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The Vanagon Charging System:

February 6, 2015 4 Comments Electrical Ken Wilford

Checking out your charging system:

It is always a good idea to occasionally check the condition of your charging system. This is the system that keeps your battery charged so that you can power your electrical items while driving down the road and also keep your battery up so that when you hop in and turn the key the van cranks right up and you are off on another adventure.

What to do? First check your voltage at the battery while the van is running. You do this with a cheap voltage tester or just take the van to your local Advance Auto/Autozone and they will do this test for you for free. You want to see between 13.5-14 volts. Some early Vanagons require you to give the accelerator a little rev before the alternator will “come in” and start working so be sure that you do this and your alternator light is out before you do the test. If you get a low reading that means that either your battery is dying or your alternator is on the way out or both. With the van not running test your battery. It should read around 12.5 volts with nothing on and the van not running. If you have a secondary battery unhook it so that you can test your main one by itself without the secondary one causing a false good reading. If your voltage is low then you are probably looking at a battery that is failing and it should be replaced. Sometimes batteries that are dying will take what is called a “surface” charge where they will seem like they take a charge and will test good immediately after you stop charging them but then a few hours later they have lost their charge. If you are having problems with a battery that doesn’t seem to hold a charge you should let it sit over night (unhooked) and then test it in the morning. That way you can see if it is holding a charge on it’s own. If it isn’t then it is bad and need to be replaced. If it is then something is draining it overnight and you need to test for that.

Many times you will find that a failing battery will kill an alternator or a failing alternator can kill a battery. Usually it is a good idea to replace both at the same time unless one or the other is brand new. Although this can be expensive it is the best way to not only ensure that your charging system is up to snuff but also ensure that your new battery or alternator will live as long as possible.

Now check your belts. The best way to check your belt for the charging system is to loosen the alternator and relax the tension on the belt. Now turn it so that you can see the inside of the belt that rides on the pulley. It should be in good condition, not shiney or worn down and with no heat cracks between the ribs. If it has any of these it should be immediately replaced. With the belt loose or off check your alternator bearing for play. Try to cock the pulley top to bottom or side to side. There should be minimal to no play in the pulley while you try this test. If you can feel the pulley cocking and you hear a “clunk, clunk” noise while doing this test then your bearings are going bad and you will soon need a new alternator even though it may be putting out proper voltage at this moment. Spin the pulley and listen for any funny noises and be sure it spins freely.

While you are in there do the same pulley cocking test on your water pump pulley. It too should have minimal play (a small amount is OK but no real looseness). Take a flashlight and look at the weephole underneath the pulley (straight below it). If it looks like green crust is around it your water pump is starting to die and should be replaced. If this locks up it can kill your motor so change it before that happens not afterward. Also check the condition of your other belts (A/C and power steering) and replace them if they need it. They can fail and take the alternator/water pump with them so it is good to be sure they are in good condition as well.

After installing a new alternator belt it is normal for the belt to stretch over time. You want to tighten it on initial install so that there is less than 1/2 inch of deflection when you push down on the belt with your finger in between the alternator and water pump. After about a week, check the belt tightness again and retighten as needed. DO NOT ignore your van when it makes squealing noises when you first start it up in the morning. This will lead to a broken belt which can take the dipstick tube and even the oil filler neck along with it (not to mention allowing the engine to overheat and self destruct).

Here at Van-Again we stock only the best quality Bosch rebuilt alternators and Continental (German) belts to keep your van happy for many years to come. A cheapy spray-paint “rebuild” alternator may be OK if you are stuck out in the boon docks on a vacation trip, but since you are doing these tests you have enough time on your hands to plan ahead for a quality rebuilt alternator and belts. It will pay off in the long run believe me.

Keeping your charging system in good repair will help you save money in the long run and also have a safer, happier Vanagon.

Copyright Van-Again 2015


Ken Wilford December 22, 2017

When you turn on the key, the red light should light. If it doesn't then either the bulb is burnt out, there is a problem with voltage to it, or the ground for it. The ground is actually the blue wire to the alternator. When the alternator isn't working, the blue wire provides a ground path for the alternator light. Once the alternator starts working above a certain voltage, the ground path goes away and the light goes out. Does this help?

navypo1 December 21, 2017

How do I test the charging system LED? Im getting something like 5v on the blue wire and the alternator is charging the battey. Just no red light when key is on and engine not running. 1983 diesel

Kenneth Corriere August 2, 2017

This is kicking my butt. I put in a new 1100 amp battery, new diodes in the alternator. Put an amp meter in series with the battery {no loss}. I replaced all bulbs with LEDs {except head lights}, However, three days of not driving the Vanagon the battery is at 12.3 volts and it won't even turn over. Recharge the battery it works great. If you drive it every day there are no problems. Just don't take the chance of going camping. You MIGHT have to walk home.

sean June 12, 2015

Darn right. I bought a cheap one from the (another vendor). NO BLUE TICKLE wire! And its a stupid self exciting one. Wish i knew that before i bought it. Now my camping relay is hot wired. Buy a good Alternator from these guys! (edited by me)

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