Voltage Drop

[bbjumper]

The PO of my G at some point replaced the headlight with a sealed beam. The Desert has some great roads and is wide open where you can travel briskly provided you can see where your goin, always a good idea to slow down after dark but more light is always better. While going back to a H4 unit I noticed the voltage at the light is 11.1 v versus 12.7 at the battery. I'm guessin that's too much spread. Anybody know what the acceptable drop would be and if going through all connections in the harness will gain anything or should I just install a relay similar to these
http://www.easternbeaver.com/Main/Wi...s/h4_kits.html
and wire it direct?

I'm not that far off, I figure I can pick up at least 1/2 v cleaning things up, but installing a relay with a starter cut out would definitely have it's advantages. The horns have a similar drop and probably why they sound like somebody stepping on a mouse.

Any experience around this would be appreciated.

Thanks

 

[SqDancerLynn1]

Check for a voltage drop across the ign switch Check for a difference between the battery voltage and the voltage at the fuse block.. Bad connection some where

 

[Steve]

As Lynn suggested, check for the drop across the ignition switch. The easiest way to do that is to compare the voltage at your fuses. Check BOTH sides of each fuse.

The MAIN fuse should have battery voltage on both sides. The AUX fuse next to it (next to the screw terminals, if you have them) will also have battery voltage. Check the other three fuses with the ignition switch ON, but also check the voltage at the MAIN fuse with the key ON, as it will be lower with the key ON and the bike not running.

If you find most of your drop is across the ignition switch, I would just use a relay to power the bike. If only the headlight is affected, use a relay to power the headlight. NOTE: the Eastern Beaver kit is a nice, high-quality kit, but you can do it yourself for about 1/10 of the price.

.

 

[Guest]

Also that 12.7 you stated as having at the battery, is that running or not? if it is while running your not charging properly.You should be over 13.25 -up to 14 volts running depending on RPM.

 

[bbjumper]

Got it, in a healthy system what would be normal drop?

And Steve, thanks I will be checking the voltage this afternoon.

hjfisk, It was checked static not running. Charging system is solid, stator and R/R unit both were done last year with OEM parts and the headlight loop has been eliminated. I'll check running volts today also.

appreciate the response

 

[rustybronco]

Less than a .25 volt drop.

My 1980 GS850G measured somewhere in the upper ten volt range to the headlight. I found the connector on the ignition switch was melted.

 

[bluewool]

The open circuit voltage drop should be just about 0.

 

[bbjumper]

The open circuit voltage drop should be just about 0.

Got it,

Thanks

 

[bbjumper]

Checked it out yesterday, have two 6 pin connectors in the headlight bucket that looks like they are partially melted, they have a .6 - .7 drop. I think that happened when my stator/rectifier fried themselves last year. Ignition switch has a .4. That's most of it, have the connectors on order and will be checking the system after they are replaced.

Another question, going to an H4 bulb, should I use a ceramic connector with that for bulbs of higher wattage?

Thanks

 

[posplayr]

The open circuit voltage drop should be just about 0.

tongue in cheek

 

[Steve]

Another question, going to an H4 bulb, should I use a ceramic connector with that for bulbs of higher wattage?

Believe it or not, the H4 bulb is probably the same wattage as the sealed beam. :-k

Some sealed beam lights might be a bit lower, but most of the ones I have seen were 55/60 watts, just like the H4. Some H4 bulbs are 55/65, but that's close enough.

As long as you have CLEAN connections, the stock wires and connectors will not be a problem.

.

 

[rustybronco]

You noticed that as well?

tongue in cheek

 

[bbjumper]

Believe it or not, the H4 bulb is probably the same wattage as the sealed beam. :-k

Some sealed beam lights might be a bit lower, but most of the ones I have seen were 55/60 watts, just like the H4. Some H4 bulbs are 55/65, but that's close enough.

As long as you have CLEAN connections, the stock wires and connectors will not be a problem.

.

Got it.

 

[jpaul]

As Lynn suggested, check for the drop across the ignition switch. The easiest way to do that is to compare the voltage at your fuses. Check BOTH sides of each fuse.

The MAIN fuse should have battery voltage on both sides. The AUX fuse next to it (next to the screw terminals, if you have them) will also have battery voltage. Check the other three fuses with the ignition switch ON, but also check the voltage at the MAIN fuse with the key ON, as it will be lower with the key ON and the bike not running.

If you find most of your drop is across the ignition switch, I would just use a relay to power the bike. If only the headlight is affected, use a relay to power the headlight. NOTE: the Eastern Beaver kit is a nice, high-quality kit, but you can do it yourself for about 1/10 of the price.

.

I'm resurrecting this thread. I was checking the voltage on the bike to try & track down why my headlight isn't very bright. I had the bike on the battery tender to make sure the battery was fully charged. With the ignition switch on but the bike not running my voltage at the battery was 12.0V, at the main fuse it was 11.3 & 10.9, across all three other fuses it was 8.8-8.9 on both sides of the fuse. At the aux fuse has voltage of 11.9 on both sides. When I first tested it, the main fuse was hot to the touch, which was just after disconnecting the battery tender.

Am I correct in assuming that the voltage drop to the main fuse, which is obviously too high at 0.7v, is probably due to a bad connection going to the fuse box, or within it. Would this also account for the fuse being hot to the touch, or would that be normal for a bike just pulled off a charger. It had cooled down within a few minutes. I'm also assuming that the identical voltage drop at the other three fuses indicates bad connections at the ignitions switch.

Edit: I just checked the main fuse with the bike off, and the voltage on both sides was the same as the battery.

 

[kdo58]

Check the ign. Connection in the headlight bucket.