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Author Topic: Charging system issue 1975 Honda 550/4  (Read 105 times)

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Offline 43and countiing

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Charging system issue 1975 Honda 550/4
« on: November 05, 2018, 04:03:40 pm »
Desperate for some guidance here: I don't do well with electrical problems. My 1975 Honda 550/4 k1 is over charging the battery (15.2 volts at 4,000 rpm with the headlight on, 14.8 with it off). I replaced the voltage regulator with a rectifier about 2 years ago, and recently clumsily broke my 50/40 sealed beam headlight, where it seemed to work ok. I just put in a not-sealed beam lamp 35/35. I have a gel battery. It reads 12.9 disconnected/not running, 14.7 engine running no lights at 4000 rpm, and the 15.2 with headlight on at 4000 rpm.
I thought the rectifier would control the voltage load. Is it possible the "alternator" if it has such a thing, is overproducing to the point a rectifier couldn't balance it? Why would it go higher when the headlights are on?
Begging for some insight...I'm 70 and this is my only ride.

Offline Robbo

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Charging system issue 1975 Honda 550/4
« Reply #1 on: November 05, 2018, 05:06:24 pm »
First question...with the original sealed beam headlight, was the charging system acting in a more “normal” fashion ?  Do you recall the charging rate at 4k rpm with headlight off and on with the 40w/50w headlight?

Second question... what is the bulb type in the new headlight?

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« Last Edit: November 05, 2018, 05:12:40 pm by Robbo »
1973 CB350 Four, 1975 CB550K

Online calj737

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Re: Charging system issue 1975 Honda 550/4
« Reply #2 on: November 05, 2018, 06:43:33 pm »
For starters, the Regulator, not the Rectifier controls the voltage to the battery.

Irrespective of the headlight change, the Regulator is getting a false reading of the actual battery voltage. This is very likely due to corrosion in your harness and through the connectors.

If you remove the BLACK wire from the Regulator, touch it with a probe from your meter and the other probe to the battery POS cable. What is the reading? I suspect you are going to see >1v. If so, then the Regulator belives the battery is actual at a lower voltage condition than it truly is, hence it is allowing more current to the battery than it should be.

You need to track down where the excessive resistance is, and clean it up. Fuse block, solenoid, grounds, etc are common locations.

As an aside, your battery may see voltage spikes of greater than 14.nV intermittently, especially if you're taking readings with a DMM. If you are reading sustained voltage above 15v, then you definitely need to sort out the offending resistance.
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Offline TwoTired

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Re: Charging system issue 1975 Honda 550/4
« Reply #3 on: November 06, 2018, 12:37:30 am »
If your black wire distribution system develops series resitance, increased loads on the system will depress the voltage in that distribution.  This makes the vreg see false voltage status of the battery, and will try to compensate by overcharging it.

Connections in the path between battery and vreg sense include connectors, key switch contacts, and fuse block components.  All may contribute to false reporting to the vreg.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
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Offline Deltarider

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Re: Charging system issue 1975 Honda 550/4
« Reply #4 on: November 06, 2018, 01:48:32 am »
43, you can do the checks that are mentioned above. I don't find your readings very worrying. I've have them often enough myself when I use a digital multimeter. So far I didn't have to replace bulbs or add destilled water to the battery and my batteries live long (7 years or more). I wouldn't be surprised that, if you connect an analogue voltmeter, you'll find readings more around 14,5 V. Some DMMs have a tendency to hold the spikes. For checking and maintenance however I'd start with the GROUND as this route is more exposed to the elements. Also a lot easier to fix.
« Last Edit: November 06, 2018, 01:51:08 am by Deltarider »
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Offline 43and countiing

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Re: Charging system issue 1975 Honda 550/4
« Reply #5 on: November 06, 2018, 03:59:27 am »
As a clarification, I installed a "Regulator Rectifier" This is how it is described, and also as perfect for my bike.


Honda Regulator Rectifier

Description
 This new unit combines your bike’s separate rectifier and regulator into one modern unit that is perfect for custom café racers! This is designed to plug into the stock wiring harness. 

Online calj737

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Re: Charging system issue 1975 Honda 550/4
« Reply #6 on: November 06, 2018, 05:17:35 am »
As a clarification, I installed a "Regulator Rectifier" This is how it is described, and also as perfect for my bike.
Honda Regulator Rectifier

Description
 This new unit combines your bike’s separate rectifier and regulator into one modern unit that is perfect for custom café racers! This is designed to plug into the stock wiring harness.
Understood, but all the advice still holds true. And the checks mentioned are required for you to ascertain the issue.
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Offline TwoTired

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Re: Charging system issue 1975 Honda 550/4
« Reply #7 on: November 06, 2018, 07:18:15 am »
The voltmeter reports difference in potential between its probe tips.  If you place one probe on battery POS terminal and the other probe on the vreg black terminal, it will report the voltage loss in that power path.  The loss will be higher with increased loads, such as turning on the headlight.
You should do this for retun connections also, battery NEG to vreg green connection.  The sum of these two measurements is the error being reported to the regulator sense. Healthy systems will lose no more than 0.5v, as reported to the Vreg.

To find offending devices, you can use the voltmeter to measure accross each device in the power pathway, such as the fuseblock or main switch.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Thinking:  It's like reading with your own mind

 

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