Author Topic: voltage drop  (Read 1426 times)

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Offline ntintruder

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voltage drop
« on: July 24, 2016, 12:24:15 PM »
 Working on turning a 1977 750f into a cafe racer. The only thing I did with the wiring was to install a relay in the headlight circuit and that worked fine, much brighter. The cafe part consisted of the usual, seat, tank, new front fender, quarter fairing and rear sets, nothing to do with the basic wiring but all at once I seem to have a  big voltage drop. lights are very dim. If I hook a 12 volt lead directly  to the various lights the bulbs are bright. I unhooked the relay to the headlight just to see if that was somehow the problem but it made no difference. Main fuse has full 12 volts and then some going in and out but the other two show only 3-4 volts when the key is turned on. I am going to start with the main fuse going to the ignition switch and work my way out. I did put new turn signals on the bike but they worked fine after installation. The only other thing was the installation of GL1000 ignition coils but that was long before this problem appeared. Has anyone else experienced anything like this?

Offline BomberMann650

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Re: voltage drop
« Reply #1 on: July 24, 2016, 01:47:12 PM »
+1 to battery condition.

Offline ntintruder

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Re: voltage drop
« Reply #2 on: July 25, 2016, 09:14:24 AM »
 No I never changed the headlight bulb. I checked the voltage to the ignition switch with a 12 volt bulb and it lit up bright. Took the ignition switch apart and cleaned it up but still getting the same results so I am going to take the battery to a shop, same place I bought it and see what they say.

Offline strynboen

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Re: voltage drop
« Reply #3 on: July 25, 2016, 09:47:39 AM »
thek the fuse holder..they often melts and burn aut..take the back side aut and thek it from there
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Offline ntintruder

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Re: voltage drop
« Reply #4 on: July 25, 2016, 03:03:59 PM »
 I have multimeters, two digital and one with the old fashioned dial, I just used the probe with the light bulb to contrast the brightness of the bulb with the voltage going into the ignition switch to  the dimness at the end of the circuits coming from the switch. Something going on in between.

Offline ntintruder

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Re: voltage drop
« Reply #5 on: July 25, 2016, 03:09:42 PM »
 I also changed the fuse block to use automotive type fuses over a year ago and all three are  functioning.

Offline ntintruder

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Re: voltage drop
« Reply #6 on: July 27, 2016, 02:08:39 PM »
 found the problem, at least the source of it. The battery will show 12 volts and then drop to around 3.5. It did this several times. Battery shop does not know why so I bought a new battery and everything is back to normal

Offline przjohn

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Re: voltage drop
« Reply #7 on: July 27, 2016, 02:54:04 PM »
Cool!  :)
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Offline strynboen

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Re: voltage drop
« Reply #8 on: July 28, 2016, 05:42:23 AM »
untill NeXT week..then you are back at 3,5 volt...somthing is eating your voltage..batteries dont just die..
sohc hondas use a 12 v 12 ah battery to funktion perfekt..smaller batteries often give problems
i kan not speak english/but trying!!
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Offline ntintruder

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Re: voltage drop
« Reply #9 on: July 30, 2016, 10:37:19 AM »
 the battery didn't just die it would show 12 volts at the battery and a minute later show 3.5, then back to 12. very strange, but the new battery is working fine. I went through the lighting circuits, the starter circuit and the ignition they all appear to be ok so I think the problem was the battery.

Offline strynboen

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Re: voltage drop
« Reply #10 on: July 30, 2016, 11:25:42 AM »
voltage can thange
..its depend of the power be used..its normal that the battery viah drop a a volt or 2,  ,use the starter..same sekund the starter stopps the volt jump up to normal..
.but vith a bad battery..even a small drav,can lover the voltage.

.litium goes bad if they are droven at low voltage for short time/or heigh volt.. just funktion at the korrekt range
a bad konnektion can give the same symtoms..renember that the erth/negative..pulls the same effekt as the positive..so both need to be perfekt
i kan not speak english/but trying!!
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i hate all this v-w.... vords