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

[danwat1234]

Yeah, I knew the alternator doesn't shut off completely, just is more passive or set at a lower voltage goal. that quote was from 'gearbox' of civicforums.

[steffen707]

It has been shown to increase mpg by 10% to eliminate the alternator. I would say that running it all the time by eliminating the eld would probably use a little more fuel then it already does in normal mode, but probably not much.

[California98Civic]

I can only simply offer my experience running without the alt since last September. The mod in this thread shuts the alt off completely if after flipping the off switch you cut the engine and bump start. Or if you never turn the alt on in the first place. The biggest gains are on the freeway, or any other driving over 40 mph, which is a condition when the ELD normally has the alt charging at 14.3 volts or so (full on). This means I can use the freeways more, get places quicker and still top 60mpg and more. That's my experience.

[mikehallbackhoe]

has anybody figured out how much this will cost ? how much battery capacity do you need, and how far can you drive at night? what brand deep cycle battery will you use? how long will they last?
what kind of charger? these are a lot of questions, but till they are answered, you really don't know how long it will take to pay for this mod. You also have to remember to charge it, and then unplug the charger. seems like a lot of work and cash for very little gain. Being able to turn your alternator on when you need it is nice, but will negate any fuel savings.
what about just replacing your alternator pulley with a 5 percent larger pulley. would this take some load off the alternator, without the extra expense and hassle of disconnecting your alternator?

[steffen707]

Originally Posted by mikehallbackhoe

but till they are answered, you really don't know how long it will take to pay for this mod.

From a strictly financial standpoint one needs to compare their current mpg with the guesstimate of 10% improvement. in 10,000 miles from 50old to 55new mpg you would save $73 dollars at $4 per gallon gas used.

in 10,000 miles from 30mpg to 33mpg you would save $120.

These figures are without the cost of charging deducted from the annual savings as that is a continual annual cost, and not an up front cost of say the batteries, charger, wire, switches, ect.

SO MANY VARIABLES..............

[California98Civic]

Originally Posted by mikehallbackhoe

has anybody figured out how much this will cost ? how much battery capacity do you need, and how far can you drive at night? what brand deep cycle battery will you use? how long will they last?
what kind of charger?

I use an Odyssey PC1200 deep-cycle battery and the 6amp Odyssey charger (total cost was near $280). The set up might last 5 years or more, with care. The cost of the switch and wire was negligible. I figure it will take about a year and a half "to pay for itself".

Originally Posted by mikehallbackhoe

these are a lot of questions, but till they are answered, you really don't know how long it will take to pay for this mod.

That's fair. I think of it maybe a little differently than a lot of people on this site (but not all, I'm sure). I don't modify my car and hypermile it primarily for direct and immediate cash savings, though I have managed to come out ahead so far. I get satisfaction from boosting this 1998 car of mine to 60+ mpg and I get a sense of autonomy from not being beholden to the automakers' pricing of new high-MPG vehicles. You are comparing the cost of the mod to direct savings from the FE improvement, but I'm partly thinking about my savings as coming from the avoidance of car payments.

By my figuring, I'm slightly ahead in cost/benefits of ecomodding (mostly through hypermiling the car) and thousands ahead in avoided car payments this year.

[mikehallbackhoe]

I'm with you when it comes to buying a new car. I drive a 1984 crx. but I still can't help but wonder if you would be better off just running a slightly bigger alternator pulley. I am all for higher mpg, but only if it puts more money in my pocket.

[steffen707]

Originally Posted by California98Civic

not being beholden to the automakers' pricing of new high-MPG vehicles. You are comparing the cost of the mod to direct savings from the FE improvement, but I'm partly thinking about my savings as coming from the avoidance of car payments.

By my figuring, I'm slightly ahead in cost/benefits of ecomodding (mostly through hypermiling the car) and thousands ahead in avoided car payments this year.

Not letting "the man" hold you down calicivic?

This is a very good point about just taking an old car and modding it to get better mileage than you can get from a new car. You're saving a bunch by not buying a new car.

I've often thought about buying a 2nd gen prius and putting in one of those booster packs. Sure it'll cost like $4000 or somehting for the booster, but when compared to buying a totally new vehicle, i'm way ahead and can still get better mileage than any new "stock" car.

I've always been 10-20 years behind on owning a new car.

[turbotomass]

My questions is in a somewhat modern 88 or 92 or even a 96-00 civic are you even able to get the amps to 10 or less? Cause I've used a VAT on a lots cars to make sure there charging and I don't think I've seen a car with that low of amps at idle even with every possible accessory off.


Has anyone driven with a voltmeter hooked to the battery with no accesories at all on and seen the volts go from 14 to 12 in the driving conditions listed?

[JanvdW]

Originally Posted by California98Civic

.................I believe the answer might be yes, because the alt will be generating power with nowhere to go. But why would you want this? The power generation itself would still be a parasitic draw on your engine.

I hope those answers help.

I thought about a system where I would have a cut-off switch for the alternator, (with a Volt meter to monitor battery power levels)

Then install a floor mounted push-button, on the floor about a foot behind the clutch pedal. If you go down a steep hill, or approach a stop, and use the engine compression to slow down the vehicle in stead of the brakes, you step on the switch, re-engaging the alternator. The alternator will then generate power from the "braking action" and not consume fuel.
You cannot step on it while the clutch is pressed.
--Obviously only applicable to manual transmission vehicles--

(accessories sold separately, batteries not included)