Virtual alternator delete.

[redpoint5]

Originally Posted by oldtamiyaphile

I don't understand the mystery surrounding this mod. The alt holds the same voltage it always did ~14v.

Everything from the various Li battery threads applies.

Except if your flammable battery sets your car on fire, you may not get an insurance pay out.

I'll never get an insurance payout since I don't insure my car (liability only insurance). I'd mount the battery in a fire-resistant bag away from flammable parts.

[teoman]

Oh ok. Makes sense.

Now all you need to do is get the alternator to charge the batt on deceleration.

[teoman]

You could wire a relay that puts a couple of diodes in series to the alternator voltage sense and wire the relay to brake lights or a manual switch.

That way when you brake the alt pushes 16v to the batteries.

[teoman]

I have been thinking about this for some time now, but can’t really get the formula in my head. I have read almost all of the threads on ecomodder. I like t calculate measure design prototype redesign and build which is probably why i never get anything done


%10 gain is mentioned. Also 0.3l/100 km is mentioned. Which would be correct for a car that does ~3l/100 km.

If i had a diesel car that consumed 20l/100 km in the city and 10l/100 km on the highway would i expect to see 2l and 1 l gain respectively?

Or would it be 19.7l and 9.7l.

If we could somehow find a better formula it would be much more informative.

Such as if a car uses 350W and sees 0.3l gain. That makes 0.085l/100Wh (i assumed a steady speed of 100kmh). Or 0.85l/kWh.

If that were correct then it would be very easy to approximate the potential gains in fuel economy.

You want to run your blower motor at 100W. Sure thing, that will cost you 0.85 liters of gas in 10 hours. If this is the case (and I do run the blower motor a lot) it makes perfect sense for me to stockup a couple of kwh of batteries in to my car.

Modern cars also have lots of electrical gizmos from fuel pumps to sensors to actuators to power steering. Then it would also be easy to calculate the gain in a more electrified car. This formula would also permit me to understand what the gains would be in city fraffic.

[teoman]

If we assume that the above figure is correct, the converion is terrible.

1l of fuel is roughly 10 kWh. In the units of the above formula, that makes 0.1l/kWh compared to 0.85l/kWh. Roughly 8.5 times less efficient.

10kWh costs 3.3 monetary units where I live and 1l of gasoline costs 6.3 monetary units. So roughly double for the same energy.

So electricity in the car costs 17 times as much. Which seems to agree with a felllow ecomodder who said it costs 20 times more.

Am I on the right track or am I completely out of it?

[teoman]

Can you tell me more about your resistor replacement.

Are you still using the standard controls or your own control buttons.

If the standard buttons how do the resistors work?

Each fan level is connected to the fan through a different value resistor? Or is there some logic where different resistors are switched on in parallel to get the desired voltage drop to the fan?

My blower just stopped working and i suspect it is the resistors. Might aswell replace it with something more efficient. Arduino based.

[redpoint5]

Originally Posted by teoman

My blower just stopped working and i suspect it is the resistors. Might aswell replace it with something more efficient. Arduino based.

If the blower stopped, it's probably the fuse or blower itself. The high fan setting normally bypasses the resistor and connects the fan directly to battery voltage. The lower speed settings normally have 1 power resistor with leads connected at various points to give different resistances.

I'd check the blower fuse since that is easiest. Next check resistor to see if it looks burned out or otherwise corroded. Finally, disconnect the blower harness and connect directly to a 12v source to see if it spins.

[teoman]

Will test the blower with 12v directly.
I did check the fuse and it appears ok. It did happen at a bumpy road so i am hoping something got lodged in the fan or the harness popped out.

Back on toppic,
Redpoint5,

I have a bank of 6 capacitors 500F each. Do you think they would be enough to start a 2L car? I will be using a boost converter to feed it to implement Luno’s implementation.

Capacitors instead of lead battery. Capacitor charged by lithium batteries. So alt is virtually disabled.

[redpoint5]

Originally Posted by Luno

replacing it with a 4S5P Li-ion pack, the size of a grown man's fist.

What is the Ah rating of your Li-ion pack? Do you know how many watts electrical consumption your car has at idle, with all the accessories turned off?

Originally Posted by teoman

I have a bank of 6 capacitors 500F each. Do you think they would be enough to start a 2L car? I will be using a boost converter to feed it to implement Luno’s implementation.

Capacitors instead of lead battery. Capacitor charged by lithium batteries. So alt is virtually disabled.

Your capacitor bank in series should be plenty enough to start the vehicle. I was able to start my 2.2L Acura using 350F rated caps.

One thing is you might need a low ohm resistor in series between the caps and battery to limit the current going to or from the battery to within safe limits.

Not sure what you mean by boost converter.

Here's my poor quality video showing a quick experiment I did starting my car with supercaps, and a LiFePO4 battery with current limiting resistor.

https://www.youtube.com/watch?v=LX_o3hl2Dv4

I have my 5 Ah Li-ion battery now, so when I get some time I'll connect it to my Acura. I think my best bet would be to put my supercaps where the original battery was under the hood, and then run some 12 gauge wire into the cabin to connect the battery, which I might velcro somewhere near the footwell. This way I could alternate between batteries, charging one on a charger while running the other in the car. Who knows how many Ah I can get from the 5 Ah battery before it drops down to the point that the alternator runs? I'd be surprised to get half the rated capacity.

[teoman]

The capacitor bank will be charged to 16V or a little less.

Whatever battery I use can be of any voltage and chemistry I want. Say a whole bunch of 18650 cells in 2 series configuration(less balancing issuses). That would make 8.4V and i can boost it to 16V. Or a lead acid which can also be boosted to 16v or whatever voltage I want.

With multiple converters i can have different The current does not travel back to the batteries. That will be the job of another circuit/converter/relay.


The idea is to replace all the power used in the car with 1-2 kWh of batteries.

Its basically a modified version of Luno’s setup, but I am trying to use all the capacity of the battery (without voltage drop and without using the alternator.

I can slowly increase the battery size untill i no longer use the alternator at all.