VRR Improvements - Kawasaki KLR 650 Forum
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post #1 of 12 Old 07-20-2014, 11:09 PM Thread Starter
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VRR Improvements

Let's have a look at the VRR. I posted the pin outs in another thread but thought some suggestions for improvement of the charging system might be of interest. Many people switch from the more primitive shunt type VRR to a more efficient series type, as I will do for my present KLR when the new one arrives. That's a separate subject from what I will attempt to address here.

Pull the seat and have a look at the VRR. I'm referencing the Gen1 here but this is essentially the same on the Gen2 and for most bikes.

Notice the VRR wire plug which contains six wires. Some VRR units have only five wires so I will explain the difference further along. If you want to improve your charging system or need to find a VRR and splice it in while in remote South America, some of this may help.

OK, two rows of three wires each:
Top row: White, Brown/White (Brown with White tracer), Black/Yellow (tracer).
Bottom row: Yellow, Yellow, Yellow.

The three Yellow wires are AC output leads from the stator in the left side engine cover. It doesn't matter in which order these are installed.

The White wire is the positive polarity output from the VRR. This connects to the white wire in the bike's harness and consulting your wiring diagram reveals that the white wire splits into two directions. This will also make clear one strange feature of the KLR. If you have some electrical "limitations" please download a copy of the wiring diagram, make several copies, store a version on your phone. If you phone me at 2 AM from under an overpass around Washington, DC and we need to talk diagnosis, a wiring diagram in your hand may help you a lot.

Grab a working copy and a pencil, then find and mark the VRR. It's usually just to the 2 o'clock of the center of the page, just beside the spark plug. The three yellow wires catch my eye most often. Trace the white wire down to the dot which shows the connection to the white wire which branches off forward, leading to the ignition switch.

Go back to the dot and trace down, then over, then down again until you encounter the Main Fuse - 20 Amp. Interesting having the Main Fuse there, right? More on that later.

Continue past the Main Fuse to the battery +.

OK, the output from the VRR connects through the Main Fuse to the battery and this is how the battery is charged by the alternator. When the key is switched on with the bike not running, the power is from the battery, through the Main Fuse, up the White wire to the junction of the VRR White wire and the White wire leading to the ignition switch.

You can see that the current flow when the bike is not running comes from the battery by way of the Main Fuse but you know that the power, when the engine is running, comes from the VRR. Let's use the conventional electron theory to assume that current flows from positive to negative in order to make following the circuit easier. We will just pretend that the power flows positive to negative rather than in the correct direction.

OK, engine off, key on. Power from the battery + through the Main Fuse, to the junction of the two white wires and on to the ignition switch in order to power the system. Power to headlight (on), tail light (on) and so forth. Hit the starter button and power from the battery +, by way of Main Fuse and White wire operates the starter relay which closes and the engine is cranked by the starting motor.

If we go back shut off the key and remove the Main Fuse, then turn on the key, the whole electrical system is dead. Check.

Here's where it gets interesting, or are you ahead of me?

With Main Fuse back in place, start the engine and note that all is operating as normal. Now, leave engine running and pull the Main Fuse out of the holder again. Everything goes off, right? If you said, "Yes." you are cheating and didn't check. ;-)

Everything is still on. Go for a ride, if you like and the bike will operate normally, excepting perhaps if you have a fairly low idle speed when the signals may not flash normally.

Before you do go for that ride, let me show you the other 1/2 of this so you're prepared: Shut off the key and then try to restart the engine. Nada! So go for your ride but don't stall the engine while doing a left turn in some intersection.

So what's going on? Why will things work with the Main Fuse out if the engine is started before removing the Main Fuse, but you have nothing if the Main Fuse is pulled before starting?

The key to these questions is the junction of the White Wire output from the VRR with the White Wire leading from Main Fuse to ignition switch. The answer is simple: power from the battery is needed in order to start the engine but once the engine is started, the power from the VRR supplies the electrical system so power from the battery is not needed. In fact, the battery can be physically removed from the bike, once the engine is running.

Ever shut the engine off and have nothing? Lights are out when key is switched back on? Stall the engine at night and blackness!

IMO, this is dangerous which is why I developed the Brown Wire Modification. While this is not directly an improvement to the charging system, you will see the importance.

Next, I will talk more about the White Wire.
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post #2 of 12 Old 07-20-2014, 11:27 PM Thread Starter
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OK, we're back at the VRR and looking at the White Wire in the plug. Let's start by making certain that the White Wire is of sufficient size to do the job. Simple voltage drop test, right?

Use your voltmeter to measure the voltage between the VRR White Wire terminal and the battery positive. One meter lead onto the battery +, the slide the other into the rear of the wiring plug to contact the White Wire's terminal. Key on will show ...how much voltage? That is the voltage drop/resistance between the VRR White and battery +.

I usually see close to 1/2 volt drop in this circuit...not liking that. There's a fairly easy improvement which is to graft (solder) a 12 gauge wire to the side of the White Wire terminal. Connect the other end of the 12 gauge wire to the battery side of the starter relay...or if you really have to...to the battery positive. Argh...

Now check the voltage drop again, VRR white to the battery +. Voltage drop = zero.

Now you're not making 5 watts of heat in that wire when charging the battery at 10 amps.

Next, let's look at the ground.
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post #3 of 12 Old 07-22-2014, 12:39 PM Thread Starter
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Next wire to consider is the Black/Yellow which is the ground wire for the VRR. This is an important circuit because high resistance/large voltage drop, in this circuit will create heat and also will cause the voltage being sensed by the VRR to appear to it to be lower than it really is. If the VRR "sees" lower voltage than is intended, it will raise the output in order to bring the voltage to the set point of the VRR design.

This is the cause of some battery over charging so worth a look. A simple check of voltage between the Black/Yellow wire's terminal in the VRR wiring plug with the meter's other lead to ground should show less than 0.2 volts. One can easily reach the terminal by probing the meter lead into the back of the plug while it is in place.

With engine running and all loads turned on, check for less than 0.2 volts. If it's higher than that, one should start looking for the bad connection. In some bikes (doesn't seem to be typical of the KLR) the ground circuit is not very good so an upgrade can be useful.
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post #4 of 12 Old 07-22-2014, 12:49 PM Thread Starter
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The Brown/White wire in the VRR plug is the reference circuit. This is used by the VRR to detect the voltage present at the switched side (the off/on side) of the ignition switch. The idea is that the VRR will adjust its output to maintain the desired maximum voltage (set point) at the Brown Wire which is closer to the loads.

This allows the VRR to compensate for resistance between the VRR/battery and the load. Nice idea, and allows them to use smaller diameter wires because voltage drop is compensated but there is a down side. The problem, like that of the Black/Yellow is that this can cause higher than desired voltage (charging) to the battery so can cause over charging.

This is, again, not as commonly seen in the KLR650 as in some other bikes but a simple voltage check will tell the tale. One way to check is to have the bike running with all loads on, then check the voltage between the VRR's White and Brown/Yellow terminals. It should be below 0.2 volts and even lower is better.

If one has a dash voltmeter only, connecting a jumper between the White and the Brown/Yellow with engine running and all loads on, should change the displayed voltage by less than 0.2 volts.

If one disconnects the Brown/Yellow terminal from the VRR, the charging voltage will go up as high as the system can output current to drive up voltage. One can put an adjustable power supply onto the Brown/Yellow and literally dial the charging voltage up and down. One can also fool the VRR into charging at a higher rate by introducing a resistance bridge into the circuit in order to create a voltage drop.
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post #5 of 12 Old 07-22-2014, 12:55 PM Thread Starter
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No idea whether anyone finds this stuff useful but since someone might, I will take the time to offer.

Another consideration is that a big problem with bike charging systems, and the leading preventable cause of failures, IME, is bad connections at the VRR plug or in the stator to intermediate harness plug (KLR stator wiring runs all the way to the VRR so one reason they have fewer problems).

Have a look at the inside of the plug from time to time to insure that it isn't showing signs of corrosion, plastic turning brown/black. I like to pop the terminals out of the VRR plug if there's any question in my mind. The terminals can be cleaned and retightened or replaced without much trouble.

Keep the plug full of some sealing media, ordinary water proof grease is OK, dielectric grease works, or my practice of spraying Fluid Film (lanolin based) or LPS (wax based) into the plugs saves a lot of problems.
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post #6 of 12 Old 07-22-2014, 01:50 PM Thread Starter
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Heat. The KLR VRR is very reliable, IME, but has the unfortunate experience of being placed under the seat. This is a mixed thing because ventilation is poor at very low speeds but air flow does occur when moving although that sheep skin or after market seat might be an issue.

When the VRR heats up, the charging voltage drops as all will have noticed because of the voltage dropping on a hot day. This is not a bad thing because a hot battery will over charge at normal/adequate charging voltage for a cool battery. This is another reason why batteries tend to use excess water in hot weather.

Automotive manufacturers have included temperature sensors in the battery box in order to compensate for battery temperature.

Some of us have relocated the VRR to an area having more air flow but not certain whether that is a benefit. It does seem to maintain a higher charging voltage under hotter conditions but have not done any research as to whether the water use becomes an issue.
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post #7 of 12 Old 07-22-2014, 02:39 PM Thread Starter
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VRR heating, shunt versus series:

Those who have an interest in charging systems will be aware of the shunt versus series voltage regulation operations. In brief, less advanced systems such as the KLR and most motorcycles, use loading to limit output. This is generally considered to be a disadvantage because this type of system causes the alternator (stator) to output full current under all operating conditions.

The only factors which act to influence output are engine RPM & heat. The unfortunate results of this type of regulation are:

The extra power which is not used as electrical output is converted into heat in the stator and VRR. This means that the stator is much hotter under lower electrical requirements.

I used to try to explain the operation to other technicians who would blame "those extra lights which you've added have overloaded the stator" for stator failures on older Wings and the like. They simply would not hear and I found that attempting to engage them further simply caused them to become angry.

If one studies the KLR VRR temperature reactions, one may reach the same conclusion as I which is that lighter loads equal a hotter VRR. This may seem paradoxical but explained by the means which this type of (shunt) VRR operates.

The VRR limits the voltage, as I hope everyone understands, it does not really "regulate" the voltage since under conditions when the voltage is below the (maximum) voltage set point, the regulator does nothing. If one were running full electrical load, headlight, fan on and such all the time, one could simply use a diode bridge or rectifier without being concerned about voltage at all. It is only when the RPM is higher and electrical loads lower that the voltage rises to unacceptable levels.

So what causes heat in the VRR?

Two main factors:
1) The current flowing from the AC source/stator passes through a set of diodes in order to rectify/convert to DC. A typical silicone diode, according to high school electrical produces 0.7 volts drop. This can be handy since one can be handy as one can use this to introduce a voltage reduction into a circuit but the 0.7 volts drop is when there is little to no current flow. When one is passing current of a significant amount through the diode, the voltage drop can be more like 1.2 volts. Of course big diodes will pass a small current with low voltage drop but little ones will experience a larger voltage drop from that same small current. One can use this effect also for various purposes.

So, let's just use one volt as the arbitrary voltage drop across our VRR diodes with the current flow. Easy to do the calculations in one's head that way. OK, if one looks at the operation of a diode bridge, one knows that each AC stator leg's current must pass through two diodes in the process of being rectified to DC.

Let's say the alternator is outputting 12 amps. That's four amps from each stator "leg" so each four amp current passes through two diodes, across 2 volts drop (two diodes at one volt drop each) so that's 4 amps x 2 volts = 8 watts. There are three legs to 3 legs x 8 watts = 32 watts of heat from the rectifier stage of the VRR.

That warms the VRR and requires that the heat go somewhere...into the air hopefully or the VRR will get really hot.

So, why did I say that the VRR seems to get hotter under low loads? Well, that's what I've noticed and measured so here's how I explain it.

The KLR VRR regulates by shunting as noted earlier so here's an explanation:
If the stator current provides more current than is required by the DC side of the charging system, the voltage will rise.

Think of it like this, take a garden hose, and turn on the tap while holding your hand around the hose. Nothing much is noticed at the outlet end of the hose but go close to the tap and repeat. Notice that the hose balloons a bit near the tap?

This is because of the resistance to flow due to the friction over the length of the hose. This relates to something we are discussing regarding Paul's oiling system experiments and also regarding carburetor jetting but enough of that side bar.

OK, now put a nozzle onto the end of the hose, close the nozzle and open the tap. Notice that the hose balloons but loses diameter as you open the nozzle?

This is because you are reducing the pressure in the hose by allowing more water flow. This is a quite good approximation of the stator (water tap) outputting current (water) into the electrical system (hose) with the effect of more current flow (more water flow) increasing voltage (pressure). We can control the hose balloon amount or water pressure by either opening the nozzle further or less(turning on or off more electrical loads), or by opening or closing the water tap (speeding up or slowing down the engine.

The shunt type voltage regulator as used by most bikes works by adding a "Tee" into the water hose. The "Tee" contains a valve which allows water flow out of the hose onto the ground to be controlled. OK let's say that you need a certain amount of water flow into your grand child's wading pool. You notice that the kids are playing and splashing out water so you run the garden hose out to the pool and adjust the nozzle to keep the pool filled by replacing the water which the kids spash out. That's nice, now you can get back to your chair and book.

Problem is, when the kids get playing more on the grass and less in the pool, the water begins to over flow too much so you have to go over and adjust the nozzle more closed. It's much further to walk to the water tap so you prefer to use the nozzle. What to do?

You uncouple the two hoses which you ran from the tap to the pool and thread in a Tee then attach a valve to the Tee and a hose from the valve goes into the drain. Now you can just open the valve on the Tee and divert more water down the drain to reduce the pool overflow without leaving your chair. Not the most high tech but keeps you seated so good solution! The problem is that the excess water is wasted but what the hey!

The shunt type regulator works sort of like that. Analogies always break down but this is close so let's run with it. OK, so the excess water is wasted and so is the excess current flow which is shorted to ground. Problem with shorting the excess current flow to ground is that we have to rectify it to DC before we dump it because it's much cheaper to make a circuit to do it that way. So, we still have the high current through the regulator making heat regardless of whether we need that current or shunt it to ground.

On top of that, the shunting requires that the excess current flow through some sort of electronic switch such as a transistor which creates its own voltage drop and heat. When the current is going to the battery, lights and stuff, it goes through the rectifier (diodes) which produce heat. When it is not needed and shunted, it goes through the rectifier, then the shunt switch so more heat in the VRR. That's why the VRR gets hotter when electrical loads are lower.
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post #8 of 12 Old 07-22-2014, 02:50 PM Thread Starter
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Series regulators and MOSFETS.

There is some confusion in the field as to what a MOSFET VRR describes. Many people believe that a MOSFET VRR is always the (superior) series type but this is not necessarily true.

In the unlikely case that someone who has a comprehensive understanding of electronics has persevered this far, perhaps they might confirm that MOSFET transistors are generally used for switching in both modern shunt & series VRR units?

MOSFET transistors have some characteristics which make them useful in both types of regulators, they are very fast reacting and have a low resistance so create less heat than the older "conventional" transistors.

I just ordered one which is advertised as MOSFET to fit a newer Suzuki but will see whether it is shunt or series. Regardless, it should produce less heat and I'm interested in seeing which type it is for the $30.00 cost.
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post #9 of 12 Old 07-22-2014, 05:22 PM Thread Starter
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Series type regulators:

Getting bored with this? Hope it's useful to someone as it takes some time to type this out from memory.

The other main way to control (limit) charging system voltage is to block current flow between the stator and the rectifier. Returning to the water hose and kids' pool analogy, this would be like squirting water from the water nozzle in spurts to match the water flow needed to keep the pool full. Shut off the water when not needed and press the nozzle when needed. Much more efficient because it doesn't waste water/make heat.

In this type of regulator, electronic switches in the form of MOSFET transistors are placed in each of the stator legs wire circuits as on/off switches. These switches literaly connect and disconnect the stator from the rectifier. In this operation, when the voltage rises to the set point, the switches disconnect the AC from the rectifier so the current flow in the stator stops rather than having the current shunted into a short circuit. The strategy is opposite from the shunt type unit which can be seen on an oscilloscope trace of the two regulators' stator (AC).

In a shunt type system, the stator voltage drops to virtually zero while the current goes to maximum. In the series type system, the stator voltage rises to the maximum which the stator's magnetic field can produce while current drops to zero. The series system is generally superior because the extra potential energy is not converted to heat.

So far as I know with regards motorcycle VRR's, all series regulators are MOSFET (equipped) regulators while only some shunt (wired) regulators use MOSFETS.
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post #10 of 12 Old 07-22-2014, 05:56 PM Thread Starter
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To jump or not to jump?

At this point, one should recognize the risk in using another vehicle to jump start a dead battery. If the bike has a shunt type regulator versus a series type, there will be issues but let's look at the rectifier first.

If one connects a battery in correct potential to the rectifier, the diodes "block" current flow so its just like trying to pass water through a check valve or closed valve = no flow. If one reverses the polarity, the circuit is virtually wide open with the only opposition being the series resistance of the wiring and components. Connect a 12 volt battery across a one volt buck circuit (one volt drop) and there will be 11 volts to create current flow. Since the remainder of the wiring and components have very low resistance it will be almost like hooking the jumper cables directly together excepting that the little regulator circuits will be in the way. The rectifier diodes will be cooked to a crisp in nothing flat. Unless you are lucky, the ignition module may suffer the same fate, depending on how it is constructed and whether the key is off.

If one connects in the correct potential, to a fully charged "12 volt" battery, no problem because the diodes will block flow and the starter + other components will be powered correctly. If the other battery is larger than the bike one and the jumper cables have low resistance, the engine may crank faster than usual but that's actually a benefit.

The risk is if the other vehicle's charging system is in operation. If the other vehicle's charging system is operating and has a set point higher than that of the bike's regulator then the bike's regulator will seek to lower the voltage by intervening in the circuit.

If the bike's regulator is a series type, it will attempt to reduce voltage by opening the circuits between the stator and the rectifier which will have no effect at all. The bike will (likely) start and the bike's stator will remain disconnected until such time as the voltage drops, usually because a jumper is disconnected. At this point the bike's voltage drops and the stator is reconnected, all continues as normal.

If the bike's regulator is a shunt type, the regulator will also attempt to reduce voltage but this will be by shunting (shorting) the positive and negative. The bike's regulator has a large enough shunt circuit to load the full capacity of the bike's stator output + a safety margin but not large enough to shunt the output of a lot more current.

So, what do we have? I shunt circuit which is designed to perhaps shunt 25 amps. It is connected to a typical automobile which has a..100 amp alternator...much, much bigger. So, the car is operating nicely, its regulator is maintaining its voltage at its intended set point which we will assume is 14.8 volts for the example. Let's say that the KLR's regulator's set point at this temperature is 14.6 volts which is not a big difference.

OK, hook up the cables. The car sees a small increase in load, the regulator says, "Voltage dropped I need to turn up the alternator output to hold 14.8 volts."

The KLR regulator sees 14.8 volts so it shunts current in order to pull the voltage down to 14.6 volts. Car reg. sees this and turns up its alternator. This goes back and forth for about the width of a . and "poof" goes the KLR regulator. Sometimes the car's set point is equal to or lower than the bike's VRR so no problem but as Dirty Harry said, "Do you feel lucky, Punk?"

So that's an over view of the charging system. Hope it is useful to someone?
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