTrader: (1)

.......troll? its been a while since ive had to think about alternators (had trouble thinking which forces caused what physics electricity/magnetism vs mechanical ).. i didnt realize things because i barely woke up.

http://www.acuravigorclub.com/Timely...Timely1201.htm

10psiLsEf2

the vehicle would still start...right?


a good strong battery will net A pretty far drive with out the alternator.

or am i not getting it?

lostforawhile

ok you get a troll pass since you were half asleep but you don't get to collect the 200 dollars when you pass go

lostforawhile

it depends on the load, if it was night and raining with the lights,wipers and defroster all going, it wouldn't go far

10psiLsEf2

dude you dont want your car to move lol!

all it takes is 1 block and then a tow truck/trailer.


idk bout this idea!

California98Civ

[Ignoring trolls.] Thanks for your comment. Looking at the wiring diagram, if I cut the blk/yel, wouldn't the field widings get power through the wht/blu wire that runs through the charging system light? I would need to find where those two wires branch-off after the under-dash #15 fuse, no?

@ EJ8_Man: I'll PM you in a second. Sounds cool. I wonder though, would a kill switch like that keep someone from just towing away my car?

@ those with MPG/HP doubts: I already charge my deep-cycle battery by plugging-in at night. I run without my alt all day. If voltage goes below 12, I reconnect the alt... I want a more convenient method for reconnecting it. This and other mods are part of how I get 60+ mpg hwy/cty combined. Much of what I do for MPG you could do for HP, and an alt optional switch would be handy for a few extra HP when you want it by keeping your alt from dragging on the engine just as you are trying to accelerate as fast as possible. Get a good deepcycle battery. I use Odyssey and Odyssey chargers.

grumblemarc

iTrader: (4)

I repeat. How much horsepower/MPG are we even talking about?

94EG8

Yes.

About 20 minutes and that's pushing it. That also means you can only run it for about 10 minutes if you plan on starting it again.

You're not getting it. It will amount to next to nothing for a mileage increase, it's also really hard on a battery to do near complete discharges like that. You're not going to come ahead on this.

California98Civ

The purpose of the thread is to discuss the best way to wire such a cut-off switch. It was not a request for a debate about whether a mod that has been demonstrated to work actually "works."

A couple posts back I responded to "lostforawhile" asking:
That question gets lost in pointless debates about the effectiveness of an alt delete that are really not the topic of the thread.

But here is what I can tell you to help your own investigation:

One important mod you want to do alongside an alternator delete is switching to a deep-cycle battery that can be discharged far lower than a starting battery and still provide normal electrical and electronic functions. Some deep cycle batteries have upwards of an hour reserve power, after which you can still fire-up the vehicle. Depending on the car and the driver, alt deletes like this have been shown to boost fuel economy as much as 10%. I am seeing about 5-7% in FE gains right now. I commute 30 miles at normal speeds everyday in this car and it works for me. What I want to accomplish with the switch is making it easier to switch back to an engaged alt on demand, with ease. With that ability I could, among other things, regenerate the battery at more advantageous times, such as coasting downhill in fuel cut-off mode, using no fuel and saving brake pads through engine braking as well. Google: alternator delete test. MetroMPG was pretty thorough, as always.

Thanks.

lostforawhile

the white blue wire simply changes state when the alternator isn't charging, the alternator light has positive on one side of the bulb, when the alternator is charging, the blue white wire is positive, since the bulb has positive on both sides, it doesn't light, when the alternator stops charging, the blue and white wire goes negative, and the light lights, some other stuff also uses the blue and white wire being positive to indicate the engine is running. The alternator can require nearly 10 horsepower to turn , one use for this idea would be a times relay and a WOT switch, when you push the pedal all the way down, it cuts out the alternator for 5 seconds or so, some cars have this factory. the only issue would be if you had a weak battery and the alternator cut out, you might be stranded.