Its under the front bumper inside that flip up door on the passenger side. Do you have your owners manual for the car?

You realize you could also just charge up the battery nice and full then drive it home....it should easily last the trip especially if all un-needed things are turned off like the radio and climate control etc...

Thanks for all your help. Other than jump starting I dont have a way to charge the battery and I dont know if that would be a good enough charge. I'm actually paying $65 for the tow. Once it is home I can figure out if its the voltage regulator or the alternator without worrying about the car being towed away. It is in a restaurant parking lot that has towing sign warnings all around for customers only so I'm nervous of leaving the car there. If the car dropped dead again on the highway coming home I would be in worse shape. I hate spending $65 for a tow after spending $40 on a cab this morning/last night but I'm just going to have to bite the bullet. Usually I would ask my dad for help but he just had major heart surgery and is not doing well. I'm just going to have to choke on the $105 wasted on the cab and tow. I really do appreciate everyone's help. Once I get it home I will try to fix it. I do think there is a chance it is the regulator. The symptoms sound similar and those bushes are only a little more than half way of a new regulator I saw (not the same model as mine).

Just jump start it and drive in 3rd. The higher RPMs will charge the battery faster. It does, however, sound like the battery has failed.

One other thing to check on the car before spending more money is the cables. Make sure the plus and ground cables have solid connections and no significant corrosion. I once had a Golf where the gremlin turned out to be the plus cable corroded up inside the insulation (voltage drop between battery and alternator ends provided the clue). And I know we all have discovered loose terminals even when we were certain it just couldn't be the case.

Yay my 16 year old car is home. Battery had enough power to lower the windows despite sitting all day in the hot sun. Last night it did not have that ability. The cables are tight. I installed the battery a couple of years ago. I think it is probably alternator or voltage regulator related because of the symptoms. The car just died while driving. I figure if the alternator and voltage regulator were working correct the car wouldn't just die while driving even if the battery got weak.

2 questions for the experts. :)

1. Does it mean anything that my battery seems to have a lot more power now than it did last night or this morning. I took the voltage regulator out. Could that be why?

2. I'm almost tempted to try and start it with the voltage regulator out. Would that be bad? What would happen if it did start without the regulator in the alternator?

1. After a lead acid battery sits for a while it will "re-gain" some of its energy, but it will quickly run down again if a load is put on it.

2. Don't start the car with the voltage regulator missing, that can damage the alternator/electrical system. :eek:

spree17, the voltage regulator brushes appear OK to me. Before buying a new voltage regulator remove the caps on the battery and check the water level ... add, as required. New Interstate batteries from a MB dealer typically last 4 years.

FYI: Your post motivated me to check my battery's water level. The cells were "dry" -- no visible water, and required about 6-8 ounces of distilled water to refill.

Perhaps add that to your To Do list.

Thanks for all the responses. I dont have a mercedes battery. I have a Walmart battery. I will check the water on it. I'm surprised you guys think the brushes are ok on the regulator. They were worn down around half the size of a new one. They had steep concaves and the brushes were not even. I wish I could narrow it down to the battery, regulator or alternator, so I dont waste money. Maybe I should disconnect the battery and bring it to autozone? Will they do a free charging and test? I would not mind buying an alternator replacement for $107 from Autozone BUT it seems like a big job to switch them out

Mr. Spree,

I wish your dad a full speedy recovery.

Although the brushes are not worn down, the regulator may be faulty. Most regulators fail due to worn brushes but the electronic or soldered components can fail and cause the alt to not charge.

now that your car is home, top up the water level and charge the battery.

Re install the regulator (with battery disconnected) then get a voltmeter (multimeter), If you don't have one get a friend to come over with one and help you out.

Check battery voltage - should be 12 volts or more. Now start the engine, the battery voltage should now read 13 to 13.5 or 14 volts.

If the battery voltage stays the same as with the engine off (12v) that indicates the regulator is faulty and should be replaced. Given that all connections are clean and tight.

Please note that when my regulator went bad, I was able to gently tap it with a screwdriver handle and it would kick in and work so I could drive the car to get a replacement, of course this was specific to the problem with my regulator at that time but it is something to consider for anyone in that situation.

I suggest this test but replace the regulator with a new one.

About the battery test, call ahead to see if they can do it, I know Canadian Tire or Part Source have the right equipment and offer free diagnosis. The battery must be fully charged prior to being tested and they should have the proper tool to put the required electrical load on it for testing as well as looking for shorted cells.
Good luck with it,
Acky

Acky,
Thanks so much for the kind words and all the detailed suggestions. I just tapped off the battery with water. The battery was very dry. I thought they made no maintence batteries now.

My current problem is I'm having trouble getting the regulater back in. I'm doing this from on top of the car. Do the bushes have to be depressed to get it back in? Are there any tricks to getting it back in? Any advice would be greatly appreciated as always. :)

You are most welcome.

I assume you are installing the new regulator to save a step and also these are usually not returnable.

As you install it, understand that the brushes will press upwards and compress the springs in the brush holders. Angle the regulator and position it at the bottom of the opening, then set it flat against the back of the alt while pushing it up into position to line up the screw holes. You must hold it in this position, as the brush spring tension will be forcing it down and on an angle.

You will see clearly what I mean once you try to line it up. It’s easier from the bottom because things are much more visible from below but you will get it in. Just take your time.
Acky

I'm trying to put the old part back in to see if the water helped the situation. I have to try and do it from up top from feel where I'm basically blind. I can get it in there. I'm just concerned I could be doing it wrong. I'm also concerned that I cant see the screw holes because the screws I took out seem like they can just fit in and out of the holes with little screwing needed.

Use a mirror, propped up and angled so you can see what you are doing. Also use a light. You can thread the screws in to just make sure the threads are not stripped.

Unfortunately we don't know what has been done in that area in the past.
Make sure the battery gets a full charge and test as required.
Acky