?????'s about running no alternator
 

So I read on here about buying a deep cycle battery and ditching the alternator. What experiences have people on here had with this? On a side note I drive a 92 civic HB and I drive 150 miles roundtrip everyday, 5 days a week for work. I'm not using A/C but I am using the radio and I get off of work at 11 at night, so i would be using my lights on the way home.

I have not had experience myself with not using an alternator, however, in my opinion, I would believe that your battery would go dead before you got home.

driving at night with lights on and no alternator = VERY bad idea

the alternator requires very little effort to spin. far less than a power steering pump, A/C or even the water pump.

If you want to make it work for your car and driving conditions, I'd recomend some LED running lights to reduce electrical consumption, install a switch for the alternator so you can turn it on when the battery needs some charging, and a voltmeter so you can keep an eye on batt volts. Then install a battery charger under the hood and park next to an electrical outlet so you can plug in your car when you park. If you can get all of that arranged, you might save some gas. Darin at MetroMPG.com saw 10% improvement in FE when he removed the alternator, but the savings were offset by the cost of running a batterycharger. It was still a gain.

There's a user here who runs no alternator and it seems to be working well for him. Here's what I had to say about the idea in another post:
He's right here on this forum...his name is rgathright and he did it on a Jeep Wrangler. Here's where he first described it:
https://www.gassavers.org/showthread.php?t=7140
I've been considering a more mild form of that, where I don't remove the alternator but just disconnect it, and I don't have to invest in an expensive battery but I can just use my existing starter battery and maybe a deep cycle battery I have for my boat too.

That thread did include this response to my post:

if you look at This Page you will find a list of all of the electrical loads that I tested with an amp meter on my 1992 civic vx, so figure out what all you are going to have running on your car while you drive, how long they are going to be running for then find a battery that has at least twice that capacity so you don't drain it down past 50% full (shortens the life of the battery a great deal), you will then be able to figure out if this is practical for you to do.

It all depends...
A fully charged lead-acid battery during the daytime running nothing but the engine... No turn signals, no brake lights, no fan no radio no lights no wipers no washer no nothing...
Can go around 400 miles on a charge.
That's assuming the battery is in good shape, and the correct one for the car.
It helps further if the battery is a size bigger than the car needs.
I usually run 1,000 cca's in all of mine, but not for this reason :p

But you take a risk, that and once the voltage drops a little your mpg suffers because the battery is no longer sending as much juice to the ignition coil(s), hence your spark plugs deliver a weaker spark.

And on a rainy night, with headlights and wipers and at least some fan?
You might make it 200 miles, maybe not... Maybe 100, maybe 50...

It all depends.

It would be my opinion that it would be better for that kind of money to see about installing some high performance 10mm spark plug wires.

I imagine the range would be even shorter on a modern small car with electric power steering and a million electrical features. Still, rgathright seems to be successful, though it sounds like he probably invested more money in it than he would save. However, he bought a really expensive battery and such.

I just wonder how well I would do in my VW on my 80 mile round trip commute. Obviously I would charge it every night, and if the voltage got too low while drivig I could always abort for that day and plug the alternator back in (or switch it back on or whatever). rgathright is using a voltage regulator which would mean you could drain the battery more; but you'd want an expensive proper deep cycle battery for that...

I can't imagine it working for more than a few miles, and being quite slugish as the battery drops in voltage, provided you don't install additional batteries.

I think you would be lucky to get 20 miles in a car without elec steering or any other accessory on.

I guess I'll try it out next week, the alt is bad in my CRX and I have to take it to a shop to get the bolt drilled out of the block that the PO broke off in it.

I'm pretty sure that the stock VX battery is a 40amp hour battery, so without damaging the battery you can drain 20amp hours out of it.

In my '92 civic vx turning the key "on" but with the engine off (dash lights completed with self check, door closed, lights off, radio off, fan off) gave a reading of exactly 2 amps, so in my figures I subtracted that number from the total reading.

Heater fan 1st setting 3 Amps
Heater fan 2nd setting 5.4 Amps
Heater fan 3rd setting 8 Amps
Heater fan 4th (highest) setting 11 Amps
all of those numbers were fresh air coming in, switch to recirculation and it added .4 amps to the highest setting due to added air drag.

Brake lights 3.2 amps

Headlamps:
55-watt low-beams (110 watts for the pair)... 110/12volts=9.167 amps
65-watt hi-beams (130 watts for the pair)... 130/12=10.833 amps

After market Radio varied from about .6 up to 4 amps depending on volume.

Cranking for about 5 seconds gave a starter draw of about 138 amps.

I don't have any numbers yet on the wipers, but I can check that as well, also the 2amp draw from the key being on is just the cars computer running, and the coil, but the coil should draw more when it's working and firing the plugs, I also now have LED tail lights, and as soon as I find my turn signal flasher under the dash I'll switch the turn signals as well.

The wipers on my VW blow a 5 amp fuse but work at full speed on a 7.5 amp fuse. So, there's a vague idea for you...

This may be true for a 92 VX (I don't know for sure) since it uses a distributor, but on cars with modern electronic ignitions the ecu reads battery volts and adjusts the coil charge time so the coils put out just as much energy regardless.

What is the minimum battery voltage that would correspond to a 50% charge and thus would not harm the battery? 11.5 volts?

Since my car has a carb and a mechanical fuel pump, I could imagine that it could run for several hours during the day (no lights on) on the interstate without draining the battery much.

I was thinking of putting a switch on the dash that interrupted the alternator field wires. I would connect a digital voltmeter to an energized wire and monitor voltage, when it dropped down to the point where it would begin to shorten the life of the battery, I could flip the alternator field wire on for a few minutes and charge it back up to a "safe" level.

With my CVCC engine, since the spark plug is igniting an extra rich mixture, I also might be able to get away with a weaker than normal spark.

Convert to manual steering, ditch the AC, and install an electric water pump:D

About 30 miles is about it... and that was with the assistance of an "emergency" alternator belt, which didn't work worth crap... rain wouldn't let up, had to have the wipers and blower on full... just hovering above freezing... soaked to the skin from standing out in it trying to rig the emergency belt... crawled it about an hour on the back roads... before it started bogging really bad at low speed... AND I was turning the headlamps off every chance I got, just running sidelights until I saw another vehicle, then popping them on lowbeam again... so I parked outside a small town garage for the night... coldest damn night ever... so I kinda have this habit of regarding people willing and eager to do away with their alternator as severely disturbed :D

2nd instance different vehicle, this time with the alternator dying, did 1 1/2 hour of highway travel in good weather before it stalled out and wouldn't go, had DRLs and nothing else running. Had cellphone, had CAA, got towed, phew.

IMO, trying to run off a regular car battery with no alternator or provision for charging, is like getting all the disadvantages of an electric car, while keeping all the gasoline bills of of an IC car... by the time you're carrying the 4 deep cycle batteries that I would consider a decent reserve source with no charging system, you probably aren't saving any gas.

Unhook the field coils, use an electric clutch if you like, but as soon as you feel the thing stumble you can hook it back up and rev the motor at 2500 for a minute or two, and not have to sleep a night in the back seat with wet clothes and only a mars bar for supper in 1-2C temps.