Most complaints that point to the battery or charging system include a symptom of hard starting or failure to start. Slow cranking, long cranking times or failure to crank can have their root causes in any - or all - of these electrical areas. Often, the job is to fix a no-start problem, period. So where do you start troubleshooting such a problem? With the battery.

Beyond a simple blown fuse or a broken wire, you can't troubleshoot any electrical, problem without a fully charged battery. A good battery has two characteristics: First, it must deliver the electric current demanded by the starter and other electrical devices on the car. Second, it must maintain enough voltage to force that current through the car’s circuits. Basic battery tests include an open-circuit voltage check, a load test and maybe a three minute charge test. Most batteries sold today are maintenance-free units, with non-removable vent caps. If the battery does have removable caps check the specific gravity of the electrolyte with a hydrometer.

A fully charged unit should show a value of 1.260 - 1.280. Less than 1.160 shows it to be fully discharged. With a maintenance-free unit you can't use a hydrometer. As an alternative, start by checking the open-circuit (no load) voltage. To do this first run the headlamps for about 10 minutes to remove the surface charge. Turn off the lamps & connect a voltmeter across the terminals. A 100% charged battery should show 12.72-12.60 volts. Voltages lower than 12.15 volts indicates less than 25% charge.

If either the specific gravity or open-circuit voltage shows a charge of 75% or greater you can continue with a load test, otherwise you need to charge the battery to get it in shape.

Once we know the battery is charged, it would be a good time to inspect some more of the basics.

Check for glazed or damaged drive belts - remember, the alternator can't get up to speed and keep the battery charged if its drive belt is slipping. Loose or corroded terminal or frayed wires also impede current flow. Simply cleaning and re-tightening your battery terminals could fix a "no-start" problem!

The load test - to check the battery can delivery a high current whilst maintaining enough voltage to operate the ignition - is next on the agenda. Professionals will use a Volt-Amp tester set to a specific load - a good rule of thumb would be the Cold Cranking Amps (CCA) rating divided by 2. However, a simple test can be made with a hand-held digital multimeter - ideally one with a Min/Max recording function.

Simply connect the meter across the battery terminals, disable the ignition and turn the headlamps on and crank the engine for about 10 seconds observing the meter reading. If you don't see a reading below 9.6V during cranking you are OK - ideally it should stay above 10V. Although you don't measure the actual current load during this test, it's a realistic measure of the battery's cranking ability under the load of its own engine and electrical system.

If the battery qualifies as OK, you can move on to some basic starter testing. To check the cranking current draw and RPM, you basically repeat the load test with an ammeter connected to the starter circuit and a tach connected to the engine. Crank the engine for about 15 seconds and note the readings.

If the voltage drops below 9.6 volts, you need to return to the battery and locate the huge current draw. If the current is higher than factory specs (check your shop manual) look for a short in the starter or suspect a binding engine. If it's lower, look for high resistance in the starter circuit. Cranking speed is usually around 200 RPM. Low cranking speed plus high current draw points to a binding engine. High cranking speed and low current draw indicates a lack of compression - a slipped timing chain is a common culprit, or leaking valves/pistons.

The cranking current draw, voltage drop and speed tests will lead you to pinpoint voltage drop tests for the starting system - divided into the control and motor circuits.

The control circuit includes the ignition switch, neutral safety switch and coil side of starter relay or solenoid. Disable the ignition then crank the engine via the ignition switch. Use a volt meter to measure the voltage drop across each component (including connectors & all lengths of wiring) during cranking. The maximum allowable drops are as follows:-

If you haven't solved the no-start problem after checking the starter control circuit or you have a slow-cranking problem, move your voltmeter to the starter power circuit.

The insulated side provides battery voltage to the motor. It includes the positive terminal of the battery, the heavy cables, the power contacts within the solenoid or switch and the motor itself. The ground side starts with the the motor ground to the engine and the low voltage ground path through the chassis, including the ground cable to the battery's negative terminal.

For these tests, disable the ignition and use a remote starter switch to crank the engine. To test the insulated side, connect the voltmeter positive lead to the +ve battery terminal and each connection from the motor back to the battery clamp. Look for voltage drops at each stage.

To test the ground side, connect the negative voltmeter lead to the -ve battery terminal (not the cable clamp!) then probe backward with the positive lead from the ground connection at the motor to the engine back to the negative clamp. Again, look for excessive voltage drops.

All of this seems too be checking for tiny readings, which we are, just how does it make such a difference? Using Ohms law (E = I x R), you will find that as little as 0.01ohm resistance causes a 2-volt drop in electromotive force - there's your cranking problem!

The final steps of this electrical exercise will ensure that the charging systems can put back into the battery what the starting system took out! After cranking, the battery will be slightly discharged, so now is a good time to check the alternator since it will deliver a high current & voltage as soon as the engine starts.

With your voltmeter & ammeter connected, turn on the ignition but don't crank the engine. Read the discharge current on the ammeter. Now start the engine & and run it @ 2000rpm, then check the charging voltage & current readings. Next, hold the engine speed @ 2000rpm until the current reading falls below 10 Amps. Now check the voltage again and let the engine return to idle.

Add the current reading taken with the engine off top the highest reading with the engine running. This value is the total output current and should be within 10%-20% of the alternator’s rated output. The voltage reading should be between 12.6 and 15.5 Volts. When the current has dropped below 10 Amps, the voltage should be at the regulated maximum. Because many vehicles have optional alternators, it's a good idea to check the specifications in your shop manual (or on the unit itself).

If your readings are outside the general limits of this test, you need to go for pinpoint current & resistance tests. Don't forget, that when testing charging system circuits, you'll still be taking basic electrical measurements that are applications of basic electrical diagnosis.