question on auxiliary lights?
- Thread starter idaxj97
- Start date
In stock configuration, the Hella 500 uses a 55W H3 bulb. Assuming that your alternator is performing as it should, you should have 13.75 volts available when the engine is running. A 55W bulb draws 4 amps at 13.75 volts. Running 4 such lamps requires 16 amps total. There is no reason why you can't run 4 lamps at 55W each. Best results will be had by running the lights through a relay so that the lamps and the switches don't share the same voltage source.
R_Lefebvre
Expedition Leader
Interesting calculation. I've always wondered though, how muc load the rest of the car requires. Cooling fans, ignition system, AC Condenser fan, HVAC fan, etc.... How could one know if all of the load is too much? Voltage on the system while it's all running?
Also, for bulbs, V!=IR. The 55W rating is at a certain voltage, not sure what. As you increase the voltage, you actually increase the wattage, and current goes up something like the square of the voltage. You have to be careful with those calculations.
Also, for bulbs, V!=IR. The 55W rating is at a certain voltage, not sure what. As you increase the voltage, you actually increase the wattage, and current goes up something like the square of the voltage. You have to be careful with those calculations.
idaxj97
Adventurer
ok so i really didnt do too well in math but what it sounds like, i could run them but I might be at my limit for the alternator? so i might want to look into upgrading to a more powerful alt. does anyone have any experience with mean green alts or have any input on another alt?
KG6BWS
Explorer
my tacoma had a 60 amp alt in it, stock. i was running 4 hella 500's on my front bumper. they worked fine, but i agree with phulesau, you wont be entirely happy with them. at real low speeds, wheelin at night, the alt wouldnt be turning fast enough and you could see the lights dim. i also noticed a major power drain if i tried winching while they were on. of course, that was my own fault for leaving them on. my opinion, fwiw, is you should upgrade the alt to at least a 100amp. i put a 130amp, that i had built at a shop, in mine and ive been very happy with the lights. even after upgrading them to the 100 watt bulbs.
the bulbs, too, are measured at 12 volts, not at the running voltage of 13.5.
the bulbs, too, are measured at 12 volts, not at the running voltage of 13.5.
monele
Adventurer
Hey just in case you aren't dead set on Hella, Costco (I know you have to be a member or have a friend who is) has IPF light sets for about $30 less than anywhere else. The Powder coated driving lights (100w) are $149 (with wiring and relay etc.) and the compsite housing with the cool, wide angle+ spot lens comes with both the 55w and the 100w lamps and the wiring kit for $89. Great deal if you aren't brand loyal.
The electrical formula is W=VA, where W equals watts, V equal volts, and A equals amps. Any of the three variable can be solved if the other values are known. The relationships between the variables is fixed. Without actually having test equipment on a particular vehicle, one can only guess at what the actual values are for a given situation, but the differences are too slight to be anything but an esoteric debate point. Standard US automotive voltage in a 12V system is 13.75 with a fully loaded battery. Key on engine off, voltage should be 12.6 to 12.7 volts. Following start up or when the system is challenged, voltage may climb to 14.5 give or take a bit. Doesn't really matter.
An incandescent bulb using a metallic element is going to create a relatively fixed draw on an electrical system because the resistance in the element wire is constant regardless of voltage, given the narrow range of voltage available in an automotive system. So, using a rated 55W bulb as an example, we can assume that the 55W variable is now a constant, i.e., 55. It could be more or could be less, but this is not a science test.
The question posed is whether a stock alternator can fire 4 such lamps without overload. Since the output of the alternator is in two variables, voltage and amperage, we have to start somewhere. I started with a fixed voltage using US standard system voltage, 13.75V. Since the wattage of the bulb is now constant and the voltage is assumed to be constant as well, all that is left is the amperage needed to complete the formula with the two given constants.
W=VA, same as W/V=A, same as W/A=V. Any of these three variations of the same equation solves for any of the three variables.
The amps needed to fire a 55W@ lamp at 13.75 volts is determined with the second variation: 55/13.75 = 4.
The rest of the question is whether the stock alternator is sufficient to fire these four lamps IN ADDITION TO whatever else is going on in the vehicle. Amperage load fluctuates in any vehicle depending of what accessories are being used, and there is no constant answer for the question. However, the amperage needed to run most any vehicle under normal conditions is actually quite low. Even older coil and point ignition systems, which drew more power than modern ones, used rarely more than 9 or 10 amps. Most headlights are in the 65/55W range, and if you have two of them, should not consume more than 4.7A each, or rounded up, say 10 amps total. Brake lights are something like 11 or 15W elements, so if you have your brights on and the brakes on at the same time, you might be using 12 amps for all four lamps. If you are running the heater blower or the A/C, add another 15A. Stereo, add maybe another 9A.
The numbers posed are not absolutes, but not far off either. With 10A for the ignitions and engine operating systems, 12A for the brights and brakes, 15A for heater or A/C, and 9A for entertainment, you are sill only consuming 46A. This is far below even a wimpy 60A stock alternator, and if your vehicle is one of those with ABS, climate controls, fuel injection, and other ancillary systems factory installed, your alternator will have been sourced accordingly.
No automaker uses an alternator that has to run at or near peak output just to service factory on board systems. There is always a large margin of available power in a stock alternator. Running a few auxiliary lights is not going to overtax a stock alternator.
And for the record, running the voltage up and down across an incandescent lamp does not change the wattage (lumen output yes, wattage no), it changes the amperage needed to achieve the rated wattage. If you change the voltage and have the amperage available, wattage output may change as well, but that is a different question entirely, and not one that needs an answer given the question posted. The real world answer is that 4 simple off road lights should not pose a problem.
An incandescent bulb using a metallic element is going to create a relatively fixed draw on an electrical system because the resistance in the element wire is constant regardless of voltage, given the narrow range of voltage available in an automotive system. So, using a rated 55W bulb as an example, we can assume that the 55W variable is now a constant, i.e., 55. It could be more or could be less, but this is not a science test.
The question posed is whether a stock alternator can fire 4 such lamps without overload. Since the output of the alternator is in two variables, voltage and amperage, we have to start somewhere. I started with a fixed voltage using US standard system voltage, 13.75V. Since the wattage of the bulb is now constant and the voltage is assumed to be constant as well, all that is left is the amperage needed to complete the formula with the two given constants.
W=VA, same as W/V=A, same as W/A=V. Any of these three variations of the same equation solves for any of the three variables.
The amps needed to fire a 55W@ lamp at 13.75 volts is determined with the second variation: 55/13.75 = 4.
The rest of the question is whether the stock alternator is sufficient to fire these four lamps IN ADDITION TO whatever else is going on in the vehicle. Amperage load fluctuates in any vehicle depending of what accessories are being used, and there is no constant answer for the question. However, the amperage needed to run most any vehicle under normal conditions is actually quite low. Even older coil and point ignition systems, which drew more power than modern ones, used rarely more than 9 or 10 amps. Most headlights are in the 65/55W range, and if you have two of them, should not consume more than 4.7A each, or rounded up, say 10 amps total. Brake lights are something like 11 or 15W elements, so if you have your brights on and the brakes on at the same time, you might be using 12 amps for all four lamps. If you are running the heater blower or the A/C, add another 15A. Stereo, add maybe another 9A.
The numbers posed are not absolutes, but not far off either. With 10A for the ignitions and engine operating systems, 12A for the brights and brakes, 15A for heater or A/C, and 9A for entertainment, you are sill only consuming 46A. This is far below even a wimpy 60A stock alternator, and if your vehicle is one of those with ABS, climate controls, fuel injection, and other ancillary systems factory installed, your alternator will have been sourced accordingly.
No automaker uses an alternator that has to run at or near peak output just to service factory on board systems. There is always a large margin of available power in a stock alternator. Running a few auxiliary lights is not going to overtax a stock alternator.
And for the record, running the voltage up and down across an incandescent lamp does not change the wattage (lumen output yes, wattage no), it changes the amperage needed to achieve the rated wattage. If you change the voltage and have the amperage available, wattage output may change as well, but that is a different question entirely, and not one that needs an answer given the question posted. The real world answer is that 4 simple off road lights should not pose a problem.
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idaxj97
Adventurer
monele said:
its not that im dead set on them when i started looking around for some lights i was looking for lights that can run stone guards the reason for this is because i travel mostly in the mountains and dont want to shove a tree branch through the light. i know that the chance of this happining with todays lights most likly will NOT happin i just dont want to take the chance.
pete.wilson
Adventurer
Hey
As most of you probably already know, the Hella 500's comes with the wiring kit that is relay controlled unlike most really cheap lights which I would refuse to use. Having a relay is the only way to run lights. I have 2 KC Daylighter 100W lights on my Grand and they work fairly well, I may add two fog style clear lights to get more width. No glare problems with the roof mounted rack.
Pete Wilson
As most of you probably already know, the Hella 500's comes with the wiring kit that is relay controlled unlike most really cheap lights which I would refuse to use. Having a relay is the only way to run lights. I have 2 KC Daylighter 100W lights on my Grand and they work fairly well, I may add two fog style clear lights to get more width. No glare problems with the roof mounted rack.
Pete Wilson
R_Lefebvre
Expedition Leader
madizell said:
That's interesting that you say that, because I removed the opaque plastic covers from one of my FF1000's a while back only to discover the lens was shattered. I couldn't understand what had happened. I assumed some kids had taken the cover off, smashed the light, and put the cover back.
You've had experience with rocks smashing lights behind a cover?
Over the years I have used:
1) the old wire grid style covers for Jeeps. At the time I thought they looked cool and hoped they would protect the lenses while driving on and off the road. After several years driving around Alaska, I removed them because they a) rusted so much I could hardly get them open or shut, b) could not adequately clean behind them, c) had to replace several headlights due to stone chips, and d) finally gave up when one was punched out by a tree branch on the trail. They collected snow so fast as to be dangerous at night.
2) the plastic style used by KC and others that completely cover the lights rendering them not usable with the cover installed. These don't stand up to contact with anything substantial. I eventually threw them all away, and most of them were repaired with duct tape by that point. They were also a pain in the butt to take off and put on and were often left at home for that reason. One or two were lost on the trail because they don't stay on well. Whether they actually provided protection from stones is anyone's guess, since they were not installed during use, and were not always where they were thought to be otherwise. These covers change state when frozen, so using them in the winter makes them highly susceptible to breakage.
3) the clear plastic sort that are supposed to be able to be left on, usually made from plexi or some form of clear poly. Same issues as with the ones you can't see through, and if you make the mistake of trying to clean mud off of them on the trail, they are permanently damaged by scratching. Light transmissivity is so low on these that they hinder use of the lights (except when new out of the box). Even if they do protect the glass lens from damage, they tend to render the lights ineffective in time. Not a good trade off. They also break easily when cold.
4) the stick-on flexible super-resilient kind of glass protector cut to fit and applied directly to the glass. These worked about the best of anything I have ever tried, when protecting glass lenses. However, they are not going to stop bullets, rocks that act like bullets, or large branches of trees. They also don't last forever, and over a period of only 2 or 3 years will yellow out to the point that they, too, interfere with the lights. They are also susceptible to heat damage, so if you run super hot lights, these won't last very long. They will bubble underneath from the heat, collect moisture and dust, and fail. Heat also causes delamination from the glass, especially at the edges, where they will again collect water and dirt. They are not easily removable unless the glass underneath is in good condition, but will hold together a lens that has been damaged, leaving the light usable at least. They did not stop my lenses from being damaged by impact. No doubt they stopped small rocks and prevented typical bullet chips from such, but not all the rocks I found flying around in Alaska were that small. So, they work but are not perfect.
5) the plastic grid style used by KC and others. These are for bling factor, not for stopping rocks. Use them if you have to. I just toss them in a box and forget them.
6) naugahyde slip on covers. Keeps off the dirt, but offers no protection from impact. Old school nonsense. If you like the way they look, fine.
7) snap on Lexan. If you can find these for your lights, they offer the best combination of protection and light transmission. They are, however, susceptible to some of the same problems as poly plastic covers in that depending on how made, they can and will scratch, so treat them nice. They will also break, but it takes a lot more to break them. Not available for all lights as far as I can tell. If you can find good quality Lexan covers, they are very durable. If they can be swiped off the lights by contact with brush and such, tape them on.
8) built in Lexan lens. These are by far the best combination I have found. High quality, scratch resistant, high light transmission. Generally SAE/DOT approved for use as a primary light cover, or made from the same stuff as used by the auto makers for their aero-style light pods. What kind of bullet they will stop, I don't know, but they are more than durable for trail use. I have yet to see on damaged on or off road. They are not, however, offered on every brand or every style of light. They are not offered on inexpensive lights, so even if desirable, they are not readily available. On the other hand, they work so well, that I might, if given the choice, select the brand and style with Lexan lenses over a similar product with glass lenses, even though they cost more.
But to answer the question directly, sure. All lens covers I have used have allowed glass lenses to be chipped, holed, or shattered by impact. The only one so far that has not failed is the built in Lexan lens.
1) the old wire grid style covers for Jeeps. At the time I thought they looked cool and hoped they would protect the lenses while driving on and off the road. After several years driving around Alaska, I removed them because they a) rusted so much I could hardly get them open or shut, b) could not adequately clean behind them, c) had to replace several headlights due to stone chips, and d) finally gave up when one was punched out by a tree branch on the trail. They collected snow so fast as to be dangerous at night.
2) the plastic style used by KC and others that completely cover the lights rendering them not usable with the cover installed. These don't stand up to contact with anything substantial. I eventually threw them all away, and most of them were repaired with duct tape by that point. They were also a pain in the butt to take off and put on and were often left at home for that reason. One or two were lost on the trail because they don't stay on well. Whether they actually provided protection from stones is anyone's guess, since they were not installed during use, and were not always where they were thought to be otherwise. These covers change state when frozen, so using them in the winter makes them highly susceptible to breakage.
3) the clear plastic sort that are supposed to be able to be left on, usually made from plexi or some form of clear poly. Same issues as with the ones you can't see through, and if you make the mistake of trying to clean mud off of them on the trail, they are permanently damaged by scratching. Light transmissivity is so low on these that they hinder use of the lights (except when new out of the box). Even if they do protect the glass lens from damage, they tend to render the lights ineffective in time. Not a good trade off. They also break easily when cold.
4) the stick-on flexible super-resilient kind of glass protector cut to fit and applied directly to the glass. These worked about the best of anything I have ever tried, when protecting glass lenses. However, they are not going to stop bullets, rocks that act like bullets, or large branches of trees. They also don't last forever, and over a period of only 2 or 3 years will yellow out to the point that they, too, interfere with the lights. They are also susceptible to heat damage, so if you run super hot lights, these won't last very long. They will bubble underneath from the heat, collect moisture and dust, and fail. Heat also causes delamination from the glass, especially at the edges, where they will again collect water and dirt. They are not easily removable unless the glass underneath is in good condition, but will hold together a lens that has been damaged, leaving the light usable at least. They did not stop my lenses from being damaged by impact. No doubt they stopped small rocks and prevented typical bullet chips from such, but not all the rocks I found flying around in Alaska were that small. So, they work but are not perfect.
5) the plastic grid style used by KC and others. These are for bling factor, not for stopping rocks. Use them if you have to. I just toss them in a box and forget them.
6) naugahyde slip on covers. Keeps off the dirt, but offers no protection from impact. Old school nonsense. If you like the way they look, fine.
7) snap on Lexan. If you can find these for your lights, they offer the best combination of protection and light transmission. They are, however, susceptible to some of the same problems as poly plastic covers in that depending on how made, they can and will scratch, so treat them nice. They will also break, but it takes a lot more to break them. Not available for all lights as far as I can tell. If you can find good quality Lexan covers, they are very durable. If they can be swiped off the lights by contact with brush and such, tape them on.
8) built in Lexan lens. These are by far the best combination I have found. High quality, scratch resistant, high light transmission. Generally SAE/DOT approved for use as a primary light cover, or made from the same stuff as used by the auto makers for their aero-style light pods. What kind of bullet they will stop, I don't know, but they are more than durable for trail use. I have yet to see on damaged on or off road. They are not, however, offered on every brand or every style of light. They are not offered on inexpensive lights, so even if desirable, they are not readily available. On the other hand, they work so well, that I might, if given the choice, select the brand and style with Lexan lenses over a similar product with glass lenses, even though they cost more.
But to answer the question directly, sure. All lens covers I have used have allowed glass lenses to be chipped, holed, or shattered by impact. The only one so far that has not failed is the built in Lexan lens.
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