Relay Failures

[emry]

Well, you guys finally got me to go out into the shop.

 

First, (V)Voltage = (I)Amps x ®Ohms and (W)Watts = V x I

 

Second, Heat increases resistance.

 

I did this using a standard automotive battery measured at 12.13v before tests and a 55w/60w H-4 headlamp bulb.

 

All measurements made using a Fluke meter.

Cold filament R = 0.5ohms across low beam connection.

Measured 3.35amp draw at 12.10v battery = 3.611ohms, 40.5w

Added battery charger

Measured 3.65amp draw at 14.65v battery = 4.013ohms 53.4w

 

 

Merry Christmas, and all those other this time of year celebrations.

 

Here a little more reading...Electrical Stuff

[docc]

David,

 

Since the beams are on a dedicated circuit the only draw on the 5 amp ( original 15 amp hi-lo beam ) fuse is the brake light, tach , three warning lights ,the regulator reference voltage amd , now, the relays for the main beams. 89 miles today and the 5 amp fuse held.

 

I put a 7.5 amp fuse in the hot wire to the hi-lo beam. You got me on that draw since both beams together ( passing switch) would theoretically draw about 9 amps ( 55 watt lo and 60 watt hi together).

 

I just switched on and held the pass switch 10 seconds without a pop or hiss. Not even any smoke .

[dlaing]

I put a 7.5 amp fuse in the hot wire to the hi-lo beam. You got me on that draw since both beams together ( passing switch) would theoretically draw about 9 amps ( 55 watt lo and 60 watt hi together).

 

I just switched on and held the pass switch 10 seconds without a pop or hiss. Not even any smoke .

So Emry's measurements seem to indicate that the wattage ratings are way off.

[Guest Guest]

No, my measurements just prove that I am actually an idiot. I measured across the wrong terminals. Oops. So here is the right measurements.

 

Low beam 4.61amps @ 12.87volts; 2.69ohm, 59.33 watts

 

High beam 5.33amps @ 12.79volts; 2.399ohm, 68.17 watts

 

Both beams 9.51amps @ 12.53volts; 1.317ohm, 119.16 watts

 

Sorry guys, the egg nog was stronger than I thought....

[emry]

See, that last post proves it....

[docc]

Ok, my brain feels better already ( earlier my wife looks over and says. " why do have your physics book out?" Er, trying to get more confused . . .

 

Emry, I wonder how much the amperage goes up as voltage rises? I noticed my Sport will usually run 13 - 14 volts at 2000 rpm.

[emry]

This was done on the low beam.

 

4.45amps @ 12.10volts Pretty typical for a battery at rest.

4.94amps @ 14.44volts about where the regulator should max out.

5.30amps @ 16.36volts this is what a bad regulator will cause just before your ECU fries. , but the headlight was still O.K.

[docc]

I'm surprised the two filaments together ( passing switch) didn't fry my 7.5 amp fuse. Maybe a 10 amp fuse would be better and still safe?

[dlaing]

I'm surprised the two filaments together ( passing switch) didn't fry my 7.5 amp fuse. Maybe a 10 amp fuse would be better and still safe?

Yah, it would suck to going around some turn in the night that required flashing the high beam, only to find yourself frying the fuse and blacking out both beams.

I'd go with the 10 amp, and maybe 15 amp if you go with that Sylvania Silverstar® 65/72 watt bulb.

mmmm Eggnog sounds good.

[callison]

My old R65 bimmer had a switch that could be "balanced" to the mid position allowing for both high and low beams to be on at the same time. Both filaments also blew out at the same time at oh:dark-thirty and I had to limp home eight miles on just the running lights in my turn signals. Let's just say that I don't encourage running both beams simultaneously except for the flash mode.

[dlaing]

Funny, My V65 SP could do the same thing...never blew a fuse or relay

[dlaing]

I'm working on a junction block to get that stack of terminals off the battery. More on that tlater.

How is that going?

I was thinking of moving some of the positive terminals down to the starter, and some of the ground to a point on the frame, under the seat....maybe close to the fuel tank at the bolts that fasten down the battery rack

[Guest Gary Cheek]

Just a note regarding circuit protection. On the headlight feeder to the relays I use a self resetting 20 amp circuit breaker. The wire is usually 12 or 14 ga. and a 20 amp breaker will open long before the wire temp is critical. Better to have a light go off and come back on in a few seconds than just stay dark.

There are 20 amp automotive breakers available that plug right in to the fuse sockets where there is sufficient space. Navigate this site for a good selection of quality wiring supplies at reasonable prices.

 

Waytekwires

[docc]

How is that going?

I was thinking of moving some of the positive terminals down to the starter, and some of the ground to a point on the frame, under the seat....maybe close to the fuel tank at the bolts that fasten down the battery rack

 

 

Having added fused feeds to the headlights, horns and an accessory plug I felt good about moving the terminals off the battery onto junction blocks. On the 2000 this meant moving the turn signal flasher over to the relay side.

 

Recently, I added a separate regulator fuse since my 30 amp was melting from the small weak connectors in the fuse block. In order to limit the number of junctions and connections in that circuit, I put that terminal back directly on the battery.

[Guest Gary Cheek]

So Emry's measurements seem to indicate that the wattage ratings are way off.

 

A 15 amp fuse will flow over 15 amps for a short time. Repeated over current will deplete that abaility.