99 Shadow ACE 750 Electrical Checks

[freerepublic]

I am checking the charging circuit according to manual. With it off the manual says there should be 15 volts on it before cranking it. This does not make sense to me nor am I getting that on a brand new battery. I have found several typ-os and instructions that needed correction in it. Can someone give me the run down on checking out the charging/regulator/coil etc.??? Thanks ahead of time:dizzy:

[mcvierh]

a 12 volt battery should read 13.2 volts when fully charged., as each cell has a nominal voltage of about 2.2 volts.

[mcvierh]

thats a tall order there freerepublic, as that etc. leaves a lot open. just a Quick charge test for you tho, as anything else would require a lot more than just a line or two of typing...The simplest way to perform a quick check is to use a volt meter. Set the meter to the 20 volt scale and connect it across the battery terminals. Your shop manual will give you a voltage output for a given rpm, which should be something like 14.5 volts at 3,000 rpm. Start the engine and bring it up to the recommended rpm while watching the meter. If the voltage reading is correct all is well with the charging system, that volt meter will let you know if all is well in an instant in the charging department, yep it's that simple.

[mcvierh]

on another note Free. you'll know if your alternator is putting out if the return voltage to the battery is 14.5-15 volts for a 12 volt system. It takes a higher voltage to recharge a 12 battery than the battery puts out.

[mcvierh]

Here goes Free. As per Biker Dan,
Electrical problems can pop up at any time and can seem hard to fix but they really aren't. Most of the time, anyway. Most everything can be "Proved" (tested) with an Ohmmeter (http://www.dansmc.com/ohmmeter.jpg) and a some things can be proved with a simple circuit tester. (http://www.dansmc.com/circuttester1.jpg)

You can get a good cheap ohmmeter, sometimes called a multimeter, from a hardware store or an auto parts store. They generally run about $20.00. If you want, you can pay hundreds of dollars for one, but for the tests we will be performing, a cheap one will work just fine.
An ohmmeter sends a very low power electrical charge through a wire and measures how much resistance there is in the wire to the charge going through it. This resistance is measured in Ohms. Your shop manual will give you the correct resistance for each wire that you test. The multimeter will measure a bunch of different things such as ohms, DC volts, AC volts, etc. Here are a few of the basic tests. They are all performed at room temperature (70 degrees or so). The word Continuity means voltage is passing through the wire from one end to the other. No Continuity means the wire is broken and voltage is NOT passing through it. Also, if we say something is wired in parallel, it means they are wired side by side. If two 12 volt batteries are wired parallel, the negative terminals would be wired together. Likewise for the positive terminals. This would still give us a 12 volt battery, only bigger. If something is wired in series, it means they are wired one after the other in a line. The two 12 volt batteries would be wired positive to negative, giving us one 24 volt battery. A shop manual will be very handy to give you the Specifications on the different coils and wires. It also will have a wiring diagram, that will give you the different colors of the wires you are going to want to test. Most of the specifications I give here are just general ones to get you in the ball park. The Shop Manual will give you the exact ones.

[mcvierh]

Before you do any testing make sure you have a fully charged battery, if there is a battery, in the bike you intend to test. Just because it will start and run without the battery DOESN'T mean it will run right. Time after time guys will bring a bike in and say "It runs good and then it don't. Misses on one side then the miss changes to the other side." Some of them just will not believe it's a bad battery or the wrong size battery. "But it runs." they say, "It just can't be the battery." But it can be the battery. If it needs a battery, and you take the battery out of the system, things can overcharge, overheat and burn out. If the system calls for a battery, make sure a good one, fully charged, is in there. The only time this would not be true, is when the Ignition System is a magneto and the battey is only used to run the horn and tail light. Now when I say "The right size of battery" I mean the battery must have enough amps to run all the things you want to test. If you don't have the right battery, you can use a big, fully charged battery, say from a car, BUT it MUST have the right voltage (6 or 12) and you MUST use big, thick jumper cables. DO NOT connect the jumpers to the old dead battery. Take the old, dead battery completely out of the bike. Connect the positive jumper cable to the positive cable on the bike. Connect the negative to a good ground on the bike. Now you can run your electrical tests. The fact that the battery is a lot bigger then the stock bike battery will not hurt anything. The electrical components on the bike will only draw the powerr they need from the battery. The battery will not "Over Power" the components as long as the it is of the correct voltage. If you leave the old, dead battery in the system, it will try to pull power from the bigger battery. At best this will throw your electrical tests off. At worst the battery can BLOW UP ! Usually, small bike batteries don't blow up... but, why take the chance

[mcvierh]

Ignition coils. Measure the resistance between the primary (http://www.dansmc.com/ign_coil_test.jpg) (low-tension) wire and ground or ground terminal. It should be very low. Like .5 to 1.5 Ohms. The primary wire is the small wire going to the CDI box or points. Next measure the secondary (http://www.dansmc.com/ign_coil_test2.jpg) (high-tension) wire and ground. (Note that on most bikes these days, the coil mounting bar, that passes through the coil and mounts it to the frame, is the ground for the coil primary and secondary wires.) This should be quite high, like 6000 to 13000 ohms. If the coil is out side the specs given in the shop manual the coil might be bad. Sometimes, a coil will work OK when cool but fail when it warms up. Let them cool and they work again. They make machines that will test coils under load. They are nice to have but can be pricey. Remember to take the plug cap off for the test. The cap can add 300 ohms resistance

[mcvierh]

http://www.dansmc.com/statora.jpg (http://www.dansmc.com/stator.jpg)Charging Stator coils. These are the coils that are under (http://www.dansmc.com/coils3.jpg) or around (http://www.dansmc.com/coils1.jpg) the flywheel. Sometimes they are both. (http://www.dansmc.com/Stator_fieldcoil.jpg) The flywheel has magnets on it and these magnets produce a charge in the coils as the run around them. Usually there will be three wires, all of the same color, coming out of these coils. You want continuity (connection) between the three wire with a low ohm reading, like .5 to 3-4 ohms. There should be NO continuity between these wire and the ground. At least most times, anyway ! If there is only one charging wire coming out of the flywheel coils it is usually grounded and has a reading of .5-1.5 ohms between the output wire and ground. If there is no resistance the coil may have wires short together. If there is infinite resistance a wire is broken. Check the shop manual specs. This is because some charging systems are Alternators, and some are Generators. There are also different flavors of Alternators and Generators and I'm not going to go into that here ! Get that shop manual out to be sure. Just to make things fun, some of the replacement coil sets have very short leads. You have to cut the old leads and plugins off the bad coils and use small wire crimps to hold the wire together. If you solder the wires together the wires can separate once the engine gets good and hot and the solder softens a bit. In other words, soldering may or may not work. Crimping won't come lose under heat. However, no one sells the crimps and they don't give you ANY extra wire AND you have to put something on the wires to keep them from shorting against the crankcase. Fun, fun, fun ! You can get little crimps from appliance parts supply houses or you can make your own by cutting the end off a wire fitting. (http://www.dansmc.com/crimps.jpg) Put the cleaned and stripped two wires in the crimp and crush them together with some vice grip pliers. Then insulate the repair with heat shrink tubing.


IGN Source Coils. These are coils, under or around the flywheel, that supply energy for the ignition. Usually, almost always, these coils are grounded. Usually, 300-500 ohms from output wire to ground.


On the above coils. Often, but NOT always, if you stick a Circuit Tester (http://www.dansmc.com/circuttester1.jpg) on the charge wire and clip the other end of the tester to ground, then kick the engine over, you will light the tester bulb briefly. This indicates you are getting some kind of juice out of the coil. But like I say, NOT always.


Trigger, pick-up or pulse coil. (http://www.dansmc.com/sourcecoil_trigger.jpg) These coils tell the electronic ignition black box when to fire the ignition coil. Usually two wires. Usually, one to three ohms resistance between the two wires and no continuity between them and the ground.


http://www.dansmc.com/rectifier1a.jpg (http://www.dansmc.com/rectifier1.jpg)Rectifier. When a coil produces electricity, it sends it out in plus or minus waves. The battery can only charge on one of these waves. A rectifier has silicon diodes that only allow half the wave to get through. Back in the 60s and 70s a lot of the little bikes had these single wave rectifiers. Now most bikes have full wave rectifiers that have four diodes. All this rectifies the AC current to DC to charge the battery. To test the rectifier, hook up the ohmmeter leads to one of the wires (http://www.dansmc.com/rectifier2.jpg) and to the ground (mounting) stud. Note the reading you get. Now reverse (http://www.dansmc.com/rectifier3.jpg) the leads from the ohmmeter and note the reading again. The exact reading is not all that important, but there should be a big difference between the two if the diode is working right. Test each of the wires this way. If any wire is very close in the two readings then the diode is leaking and no good. If there is no continuity, then the diode is shorted out and no good. Be careful not to turn the bolt holding all the diodes together. This can short them out. It is possible to test the rectifier with a circuit tester by adding a D flashlight battery in line with the circuit tester. You want to see the light, light in one direction and not in the other. If all of a sudden you start blowing the main fuse, it's possible one of your rectifier diodes has failed, letting current, from the battery flow back to ground.



Voltage Regulator. All the current from the charge coils would over charge the battery if we let it, so we need a voltage regulator to keep the battery charged at 12 volts. Your ohmmeter should have a DC volt scale. Set it at 20 volts and connect the positive and negative leads to the right battery terminals. Make sure the battery is fully charged, so we get a correct reading. Start the bike and rev it up. The volts should go up to 13.8-14.5 volts and then stay there. Much more, and it will over charge the battery. Much less, and the battery will never charge up. Some voltage regulators (http://www.dansmc.com/voltagereg.jpg) can be adjusted and some cannot. If you can't get it's cover off or if it is all sealed up, it's non adjustable. If you can get the cover off, you can clean the little contact points and adjust it with a screw driver till you get the right charging rate. Most, nowadays, are not adjustable. Most of the newer bikes have the Rectifier and Voltage Regulator as one unit. If either one goes you have to replace both. AC current will light the headlight and everything else. Light bulbs don't care if it's DC or AC current. If you have a dirt bike and don't need a battery you can get an after market voltage regulator for $30-40 and it will keep you from blowing bulbs. A number of the older, smaller, bikes had no voltage regulator. I guess they thought the battery would soak up the extra current... they were wrong, so put one in. There also is a cheap after market rectifier/voltage regulator unit you can put on, if you need a battery. It will also work on some street bikes too, but you have to make sure it matches the charging system

[mcvierh]

Voltage Drop Testing. OK, let's see if I can explain this right. When you measure the voltage on a battery by putting the positive ohmmeter lead on the positive terminal and the negative lead on the negative terminal, you are actually measuring the voltage pressure between the two terminals. The positive terminal reads 12.6 or so volts and the negative terminal reads zero. The wiring circuitry in the ohmmeter subtracts the negative lead voltage from the positive lead voltage (12.6v-0v=12.6v) and you end up with the reading 12.6 volts. What does all this mean ? Well, if you connect the positive ohmmeter lead to where the power starts. Like the positive battery terminal, and the negative lead to where you want the power to go, like a starter. Now run the starter. You should get a ohmmeter reading of zero. If you get a reading, that is the voltage drop. This indicates resistance in the starter cable or in the connection to the battery or starter. Another way of thinking on this is that the voltage drop is the number of volts that you lost over that connection. The reading you get on the ohmmeter is number of volts you have lost. You can test the ground connection side of the starter too. Connect the negative ohmmeter lead to the negative battery terminal and the positive ohmmeter lead to the starter body. Again, crank the starter. A DC circuit should use all the available voltage, so the reading should read close to zero or not more than .4 volts.

[Dcfam]

That's service. Have him send your fee to paypal.

[mcvierh]

Remember, the ohmmeter may have some internal resistance, usually .5 ohm. Hold the ohmmeter leads together to find out what that resistance is and subtract it from your test readings. Take the readings when the part has warmed up to 70 degrees or so. If you don't, the readings will not be accurate. Take several readings and, if you have several ohmmeters, use them all. The more readings you take, the less errors you will make ! Most of the specs are given plus or minus 10-20%. Of course, some of the specs the factories give out may not even be right !

There you go Free, that should keep you busy for some time.

[firefighter212]

That needs to be a sticky!!!!!!!!!!good find Brother McVierh

[919jackass]

good job on the explaination like always mcvierh !

[freerepublic]

WOW. Thanks McV. I will put your info to good use. I knew my manual did not make sense telling me 15 volts. I do have a good meter I borrow from work so I am set there. If your ever in the ATL of the GA I owe you a few rounds.:thumbsup: