This article and thirty-seven other technical articles can be seen and read on-line for repair issues on the VW MK4 Series TDI at URL: HTTP://WWW.VWTDIREPAIR.COM (Darell's VW TDI Maintenance Page).
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The storage battery is suspected of being too weak to start the Beetle TDI. The starter motor has to turn the flywheel from 150 to 200 rpm's in order for the engine to start. The battery will need to be tested to determine its condition.
In this discussion, you will have an arsenal of information to guide you in diagnosing and maintaining your Beetle's storage battery. The average life of a storage battery is less than three (3) years.
Included in this discussion are the techniques that I have used over the years to service and extend the life of marine and storage batteries past the manufacturers' warranty date.
The storage battery in your Beetle TDI has a "magic eye". This device is a minature hydrometer. When the light glows "green", the battery per advertisements is said to be in good condition. This is not true. The "magic eye" only measures the electrolyte in that cell. The voltage in that cell measures two (2) volts.
This measurement does not indicate the true condition of the battery. A proper check is made by measuring the electrolyte in all six (6) cells of the battery which should total twelve (12) volts. The voltage is generated from a lead-acid battery.
Lead-acid batteries used in VW Beetles can be serviced in or out of the vehicle. An adhesive decal (marked + and -) is placed across the filler caps by the manufacturer. Use a razor blade or gasket scraper to remove the decal (Figure 38-1). Place a nickel in one (1) filler cap and remove the cap.
The water level can then be checked for that cell. If the water level is above the top plate, the battery, in most cases, can be recharged. If the water level is below the top plate, the battery has been damaged from lack of water causing "sulfation". Battery checking procedures are discussed in paragraphs below.
Note
When adding water to the cells make sure it is distilled. Do not overfill which could cause gas to be emitted from the vent and damage the painted surface.
Figure 38-1 Removing Decal to Battery Filler Caps
Note
In most VW's, the "magic eye" indicator shows green, black. red, and yellow readings. The nomenclature is: (1) Green - 75 percent charged, (2) Black - 50 percent charged, (3) Red - 25 percent charged, and (4) Yellow - Low or discharged. A green reading in the sight glass of the "magic eye" indicates the battery is 75 percent charged only in that cell and not all six (6) cells of the battery.
Battery Maintainers
Auto Zone will miss a sale of a new battery when you hookup a battery maintainer (available at auto parts stores) to your Beetle's battery when not in use. This device is a battery charger, maintainer, and desulphator conditioner. A battery maintainer will condition a battery preventing "sulfation". The conditioner extends the life of the battery. Figure 38-2 shows a typical battery maintainer installed on a twelve (12) volt battery.
Figure 38-2 Typical Battery Maintainer or Conditioner
Battery Charging
Mercury Marine stresses to students, a marine or automotive battery is a "perishable" item. It is doomed for failure you just don't know when. The battery fails, in most cases, due to "sulfation". It is caused by overcharging, and low water levels in the cells of the battery. Cells with lack of water will harden the plates causing "hard sulfation". The battery will then not take a proper charge.
You should never "fast charge" the battery in your Beetle TDI. A "fast charge" is in reality a surface charge that will shorten the life span of the battery. The battery should be charged using a battery charger that has a two (2) and ten (10) amp settings for a "slow" charge. Your Beetle's lead-acid battery should be charged with no more than six (6) amps or 10 percent of the battery capacity rating. Figure 38-3 shows a typical battery charger that is used to "slow" charge the battery in your Beetle TDI.
Note
Charging a low or discharged battery on the two (2) amp setting can take up to seventy-two (72) hours to fully charge the battery.
Figure 38-3 Typical Battery Charger
Note
VW recommends that the storage battery in your Beetle TDI should be removed from the vehicle before charging. Batteries emit gas which can settle and damage the painted finish on the vehicle.
Jump Starting Battery
Jump starting a storage battery is the process of starting the engine of one (1) vehicle by connecting it to the battery of the other vehicle. Check he condition of the dead battery before making any connections.
Warning
Jumping starting a battery in a disabled vehicle can be dangerous if precautions are not taken. Batteries that are completely discharged or low on electrolyte can explode. The resulting sparks could ignite the fuel vapors or battery gasses. Lastly, make sure that the vehicles bumpers do not touch when making connections.
The owner of a $30,000 bass boat on Grand Lake in Oklahoma did not observe the above warning and advice. While replacing a defective trolling motor battery, an electrical arc occured. Gas vapors in the bilge ignited and the fiberglass rig burned to the ground in less than 10 minutes. The lesson to be learned here is to use common sense and take pecautions when jump starting and working around storage batteries.
When making the connections to the dead battery and the good battery with the battery jumper cables, follow the below steps:
1. Make certain that the vehicles bumpers do not touch.
2. Connect the POSITIVE (red) jumper cable to the POSITIVE (red) post of dead battery.
3. Connect the opposite end of the POSITIVE (red) jumper cable to the POSITIVE (red) post of good battery.
4. Connect the NEGATIVE (black) jumper cable to the NEGATIVE (black) post of post of the good battery.
5. Connect the opposite end of the NEGATIVE (black) jumper cable to a good ground connection away from the battery in the vehicle.
The storage battery in your Beetle TDI provides power to be available at all times to components; such as, radio, alarm system, power door locks, power windows, and the engine control module (ECM). Use a device known as a memory keeper to prevent loosing engine management settings that are programmed in the ROM memory of the ECM. Figure 38-4 shows a memory keeper powered by a nine (9) volt battery. The memory keeper is inserted in the cigar lighter It is located in the cabin compartment of the Beetle TDI.
Note
If a memory keeper is not installed, all computer settings in the ECM's memory will be lost. The values will have to be re-programmed into the memory of the ECM with the Vag-Com scan tool or equivalent.
Figure 38-4 Typical Memory Keeper
Warning
When disconnecting the battery, remove the negative cable followed by the positive cable to prevent accidental arcing by a tool, etc.
Arcing can cause serious damage to the electrical system and ECM. When installing the replacement battery, install the positive cable to the positive battery post followed by the negative cable to the negative battery post.
Warning
Wear safety glasses and remove jewelry when working near a storage battery. Battery acid and emitting gas can cause permanent blindness.
The following is a list of some of the causes for a discharged battery:
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Voltage drains caused by trunk or interior lights that stay "ON" with ignition "OFF".
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Starter motor drawing excessive current.
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Defective alternator not supplying the required current to fully charge the battery.
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Low charging voltage.
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Broken accessory belt.
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Corroded, dirty, or damaged electrical wiring and connectors.
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Extended cranking periods by the owner for a no-start condition.
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Accessories left "ON"; such as, interior and head lights.
The following lists some causes that will reduce the lifespan of an automotive storage battery:
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Overcharging - This will cause a loss of electrolyte causing damage to the lead plates. The lifespan of the battery will be shortened.
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Hard Sulfation - This condition occurs when a battery slowly drifts into a discharge over a period of time. A low electrolyte level in the cells of the battery will accelerate discharging as the lead material on the plates hardens. The battery will not take a proper charge. Unscrew each cap and check the electrolyte level. If the level is above the top plate, the battery can be recharged. If the level is below the top plate, the battery has been exposed to "hard sulfation". Sulfation can sometimes be reversed by "slow-charging". Connect the leads of the charger to the positive and negative posts of the battery. Set the rocker switch to the two (2) amp setting. Charge the battery for a minimum of seventy-two (72) hours as shown in Figure 38-5.
Figure 38-5 Charging Discharged Battery
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Deep Cycling - Occurs when a battery sustains a deep discharge and is recharged a number of times. This causes shedding of the active material on the plates. It then settles in the bottom of the battery case resulting in a short between plates.
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Battery Freezing - Occurs when a weak battery freezes in the cold weather. This condition can cause a battery to explode.
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Excessive Vibration - Can be caused by broken battery tray tabs. The battery is not anchored and stable. Excessive vibration can cause internal damage to the battery.
Follow the below steps to remove the storage battery from your Beetle TDI:
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Release the hood lever inside the cabin compartment.
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Pull forward on the outside hood cable and open the hood.
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Place wheel chocks behind the rear wheels.
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Place the gear selector in Park or 1st gear.
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Install a memory keeper device in the cigar lighter of cabin compartment (Figure 38-4).
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Remove the top engine cover (there are no screws or bolts) and set aside (Figure 38-6).
Figure 38-6 Removing Top Engine Cover
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Using a 5mm 3/8-inch hex bit socket and a 3/8-inch square drive ratchet, remove the bolt that secures the power steering reservoir (Figure 38-7). Figure 38-8 shows the location of the reservoir bolt.
Figure 38-7 Removing Power Steering Reservoir Bolt
Figure 38-8 Power Steering Reservoir Bolt Location
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Using the fingers, press the tab on the battery top cover and remove cover (Figure 38-9).
Figure 38-9 Removing Top Battery Cover
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Using the fingers, press the two (2) tabs and lift up the fuse box top cover (Figure 38-10).
Figure 38-10 Opening Fuse Box Top Cover
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Using a 1/4-inch square drive 10mm socket and 1/4-inch square drive ratchet, remove the positive cable (red) to the fuse box (Figure 38-11).
Figure 38-11 Removing Positive Cable on Fuse Box
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Use a 10mm 1/4-inch square drive socket and a 1/4-inch square drive ratchet to remove the clamp that secures negative cable to the negative battery post. Repeat the same procedure for the positive battery cable (Figure 38-12).
Figure 38-12 Removing Negative Cable From Battery
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Detach the cable attached to the cable clamp on battery cover (Figure 38-13).
Figure 38-13 Removing Cable From Battery Cover
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Detach the battery cover from the locating tabs with the fingers and flat-blade screwdriver. Remove the battery cover (Figure 38-14).
Figure 38-14 Detach Tabs From Battery Cover
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Using a 3/8-inch square drive 13mm socket and 3/8-inch square drive ratchet and long extension, remove the battery hold down bolt and clamp from the battery (Figure 38-15).
Figure 38-15 Removing Battery Hold Down Clamp
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Using the battery strap, remove the battery from the vehicle and place on the work bench for testing.
Caution
The battery is heavy. To prevent injury to the back and groin, bend the knees and use both hands when removing the battery from the Beetle TDI.
Common tests to check the condition of your Beetle TDI battery are listed below:
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Open Circuit Voltage (OCV) - This test is conducted to determine the state-of-charge of your Beetle's battery. A digital multi-meter (DMM) is used to measure the voltage across the terminals of the battery. A reading on the display of the DMM of 12.50V or higher would indicate that the battery is fully charged. If the reading were 12.3V, the battery is 75 percent charged. A reading of 12V or less would indicate the battery is in a discharged state (Figure 38-16)
Figure 38-16 Battery OCV Test
Note
The battery OCV test only determines the state-of-charge and not the overall condition of the battery.
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Specific Gravity Measurement - A battery hydrometer or ball type can be used to check a battery for a state-of-charge. A hydrometer measures percentage of sulfuric acid in the battery electrolyte in terms of specific gravity. As a battery water level drops from a charged to a discharged state, acid leaves the solution and enters the lead plates. This causes a decrease in specific gravity of the electrolyte. A fully charged battery should show a reading of 1.270 at 68 degrees F on the scale of the hydrometer. For all the features, see the instructions that came with the instrument (See Figure 38-17).
Figure 38-17 Battery Hydrometer Test
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Battery Drain Test - When there is a constant drain on the electrical system on your Beetle, a simple test can be made to determine the cause. Turn "OFF" all accessories in the vehicle. Insert a memory keeper in the cigar lighter. Remove the negative cable from the negative battery post. Set the selector switch to amps or auto ranging setting. Connect one (1) lead of the DMM to the disconnected negative cable. Connect the other lead of the DMM to the negative battery post. A reading on the DMM of 100 milliamps or less would be NORMAL. An excessive battery drain of 500 milliamps or more would cause the battery to discharge. Troubleshooting this problem is time consuming. One (1) method that is commonly used is to remove fuses from the fuse panel one (1) at a time until the problem circuit is located. At this point, a wiring diagram of the electrical system would be needed to pinpoint all of the wiring points and connector locations. Using the wiring diagram, move upstream to check the suspected component and wiring.
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Battery Load Test - The most accurate test you can make to determine the condition of a storage battery is the load test. A battery load tester is used to perform the tests. The load test evaluates the ability of the battery to operate the starter and accessories while supplying a large current for fifteen (15) seconds or more. If the battery voltage drops below 9.6 volts, the battery is defective and will have to be replaced to restore the electrical system to working order. A load tester can easily pay for itself the first time the tool is used. The tool costs less than twenty (20) dollars. It can be ordered from an Internet auto parts store front and auto parts supply centers. Figure 38-18 shows a typical load tester and setup used for this test.
Figure 38-18 Typical Battery Load Tester
Note
The battery should be topped off with water in all cells before conducting a load test. The results of a battery load test are valid only when the battery is fully charged.
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Charging System Test - Professional test equipment is not needed to perform an electrical system charging test on your Bettle TDI. While the engine is running (1500rpm's), place the negative test lead (black) of the DMM to the negative terminal of the battery. Place the positive test lead (red) to the positive terminal of the battery. The reading on the display of the DMM should be 15 volts or higher. This reading would be an indication that the alternator is charging the battery. A reading of battery voltage (12V) on the display of the DMM would indicate a problem in the charging system. The alternator is not charging the battery causing the battery to discharge. To troubleshoot the electrical system, the DMM is used to check the components of the alternator; such as, loose connections, broken wires, or a defective diode bridge.
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Battery Wet Test - A battery in good condition will measure two (2) volts per cell. The DMM is used for this test. Two (2) large nails were used as conducting rods. All of the filler caps were removed. To start the test, place one (1) nail in the last cell or negative post. Place the other nail in the cell that is next in series. Place the negative test lead of the DMM (black) to one (1) of the nails in a cell. Place the positive test lead of the DMM to the nail in the next cell. Set the scale of DMM to the VDC setting. The reading on the display of the DMM should show two (2) volts (See Figure 38-19). Repeat the tests for the remaining cells. Each cell should measure two (2) volts. A voltage measurement higher than two (2) volts would indicate a defective cell. The battery would have to be replaced.
Figure 38-19 Battery Wet Test
Before installing the replacement battery, clean the negative and positive posts with a battery post brush for a good cable connection. Figure 38-20 shows a new replacement battery positive post being cleaned with a battery post brush.
Figure 38-20 Cleaning Battery Post With Brush
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Next, clean the negative and positive battery cables. They should be cleaned with a battery brush to remove all corrosion and contaminants (Figure 38-21).
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To prevent corrosion of the new battery, wash with baking soda and water and thoroughly dry.
Figure 38-21 Cleaning Cables With Battery Brush
Note
When replacing your Beetle TDI battery, the dimensions (length and height) should be the same as the defective battery. Also, the specifications; such as, amperage rating, and cold cranking rating should be the same as the removed battery.
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Mount the replacement battery into the battery tray as shown in Figure 38-22.
Figure 38-22 Mounting Replacement Battery in Battery Tray
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Install the battery hold down bolt and clamp that was previously removed (Figure 38-23).
Figure 38-23 Installing Replacement Battery Hold Down Bolt and Clamp
Note
When installing the replacement battery, make sure that the center notch of the battery foot is aligned with the hold-down clamp hole in the battery tray.
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Install the positive cable followed by the negative cable to the positive and negative posts.
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Install the battery cover and cable to the clamp that was previously removed (Figure 38-24).
Figure 38-24 Install Battery Cover
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Install the bolt to power steering reservoir that was previously removed.
Continually energizing the starter motor can quickly discharge the battery in your Beetle TDI. A weak battery will put a strain on the electrical system. Erratic information from an input sensor to the ECM can result in error codes.
When a battery is replaced, it is recommended that the system be checked for error codes that would cause the check engine light (CEL) to turn "ON" (Figure 38-25). The Vag-Com scan tool or equivalent is used to clear trouble codes in the ROM memory of the ECM.
Figure 38-25 Location of CEL on Beetle TDI
The Vag-Com scan tool interface is mated to the pins of the diagnostic link connecter (DLC) located on the left-hand drivers side of the Beetle. The DLC enables the ECM to communicate with the Vag-Com. Figure 38-26 shows the Vag-Com scan tool setup to check for trouble codes in the engine management system of the Beetle TDI. Once the codes have been recognized by the scan tool, they can be cleared to turn "OFF" the CEL.
Figure 38-26 Vag-Com Setup on Beetle TDI
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Road test the Beetle for proper operation.
Flat-blade screwdriver
Single-edge razor blade
Gasket scraper
Nickel
Safety glasses
Battery maintainer
Battery charger
Memory keeper
Wheel chocks
5mm 3/8-inch square drive socket
3/8-inch square drive ratchet
1/4-inch square drive ratchet
1/4-inch square drive 10mm socket
13mm 3/8-inch square drive socket
3/8-inch square drive long extension
Digital multi-meter (DMM)
Hydrometer
Battery load tester
Replacement battery
Vag-Com scan tool
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