The "I'm not a hybrid" hybrid idea

[dcb]

I'm not convinced about the need for 14 volts, if folks here are already making more mpg without the alternator, then isn't that the point? Have any of these folks said it was a problem? Most every electrical component I know has some degree of tolerance, and alternator (and belts) do break.

I would definitely test that theory before buying a DC-DC converter, but use fillup to fillup data and not instrumentation. Changing the system voltage WILL affect your injector pulse length, your cars computer should be able to handle it though (that is reflected in the pulse length change).

Plus all your cars lightbulbs will probably last forever

[chuckm]

dcb, I think you're correct about the ECU being able to compensate. But orangeboy's experience says that the voltage does make a difference in FE on an alternator-less system.

[The Atomic Ass]

Originally Posted by chuckm

Does a water pump count? And yes, A/C is quite necessary. I minimize how much I use it, but 100F heat with 98% humidity is quite intolerable. I've sweat through shirts, front and back trying to avoid the A/C.

A/C does not need to run nearly as fast as the engine, so it could be put on an electric motor by itself. The drag of the motor through the electrical system, assuming you keep the alternator to power it, will be substantially less than directly connected to the engine.

[Christ]

Water pump -

Depends on the vehicle as to whether you have to design it in to your plans.

Most cars with timing BELTS have the water pump driven by the belt, so you don't have to compensate for it at all. (It's still a power drag, though, and there are WP delete kits that relocate your Tbelt and run the pump w/ an e-motor for some cars. Honda comes to mind.)

If you already have an electric water pump, you can get an electric one, a kit to make it electric, or just leave it belt driven. It's one of those things that you don't want to do without, for sure.

If you have a fear or running out of charge, you can always use a starter/generator motor to do what you're suggesting, so that you can just reverse the field and it will charge instead of drive, but you'll still have to have a way to mechanically link it to the crankshaft of the engine. (Like another belt.)

[jamesqf]

Originally Posted by Christ

B/c your car doesn't run on 12V, even though they're 12V (nominal) batteries.

Maybe your car doesn't, but all of mine (excluding the Insight, of course) have run just fine on 12V, as for instance engine-off coasting, or when an alternator goes out.

[dcb]

Originally Posted by chuckm

dcb, I think you're correct about the ECU being able to compensate. But orangeboy's experience says that the voltage does make a difference in FE on an alternator-less system.

Yah, I'm not sure OrangeBoy is convinced either Anyway you will increase the demands on your battery if you increase system voltage and reduce your "range". Applying more voltage means your electrical components will draw more current.

If your car works fine without it, and there is a range and cost penalty with it, I'm having a hard time understanding why it is there.

[chuckm]

Anyway you will increase the demands on your battery if you increase system voltage and reduce your "range". Applying more voltage means your electrical components will draw more current.

I'm just aiming to maintain the same voltage as currently supplied by my alternator and battery. I'd much rather keep my headlights as bright as they are now (the difference between the luminosity at 14.5 and 12V is probably directly proportional to the voltage and 17% is an awful lot of light).

Christ, you may be right about my water pump being driven by the timing belt. But I think it is driven by the serpentine, or so one of the moderators at Corolland.com said. The picture of the water pump at autozone seems to show a belt pulley as well.

My thought is to attempt to size my battery pack to run my electrical system and "electrocharger" for 100 miles (running down to ~75% charge). That will give me a fair amount of spare capacity for longer drives and maximize battery life. Since the electrocharger can run at a constant rpm, the controls should be relatively easy: on or off. I'd probably look at a kit like this one for my e-motor kit. I would think that this would be powerful enough to do what I want.

[AmpEater]

Originally Posted by dcb

I'm not convinced about the need for 14 volts, if folks here are already making more mpg without the alternator, then isn't that the point? Have any of these folks said it was a problem? Most every electrical component I know has some degree of tolerance, and alternator (and belts) do break.

Sure, it works. We know that. But is it optimal? Perhaps that 10% fe improvement could really be 15% if the engine was getting the power it needed for a hot spark, properly calibrated injector pulse, etc.

Of course a car should be able to run with a broken alt belt....but for how long? Any engineer working on a new design has the answer....just long enough to get it to a shop and get it fixed. When every device/system that manages, runs, and protects an engine expects to see 14v there is certainly no benefit to 12v, 11v....but there could very likely be a detriment.

[MetroMPG]

Originally Posted by AmpEater

I once read that a race team measured a 10hp drop for each volt below 14.5v.

Goodness! That means when my alternator is disconnected (running at 12v) my engine is making minus 100 horsepower!!

---

Here's one reason I would go with a hybrid type "boost pack" vs. an alternator delete (and I have a fair amount of experience running without an alternator).

In a word, "range anxiety". (Thank you GM)

Yes, you could always hook up your alternator again if you realize you're not going to make it to your destination before the 12v juice runs out.

HOWEVER, if you ever partially deplete your battery and then turn the alternator back on, you will take a massive fuel economy hit with the alternator running at high field current straining valiantly to bring the battery back up to ~14 volts again. Ask me how I know this.

Depending on how badly you misjudged your "range", your fuel economy could even be worse than if you'd just left the alternator connected from the beginning.

I dream of a lightweight, intelligent, portable lithium ion "boost pack" system that retains the ~14v level in the starting battery while the alternator is disconnected:

• the boost pack chemistry is better suited to deep discharges than lead acid (lower battery cost/cycle if done right)
• it has the advantage of being lighter than auxiliary lead acid batteries
• it's portable - could use it to power other 12v stuff sometimes
• it's portable - bring it inside to recharge instead of running a cord to your car, if not using PV solar panels on the car to recharge
• if/when you run out of range, you simply turn on the alternator to re-supply power; no massive "recharge" MPG hit since your battery was kept up by the boost pack

Just thinking out loud.

[MetroMPG]

Originally Posted by MetroMPG

HOWEVER, if you ever partially deplete your battery and then turn the alternator back on, you will take a massive fuel economy hit with the alternator running at high field current straining valiantly to bring the battery back up to ~14 volts again. Ask me how I know this.

Of course, you could also carry a small, fully charged 12v "backup" battery to swap in place in this situation, and avoid the big "recharging" MPG hit.

(Or switch your OEM starting battery out of your auxiliary pack circuit, or... you get the idea.)

But the Li-ion pack idea seems cooler to me.