"plug-in mild hybrid" upgrade
 

I have an idea for a device that will offload the alternator and therefore improve fuel economy. Basically, it will consist of some batteries along with a voltage regulator and control electronics. It will be wired to disable the alternator and take over maintaining charge and voltage. Once it is discharged, it will allow the alternator to take over as usual. It can be made easily removable for charging or a charging connector be integrated into the system.

A simple implementation can just be a battery and voltage regulator that connects to a 12v power outlet. Since the outlet cannot handle enough current to run some large loads like the headlights or A/C, it will only partially offload the alternator.

If the alternator is on a dedicated belt, the belt can even be removed to eliminate all the associated friction losses. Of course, automatic switchover will be impossible if that's done.

A battery charging another battery? Did I get that right? Doesn't sound advantageous to me.

How about using the alternator only when engine-braking?

if you were to use a cog belt instead of a v belt that would take care of alot of the friction issues, then it would just be spining weight and the air drag that some alternators have of their crude fan so a better fan might be in order as well.
you can get dc/dc converters that will drop voltage down from 24 or 48 or even 144 volts dc down to 12 or 13.2 volts dc for running lights in electric cars off the traction battery.
if the alternator is not hooked up to a load then it's field coils are off as well and it's just dead spinning weight.

The point is that the batteries in the upgrade are designed for deep cycle, so they substitute for the alternator. You just plug it in to recharge it.

Why not just run deep cycles and have an alternator cutoff switch?

Deep cycle batteries are not good for starting and the load voltage would be lower. With my idea, the normal starting battery is kept charged, keeping the 14.4v expected by all the loads. The device can also be easily moved from vehicle to vehicle. It can also be used as a portable power supply for other applications.

Then stop using your starter, most driveways and parking lots have enough slope to bump start.
or with the system I discribed if you had your normal battery for starting that acted as a buffer with the dc/dc converter your lights would never dim and you could still use your starter.

Rpm limit switch, micro switch on throttle. tap into brake light switch, and relay

Rpm > idle + no throttle= power to relay and connect alternator

Brakes on= power to relay and connect alternator.

I have a deep cycle in my car and it starts up way better than when I didn't have the deep cycle. It's an optima yellowtop, so that may have something to do with it.
If you're worried, keep the car plugged in when you start it, thus relying a bit less on the battery, then unplug quickly, get buckled in, and off you go.

I'm doing this on my car. I have everything set up, but still setting up my mpguino to get a good baseline without the alternator plug-in delete.
Since I only have a 20 minute commute, I'm just going to disconnect my belt and run off the battery. I just need to make some LED headlights designed for my new 12.5v instead of 14.5, or rig up a way to re-aim my lights and use my high beams when I'm using just battery.

I want to add wunna these:

http://i146.photobucket.com/albums/r...encher/09b.jpg

I think hauling around the extra weight of the battery will out weigh any real benefits unless your driving an extra heavy car. Even if it did work you still have the same problem of an electric car( your using energy from a power plant instead of gasoline ).

NiHaoMike: this has been done successfully already.

GasSavers member Brock saw a 5-7% increase in fuel efficiency even with this inefficient setup: He put two 6v golf cart batteries in his Jetta (in addition to the OEM battery), plus a DC/AC inverter connected to a 55A charger (to the OEM battery) which would keep system voltage at 14.4v.

http://metrompg.com/posts/photos/tdi-jetta-z.jpg

He "manually" removed the alternator load from the engine by pulling its main fuse. (That way he could put it back in when his wife drove the car, so she wouldn't have to worry about monitoring the "boost pack" voltage.)

Details here: Plug-in Blackfly: going alternator optional nets +10% mpg - MetroMPG.com ... near the bottom of the page.

The caveat in this approach is that batteries are consumable items. You'll save energy doing this, but without a cheap source of batteries (or unless fuel is far more expensive), you probably won't save money.

It's not necessarily a problem - power plants (even coal fired ones) generate power more efficiently than gasoline engines, so the net energy use is lower. Also, many people have access to renewable (clean) electricity generation so net pollution is lower too.

MetroMPG -

If it's a standard 120 volt connection, you could use one of those kill-a-watt gizmos to meter your electricity and then add the "virtual gallons" to your fuel log :

Convert gallon [U.S.] of automotive gasoline to kilowatt-hours - Conversion of Measurement Units

http://ecomodder.com/forum/attachmen...1&d=1234201757

CarloSW2

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Lead acid batteries are about 75 to 85% efficient. ( http://www.sandia.gov/pv/docs/PDF/batpapsteve.pdf )

A 14.4V charger is about 86% efficient. (
stepdown transformer 95% efficient * efficiency due to diode losses = .95 * (1 - (1.4/14.4)) = 86% )

average efficiency of powerplants = 33% Power Plant Efficiency Hasn’t Improved Since 1957 : CleanTechnica


transmission and distribution efficiency = 93.9% http://tinyurl.com/dghtoh


so 100% * .33 * .939 * .86 * .85 = About 23% efficient. Just about the same efficiency as a typical car engine

nice calculation connclark

i think in europe we have better power station efficiency. closer to 45%. internal combustion engines are only 20% efficient (diesel is better.)

The figures I've seen are 40% for diesel and 30% for gassers, but I can't find that source anymore, so don't listen to me...

Nice calculation ConnClark. However, I once calculated efficiency of an engine using EPA mileage for my Matrix and Paseo. It came out to 13% for each. 23% would be a HUGE increase. Ironically, thats about what it came out to be when I plugged in my summer mileage for the Paseo (which wasn't too far from 100% above EPA). There are pretty huge gains to be had for supplimenting or replacing gasoline for electric power.

The 23 % efficiency is for the engine alone. Using mpg you have to account for transmission, drive line, aero, rolling friction, etc...

some more efficiency factoids.....

A typical new car engine is more like about 25 to 28% efficient. A diesel is about 30 to 45%.


A modern supercritical Rankine cycle power plant is about 42% at best. (if your power plant is more than 10 years old don't plan on this being the case)

clean energy ( geothermal, solar, wind, hydro electric, and biomass) made up only 7% of US power sources in 2006 and 90% of that was biomass and hydro electric based.

I wonder what prices it was based on. I don't think it would be accurate as there's no way to enter gas and electricity prices.

As for cheap batteries, some used ones that are still in OK condition should be cheap enough and work well.