# Do you agree with this guy... HID install...
**URL:** https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345
**Category:** NYSpeed Automotive
**Created:** [January 26, 2006, 11:51am UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345 "2006-01-26T11:51:15Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [January 26, 2006, 11:51am UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/1 "2006-01-26T11:51:15Z")
Installing HIDs today…
> A word about Power
> The XenonDepot kit included a very nicely made wire harness that provides power directly from the 12v battery main and uses the existing H1 bulb socket to switch the relay. This allows the kit to draw power from the battery mains instead of the existing headlight power circuit.
>
> Unfortunately, in the Elise, the battery is far in the back of the car, while the headlights are (quite sensibly) in the front. I could find no easily-accessible source of high-current power in the front crash structure. Arno on EliseTalk explained that there is a 50A power lead available somewhere under the dash, but running wires to it would be quite a bit of work, requiring removal of the dash top and likely drilling.
>
> For this reason, I wanted to find out if a separate power source (with relay) is not actually necessary, meaning I could power the HID ballasts directly from the headlight circuits. This is a controversial approach, and I encourage you to do your own research before doing the same.
>
> Power Demands
> The HID ballasts are rated “20A Max” each according to the silk-screen labeling. However, HID lighting in general takes less power than normal Halogen (incandescent) lighting. Hard numbers are hard to come by, so measurements were in order.
> First, the stock headlight bulbs draw 4.5A each. There is a large inrush current as the filament first heats up, but it’s very fast – too brief to measure. With the engine off, the stock wiring provides 12.0v to the H1 connector under load – excellent voltage, so I’m not worried about sagging below the 9v minimum required by the ballast.
>
> The HID Ballasts draw a large amount of current when first powered on as they ignite the arc and heat the salts in the capsule. It is this startup current that could blow fuses or cause damage to underrated wiring. I measured the highest startup current when the bulbs were cold (green line on chart), and it quickly drops off as they warm up. The highest peak reading was 17A!
>
> Restarting the HID arc while the bulb is hot takes considerably higher voltage (up to 23 kV) to ignite, but actually less current. You can see the red line in the graph showing a lower current peak after the bulb has been resting one minute off and then restarted.
>
> This is clearly beyond the capacity of the 10A fuse… or is it? The automotive fuses are “slow-blow”, so they can take a bit more than the rated current for a brief amount of time. According to Bussmann’s spec for the ATC fuse, we should be able to withstand around 17A for a full second without melting. The current spike is actually shorter than that, and the full time spent above 10A is about two or three seconds. In my sample set of two fuses, they have not blown at startup. Your mileage may vary, especially if you see subzero temperatures or have a different ballast core. I will be carrying a few spare fuses in the car, but I’m comfortable with that for now. I will say that I have heard three first-hand reports of HID installations on the existing power wiring, and none have reported power or fuse problems.
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### Author:  [@Fry](https://forums.speedlife.net/u/Fry)
#### Post date: [January 26, 2006, 12:01pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/2 "2006-01-26T12:01:41Z")
What AWG are the headlight wires? I wouldn’t think that you would have to worry much about the wiring. The spike isn’t really all that high. That is, assuming he was measuring with something that sampled fast enough to record close to the true peak… It looks to be above 10 amps for ~3 seconds when cold… I agree with his thinking that those 10A buss fuses won’t last long…
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### Author:  [@MPD47](https://forums.speedlife.net/u/MPD47)
#### Post date: [January 26, 2006, 12:13pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/3 "2006-01-26T12:13:22Z")
Why dont you just spend a day, carefully route hot wires from the battery, hidden, upto the ballasts.
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### Author:  [@RuBiCaNT](https://forums.speedlife.net/u/RuBiCaNT)
#### Post date: [January 26, 2006, 12:27pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/4 "2006-01-26T12:27:16Z")
Battery relocation to the hood… :lol: Anyway, it looks too much like a “close shave” to me to risk especially with a car like this. Why risk starting an electrical fire. Take your time and do what Mike suggests, running the larger gauge wire to the trunk and use a relay or relocate a smaller battery to the front of the car.
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### Author:  [@Anonymity](https://forums.speedlife.net/u/Anonymity)
#### Post date: [January 26, 2006, 12:30pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/5 "2006-01-26T12:30:21Z")
P=I^2R
I would run the wire because of the voltage/ current drop across splices.
just me.
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### Author:  [@djnickthemix](https://forums.speedlife.net/u/djnickthemix)
#### Post date: [January 26, 2006, 1:00pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/6 "2006-01-26T13:00:37Z")
id rather see if the fuse blows rather than running crappy wires to the truck. why not use a 15a fuse? the wireing allready provided can probably take 10 constant. when they run power wires to your house they actually underrate the guage wired used and use the fact that the heat from the current draw will actually be cooled by the air surrounding it.
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [January 26, 2006, 1:03pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/7 "2006-01-26T13:03:22Z")
i found some HID kits that are plug and play for the lotus and use factory wiring. I think i will be OK. I will bench test them before installing them.
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### Author:  [@Bucker](https://forums.speedlife.net/u/Bucker)
#### Post date: [January 26, 2006, 1:05pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/8 "2006-01-26T13:05:02Z")
> Unfortunately, in the Elise, the battery is far in the back of the car, while the headlights are (quite sensibly) in the front.
> That made me L O L. Do it, if fuses start popping, run a hot wire from the back.
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### Author:  [@Fry](https://forums.speedlife.net/u/Fry)
#### Post date: [January 26, 2006, 1:45pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/9 "2006-01-26T13:45:13Z")
Again, what gauge wire is already run to the headlights?
AWG Ampacity
18 14
16 18
14 25
12 30
10 40
That’s for mult-wire copper conductors with THHN insulation at 30\*C.
You’re probably fine. Keep some extra fuses in the glove box. (Does it have one? Picturing what the glove box in a car that size must be like, is there even room for more than a couple fuses along with your registration and insurance?)
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [January 26, 2006, 1:46pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/10 "2006-01-26T13:46:34Z")
the glove box is called the fuel door. 😛
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### Author:  [@Fry](https://forums.speedlife.net/u/Fry)
#### Post date: [January 26, 2006, 1:47pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/11 "2006-01-26T13:47:39Z")
> [@fastandcheap](#):
>
> P=I^2R
>
> I would run the wire because of the voltage/ current drop across splices.
>
> just me.
FYI You won’t get a current drop across splices. What goes in must come out.
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### Author:  [@Fry](https://forums.speedlife.net/u/Fry)
#### Post date: [January 26, 2006, 1:49pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/12 "2006-01-26T13:49:00Z")
> [@newman](#):
>
> the glove box is called the fuel door. 😛
LOL seriously? It kinda seems like a go-cart on 'roids, with a nice body.
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [January 26, 2006, 1:54pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/13 "2006-01-26T13:54:04Z")
> [@BikerFry](#):
>
> FYI You won’t get a current drop across splices. What goes in must come out.
true, but what i think he is saying is that compared to a non spliced wire, you will see higher current due to less resistance…
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### Author:  [@newman](https://forums.speedlife.net/u/newman)
#### Post date: [January 26, 2006, 1:56pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/14 "2006-01-26T13:56:25Z")
> [@BikerFry](#):
>
> LOL seriously? It kinda seems like a go-cart on 'roids, with a nice body.
pretty much… and Jeremy Giambi is in the mail…
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### Author:  [@focusinprogress](https://forums.speedlife.net/u/focusinprogress)
#### Post date: [January 26, 2006, 3:29pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/15 "2006-01-26T15:29:36Z")
> [@djnickthemix](#):
>
> id rather see if the fuse blows rather than running crappy wires to the truck. why not use a 15a fuse? the wireing allready provided can probably take 10 constant. when they run power wires to your house they actually underrate the guage wired used and use the fact that the heat from the current draw will actually be cooled by the air surrounding it.
actually thats a bad principle to ride on, i followed that idea and this is what happened:
[http://www.nyspeed.com/forums/showthread.php?t=3969&highlight=wiring](http://www.nyspeed.com/forums/showthread.php?t=3969&highlight=wiring)
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### Author:  [@Anonymity](https://forums.speedlife.net/u/Anonymity)
#### Post date: [January 26, 2006, 5:25pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/16 "2006-01-26T17:25:13Z")
> [@BikerFry](#):
>
> FYI You won’t get a current drop across splices. What goes in must come out.
thank you for correcting me.! or should i say allowing me to correct my train of thought. I am not speaking for all cars wiring but the honda wiring that i have taken apart used a may different gauges of wiring in on single path! now when you are dealing with DC; current is cridical.
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### Author:  [@boardjnky4](https://forums.speedlife.net/u/boardjnky4)
#### Post date: [January 26, 2006, 6:13pm UTC](https://forums.speedlife.net/t/do-you-agree-with-this-guy-hid-install/7345/17 "2006-01-26T18:13:13Z")
i think in newmans case, the fuse will blow before it starts an electrical fire. Just dont replace the fuse with a higher amperage fuse and it see how it goes