Test: Alternator vs. no alternator = 10% MPG gain @ 70 km/h

[jasonck08]

There is a difference between charge voltage and reseting voltage of a Lead acid battery. Charge voltage will often be 13.2-13.8 or so... But the voltage will settle down to ~12.6v after an hour off the charger.

Same is true with most battery chemistries... Ni-mh, Ni-Cd, Lifepo4. Lithium cobalt cells, don't really settle down much if at all.

[Piwoslaw]

Originally Posted by Nerys

also remember you are running the car on a single "starter battery" which was never designed for that kind of load.

this is why we would use TWO deep cycle batteries.

Some cars have two batteries. The higher-end version of the Peugeot 607, for example, has a starter battery next to the engine, plus a second batt in the trunk to power all the accessories.

What would happen if a standard starter battery was hooked up in parallel with a deep cycle batt? My guess is that either you would never get the full potential of having a deep cycle, or the starter battery would need replacing pretty quick.

[jasonck08]

@ Piwoslaw. It's never a good idea to hook up different battery types in parallel or in series. Bad things can happen... Always want to hook up batteries that are as similar as possible (e.g. model, capacity, similar number of cycles etc.)

[watahyahknow]

Originally Posted by Frank Lee

I don't know how he did it, but obviously it works!

sorry i had to stop reading here for a bit , the mad max moviecar doesnt actually have a working supercharger , it was mounted on a rack bolted over the stock engine and powered with an 12 volt electric motor .
a good supercharger can freewheel so you can still run it without a belt should it break and limp home

as for the alternator : good ideas , i was thinking electric clutch as whell but mounted at the crank end
the gasengine can be used without electricity by mounting a magneto distributor Vertex Magneto for VW Engines by Great Plains Aircraft Supply Co., Inc. there a few more companies making them for racecars mallory is one of them
you could do away with a belt and parasitic drag to the waterpump by mounting an electric waterpump HV Electric Water Pump Small Block Chevy For Sale some models have a bolt on model like this one others have to be made to fit
powersteering ...... we dont need no stinking powersteering again less parasitic drag , there are manufacturers that use electric power assist motors in the steeringcolumb instead of the hydraulic system used in most american cars but popeye arms are cheaper still
so we can do away with practicly the whole fan belt setup (the only exeption being the alternator ) until the battery runs low and that might depent on the time of day since its only needed for the radiator fan interiour fan lights blinkers and startermotor (lights being the biggest draw of power)
i wonder how mush a battery made from A123 M1 Li-Ion cells would run yah , i seen 12 batteries that are powerfull enough to start a car the same way a lead bettery does but its only half the size and weight so you can run 2 with a battery switch and basicly never run without power

[jasonck08]

@ watahyahknow

Even 4x A123 26650's can start most 4 cylinder gas cars. They are extremely powerful cells and capable of upwards of 120 Amps pulse current.

Some racers replace their car battery with one very powerful small Li-ion battery, just for starting the car. Keeps weight down.

[markweatherill]

This thread prompts me to ask:

is there any gain in turning the alternator 'off' while cranking? I'm presuming that while the starter is spinning the engine up, it's also spinning the alternator which, because of the big draw on the battery is going to effectively put a brake on the engine...maybe.
Do those of you who run without alternators notice any easier starting?
Or is it the case that an alternator can't do much generating at cranking speeds and therefore doesn't really drag that much while cranking..?
Thanks.

[MetroMPG]

Good question.

Don't know the answer, but I suspect the alternator isn't energized while starting.

- Either because it's not spinning fast enough, or,

- because the computer tells it not to (as on my Firefly, which doesn't activate the alternator after a starting until engine RPM exceeds ~1900 RPM - ie. until you start driving).

[Christ]

My golf a also won't turn on the alt until rpm goes over some 1100 after starting.

[markweatherill]

I just got home and checked the circuit diagram for the alternator on my Toyota. One of the lines going to it comes from the ECU so it sounds like the manufacturers have this covered.

[Nerys]

the problem I see with the A123 cells is how to RECHARGE them with the car. is the alternator output with NO battery buffer stable enough to run a 12v lithium charger? how would that work? what about running the car's stuff etc..

maybe a wee tiny tractor battery to stabilize the system and the A123's to start with?? then again I think the tiny tractor batter WILL start a metro.