Upgrading lights to LED good or bad?

The 12volt battery is being charged by the HV battery via DC to DC converter when the car is powered on.
You will not notice any difference as far as extending EV distance, maybe a few feet if that. during normal driving at night with headlights on, there are 6 w5w incandescent bulbs that are part of the parking light system, 2 yellow side markers in the front, 2 white front markers above the headlights and 2 license plate lights in the back. This is not counting the rear red parking lights/brake lights as they are already LEDs. The 6 W5W bulbs are rated at 5 watts each. If you replace all of them with 5 LED 5050 SMD bulbs, you'll reduce the power consumption by just over 24 watts total. Each 5050SMD LED draws .18 watts. The turn signals and reverse lights are 21 watts each but they are normally not on so changing them to LEDs will not save you any energy. I'm not sure if you have OEM fog lights or not but H11 takes 55w each. Replacing them to HID will save you 40 watts both. Same with headlights and high beam unless you already have LED headlights. Replacing all the incandescent bulbs to LEDs will only save you a couple hundred watts of power at the most assuming you drive with all the interior lights on with hazard lights flashing in reverse with either fog lights or high beams on at night. With all the parking light bulbs replaced by LEDs your car may draw 14,975 watts instead of 15,000 watts when in EV. You'll probably extend your EV distance by 13 feet.

 

The advantage is if you mistakenly leave them on over night, say, if you don't quite get a door closed, it is less likely that you will completely drain your 12V battery leaving you stranded.

To be a little more precise about the math above, the Prius plugin uses 129.7 Wh per mile. If you drive for an hour with the lights on, and save 25 watt-hours (for just the parking lights) that you save will get you 1017 more feet (1/5 mile) in EV mode.

 

The lights that really matter (brake and rear parking that are on the most) are already LED.

 

offroader, welcome to PC! To add to the above posts...one member here who converted all of his interior and some exterior lights to LEDs, reported a problem it triggered with the TPMS system. I think it had to do with the wrong LEDs over the license plate. He had to go to a dealership to get it figured out.

 

this calculation is completely wrong. I'll post the why when I get home from the LA meet.

 

Prius PHEV uses more than 129.7hw/m. If this true then the Prius PHEV has a range of just over 24.5 miles. Even though the PHEV has a 4kw pack, the usable enery is 3.2kw due to Toyota's battery management system. 3200w/129.7khpm=24.67 miles...Impossible!

It has been well documented that the Prius PHEV has a range of 12-15 miles. Let's use a realistic number of 13 miles. 3200wh/13miles=246.1538whpm. Others have calculated that a Prius, PHEV or not, uses roughly 250whpm on average. Let's say that the 250whpm is consumed at the speed of 40mph.
250wh X 40miles = 10,000hw required to travel 40 miles. So it takes 10,000 watts of power to propel a Prius at the speed of 40mph. This is a realistic number because according to this video at Plug-In Supply a Prius running on EV mode at the speed of 60mph consumes 100 amps. The video does not mention the voltage but since it's a converted Prius, it's between 205 and 240 volts. That's at least 20,000 watts of power.

Now, the incandesent bulbs that will be turned on and in use for the duration of the drive are the parking lights. Replacing all the lights to LED will not save you any energy if you don't use them. How often do you drive with turn signals or hazard lights fashing the whole time or drive in reverse for more than a few feet or drive with interior lights constantly on? Almost never right? This is why I chose the parking lights as an example. On the Prius there are 6 W5W 5 watt bulbs for gen III and 8 bulbs for gen II I believe. I'm just repeating post 2 here. According to Who Cares, 3528 LED Or 5050 LED Diode? a single LED on this 2 T10 194 168 W5W 5-SMD Car Side Wedge LED Light White For Sale consumes .18 watts. so A single W5W bulb with 5 5050 SMD LED consumes .9 watts. a regular W5W bulb is rated at 5 watts. Replacing all 8 parking lights with LED will save you around 30 watts, give or take a little.

Now your consuming 9,970 watts traveling at 40mph with LED parking lights instead of 10,000 watts with incandescent parking lights. 10,000/9,970= .3% more efficient. You will travel .3% further with LED than incandescent. To put it in prospective, you'll travel just under 16 feet further per mile with LED than incandescent.

 

Using 250 wh/mile:
16 feet per mile * 40 miles per hour = 640 feet per hour
Using 125 wh/mile:
= 1280 feet per hour, which is what I said.

So the same result, just different assumptions for wh/mile (and different units). I just picked the first value for wh/mile that I found. TheForce says in http://priuschat.com/forums/prius-phev-plug-in-modifications/63232-miles-per-kwh.html that he gets 150 wh/mile (on flat roads). Whatever.

So, to the OP, in your 2011 non-plugin Prius, if you are driving just in EV mode with your lights on, at 25 miles per hour (I can't drive much faster than that in EV mode without a EV mode switch), Let's guess 2.5 miles of EV mode, or ten minutes, running with LEDs rather than incandescents gets you another 128 feet.

Alternatively, if you run on gas, and keeping a constant state of charge, LEDs over incandescents saves you 30 watts, or 250 watt-hours over the course of an entire tanks worth, which is equivalent to 1-2 miles of EV mode, or basically the difference between an almost fully charged battery and a discharged one. (Whether your battery is fully charged at the end of the tank of gas depends on other factors of course.)

p.s. TPMS = tire pressure management system, a system for telling you when your tire pressure is low.

 

If there are any reason to go LED it is rear brake lights for safety. The LEDs get to full output 0.2sec faster then incandescents. Doesn't sound much but at 60MPH it is more then length of the car, difference btw somebody rimming you from the back or stopping just off you rear bumper. But Prius already has LED brake lights...

Also if you travel at highway speeds (50MPH and up) the battery is kept at near full charge, any savings you'd have will be offset by more regenerative energy wasted, just saying. Besides savings will be about what radio consumes, right?

You can get bigger MPG improvements by getting LRR tires good luck.

 

OP: Read the red update on the first thread of this member's post:


http://priuschat.com/forums/gen-iii...-tire-pressure-warning-light-dead-sensor.html

Also, search the forum for all his threads and you will find the original effort he did to convert his incandescent bulbs to LEDs.

 

Theoretically, it makes sense on paper but in reality, changing the bulbs to LEDs will not extend any EV range at all. Years ago, I used to take 650 mile trips once a month. I had installed a 3,000 watt stereo system in my car. I have done quite a few trips with the system off and system on at 750w-1500w the whole way. I noticed absolutely no fuel consumption difference at all. 25 watts is nothing. It's only 2 amps at 12.5v. The decreased electrical load is not sufficient enough to cause increase in fuel efficiency. A subtle difference in pedal pressure will do more to increase your fuel efficiency than changing bulbs to LED.

 

First, you say my calculations are wrong, when I show that your calculations match mine, you say calculations are worthless and don't match reality. As evidence of that you pull out an unsubstantiated anecdote with a completely different variable. If you want to convince me that you aren't just trying to defend your first flippant guess, you will need to provide data taken from controlled experiments, with correlations and statistical significance.

As for statements like "25 watts is nothing", they defy the known Laws of Physics. 25 Watts is 25 Watts; it is most emphatically not 0 Watts.

Reality might trump theory, but theory trumps anecdote.

 

True, but that statement is being put in the context of fuel economy. Do you have data showing 25 Watts does impact fuel economy? Otherwise, it is "nothing."

 

The context is extra EV mode. You can see my calculations above.