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Tech Tips Index > Suzuki King Quad 450/700/750 Sign up or Logon

Battery charging poorly (Regulator direct wire mod) - All Models

by Glenlivet, 2009-02-27

A team effort by Suzuki owners.

First we want to be sure that what is wrong really is a charging problem and not something else like the Battery Drain Issue discussed in that Tech Tip, a poorly initially prepared battery discussed in This Tech Tip, or that the battery has simply developed poor contact at the posts from corrosion (more common than you might think!)
The way to tell if it's really a charging problem is to take a voltage reading when the ATV is idling, measured across a healthy charged battery and using a good meter.
The charge voltage should be very close to 14 volts, above or below within a few 10ths.

Several owners have experienced problems with battery charging and with poor low speed operation and stalling, particularly it seems with the '07 King Quad models. (though other models that have developed bad grounds as described below, can benefit as well) *

One possible reason for a low charge voltage in the King Quad is found to be that the connection from the regulator to either or both ground and/or battery positive, can be bad.
This results in reduced battery charging and vehicle operating voltage.
The relatively simple cure is to hard-wire the regulator output directly to the battery. People who have done this on their King Quads and who had been reading charge voltages little greater than the battery's resting voltage, have seen immediate increases to the low to mid 14 volt range. Just where it should be.

Here is where the regulator hides, just behind the left side fender/body plastic. Here it peeks out after removing the 'oil check' cover.
Photo: Zundappchef

Basically what you are doing is making a more secure electrical connection between the output of the regulator and the battery, using larger wire and direct connection that is not reliant on the vehicle ground.
According to the wiring diagram the wires this mod introduces are in no way a shortcut nor do they make a path of conductivity not intended by Suzuki engineers, they (the wires) simply provide a solid electrical path from the charge regulator to the battery, one not reliant on the vagueries of a vehicle ground.
Here is the regulator plug. There are five wire connections. The three yellow are the wires from the generator to the regulator and they carry 75 volts in any two of the three when measured paired.

The red and the black/white stripe ones are the ones we want.

Photo: Zundappchef

The simple modification is to tap into the black/white stripe wire just as it exits this plug and run a good 14 gauge or larger wire from there to the battery negative.
In the same way and as an option you can tap into the red wire and run a 14 gauge wire from here to the battery positive terminal.

A good tap would be carefully baring a section of the wire a short distance from the plug, soldering on your wire tap, and then covering the joint with several applications of 'liquid tape' or alternately wrapping the soldered joint in heat shrinking tape and applying a heat gun.

Many people who formerly had low charging/operating voltage have seen their voltage at the battery posts increase by .5 to 1.5 volts or even more in a few bad cases, just by installing this direct wiring mod.

Here the wires are ready for installing. Zundappchef has chosen spade lugs for the taps. These are good due to their relatively large contact area and sliding connection.

The regulator plug output side has it's red and black/white stripe wires cut and fitted with crimped on spade males. The stock wiring is fitted with crimped female/male tap connectors. The fittings are crimped on and heat shrink insulated.

Now before Zundappchef plugs everything together for the final installation he slips large heat shrink tubing over each plug set.
A treatment of the plugs with dielectric grease before they are hidden away (forever?) would be good insurance.

And here is the finished wiring upgrade, after a heat gun has shrunk the insulating tubing to the connections. The new wires have not yet been fished upward to reach the battery.
The heat shrink protects the joint and makes a virtual waterproof seal, and provides a good measure of physical bond holding the plugs together against light to moderate forces that might try to shake them apart.

The other ends of the new wires will attach to the battery +12V, providing the positive path of conductivity needed for the regulator when this path is less than adequate on some machines.

It is helpful and safer to use the battery positive found on the protected side of the main fuse, or to introduce your own inline fuse when making a new positive regulator wire to battery line. When the main fuse is chosen be careful to connect to the protected side of the fuse, not to the starter side of the starter solenoid wire, otherwise the starter will see +12V from the regulators original factory wire and the starter will try to operate.

Good job Zundappchef!

A word of caution: The use of the commonly available 'Scotch Locks' for such things as this mod, is not recommended. These taps use a narrow blade-like slotted connector plate to cut down through an insulated wire without the need to prepare it by stripping insulation. While quick and easy to use, they are a decidedly poor way to make a secure electrical connection and are widely reviled among professional installation technicians for their poor performance and unreliable tiny contact area, particularly in weather-exposed applications.

* This Tech Tip uses pics from Zundappchef's (Netherlands) version of the modification, whom he credits to Carlosio (Spain), who modestly says he merely improved on an idea he got from sskingquad (Canada), who in turn says "I actually didn't do this myself... I had a Suzuki tech from Suzuki Canada come and test my charging system... ...and he found that the wiring harness just didn't have sufficient ground and therefor was not charging enough..."

Look at that, people from all over the world contribute to identifying and fixing this problem (including others not yet named), and nobody is claiming credit, just crediting those before!
I think they all deserve the credit.

gowen's (Canada) refinement:

"This mod recommends adding a direct connection from the positive wire at the voltage regulator to the battery positive. This IMO is a no-no, bad thing to do as it bypasses the main 30 amp fuse protecting the wiring harness and all the associated electrical equipment.

A better solution IMO is to take the new wire spliced (soldered) to either one the two positive wires at the voltage regulator to the positive wire connection at the starter relay (located beside the battery). This is the location where the positive in the wiring harness connects to the battery positive thru the 30 amp main fuse.

G/L Edit: Be careful to choose a small red wire just where it exits the plug, not the big red one that goes to the starter!
Or just connect your own 30 amp inline fuse to your new regulator positive wire, and put it straight to the battery positive post.

Another suggested revision is to take a negative wire from one of the two at the voltage regulator, first to the mounting bolt on the regulator, then continue with another wire to the battery ground connection on the starter motor. This improves the ground connection between the engine and the frame as well as the regulator to battery. I offer this suggestion as it appears that all the electrical items on the king are provided with a ground wire in the wiring harnass, except for the ignition coil which as (I'm guessing the size) a #20 ground wire. As the engine is rubber mounted this #20 coil wire is the only conductor between the engine and the frame (that I can find). In theory the only current passing between the engine and the frame is the spark current. An alternate pathway for the negative current is thru the drive train bearings, not a good pathway for use.

However a couple things to note on the wiring harnass, first both the negative and positive wires in the harnass have multiple splices with compression fittings, and even though the harnass has two negative and two positive wires at the voltage regulator and at the start relay, due to splices the harnass only one positive and one negative wire actually exists between these two components. So if and when the compression fitting in the harnass were to corrode, and the negative wires are more prone to corrossion than the positive wires( as commonly seen at the battery posts), the little #20 ground wire on the coil could be handling more than its fair share of the negative conductor current. Increased (overload beyond it current rating) current on this little wire will result in an increased voltage drop in the system.

To summerize my suggestions. If the charging voltage is low at the battery, first run a wire from the regulator to the frame then another from the frame to the engine ground connection on the starter motor. IMO this will likly solve the majority of the charging problems. If not then add a new positive conductor from the regulator to the start relay and not directly to the battery.


This is the most asked question on Nyroc. Average question posted on this subject is 28 times a year. We like to help everyone but we are starting to sound like a broken record on answering questions on the subject. As most are not doing a search on the site or using Google "Nyroc atv direct wire mod"

So please help us help you by doing your part on this subject.

Here is just a few of the links that have been posted on this subject over the years.

Info Read 1

Info Read 2

Info Read 3

Info Read 4

Thank you for helping us help you.


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