Air Conditioning

[~tc~]

Does the Kizashi have an electric compressor, or belt driven? In every other car I've ever had, the AC didn't drop huge electric more than 0.1 volt - the blower on high would drop it almost 1 volt.

[KuroNekko]

Does the Kizashi have an electric compressor, or belt driven? In every other car I've ever had, the AC didn't drop huge electric more than 0.1 volt - the blower on high would drop it almost 1 volt.

It's belt driven with an electronically activated clutch much like most other cars. I believe the flickering may be more from the strain of running the A/C than the A/C's actual electrical draw. Much like how the resistance of the A/C compressor causes the engine to work harder and use more fuel, maybe it causes the alternator to generate less power as they are all on the same serpentine belt. Regardless of the mechanics, I definitely noticed flickering and sometimes failure of a bulb while the A/C was running and the car was idling or at low speeds. I had yet to see this until I used the A/C for the first time since installing the LED conversion kit.
I need to ground the capacitors correctly to get them working properly.

[~tc~]

That would make sense. You may want to look at a new battery also.

[klement]

Hmm, I think the alternator should always generate the right amount of current ... what changes is the load it puts on the engine (up when the consumption goes up, down etc.), right?

[KuroNekko]

That would make sense. You may want to look at a new battery also.

No doubt the battery is not at its peak. I have the original factory battery. Rather surprised it made it through the "Polar Vortex" this winter.

Hmm, I think the alternator should always generate the right amount of current ... what changes is the load it puts on the engine (up when the consumption goes up, down etc.), right?

No, I think the alternator actually outputs more electrical power when the engine revs higher as the alternator is connected to the engine's crank pulley via a belt. This would also explain why when you have a dead battery and the car is idling, the car's electrical power is weak and the lights dim. However, when you step on the accelerator, the electrical power is increased. This is because the engine forced the alternator to turn faster and generate more electricity. This would also explain why my LEDs don't flicker while I'm driving with accelerator input, but flicker when I'm coasting at low speeds or idling.

[klement]

That would make sense. You may want to look at a new battery also.

No doubt the battery is not at its peak. I have the original factory battery. Rather surprised it made it through the "Polar Vortex" this winter.

Hmm, I think the alternator should always generate the right amount of current ... what changes is the load it puts on the engine (up when the consumption goes up, down etc.), right?

No, I think the alternator actually outputs more electrical power when the engine revs higher as the alternator is connected to the engine's crank pulley via a belt. This would also explain why when you have a dead battery and the car is idling, the car's electrical power is weak and the lights dim. However, when you step on the accelerator, the electrical power is increased. This is because the engine forced the alternator to turn faster and generate more electricity. This would also explain why my LEDs don't flicker while I'm driving with accelerator input, but flicker when I'm coasting at low speeds or idling.

If the alternator output is directly proportional to the engine revs then where does the extra power generated go when not needed? The battery can store only so much energy, right? So when the battery is full and you turn off, say, your lights and do not change any other conditions (engine speed etc), then there must be a way to compensate for this. The energy generated (or to be more precise converted (from the rotational energy to electric energy)) by the alternator cannot just disappear.

[Woodie]

Alternator output is controlled by what is needed to meet demand and recharge the battery. But it is also limited at low RPM.

The A/C clutch and the fans on the condenser draw quite a bit of electricity, plus the compressor will slow down the engine a little, further reducing what the alternator is putting out. There is an idle up system to compensate for the load, but they're not always exact. I've never noticed whether mine slows down or not.

[KuroNekko]

If the alternator output is directly proportional to the engine revs then where does the extra power generated go when not needed? The battery can store only so much energy, right? So when the battery is full and you turn off, say, your lights and do not change any other conditions (engine speed etc), then there must be a way to compensate for this. The energy generated (or to be more precise converted (from the rotational energy to electric energy)) by the alternator cannot just disappear.

The alternator's role isn't just to generate electricity to charge up the battery. It's main role is to generate electricity for the car while the engine is running. This is why alternators are also called generators. While I don't think the electricity generated by the alternator is on an ever-increasing scale based on engine RPM, it's definitely outputting more electrical power at say 3000 RPM vs. 800 RPM.

The main purpose of the battery is to provide the electricity to start the car. Once started, it's the alternator that provides most of the electrical needs of the car to run. This makes sense as it's generating electricity instead of just storing and releasing it which is what a battery does. It's also why cars with dead batteries run once jumped. It's the alternator that's powering the car at that point.

The role of the alternator and its generation of electricity from engine power is also the focus of new technologies that improve fuel economy such as Mazda's i-Eloop. It uses a large capacitor and a DC/DC converter to alleviate the alternator's role, therefore the engine, in powering the electrical components. The capacitor can use electricity generated by the alternator and the regenerative braking system to power components at a later time to take the load off the alternator/engine. This results in better fuel economy as the capacitor's power contributes to powering components like the A/C, headlights, etc.

Interestingly, had I owned a Mazda with i-Eloop, my LED bulbs theoretically would not flicker as the car's capacitor would be powering them with a more stable supply of electricity instead of just the alternator and the weakening battery as in my Kizashi. Hence, this is why I have small capacitors just for the LED kit's harness to compensate for the unstable voltage to the LEDs in DRL mode.

[~tc~]

An alternator is different than a generator. Alternators require a small amount of electricity to be present from the battery to generate the field. This results in a more constant voltage, unlike a generator that truly varies with RPM (drive an old car and see how the brightness of the lights is constantly changing with RPM)

The battery provides the voltage "floor". If you draw more than the alternator can provide at 14V, the extra comes from the battery at 12V, and dropping more the more you draw.

The only real difference between a capacitor and the battery in this application is the speed with which they react - the cap is MUCH faster.

[LPSISRL]

The the alternator provides current at 12 volts to supply the car's electrical needs. The amount of current and voltage will vary with the speed of the engine. There is a voltage regulator that limits the voltage to about 14.5 volts. Think of the alternator as a water pump driven by the engine where pressure is measured in volts. The water flow the pump can provide is current flow and measured in amps. The battery is a big tank of water stored at the pressure the pump provides. Your electrical needs (load) are sprinklers that demand water at a given pressure to shoot the water far enough to water the grass. The more sprinklers you add, the more water flow you need at a given pressure to keep them shooting the water far enough. So the pump not only keeps the sprinklers running, but also keeps the tank topped off and up to pressure. Take away the pump (alternator), and the tank (battery) can still keep the sprinklers going until enough water is drained from the tank that there's no longer enough pressure (voltage) to drive the sprinklers. (load) The pressure the pump can put out is limited by a regulator so you don't burst the hoses or break the sprinklers. So when the engine slows down, like at idle, it may not be able to provide enough current for all electrical devices demanding current. When that happens, the voltage drops, lights dim, fan slows down etc. Just like what would happen with the sprinklers if the water pump was slowed, especially if the battery is weak and can't maintain the load.