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Power Junction - Key Element in the GW Electrical System

Posted: Sun Nov 12, 2017 10:54 am
by Rednaxs60
Power Junction – Key Element in the Electrical System

I have been perusing the various forums and the internet regarding the design and operation of the electrical system on my '85 LTD. My understanding of the electrical system on my '85 LTD may not be a definitive understanding, but what I have found provides me with a basis from which I can feel comfortable that I have a good grasp of the system as a whole.

I found this article on the internet and it is one of many that has helped me formulate my understanding of the electrical system of my '85 LTD: ... wire.shtml

This article articulates the differences between a one and three wire alternator, and how each works. The most interesting aspect for me is not just the understanding of how to hook up either, nor the pros and cons, but the understanding of how the electrical and charging system on our bikes actually works. From this I now have a better understanding of where I should connect any new additional loads so that the system can operate and compensate for what I have added and this, IMHO, is the crux of what I have read and mentioned here.

With this in mind I submit the following as my understanding of the electrical system on my '85 LTD. Hope you have a good read and enjoy the ramblings of a DIY backyard mechanic. Cheers

I have been working on my '85 LTD since I bought it 2 years ago to bring it back to as close to as new condition as possible (operationally yes - looks, not too bad) and have been trying to understand the various aspects of this bike and how things interrelate.

Most of the issues with my '85 have been from time and lack of maintenance, or just needed to be dealt with. I have browsed the various forums, and the internet to learn about the issues and to determine what has been done by the GW community to overcome some issues.

One of my issues of late is understanding the electrical system as the '85 fuel injected model is a power hungry bike. This was known by Honda because the stator was upgraded to approximately 500 watt compared to the 350 watt stator of the carbureted models.

When I bought my bike all worked well; however, it was 32 years old and required upgrades in certain areas, and needed to be cleaned up wiring wise. One of the items I had to address was replacing the stator as it failed shortly after I had the bike. To rectify this situation I installed the alt mod commonly called the “Poorboy”.

The charging system is relatively simple with the stator, or alternator, providing power to the electrical system, and topping up the battery. The battery is essentially used for staring and a power supplement when the stator, or alternator is not producing sufficient power to operate the electrical system. Once the charging system starts to produce sufficient power to operate the electrical system, the battery is topped up and is there for the next power shortage.

During my alternator modification, I removed the old charging wiring and installed new alternator wiring as I thought it should be done. I researched the differences between a one and 3 wire alternator, and installed a 3 wire alternator. I wired it so that it met my requirement as I saw them, with the exception of hooking up a sense wire. The alternator did work, but in hindsight, I should have installed the sense wire. Sometimes you just have to live with what you have decided and take a life lesson.

I have been doing additional research regarding electrical systems and have found that an alternator or stator can essentially become primarily a battery charger, instead of the power supplier to the electrical system. This occurs when the charging system is reacting to a power drain caused by a depletion in the battery charge because of the additional accessories that have been added to the system using the battery as the power supplier. These items can be heated clothing, hand grips, additional running lights and such. These accessories were added to my bike as well and took power directly from the battery.

Using the battery in this way is counterproductive to the intent of the charging/electrical system as the battery is intended for starting and as a power supplement when necessary. It is also hard on these smaller batteries and may cause the battery life to be shortened considerably.

The amount of power required to compensate for the power drain on the battery is also an unknown. The condition and age of the battery is a compounding factor when additional power is required. The power requirement may only be 5 amps, but the drain on the electrical system may indicate a different amount.

When we do this, the electrical system senses a power drain and the regulator/rectifier output is increased to compensate. The unknown here is that the output required is not known, nor is the duration. If the power drain continues such that equilibrium cannot be achieved, it is probable that the regulator/rectifier output may be increased over time in order to rectify the power loss. I will submit that if this condition were to exist and persist, it is not out of the realm of possibility that there could be a negative impact on the charging system components.

I mention this because all too often we install new items/accessories, and power these directly from the battery using in line fuses, instead of hooking these items properly into the electrical system. The regulator/rectifier does not properly see the electrical demand caused by these additions because we have bypassed the electrical system monitoring mechanism, the regulator/rectifier sense wire that is extremely important in the correct/proper operation of the regulator/rectifier, and the charging system

The regulator/rectifier only senses that there is a drain on the charging system, the exact reason is not known, but additional power is required. The regulator/rectifier provides additional power to the electrical system because the battery is drawing power from the system. In doing so, it is possible to overcharge the battery causing premature failure of the battery, and possibly the alternator/stator/regulator-rectifier as well. This is because the regulator/rectifier power output is directly related to the information the sense wire is providing to the regulator/rectifier based on the demands of the electrical system, and as long as the drain persists, the regulator/rectifier will try to compensate as quickly as possible.

The sense wire is reading an electrical system requirement of “X” when in reality, the system requirement is “Y”. The battery is drawing power from the electrical system so the sense wire indicates a depletion in electrical power, and the regulator/rectifier adjusts to suit. The loads that are causing the battery charge to be depleted can be cycled on and off, or increased/decreased when in operation; however, for the electrical system to react in a timely manner, the sense wire needs to “sense” these various conditions, but cannot because these loads are external to the electrical operating system. This can cause the electrical system to either have less power than needed, or more than required on a regular basis with an unknown duration for each. This does not bode well for the electrical system considering the regulators/rectifiers used with a stator are not that efficient. The regulator/rectifier in an external alternator is much more accurate and timely in its operation, but also needs to know from the sense wire the actual load as it fluctuates.

To understand how this is done, you have to have an understanding of how the wiring is configured and why.

The Power Junction

There is a power junction buried in the electrical wiring harness. This power junction is the principle electrical junction in the bike's electrical system that makes everything work as it should.

Wiring Power Junction
Wiring Power Junction

When I removed the old charging system wiring from my bike, I noticed that the two red/white wires from the regulator/rectifier were joined just inside the wiring harness into a single wire going to the starter solenoid to provide a charge to the battery. I also noticed that this wire was also joined to the red wire from the starter solenoid going to the ignition switch. This is the Power Junction where the power from the alternator/stator goes directly to the bike's electrical system with a power bleed to the battery for battery charging. Unwittingly, I removed this power junction and wired the system as I thought it should be wired.

This Power Junction is shown in the various schematics for our bikes. Here is a picture of an electrical schematic showing the Power Junction.

The power junction depicted in the above schematic separates the electrical into two distinct areas. Downstream of the power junction is the battery, starter solenoid, and as I have mentioned the battery is for starting and a power supplement. Upstream of the power junction is where the majority of the power is required and it is also the area of the electrical system that controls the output of the regulator/rectifier as it is where the sense wire gets its electrical inputs. There is very little input into the electrical system from downstream of the power junction because the design is such that there should not be.

In conjunction with the power junction is the regulator/rectifier sense wire that is connected to the electrical system after the ignition switch. The sense wire provides the regulator/rectifier with the electrical system load information, allowing the regulator/rectifier to sense what the electrical system is doing and adjust the output accordingly. For the stator this means the regulator/rectifier will “dump” power to ground when not needed instead of into the electrical system, and allow for an increase when necessary. For an alternator, this means reducing or increasing the output according to need(s). The battery in these cases is only being charged, and once fully charged does not draw a lot of voltage/amperage from the charging system. The battery only comes back into play when the charging system cannot keep up with the demand such as at idle, and in stop and go situations for instance.

So how does this affect how we add items/parts to our bikes. The simple answer is that you need to locate the power junction, and quite possibly install new wiring to compensate for the items being added to your bike. You have to install additional power loads such that the alternator/stator through the sense wire to the regulator/rectifier can compensate for these new loads when being used. This means not powering these additional loads from direct connections to the battery.

There are some OEM fuse blocks that have additional terminals available for add on. If there are terminals available, it would be prudent to install and hook up a second fuse block or power bus to these terminals and power your accessories from here.

Since I had rewired the charging system as I thought it should be, the positive terminal on the battery was always a mess and required cleaning on a regular basis. I could not think of a reason for this, and just kept cleaning the positive terminal on a regular basis, not to mention that I had a few extra wires attached to this post as well. I am of the opinion that the battery was being overcharged because of how I wired the new alt mod and having additional loads powered directly from the battery. These changes fortunately were not significant enough to degrade the battery – load tested twice since July, but enough to cause the mess at the positive terminal.

I am now of the opinion that my electrical problems were also aggravated because of the additional load on the system and the fact that these load(s) were not being sensed properly by the system.

Here is a schematic from the article I referred to at the top of this post:

I have rewired my alt mod to suit what I have learned from this article, and find that the system is working much better. The 14 volt junction in the above diagram is where all power connections are. The power to the ignition switch, to the accessory fuse block that I have added, and heated clothing connection to mention a few all come from this power junction.

I now have a correct voltage reading on the dash voltmeter. I have a positive bus bar to add wiring for additional power requirements that will integrate into the electrical system power requirements, be “noticed” by the alternator sense wire, and allow the alternator regulator/rectifier to compensate for the additional load(s) are applied and removed. This will/should also prevent abuse of the battery because of external loads indicating a battery discharge when in actuality the power requirement is not because of the battery. I will also be able to “daisy” chain more positive bus bars if required, and have the new loads integrated into the electrical system. The only additional connection on the battery is the wire harness to plug in the battery tender. I have moved this to the new power junction because I do use it for other reasons when out and about.

I have tried to relate my layman's understanding of an intricate issue, and how I have had to correct the wiring on my '85 LTD to ensure correct operation. I am not an electrical engineer, but I think the premise from this article is extremely valid and valuable to my understanding - and hopefully yours - of the GW electrical system.

I hope you, the reader, have enjoyed my ramblings, and possibly this has provided some food for thought.


Re: Power Junction - Key Element in the GW Electrical System

Posted: Sun Nov 12, 2017 12:17 pm
by julimike54
Good info. Question would be if the sense wire is measuring the battery post, wouldn't that do a similar sense of the 'power' junction?


Re: Power Junction - Key Element in the GW Electrical System

Posted: Sun Nov 12, 2017 2:08 pm
by Rednaxs60
julimike54 wrote:
Sun Nov 12, 2017 12:17 pm
Good info. Question would be if the sense wire is measuring the battery post, wouldn't that do a similar sense of the 'power' junction?

Thought about that as well. The schematic of the basic main power system shows that the battery as part of the total electrical load. The issue with using the battery as the power source is the battery is a power sink that shows the system that it needs voltage - different from amperage (current), and the electrical load in amps attached to the battery is not being seen as the load on the system.

When the battery is fully charged it "resists" the input of more power, and in essence, falls off the electrical load requirement. If you were to instrument the battery, I would think you would see a trickle charge being applied at all times to the battery.

The reason I mention voltage in regards to the battery is that the battery condition is directly related to the battery voltage level, and there is a relatively narrow range of battery charge from good to bad. The battery for my '85 LTD has a charging rate of 2.1 amps, but the electrical/charging system does not see this specific load requirement, what it does see is a gradual reduction in power based on voltage going to the battery until the battery is at 100% charge.

The other issue with using the battery as a power source is that the battery can accept a variable charging rate that if it is not being topped up in a timely manner, the charging system will probably provide as much power to the system to accomplish this as it determines is required. The electrical/charging system likes to be in a state of equilibrium.

So in my mind, the electrical/charging system needs to see loads specifically, especially when these loads are variable, can be turned on/off or fluctuate when in operation. For example, you install new driving lights and when on draw 5 amps. Hooking these into the electrical system such that the new requirement is seen as a load, the regulator/rectifier will increase the electrical output by approximately the required amount when on, and reduce the output by the respective amount when these lights are turned off. Taking a power source off the battery would indicate to the electrical system that the battery requires additional power/voltage to bring it back to 100%. When the battery is not being used as a power source, this top up is done rather quickly. With the battery being used as the power source, the electrical/charging system continues to see a requirement to provide power to the system to top up the battery regardless of the load attached to the battery.

It has been mentioned on numerous occasions that the stator output is at max for the speed the bike is operating at. If the battery charge is lower than 100% for the condition of the battery, the electrical/charging system may output more power than the system actually requires to get the battery back to 100%. In doing this, the charging system components and the electrical system could be compromised and result in premature failure.

I mentioned that loads using the battery as a power source are an unknown quantity to the electrical/charging system, and if you consider the battery as a power sink, this is hard to regulate. The charging rate in amps for the battery is also determined by the manufacturer, and a charging rate in excess of this does damage to the battery.

Getting back to my dissertation and what I have learned from it is that we all are aware of power requirements based on amperage. The 1500 crowd is constantly discussing alternator upgrades as are the 1000/1100/1200 Poorboy/stator club. Since this is the case, it behooves us to properly introduce new loads into the electrical/charging system. This means not using the battery as a power source because the battery is primarily to start the bike and provide a supplemental power source when needed.

I have a 55 amp external alternator on my '85 LTD. I can load up the electrical system to suit, but probably will never get to this level. When I consider the electrical load, I consider the amp rating of the alternator, the battery does not enter the equation. The battery enters the equation when I want to start the bike, or when it needs to be charged as the charging rate is specified for each type and size of battery.

Having mentioned the above, I would submit that when we are looking at adding additional loads to the electrical system, we consider the size of the power source, alternator or stator, and hook the new load into the system so that the load affects the stator/alternator specifically. I would further submit that when this is being done, the battery should never enter into the equation as a power provider, specifically do not hook any loads to the battery. In doing this, we ensure that the system is wired correctly, and should work well.

Using a power junction as shown in the Basic Main Power System schematic allows you to add additional power junctions, keeping the electrical system properly wired.

You may ask about what to do with the grounds for all these potential additions. I have added a separate ground bus to accommodate existing and new grounds. I can add additional ground bus bars if required form this main one. You may also query that this has to be hooked either to the battery or to a main ground point. I have mine hooked to the battery, and if you notice on any battery that has additional ground wires attached, the negative post generally never gets any additional corrosion, it seems to always be the positive post.

From what I have learned, I would think that some of the issues with stator/regulator-rectifier failure could be related to our lack of understanding of the electrical system and how we have been utilizing it. Maybe not all, but the bike designers designed these bikes to do everything they could think of and do them well, then we buy them and all bets are off.

So for my money, keep the battery out of the equation and look at hooking up existing or new additional electrical loads to the electrical system so that these loads can be seen by the alternator/stator through the sense wire.

Long explanation - probably longer than required, but this is not a simple topic. Hope I have answered your question.

Just my thoughts.


Re: Power Junction - Key Element in the GW Electrical System

Posted: Sun Nov 12, 2017 8:05 pm
by Rednaxs60
I have done some additional research to further corroborate my last post regarding hooking loads up to the battery. Most references are about automotive (car) batteries, but the premise is the same.

"An automotive battery is a rechargeable battery that supplies electrical energy to a motor vehicle. It is also known as an SLI battery (starting-lighting-ignition) and its main purpose is to start the engine. Once the engine is running, power for the car's electrical systems is supplied by the alternator. Typically, starting discharges less than three per cent of the battery capacity. SLI batteries are designed to release a high burst of current and then be quickly recharged. They are not designed for deep discharge, and a full discharge can reduce the battery's lifespan.

As well as starting the engine an SLI battery supplies the extra power necessary when the vehicle's electrical requirements exceed the supply from the charging system. It is also a stabilizer, evening out potentially damaging voltage spikes. While the engine is running, most of the power is provided by the alternator, which includes a voltage regulator to keep the output between 13.5 and 14.5 V."

With this in mind, adding external loads directly to the battery would, IMHO, negate the three design aspects mentioned above.

Providing a high burst of energy and then be recharged quickly is negated because the battery is now being used as a load centre similar to a deep discharge/deep cycle battery used in an electrical system such as on a boat, RV and such. The deep cycle battery has less instant energy, but greater long-term energy delivery, ergo, used as a load centre.

Providing additional power when the vehicles electrical requirements exceed the supply from the charging system. The battery is already taxed to provide power to external loads that are connected directly to the battery when the bike is operating, reducing the effectiveness of this requirement.

The battery is an electrical system stabilizer. If the battery is being used as a load centre, its effectiveness as a vehicle to even out electrical system spikes such as loads being removed, is reduced.

Another issue is that heat is considered the primary reason for battery failure. Continuous high amperage charging of the battery will cause the battery temp to rise such that the battery internals start to fail.

Sulfation occurs when the electrodes become coated with a hard layer of lead sulfate which weakens the battery. It occurs when a battery is not fully charged and remains discharged. Sulfated batteries should be charged slowly to prevent damage.

You must put back the energy you use immediately. If you don't, the battery sulfates, which will affect performance and longevity. The alternator is a battery charger. It works well if the battery is not deeply discharged. The alternator tends to overcharge batteries that are very low and the overcharge can damage batteries. In fact, an engine-starting battery on average has only about 10 deep cycles available when recharged by an alternator. Battery tender comes to mind.

Parasitic drain - if you have clocks, engine management computers, alarm systems, etc. and these devices are operating without the engine running, the battery is being drained. You may have parasitic loads caused by a short in the electrical system. If you are always having dead battery problems, most likely the parasitic drain is excessive. The constant low or dead battery caused by excessive parasitic energy drain will dramatically shorten battery life. This is another reason to have a battery tender.

The electrical system components are definitely worth researching and refreshing our minds on what they are, and why these are in the system. The battery is one of these components that I have taken for granted, and I suspect most of us do.

One of the few times I did not was when I lived on a boat for five years and the replacement cost of the deep cycle batteries on board, LIfeline type 8D, was $650.00 per and weighed in at 160 pounds (not easy to get out of the engine compartment). Premature aging of these was not an option.

Just a few more thoughts on the electrical/charging system.


Re: Power Junction - Key Element in the GW Electrical System

Posted: Sun Nov 26, 2017 8:29 pm
by Rednaxs60
I have been working on my article regarding the electrical system power junction and it has blossomed into a 22 page dissertation on the electrical system and components. I have new information to corroborate and support what I have mentioned in this thread and with the additional material I have since added.

In this regard, I feel it is necessary to start a new thread specific to the operation of the 1200 electrical system. There will be duplication in some areas, but overall my intent will be to provide my understanding of the electrical system, and how it applies to us all.

I will be using real world examples to substantiate my premise.

I must caveat this with the fact that I am just a simple layman trying to understand a complex topic.

So without further ado, I'm off to start a new thread that this will be cross referenced to.