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vamram 
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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 Posted: Tue Dec 09, 2014 5:31 pm Post subject: H4 Headlights cause voltage drop? |
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Hello Samba,
I recently upgraded my headlights from stock sealed beams to H4 and to a 90 amp alternator. Despite the bigger alt, I still get a 2+ voltage drop when running w the headlights.
Do I need a 2nd headlight relay? If so where do I install it?
My bug is a stock 72 super, and everything electrical works- seat belt buzzer, horn, radio, door light, etc etc.
Thanks!!
Victor
_________________
Eventually, "we are what we pretend to be.’”
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'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
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Bashr52
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Joined: July 16, 2006
Posts: 5666
Location: On an island in VA
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| Posted: Tue Dec 09, 2014 5:35 pm Post subject: |
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| Yep those H4 bulbs will draw a ton of power when they fire up. You will need a relay on those lights, depending on what wattage you have you are probably on the hairy edge of over taxing the stock wires. Install the relay anywhere you want. |
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Tue Dec 09, 2014 7:11 pm Post subject: |
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They're 55/60w. So is it just a 2nd relay like the factory one?
Thanks!
Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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Donnie strickland
Samba Member
Joined: December 21, 2009
Posts: 2403
Location: Moody, AL
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| Posted: Tue Dec 09, 2014 8:07 pm Post subject: |
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If they're 55/60W, they're not drawing any more power than the stock lights were, and neither will they "overtax the wires". If you're getting a big voltage drop, look for poor connections and bad grounds.
I just added these to my car (with the stock generator) and there was no change in the voltage draw over the stock lamps.
http://www.busdepot.com/0301600118
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MacLeod Willy
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Joined: February 18, 2014
Posts: 933
Location: Ontario Canada
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| Posted: Tue Dec 09, 2014 8:18 pm Post subject: headlites |
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If those headlites are drawing more than the 90amp your alternator is rated at, you might want to invest in a fire extinguisher.
Like the others said, check for a poor body ground.
Not exactly sure what you mean 2- voltage drop. Does it drop from 14.4 down to 12.4?
What does the DVOM read at the battery with hi beams on, fast idle? |
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Tue Dec 09, 2014 8:45 pm Post subject: |
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Yeah, i have a nice 2.5 lbs halotron extinguisher w/in easy reach. I bought my headlight enclosures from the busdepot as well and the h4's from the local FLAPS.
Sounds like I need to trace down a short. The wires are intact at the fuse box, original wiring. Where there may be issues is in splices coming out of the quarter plane into the fender.
I do know that my relay is shot - the lights are stuck on high beam all of the time. Could the worn out relay be the source of the voltage drop?
And yeah, it's a drop from 14+v of anywhere from 2-3 volts. Reving the engine will bring it back up but not much past 12.
I'll check the voltage at the battery w/the hi beams on tomorrow and report back.
Thanks for all of the troubleshooting tips and suggestions!
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Wed Dec 10, 2014 1:12 am Post subject: |
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| vamram wrote: |
| Sounds like I need to trace down a short. The wires are intact at the fuse box, original wiring. Where there may be issues is in splices coming out of the quarter plane into the fender. |
Its probably not a short. You should try cleaning up connections to improve current flow. Even if this is a not the problem it can only help to have solid clean connections throughout your electrical system.
| vamram wrote: |
| I do know that my relay is shot - the lights are stuck on high beam all of the time. Could the worn out relay be the source of the voltage drop? |
Not likely, but you should get the relay fixed. As a temp fix, swap the yellow and white wires on the dimmer relay. It will now power the low beam fuses/lights.
| vamram wrote: |
And yeah, it's a drop from 14+v of anywhere from 2-3 volts. Reving the engine will bring it back up but not much past 12.
I'll check the voltage at the battery w/the hi beams on tomorrow and report back. |
Where did you previously take the voltage reading?
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DeathTrap
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Joined: February 26, 2004
Posts: 1757
Location: Sacramento/Vermont
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| Posted: Wed Dec 10, 2014 1:58 am Post subject: |
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put your test meter between the light fixture and the negative terminal of the battery
you may indeed see the missing 2volts to be a ground issue
if nothing
then do it between the fliment post and the positive post to confirm voltage drop
if you put the meter leads between the area of loss it will show 2volt differential
or portion adding up to |
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Wed Dec 10, 2014 4:55 am Post subject: |
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Ashman & D-Trap - thanks for the troubleshooting tips. I haven't actually measured it w/a voltmeter yet. I have a VDO voltage gauge and have been going by what it reads, the drop in RPMs, and the horn sounding like a dying hyena. I'll pull out the volt meter and clean the contacts when I get home from work tonite.
Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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MacLeod Willy
Samba Member
Joined: February 18, 2014
Posts: 933
Location: Ontario Canada
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| Posted: Wed Dec 10, 2014 8:48 am Post subject: volt |
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It really sounds like body ground. Run a temp jumper from the neg at the battery to the BARE METAL spot on the body under the rear seat. The horn does draw a lot in addition with the hi beams.
Heck you have 90amp you are only using maybe 12 or 13A.
Don't use the VDO gauge that is only a reference Use a DVOM or analog at the battery and let us know |
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Mr.Duncan
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Joined: May 12, 2012
Posts: 3542
Location: Houston, TX
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| Posted: Wed Dec 10, 2014 10:13 am Post subject: |
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question.  
When you installed that 90 amp alternator, Did you upgrade the postive output wire running to the battery from it?
You need to run a second wire (most add it from the alternator, to the right side of the engine, and connects up to the battery + connection on the starter.)
Otherwise, that 90amp alternator is trying to push all that extra juice through the stock wire that runs to it, which is to small.
I agree you should check your grounds too.
Most over look the transmission ground strap.
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Wed Dec 10, 2014 12:11 pm Post subject: |
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| Mr.Duncan wrote: |
question.
When you installed that 90 amp alternator, Did you upgrade the postive output wire running to the battery from it?
Most over look the transmission ground strap. |
Yikes, nope, didn't know that. What gauge should that 2nd wire be - 10? 12? Or better yet, if I replace the stock one so as to keep the link to a single wire, what gauge should that replacement wire be?
The tranny ground strap is "new" and clean, i replaced it in July.
Thanks,
Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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Bashr52
Samba Member
Joined: July 16, 2006
Posts: 5666
Location: On an island in VA
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| Posted: Wed Dec 10, 2014 12:38 pm Post subject: |
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| Donnie strickland wrote: |
If they're 55/60W, they're not drawing any more power than the stock lights were, and neither will they "overtax the wires". If you're getting a big voltage drop, look for poor connections and bad grounds.
I just added these to my car (with the stock generator) and there was no change in the voltage draw over the stock lamps.
http://www.busdepot.com/0301600118 |
IF they are the stock size they shouldnt take any more power when lit than the STD lights which is true, but the initial surge to light those bulbs is more taxing than the stock bulbs. On 40+ old year wiring thats not something I'd want to leave to the stock wire alone. It would be a good idea to run a relay for those lights. The relay that is in there now is the just the high/low relay, not an actual power relay for the lights. |
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Wed Dec 10, 2014 12:58 pm Post subject: |
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Not being very electrically-savvy myself, do you have a recommendation on the name of the relay I should look for at my FLAPS? Is it just called a "power relay for the lights?"
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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Mr.Duncan
Samba Member
Joined: May 12, 2012
Posts: 3542
Location: Houston, TX
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| Posted: Wed Dec 10, 2014 1:17 pm Post subject: |
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| vamram wrote: |
| Not being very electrically-savvy myself, do you have a recommendation on the name of the relay I should look for at my FLAPS? Is it just called a "power relay for the lights?" |
for the alternator, run a 2nd wire, same gauge as the stock one currently running to it (so you have two wires)
for the lights, I have the same ones, yet i have 100/90 watt bulbs in them 
I use one relay, to control the low beam of both bulbs, and another relay to control the high beam of both. This keeps them from burning up my headlight switch.
I order my electric supplies from here, since I tend to use alot.
Two of these.. these relays have more pins than you need, but that's just simply what I went with.
http://www.delcity.net/store/Relay-&-Socket-Harness-Kit/p_72563
so, my low beams are 90 watts each (180 watts)
180 / 12 (volts) means they use 15 amps. This relay (linked above) can handle up to 40 amps Open, and 60 amps closed.
Cheers-
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Red 1971 Squareback Thread
Red 1966 Beetle Thread
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1971 Green Super Beetle (sold)
1966 Ghia (sold)
1971 Blue Super Beetle (sold)
1966 Java Green Std Beetle (sold)
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7304
Location: NOVA
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| Posted: Wed Dec 10, 2014 2:20 pm Post subject: |
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Mr. Duncan, thanks for the explanation and link. I will add that to the list of things to check on the Bug and add to it.
What happens w/the stock relay if I put these in place? If i'm understanding your explanation, the stock relay stays in its place and I install one of these in-line for the low beam wires and one for the high beam wires. So i'm adding two relays....?
Any chance you could post a picture of how one of these sits in your wiring?
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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Mr.Duncan
Samba Member
Joined: May 12, 2012
Posts: 3542
Location: Houston, TX
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| Posted: Wed Dec 10, 2014 2:29 pm Post subject: |
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| vamram wrote: |
Mr. Duncan, thanks for the explanation and link. I will add that to the list of things to check on the Bug and add to it.
What happens w/the stock relay if I put these in place? If i'm understanding your explanation, the stock relay stays in its place and I install one of these in-line for the low beam wires and one for the high beam wires. So i'm adding two relays....?
Any chance you could post a picture of how one of these sits in your wiring? |
Stock relay just switches power from High/to/low circuits. Like this:
Battery-->Ignition switch-->fuse block-->Headlight switch-->Stock relay---> sends it to the according High/Low circuit in the fuse block. then to the headlights.
The high amps will kill a headlight switch, But since you have 60 watt H4 bulbs, you really don't need relays to take the load off the headlight switch.
You could just check/replace the wiring to the headlights with new wires.
check the headlight grounds.
IF you get higher watt bulbs like me, you WILL need to add relays to protect the headlight switch.
but you could add relays , this will take the AMPS off of the switches to protect them.
here is a diagram of adding the TWO relays to protect the:
ignition switch, headlight switch, etc...
just like how people add hot start relays to the starter solenoid, it takes the 30 amp draw from the ignition switch down to .03 amps....
get some SPST 30 amp relays..
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(Owner) www.vintagecarleds.com
Red 1971 Squareback Thread
Red 1966 Beetle Thread
---------------------------------------------------
1971 Green Super Beetle (sold)
1966 Ghia (sold)
1971 Blue Super Beetle (sold)
1966 Java Green Std Beetle (sold)
1971 Red Squareback (sold)
1966 Red Beetle |
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MacLeod Willy
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Joined: February 18, 2014
Posts: 933
Location: Ontario Canada
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| Posted: Wed Dec 10, 2014 3:46 pm Post subject: lights |
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| You might even make it simpler by using the 87a terminal for low beam in the off position and fire the relay just for hi. Maybe? |
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Aussiebug
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Joined: June 03, 2002
Posts: 2162
Location: Adelaide Australia
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| Posted: Wed Dec 10, 2014 4:13 pm Post subject: |
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| Bashr52 wrote: |
| Donnie strickland wrote: |
If they're 55/60W, they're not drawing any more power than the stock lights were, and neither will they "overtax the wires". If you're getting a big voltage drop, look for poor connections and bad grounds.
I just added these to my car (with the stock generator) and there was no change in the voltage draw over the stock lamps.
http://www.busdepot.com/0301600118 |
IF they are the stock size they shouldnt take any more power when lit than the STD lights which is true, but the initial surge to light those bulbs is more taxing than the stock bulbs. On 40+ old year wiring thats not something I'd want to leave to the stock wire alone. It would be a good idea to run a relay for those lights. The relay that is in there now is the just the high/low relay, not an actual power relay for the lights. |
"IF they are the stock size they shouldnt take any more power" I agree. Outside the USA, VW kept the bulbs and reflector style headlights, so when halogens first became available in the 1970s, I started using them. I replaced the standard 40/45w headlight bulbs with 55/60w H4 P45t (double step base) halogens and have not needed anything more since then, and I've done a LOT of night driving in my bug. 60w nice white lights with the big 7" reflectors makes for excellent night time driving.
The stock wiring does not need changing, no relays are needed, and the stock fuses are OK too - for those with bulbs and reflector headlights, it's just a straight bulb swap (I still have the stock 30 amp generator).
VAMRAM,
Yes, you need to check your wiring connections, especially the ground connections (for the headlights - brown wires tek screwed to the body near the fuel tank). And clean the body to tranny strap under the car at the nosecone of the gearbox - that's the "return" path for the alternator to the battery.
Re the 90 amp alternator. Generally this is overkill, but since you already have it, you certainly do need to upgrade the wiring from the alt to the battery since the stock wire there can handle 50 amps, but will cook if the battery gets a little flat and the Alt tries to push 90 amps though that wire to charge it; and if you start using excessive power up front you need to upgrade the wiring from the battery up to the terminal 30s on the headlight switch (which is used as a junction box by VW), the stock main red wire is good for 50 amps but not much more.
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Last edited by Aussiebug on Wed Dec 10, 2014 4:22 pm; edited 1 time in total |
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MacLeod Willy
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Joined: February 18, 2014
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Location: Ontario Canada
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| Posted: Wed Dec 10, 2014 4:21 pm Post subject: lights |
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Why not fire all 4 of the filaments on hi beam. You will see the red in their eyes then  |
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