Hey Guys,

This one is a bit strange. Today I woke up to a dead car. When I hit the unlock button on the fob the car would beep really quietly but wouldn't unlock the doors. So I manually unlocked the driver door and tried to start the car with no luck. I hooked the battery up to a battery charger for a little over an hour, started the car no problem, and went for a 30 minute or so drive. Hours later and the car is now completely dead. When I hit the unlock button now the car doesn't even beep anymore.

I had the alternator replaced early this year.

Any ideas what may be causing this? I'm going to hook the battery to the charger overnight tonight.

Thanks in advance!

 

Your alternator may have been a dud.

Did you rebuild your old unit or get a rebuilt off the shelf. Rebuilding your own is usually the preferred alternative.

 

Get it started again, then measure voltage at battery with engine running well above idle. Should be between 13 and 14.5 Volts DC... if below the alternator is likely not doing its job.

 

It was replaced with an OEM alternator. I do have a warranty on it.

 

Thank you for the tip, I will give this a try tomorrow morning!

 

This could have several possible causes:

1) The battery itself is failing

2) The alternator is faulty

3) The false bulkhead connector under the bonnet is faulty or intermittent. This supply line is critical as it supplies both the high current to the starter, and also the charging current from the alternator back to the battery. If this connection corrodes or fails, then it will prevent the starter from obtaining the high current needed & will also prevent the alternator from properly charging the battery.

As advised by QuadManiac, you need to measure the voltage at the battery with the engine at a fast idle speed-above 1000rpm. You should see around 14v with no heavy electrical loads switched on.

Progressively switch on the heavy electrical loads like the headlights (main beam), foglights & heated rear windscreen. Raise the engine speed to around 1500rpm & check the battery voltage again-it should be well above 13V & should really be around 13.5v or higher.

If you're getting below 13v or have dropped down to around 12v with a heavy electrical load at a fast engine idle speed, then either the alternator is faulty or the false bulkhead connection is failing & preventing the proper charging current from reaching the battery from the alternator-this is quite a common fault as the connector can corrode.

Also, don't rule out a faulty battery-they should never be left in a discharged state as they can sulphate & won't recharge properly.

Another possibility is that the battery is gradually losing charge to 'residual/parasitic current drain'. This is where some of the car's electrical circuits do not shut down completely when the car is locked for the night & continue to draw a small current which can flatten the battery over a period of a few days. The usual suspects for this are the alarm circuits, glovebox switches leaving the light on, security systems & phone circuits etc.

 

(1) If you have either had or have given a Jump Start

(2) Charged your Battery without disconnecting one of the Terminals first

(3) Had any welding done on the car (ie) exhaust pipe (muffler) etc

Then anyone of the above could 'toast' the diodes in your alternator

But my bet is that you have a leakage to earth, that could be caused by any number of things including condensation or wet weather

Have your battery tested, as if its old then it may not be holding its charge, or may even be resistant to being charged altogether.

 

I had an Interstate Battery that would test fine when I took it into the Interstate dealer TWICE. But, I'd occasionally come out in the morning to a dead battery. Also, if I checked it at home with my battery charger/tester, it would test fine MOST of the time, but once in a while, it would give me a code for an internal break. I believe it was an intermittent break inside the battery.

I replaced the battery and never had the problem again.

 

I haven't had a chance to test the voltage, but here's a quick update on what the car is doing today.

I had it on charge overnight and it started just fine this morning. Upon starting it I had an engine light which came up as a "ECM control relay." I cleared the code and it hasn't come back yet.

Also I did notice a little moisture down where the spare tire sits in the trunk. Not much, but there are a few drops of water.

 

Another possibility is that your battery may have a dead cell, which is another possible cause that I am leaning towards.

The reason being that with a dead cell, you may be able to charge the battery enough to start the car but when you switch on all the gizmos like Headlights/Aircon/Stereo/ etc The Battery can then go quickly down hill.

A normal voltmeter won't tell you much, you need it properly tested under load at a garage (which takes just a couple of minutes)

If you are using a battery charger, its always better to take the battery off, or at least disconnect one of the battery terminals, as a spike of current can take your alternator diodes out.

A dead cell can happen because of the age of the battery/lack of maintenance if the battery is not maintenance free or even overcharging.

The more times you disconnect/reconnect your battery, the more chance there is of a 'possible' spike that could mess up your ECM relay and if that goes wrong, you are looking at serious money.

So best to get the problem sorted out ASAP

 

Unfortunately I didn't disconnect the battery while using the battery charger. Wish I did.

I've cleared the code on the car and when you go to start it the next time it will reappear.

The code is P1606 - ECM Control Relay Output Circuit. I've never had this code come up in the past.

 

This would imply that the ECM is sensing low current at its power supply. That is consistent with a battery/charging circuit problem.

So, if you can chase that down it will go away.

Try disconnecting the battery ground and trickle charging the battery for a full 24 hours.

Then connect the negative cable. Wait ten minutes for the voltage to stabilise and measure it. Come back in two hours and measure it again. What you are looking for is excessive drop in voltage indicating a current leak somewhere.

Of course, if you are up to it, you can measure current leakage between the alternator output and ground with the key off. It should be zero. Otherwise, suspect the diode pack or regulator.

You can also trickle charge as above, start the car, stop the car and then disconnect the negative cable again. Come back in 24 hours, reconnect and start again. What you are trying to do is to prove or disprove that the battery is the culprit. If the car starts fine, it is not the battery.

Moisture in the trunk is also a problem that needs to be attended to before the electronics under the fusebox are affected. Is the top of the battery clean and dry. If not, it is a leakage path between positive and negative poles. If there is a greasy looking film on top, clean off with a mix of warm water and baking soda on a rag, and dry it off with paper towels.

 

So I took the battery to my local Canadian Tire and they tested it. The results said the battery was absolutely fine. I brought it home, put it back in the trunk and left it disconnected. I tested the voltage the next morning and it hadn't dropped at all.

So now I know it's not the battery and something in the car. I'm going to take the car to the mechanic who did the alternator. Any other suggestions?

 

Start the car & measure the voltage across the battery terminals-it should be close to 14v with no heavy electrical loads switched on.

Then raise the engine speed to around 1500rpm & switch on the headlights (main beam), foglights & heated rear screen-you should be getting at least 13v across the battery & ideally above 13.5v with a heavy electrical load.

If you get below 13v or around 12v, then either the alternator is not charging, or there's a connection problem somewhere-usually the false bulkhead stud in the engine compartment.

 

Where is a reasonable place to buy batteries for a 2001 VandenPlas?

 

Autozone, Advance Auto, O'Reilly, etc. Check the web sites for coupons and sales.

 

The car started and ran for two days without problems and then back to the usual battery issues.

I woke up today to a dead car, tested the battery and it was reading 0.5. I hooked it up to a battery charger for about 10 minutes, unhooked, and re-tested it. The battery now shows 12.00. I hooked the terminals back up and started it no problem.

Can somebody explain this?

 

What voltage do you get across the battery when the engine is actually running? You should be getting very close to 14v. This test will confirm that the alternator is charging normally.

You might have excessive current drain from the battery when the car is locked up overnight-it's possible that not all the vehicle electrical systems are shutting down, and so the battery gradually loses charge overnight.

If you measured the battery voltage on the dead car at 0.5v, then the battery was obviously totally & completely flat as a pancake. It needs to be fully recharged as soon as possible, otherwise it could sulphate & cause plate shorts internally which will render the battery useless.

A fully charged battery in good condition left standing for several hours with no electrical load should show above 12.6v & close to 13v.

If you have residual current drain, you need to remove the battery earth lead & connect a multimeter set to the Amps range in series with the battery negative terminal & the earth lead connection. Then carefully close the boot, leaving the multimeter outside the car for observation. Lock up the vehicle normally & wait for at least 30 seconds for all the systems to shut down. Then check the current reading on the multimeter-it should be less than 0.05 Amps. If you get around 1 Amp or anything around that level, then you've got a problem with electrical circuits which are not shutting down properly & draining the battery overnight.

This is not an easy thing to track down, so patience & a full set of circuit diagrams will be required, so you can individually isolate each circuit & then test for residual current drain.

A likely suspect is the main diode pack in the alternator becoming 'leaky' with age & heat. The diode pack is meant to stop current flow in the reverse direction, but they can become slightly 'leaky' with age & drain the battery charge in a few days.

Either way, there's no quick fix & you'll need to carefully & methodically work your way through the problem-starting first with checking the main system voltage at the battery with the engine running.

 

How do you remove and replace the bulkhead power stud in a 95 jaguar

 

How do you remove and replace the bulkhead power stud in a 95 jaguar xj6