How to Install an alternator cut-off ("kill") switch on a 1998 Honda Civic

[steffen707]

Originally Posted by California98Civic

I basically agree, but remember that I have disabled only two of the signal wires, not the large gauge charging wire to the battery, and I can still completely cut-off the alternator. I put my switch in the off position and when I restart the engine with a "bump" or "roll" start, the alt is not on anymore. And it has never come back on in 7 months since unplugging the alt and the two or three months since completing the kill switch project that starts this thread.

I learned, using a process of elimination method you recommended, that if I disabled only the blk/yel and left the wht/blu connected (for the "battery" light on the dash) the alt would come back on. When I studied the wiring diagram it seemed the battery light was able to give just enough power to the alt to fire it up on its own. I'm not fully confident I am correct about that because it is not what seems logical in terms of design, but it is what experiment showed me, so I have followed it.

Yeah, sometimes its just easier to do what you "KNOW" works, than what makes sense. I don't know if I'm going to do all 4 wires or just 2 of them like you did California, but I charged the battery last night from 12 volts after 3-4 days to 12.8 with my charger connected to my killowatt power reader, and it said it cost me like 8cents to charge it. Now I gotta do some calculations to see if its worth it.

My calculations are as follows
$0.10 / 3days * 365days per year = $12.16 per year
$12.16per year / $4 per gallon = 3.0416 gallons I could buy with that $12.16 cents if I didn't spend it on electricity.
3.0416 gallons * 45miles per gallon = 136.8 miles I could drive on that gasoline
136.8 miles / 1.8miles per gallon increase = 76 gallons needed to be used to equal things out. So as long as I drive more than 45miles per gallon * 76 gallons = 3420miles in that year of paying $12.16 for electricity, I will be better off.

I didn't take into account the possibility of killing the battery earlier than normal, and I know I could have just compared the 8-10 cents it cost to charge to what mileage I actually did drive and gallons I did use in the last 3 days; however, I was doing a ton of tests, that gave me horrible MPG over this past week.

I'll try and do some more calculating after I stop messing with the car for a while.

[steffen707]

Actually i got bored and tried the other calculation. If it cost me $0.10 to charge up the battery and gas costs $4 per gallon. I could have bought .025 gallons of gas, at 45mpg I could have driven 1.125 miles. Divide that by my increase in gas mileage of 4% of 45mpg is 1.8. Which is .625gallons at 45mpg is 28 miles. So as long as I drove 28 miles that $0.10 cent charging cost was worth it.

I know I drove at least 70 miles, so i'm ahead, right?

[cbaber]

Try using the feature to update your previous posts, rather than making posts one after the other. Keeps the info more organized and easier for people to read these threads.

[steffen707]

I get what you're saying, but having all 3 posts combined into 1 large post makes it harder to read through. If you break up the posts then it gives a natural break in the information.

Otherwise this whole thread would be one long run-on paragraph.

[BrianAbington]

I don't know if anybody still makes one (because I've been out of the car audio game for a while now) but in the late 90's my friends neighbor had a rather large sound system in his GMC jimmy. He had an alpine alarm that monitored the voltage of the battery and if it dropped below 12 v it would start the truck and recharge it to 14 v. We could probably learn more about the monitoring system to adapt an automatic setup with an over ride incase ti decides to not work while driving.

[turbotomass]

Originally Posted by steffen707

Actually i got bored and tried the other calculation. If it cost me $0.10 to charge up the battery and gas costs $4 per gallon. I could have bought .025 gallons of gas, at 45mpg I could have driven 1.125 miles. Divide that by my increase in gas mileage of 4% of 45mpg is 1.8. Which is .625gallons at 45mpg is 28 miles. So as long as I drove 28 miles that $0.10 cent charging cost was worth it.

I know I drove at least 70 miles, so i'm ahead, right?

so then your able to go 70 miles on a fully charged battery without an alternator?

you still have to take into consideration paying off the deep cycle battery. by any chance did you buy the highest reserve capacity battery you could fit in the car?

[turbotomass]

Originally Posted by BrianAbington

I don't know if anybody still makes one (because I've been out of the car audio game for a while now) but in the late 90's my friends neighbor had a rather large sound system in his GMC jimmy. He had an alpine alarm that monitored the voltage of the battery and if it dropped below 12 v it would start the truck and recharge it to 14 v. We could probably learn more about the monitoring system to adapt an automatic setup with an over ride incase ti decides to not work while driving.

The honda charging system is supposed to do this, but from my understanding it's limited. I've never had an actual voltmeter in my car to even look and see what the computer is doing.

[steffen707]

Originally Posted by turbotomass

so then your able to go 70 miles on a fully charged battery without an alternator?

you still have to take into consideration paying off the deep cycle battery. by any chance did you buy the highest reserve capacity battery you could fit in the car?

I was able to go 70miles but that was in low charging mode, not "no charging mode".

I havn't purchased a deep cycle yet, I wanted to test it out first.

[danwat1234]

Summary of what ELD does, from secret way to gain a bit more mpg - Honda Civic Forum
------------------

The civic computer instructs the alternator to drop from 14.5 volts to 12.5 (ie. not charging the battery) when all of the following are true:

- Load below 10A
- Speed below 40 MPH
- Engine speed below 3600 RPM
- Coolant temp above 140 F
- A/C off
- Intake air temp above 65 F
- Brake switch off
- Fuel cut-off not active


In other words, the alternator is essentially "idling" when the load on it is low, the car is warmed up and being driven gently. Note that the alternator reverts to normal charging when braking or decelerating (fuel cut-off mode), which is like a simple form of regenerative braking found in modern hybrids and electric vehicles.
------------------

I myself have taken out the ELD, so whenever the engine is on, a bit over 14V are at the battery posts. I feel as though this will help increase the life of a regular lead acid battery, as it's being charged whenever I'm driving. Especially good in winter. I managed 36.6MPG on a trip to the beach in my 99 Civic DX auto with the ELD removed.

Do you think it eats much fuel? The alternator isn't working very hard to keep the battery at 14.2V.

EDIT: I don't think Canadian Civics have an ELD

[steffen707]

Originally Posted by danwat1234

The civic computer instructs the alternator to drop from 14.5 volts to 12.5 (ie. not charging the battery) when all of the following are true:

This isn't entirely true, when the ecu grounds the alternator control circuit "C" wire, the alternator does drop to 12.5 volts, but it is in fact still charging. I tested this with an almost dead battery that couldn't start the car. I jumped it and while grounding this "C" wire the car ran just fine.