Conducting various tests and learning the exact parameters of a motor is useful in at least four cases.
- The first case concerns buying a used motor. As a rule, a motor has got a tablet with all characteristics and documentation with the same detailed information. Sometimes, when you purchase a used motor from a private seller, the data can be missing. In this situation, a strategy to perform tests to learn the characteristics of a motor is correct.
- The second situation happens when something is wrong with the motor, and you would like to repair it. Measuring AMP draw can exclude or confirm problems with the inner electric circuit, power consumption, and overall effectiveness of a motor. The test is important but not difficult to perform by yourself.
- The third case concerns custom motors. Suppose you are an enthusiast and want to assemble your own trolling motor from different parts. In this case, amp draw tests are obligatory, as you have to make sure what kind of battery to apply.
- The fourth situation is advice from many experts. They recommend decreasing the electricity power of a starting device. Such a procedure lets a battery last much longer.
What can happen if you neglect the amp draw test?
You will waste money by picking the wrong battery. If the power of a battery is not enough, it will not start the motor at all.
You risk burning or overheating a motor with a too strong battery. Excessive heat can make motor lifespan significantly shorter.
You will ruin the motor completely or overpay for another repair. As we said, you can perform the test by yourself if you know how to prepare and the instruments you’ll need.
Amp Draw Test: Preparation and Instruments
First of all, never repeat the mistake committed by many motor owners. They used to measure amp draw with a simple multimeter. What was the procedure? They turned the multimeter into the amp meter mode and plugged it into a single clamp of a battery. The clamp went off, one probe attached the battery itself, and the other touched the plugged-out cord.
The motor started, but no one knew the amp draw. It happened because simple multimeters are not able to count the amp draw more than 10-20 amp. A starter of even a small motor starting device is able to give away about 100 amp. Simple multimeters will burn.
To measure the amp draw of a motor properly, you need a special instrument called amp clams. As it follows from the name, they have got special clams. You need to grab the cord you would like to test with them.
If you do not have such clams and want to assemble your own meter, you will need a set of amp shunts. Get a pair of reliable cords as well. Also, you can test the amp with special flexible probes.
Note that the main principle of working with the ampere meter is its application into the broken circuit. It is called a series connection. It becomes a part of the circuit, and the electricity must pass through it completely.
So, you need to organize the circuit break. And note that the regimes of measuring voltage and amperage differ.
Obviously, you will need something to protect yourself. Take a look at protective glasses. When something goes wrong, a motor or a battery can burn or even blast. So, you’ll need to protect your eyes from flying splints. We recommend darkened glasses to provide protection from light flashes.
—While working with electricity, you need to protect your skin from contact with electric cords and parts. Gloves are an obligatory item. Try putting on something that covers the skin on your hands as well.
Let’s conclude. You need special amp clams that are used in automobile repair shops for conducting a proper test. If you do not have them, you will need a powerful amp meter, flexible probes, and a pair of cords.
Protection is essential, as you are going to work with electricity exceeding normal ratios for a human’s body.
Safety Measures and Useful Tips Before the Start
As we said, you should wear protection from electricity. Besides that, you need to establish a workplace properly:
- Conduct a test in well-enlightened rooms.
- Make sure that every instrument, the motor itself, and a battery are dry and free from water particles. They can carry electricity. They can spoil the test or even damage the instruments of your body, in the worst cases.
- If you need to clean the clams or other metal parts of the system, use special volatile fluids.
- All the cords must have isolation.
- During the test, make sure that the amp meter does not touch any other metal parts of a motor. The motor itself, if it is pulled out from a boat, should lay on an isolative rubber cloth.
- Do not use any wooden bulkheads or instruments during a test. Though dry wood does not carry electricity, it burns well.
- A working motor can be dangerous for your fingers and other body parts. The motor should be stable during work. It will shiver, and you must be sure it will not fall. Turn it on only when you make sure that nothing is inside a motor.
It is better to conduct a test with a person ready to help in holding a motor or making a starter work.
Test Algorithm
When everything is ready, you can start the test:
- Charge the battery of the motor. The starting device must be fully charged to show the real amp draw of a motor.
- Set your meter to the amp regime. Set the acceptable diapason. If you estimate 50-100 AMP from your motor, set the diapason from 0 to 100.
- Find a power cord and attach the clamp amp meter. If you have got a custom assembled meter, attach the cords of a meter to a motor cord and the unplugged power cord. As we said, you need to break the electric circuit and install a meter into it. It does not matter if you choose a plus or a minus cord for a test. Measuring only one cord at a time matters. Two or more motor power cords will cancel each other, and the amp ratio will be compromised.
- When a starter works, you will see the amp draw. Note that you need to let the motor work for some time to exclude the starting electricity tension. It is an extremely excessive charge that comes in the first seconds after a motor starts.
- Repeat the procedure several times and write down the amp draw ratios every time.
- You must conduct the procedure in different conditions to make the ratios wider and more truthful. After several tests, you need to count the simple average of the ratios to get the most truthful result.
Note that you need to give the battery a rest after every test. The less charge stays in the battery, the lower the amp draw ratios are.
Remember that a warm motor is easier to start than a frozen one. So, before starting a test, you should warm it before the test and keep it indoors.
Be ready to see that the current amperage can be both lower and higher than a maximal one written down on a plate. If the amperage is higher, you need to check the voltage first. When the voltage is not enough, the motor tries to compensate them with higher amperage.
Slightly lower amperage are natural for the old motors that wear out in time. If the decrease is significant, it means that a part of a motor electric circuit does not get electricity. Look for cord or detail damages in this case.
Conclusions and Final Tips
Proper interpretation of the amp draw lets you calculate all the parameters of a motor. The more you know, the more effectively you will use your motor without breaking it.
Amp draw is useful to identify the problems as well. Increased amp draw of a motor can be caused by:
- total wearing out of a starting device or a motor on the whole;
- the short circuit in the electrical circuit of the motor;
- bad contacts between a battery and a motor, or between the power part of the motor itself;
- other minor or major breaks.
Anyway, by testing, finding, and eliminating these problems you will increase the lifespan of your motor and its battery. Some trolling motor owners fear that a higher amperage will burn the starter. Do not worry, as the device will not take more than it needs.
Knowing a proper amperage is essential even if you know the nominal amperage of the current motor. Different manufacturers use different details, increasing or decreasing the total amp draw.
To take the exact tests, you need to calibrate your instruments at least once a year. Proper amp draw means the more exact choice of a battery, less excessive electricity consumption, longer lifespan, and more money staying in your pocket.
