The Autopian sits in a SLATE

[fuzzyweis]

Plus on an EV halogens would just take a bunch more electricity eventually from the EV battery and range?

It doesn't exactly work like that, the DC-DC inverter on an EV is set to output a specific amount of 12v power, like the one on my Ranger does 1500w, that's it's output regardless of draw, so it has power to run the hi-fi stereo, charge the 12v battery, run the hvac blower and all the lights at the same time, if none of that is on, it's still outputting that power at the ready, it's not like you turn all that off and you get that power back. Plugging in a phone charger or adding some kickass off road lights doesn't really hit the high voltage battery, it may bog down the inverter and cause it to draw down the 12v battery causing other issues, but the draw from the high voltage battery will be fairly steady.

The HVAC heating unit(either heat pump or element) and Air Conditioner are run off the high voltage pack, and those can impact range by quite a bit.

-Jim

 

[Paul]

It doesn't exactly work like that, the DC-DC inverter on an EV is set to output a specific amount of 12v power, like the one on my Ranger does 1500w, that's it's output regardless of draw, so it has power to run the hi-fi stereo, charge the 12v battery, run the hvac blower and all the lights at the same time, if none of that is on, it's still outputting that power at the ready, it's not like you turn all that off and you get that power back. Plugging in a phone charger or adding some kickass off road lights doesn't really hit the high voltage battery, it may bog down the inverter and cause it to draw down the 12v battery causing other issues, but the draw from the high voltage battery will be fairly steady.

The HVAC heating unit(either heat pump or element) and Air Conditioner are run off the high voltage pack, and those can impact range by quite a bit.

-Jim

I mean, it really wouldn't make much sense if you draw more power it has to come from somewhere. You can't just create a large amount of power and it goes nowhere unless it's charging a battery instead of powering things. So when the battery would be worn down by the extra load it would demand more from the converter to bring it up to the state of charged? I asked AI for what it's worth.. "Yes, the DC-DC converter draws variable power based on the real-time electrical load of the vehicle's 12V system. It adjusts its output to support components like headlights, climate control fans, and infotainment while maintaining the 12V battery's charge."

 

[fuzzyweis]

I mean, it really wouldn't make much sense if you draw more power it has to come from somewhere. You can't just create a large amount of power and it goes nowhere unless it's charging a battery instead of powering things. So when the battery would be worn down by the extra load it would demand more from the converter to bring it up to the state of charged? I asked AI for what it's worth.. "Yes, the DC-DC converter draws variable power based on the real-time electrical load of the vehicle's 12V system. It adjusts its output to support components like headlights, climate control fans, and infotainment while maintaining the 12V battery's charge."

It may operate similar to a car alternator with a regulator, but it's still not a big hit to the power, like with my Ranger(which has halogens) running maximum draw of 1500w for an hour is 1.5kWh, on a truck like the Slate that's only 3% of the standard battery capacity, driving above 50mph or using the heater/AC will draw much more than that. So rock those Hella lights on the roll bar and don't stress it.

-Jim

 

[bloo]

It doesn't exactly work like that, the DC-DC inverter on an EV is set to output a specific amount of 12v power, like the one on my Ranger does 1500w, that's it's output regardless of draw...

I'm afraid that isn't quite right. A DC-DC converter rated for 1500 Watts won't consume that much all the time. Power depends on the load. For example, 100 amps at 13.5 Volts is 1350 Watts at the output. There will be efficiency losses, so maybe 10% more power on the input side - roughly 1485 Watts.

A converter will draw some power at the input is the output isn't loaded. Even so, it'll be nowhere near the rated output power. Rough guess will be about 10 watts output active and unloaded, and less than a milliwatt output off in standby.

 

[phidauex]

I'm afraid that isn't quite right. A DC-DC converter rated for 1500 Watts won't consume that much all the time. Power depends on the load. For example, 100 amps at 13.5 Volts is 1350 Watts at the output. There will be efficiency losses, so maybe 10% more power on the input side - roughly 1485 Watts.

That's true, a power supply will only output as much power as is being requested from it, plus a small amount for its internal operation.

One of the fundamental laws in electrical engineering is Kirchoff's Current Law, which says that that sum of all currents at a node in a circuit must always be 0. Or more intuitively, if current is going into a part of your circuit, that exact same amount must be exiting that part of the circuit. You can't have current that goes nowhere.

So a power supply rated to 1500W, but with nothing connected to it can't be consuming 1500W, since there is nowhere for that current to go. If 1500W was its internal consumption, then it would be a very poor power supply indeed, and would be screaming hot.

All this said, however, the end result is that the impact of lighting and audio on range will be negligible. The amount of energy needed to fling a 4000 lb object up to 75 mph dwarfs any accessories you can conceive of.

 

[bloo]

That's true, a power supply will only output as much power as is being requested from it, plus a small amount for its internal operation.

One of the fundamental laws in electrical engineering is Kirchoff's Current Law, which says that that sum of all currents at a node in a circuit must always be 0. Or more intuitively, if current is going into a part of your circuit, that exact same amount must be exiting that part of the circuit. You can't have current that goes nowhere.

So a power supply rated to 1500W, but with nothing connected to it can't be consuming 1500W, since there is nowhere for that current to go. If 1500W was its internal consumption, then it would be a very poor power supply indeed, and would be screaming hot.

So you're an engineer, huh? You can't spell "geek" without "EE". Lowercase if you're also a 20th century modernist poet.

You could get constant power with a shunt regulator. But the series resistor and Zener would be m a s s i v e.

 

[phidauex]

So you're an engineer, huh? You can't spell "geek" without "EE". Lowercase if you're also a 20th century modernist poet.

Haha, sadly yes, I'm a PE in Power Systems Engineering. I work in utility-scale renewables and storage - currently buying about twice as many batteries per year as Slate will be... Demand is high. But the technology element is part of my interest in Slate - I think it is wise for them to be designing all electric, battery prices stayed stubbornly high between demand and tariffs, but the long term production capacity all points to continued decreases over time.

 

[AKrietzer]

Does the 12 volt battery only get charged by the big battery, or does it also get a trickle charge when the EV is plugged in? If you leave a radio or lights on when not plugged in, will that run down both the low and high voltage batteries over time? I have heard stories of Lucid cars that are difficult to open the doors if the 12 volt battery is dead.

 

[phidauex]

Does the 12 volt battery only get charged by the big battery, or does it also get a trickle charge when the EV is plugged in? If you leave a radio or lights on when not plugged in, will that run down both the low and high voltage batteries over time? I have heard stories of Lucid cars that are difficult to open the doors if the 12 volt battery is dead.

Different EVs have slightly different logic, but generally speaking the DC/DC is charging the battery whenever the car is "on", or if the car is "off" but actively charging. When the car is "off", or connected to a charger but not charging, the DC/DC will be off. However, there is a charging logic either based on a low SOC signal from the 12V BMS, or just a timer, where the DC/DC will turn on for a while and top off the 12V battery. Remains to be seen what Slate's approach is, but overall, yes, the 12V battery will be kept charged by the HV battery whether the car is on or off.

There have been missteps here and issues with various cars, including my MachE, but recent software updates have tended to resolve the problems.

 

[atx_ev]

It doesn't exactly work like that, the DC-DC inverter on an EV is set to output a specific amount of 12v power, like the one on my Ranger does 1500w, that's it's output regardless of draw,

-Jim

Thats not true. Power is V * A. If no amps are flowing there is no power.

Voltage is a bit like water pressure, and you can have pressure with no flow. When you turn the spigot on you now have flow (current).

So no, I guarantee you are not outputting 1500w no matter what.

 

[fuzzyweis]

I sit corrected, but will say the 12v systems can't draw beyond what the DC/DC inverter can output, plus a little from the 12V battery as a buffer, and as others have said in the grand scheme of kWh the truck has available that's a fairly low draw.

As a fer instance, the battery refresh procedure on my Ranger(nickel batteries) is to run it until it literally dies, we do this by driving it around until the low fuel(charge?) light blinks and the power limit light comes on, then leave it in the driveway with the defroster set to max heat. I just did that this past weekend and my truck, which only got 45 miles out of it indicating low 20's for kWh of capacity, still ran for 2 hours with the heater and blowing going full blast before it finally died.

Long way to say, the 12v drain on the battery shouldn't be a concern, the battery's thermal regulation may be more of an impact on really cold or super hot days.

Short clip of my Ranger's dash during the drain, the flashing lights are fine

 

[phidauex]

I sit corrected, but will say the 12v systems can't draw beyond what the DC/DC inverter can output, plus a little from the 12V battery as a buffer, and as others have said in the grand scheme of kWh the truck has available that's a fairly low draw.

As a fer instance, the battery refresh procedure on my Ranger(nickel batteries) is to run it until it literally dies, we do this by driving it around until the low fuel(charge?) light blinks and the power limit light comes on, then leave it in the driveway with the defroster set to max heat. I just did that this past weekend and my truck, which only got 45 miles out of it indicating low 20's for kWh of capacity, still ran for 2 hours with the heater and blowing going full blast before it finally died.

Long way to say, the 12v drain on the battery shouldn't be a concern, the battery's thermal regulation may be more of an impact on really cold or super hot days.

Short clip of my Ranger's dash during the drain, the flashing lights are fine

Haha, sorry a bunch of engineers jumped on you. But your conclusion is still right, the 12V draws will have negligible impact on range.