How long will battery last without alternator? - PeachParts Mercedes-Benz Forum

thelazzarusman · #1 08-09-2008, 12:20 AM

This is the third month of my alternator and battery woes with the SDL. I had a dead battery in May, replaced it, found the new one soon dead in June, determined the alternator was the problem, replaced the voltage regulator in July, and ran fine for three weeks. Now the battery is no longer charging. I'm in middle-of-nowhere, SC, on Friday night. The local stealership doesn't have voltage regulators or alternators available, and wants me to wait until next week.

Problem is I have to be in Baltimore/DC by Sunday--an eight hour drive. Since I can charge the battery and jump the car with my handy portable device, how many hours, roughly, can I run the car with "normal" operation (i.e. with A/C on low, lights only if necessary during daytime, wipers if raining) if the alternator isn't putting any juice back into the battery?

Of course, I'll get her fixed as soon as I get where I'm going, so this won't be a torture test.

Your wisdom is appreciated!

DL

dkveuro · #2 08-09-2008, 12:26 AM

Less than an hour with those consumables on..

Main problem is bushes or regulator.... next highest is Blue wire from alt' cut or broken....then of course loose/missing belt.

BATT - Ground tight near hood hinge ?

Then check the plastic connector holder on the passengers side front inner fender..three wire loom...most all Red.... to starter and charge system..can burn..loose...etc.

Pull fuse cover and roll over all fuses as can corrode in holders .\

Check on Saturday with all the local auto parts houses..NAPA often stock the reg's and occasionally the alt'.

nickofoxford · #3 08-09-2008, 03:29 AM

with AC, lights, wipers when needed.. you'll get 2 hours at the most. my 240D has a newer battery (about a month or so old) and im installing a whole new exhaust system on it, so can't run it too much without annoying the neighbors and smoking up my garage

i've been listening to the radio, loud enough to hear while im under the car working on rust everyday for the past week and she still cranked over fine this afternoon to put all four wheels on ramps

so if you're just listening to the radio with the AC blower on low you'll be alright, lights will kill you though.

Brian Carlton · #4 08-09-2008, 09:02 AM

Your problem is the lights and the wipers. The a/c draw is about 3 amps.

If the battery is fully charged and you only have a 3 amp draw from the a/c and some minor draw for the gauges, I'll bet you can go 6 hours with it.

Remember, the worst that can happen is that you lose the a/c and the radio.......the engine won't stop.

Once you need lights and wipers, all bets are off.

I drove the SD for two hours with no alternator.........no lights or wipers..........it had plenty of power for that trip.

One additional assist: If you can connect the portable device to the battery and secure it, you'll have that much more reserve capacity for the trip.

lowriderdog37 · #5 08-09-2008, 09:51 AM

Your car will run forever without a battery, after it's started of course. Given that, I would suck it up and put the windows down, cut the radio and drive during the day. That way you would have some battery left if you required the lights or wipers along the way.

Only for emergency use of course...I would never run my car like that for weeks, push starting everywhere I went.

kerry · #6 08-09-2008, 10:33 AM

I agree. Drive during the day, open the windows, put Rain-X on the windshield and use an IPod. You could drive across country.

tangofox007 · #7 08-09-2008, 10:39 AM

A cold front has just moved through SC and high pressure influences the area today. Temps will be mild for August. (I almost needed a jacket when I went out to get the newspaper this morning!!!) Put the windows down and drive. Aside from afternoon thunderstorms, you won't need the lights or wipers.

And fill up your fuel tank before you leave SC. And don't stop at "South of the Border!!!"

Jeremy5848 · #8 08-09-2008, 11:07 AM

Quote:

Originally Posted by kerry

I agree. Drive during the day, open the windows, put Rain-X on the windshield and use an IPod. You could drive across country.

All I can add is . . . minimize turn signal use, don't shut the engine off at stops (use a second key, if you have one, to lock/unlock the doors from the outside), if you need fuel, go to a truck stop where no one will notice your engine idling.

Jeremy

tangofox007 · #9 08-09-2008, 01:14 PM

Quote:

Originally Posted by Jeremy5848

don't shut the engine off at stops (use a second key, if you have one, to lock/unlock the doors from the outside

Or better yet, remove the vacuum line from the shut-off solenoid and remove the key and take it with you. The steering lock will prevent the car from being driven, even though the engine is running. (Which is not to say that you need to leave the engine running; a decent battery should be good for a few dozen starts.)

lowriderdog37 · #10 08-09-2008, 01:56 PM

Quote:

Originally Posted by Jeremy5848

All I can add is . . . minimize turn signal use, don't shut the engine off at stops (use a second key, if you have one, to lock/unlock the doors from the outside), if you need fuel, go to a truck stop where no one will notice your engine idling.

Jeremy

Or if you want to have fun like I do...go to any gas station, leave the car running and when somebody pitches a fit, remind them that diesel fuel isn't flammable, it's combustible. If they don't believe you, get a cup's full of it, take it away from the pumps, then light a match and drop it in the cup.

ichbineinekrous · #11 08-09-2008, 01:59 PM

I made it from southeastern PA to between DC and Richmond at night with a charged battery and no alternator. Using headlights. I pulled into a Wal-Mart, it was the only thing open at 9pm, bought a new battery and almost made it to Raleigh, NC. Drove the last 45 miles with no headlights. Luckily it was a full moon.

lowriderdog37 · #12 08-09-2008, 02:06 PM

wow, that a lot of batteries. Do you have a charger you can recharge with overnight? It'll probably cost less than buying all those new batteries.

Ryan Z · #13 08-09-2008, 02:35 PM

If you ever find out the cause of your failed alternators, let us know. I'm on my 4th one in a little over a year. Maybe you will find the common cause of electrical trouble.

----------------------
1984 MB 300 SD Turbo

Jeremy5848 · #14 08-09-2008, 04:07 PM

Quote:

Originally Posted by tangofox007

Or better yet, remove the vacuum line from the shut-off solenoid and remove the key and take it with you. The steering lock will prevent the car from being driven, even though the engine is running. (Which is not to say that you need to leave the engine running; a decent battery should be good for a few dozen starts.)

Clever, I'll keep it in mind "just in case."

Jeremy5848 · #15 08-09-2008, 04:14 PM

Quote:

Originally Posted by lowriderdog37

Or if you want to have fun like I do...go to any gas station, leave the car running and when somebody pitches a fit, remind them that diesel fuel isn't flammable, it's combustible. If they don't believe you, get a cup's full of it, take it away from the pumps, then light a match and drop it in the cup.

You can do a similar trick with gasoline. Many years ago, living in Tucson, I was working (outside) with a small cup of gasoline, cleaning some parts. Up walked neighbor "Rocky" and showed me how he could drop his lit cigarette into my can of gasoline and it would just go out. I was backing away at the time

but he was right. Not sure about a lit match, though.

OTOH, I did an experiment with biodiesel (B100) and had a hard time getting a shallow pan of it to ignite, even with a torch (MAPP gas too, not just propane). When I finally got it hot enough, it did burn quite nicely but it took awhile.