Gnomeish

Battery not charging - alternator or something else?

25 posts in this topic

Hello all,

 

I've got a 2006 Smart Fortwo. Just over 60k KMs. Got it about a year ago. Still very bad at all things "car" - so forgive me any ignorances.

 

Last Thursday I messed up and left my car lights on while at work. Came out after to nice and dead battery. I got a jump from a co-worker, drove home, and didn't think too much of it. I was sitting in my driveway looking up on my phone how long to run my car to charge the battery when it died on me. I thought it was weird, but I hooked up the battery to a charger and went to work the next day and everything seemed fine. By Saturday, the red battery light was on.

 

On Monday picked up a fresh battery, cleaned all my terminals, and swapped it out. I checked all the connections I could see and they all seem tight and clean. Again, things were fine the next day. Wednesday, the light was back.

 

This entire time, since that jumpstart, I've also noticed my headlights flashing a little brighter every 4~5 seconds for a split second. This would go for about the first five minutes of my drive before it would stop/

 

When I tested my new battery, I was seeing around 12.9v when the car was off, and when I would turn it on, it would spike to 14+ for a moment as I could hear the alternator attempting to go (and it would, for a second, before shutting off) and then drop again. Revving the vehicle didn't change this much. I assume this is about the same timing as the issue with the lights.

 

I've read every topic I can find about battery issues and alternators, but I've not read much about this particular issue. Everything was totally fine before the jump (I confess I know very little about jump starting, and I'm not sure if my co-worker did it in a safe way or not). It seems like the alternator CAN work...something is just stopping it from working? I don't have a jack or anything to get a good look under my car and I can't seem to locate or see the state of my alternator. From what I've read, my only guess is that the jump was bad and it did something to a connection or wire or fuse or something? I've read that the alternator has something that regulates the voltage it should be getting and so if something is weird, it might keep shutting it down...?

 

If anyone has simple ideas for me to test, please let me know. If you think this just sounds 100% like a bad alternator...ouch...I'm not in a great place to drop a ton of money on that right now. Would love any information you can give!

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Posted (edited) · Report post

worst case scenario is getting an alternator from rockauto...last time i checked they were around $165....plus small shipping fee and hst..no brokerage charges the way they ship

 

 

also check your ground strap on rear of trans area...it might be loose or rotten

 

 

your alternator is on front right of engine...

Edited by LooseLugNuts
spell check

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165? Wow, that is definitely a lot less than I expected. That is very good to know, thank you.

 

I'm not quite sure what you mean by ground strap on rear of trans area. Do you have a picture or something of where that would be?

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Is 2005 same alternator as 2006?

 

 I’m surprised to see this available from the US since they never sold the diesel in the US, I had pay way more than that just to get mine rebuilt and it took forever to get parts for the rebuilt.

 I’m almost tempted to buy one as spare since it’s the only part that has failed me since I bought the car New in 2007.

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The 2005 and 2006 are the same.

Changing the alternator can easily turn into a 3-4 hr job, especially if you're doing it yourself in a cold garage.

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Posted (edited) · Report post

the info shows 05 06 and 07 cdi for that alternator 

 

Buyer's Guide : POWER SELECT 23901N Alternator / Generator
SMART FORTWO 2005-2007
Please refer to catalog for application details.
 
 
also if youve never ordered from rockauto dont worry its easy...they charge the duties/taxes themself so no surprise brokerage fees when it arrives....total price is shown before you pay
Edited by LooseLugNuts

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8 hours ago, LooseLugNuts said:

What about the core charges? They always want the old alternator when buying a rebuilt

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On 2/2/2018 at 9:32 PM, Gnomeish said:

Hello all,

 

I've got a 2006 Smart Fortwo. Just over 60k KMs. Got it about a year ago. Still very bad at all things "car" - so forgive me any ignorances.

 

Last Thursday I messed up and left my car lights on while at work. Came out after to nice and dead battery. I got a jump from a co-worker, drove home, and didn't think too much of it. I was sitting in my driveway looking up on my phone how long to run my car to charge the battery when it died on me. I thought it was weird, but I hooked up the battery to a charger and went to work the next day and everything seemed fine. By Saturday, the red battery light was on.

 

On Monday picked up a fresh battery, cleaned all my terminals, and swapped it out. I checked all the connections I could see and they all seem tight and clean. Again, things were fine the next day. Wednesday, the light was back.

 

This entire time, since that jumpstart, I've also noticed my headlights flashing a little brighter every 4~5 seconds for a split second. This would go for about the first five minutes of my drive before it would stop/

 

When I tested my new battery, I was seeing around 12.9v when the car was off, and when I would turn it on, it would spike to 14+ for a moment as I could hear the alternator attempting to go (and it would, for a second, before shutting off) and then drop again. Revving the vehicle didn't change this much. I assume this is about the same timing as the issue with the lights.

 

I've read every topic I can find about battery issues and alternators, but I've not read much about this particular issue. Everything was totally fine before the jump (I confess I know very little about jump starting, and I'm not sure if my co-worker did it in a safe way or not). It seems like the alternator CAN work...something is just stopping it from working? I don't have a jack or anything to get a good look under my car and I can't seem to locate or see the state of my alternator. From what I've read, my only guess is that the jump was bad and it did something to a connection or wire or fuse or something? I've read that the alternator has something that regulates the voltage it should be getting and so if something is weird, it might keep shutting it down...?

 

If anyone has simple ideas for me to test, please let me know. If you think this just sounds 100% like a bad alternator...ouch...I'm not in a great place to drop a ton of money on that right now. Would love any information you can give!

Here are a few tips to check.

NOTE: to replace the alternator in a Smart car the motor needs to be lowered.

 

 

The First Things to Check

 

 

When the battery goes dead, the condition of the battery and the alternator are two of the first things to check. However, do not assume that if the battery is good then the alternator must be bad and the cause of the problem. Here are a few tips on how to use common tools to diagnose charging system problems to prevent unnecessarily replacing the alternator. These are general suggestions that may not apply to every car. .

  1. Using a multi-meter, measure the voltage across the battery posts with the engine off. It should be 12 or 12.5 volts. If it is less than 12 volts, then the battery needs to be charged, something is draining the battery or the battery cannot hold a charge and needs to be replaced.
  2. If the battery voltage is around 12 volts, then start the engine and again measure the voltage across the battery posts. It should have increased to 13 or 14 volts if the alternator is working and charging the battery.
  3. If the battery voltage did not increase with the engine running, then verify the alternator and battery have good electrical connections. Make sure the battery cable terminals are tight and free from corrosion. Look for loose connectors or frayed cables. Use the multi-meter or a test light to verify the body of the alternator is grounded (zero resistance between the alternator and negative battery post).
  4. If the battery voltage is well above 14 volts with the engine running, then the alternator could be producing too much current and overcharging the battery. Maybe the voltage regulator (internal to some modern alternators) is bad. Or the battery is weak and a vehicle computer has temporarily raised the voltage limit. It might still also be bad connections or loose wiring. Some vehicle lights being brighter than others can be a symptom of this type of problem, because the alternator produces more energy to overcome the resistance of a bad wire or connection.
  5. The condition of the alternator belt is the next thing to check. Of course make sure the belt is not broken. Also look for a belt that is loose and slipping. It would probably be making noise.
  6. If in step 2 the voltage across the battery terminals was 13 to 14 volts with the engine running, then the alternator is properly charging the battery. That is good news, but there is another alternator electrical problem to check for. Sometimes an alternator can charge fine when the engine is running but drain the battery when the engine is off. It probably has something to do with the rectifier diodes in the alternator not properly blocking current from draining away from the battery. This problem may be intermittent. . Disconnect all the electrical connections from the alternator when the car is put away for the night. If the battery never goes dead with the alternator disconnected but goes dead when the alternator is hooked up, then that might point to an alternator diode problem.  The diodes are buried so deep inside many modern alternators that replacing the entire alternator is often the most practical option.
  7. If the battery goes dead when the car sits (engine off) with the alternator electrical connections disconnected, then something else is draining the battery. Check first for the most obvious battery drains such as any lights left on (headlights, trunk light, ashtray light, etc.). After that it gets harder to track down the problem especially on modern cars.
  8. Finally, there are the mechanical alternator problems. Unusual screeching or grinding sounds might come from a bad bearing in an alternator. However, the noise might also be coming from a loose belt, misaligned pulleys or worn out belt tensioner. Use an automotive stethoscope to verify where the noise is coming from. Avoid damaging new alternator bearings by making sure the belt pulleys are aligned, the belt tensioners are good, the belt is not over tightened, the alternator mounting bracket is not cracked or that there is not some other mechanical problem.

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1 hour ago, caldense said:

What about the core charges? They always want the old alternator when buying a rebuilt

 

check the car out first

 

then worry about replacing it if it fails your checks

 

im starting to think you didnt even click the links because it clearly shows no core charge..in stock one is 100% new....the rebuilt one is out of stock and has no price showing so no way to tell but i do know that normally you have to cover shipping to get the core charge back...and if my memory is right rockauto lets you pay less than normal for shipping by printing up a label under their account

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Wiring diagram of heater boosterSAM.pdf

Above diagram also shows alternator.

 

Check interior engine connector X26.  Check connection D+ at alternator.  Disconnect D+ at X26 and wire in test lamp about 5 Watt between D+ and battery plus pole, then start engine and check battery voltage.  Alternator will now be confirmed faulty if voltage does not rise above 13.5 Volt.

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This just happened to us, intermittently working voltage regulator on a new/exchange alternator.  Get a ScanGauge and check the V when driving.  If it's under 13.7V at the peak, the alternator is toast.  It won't charge a battery below about 13.5V.  It's a pain of a DIY job so I had the dealer do it and they ended up doing it twice, once for free due to the bad replacement alternator.  If you pay someone to do this, have that person or shop check the intercooler for chafing holes too.

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Regulator assembly is cheap. Bosch part number F 00M 144 137. 

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roughly 100 bucks

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Share your sources?  I have a spare one to re-regulate.

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7 hours ago, tolsen said:

Wiring diagram of heater boosterSAM.pdf

Above diagram also shows alternator.

 

Check interior engine connector X26.  Check connection D+ at alternator.  Disconnect D+ at X26 and wire in test lamp about 5 Watt between D+ and battery plus pole, then start engine and check battery voltage.  Alternator will now be confirmed faulty if voltage does not rise above 13.5 Volt.

I have no clue where this X26 is located in the SAM unit? This may make sense to someone who has opened the SAM up and traced the circuit but is totally useless to anyone else. Why would you post something so complicated when there is an easier method of explaining this?

 

x26.png

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Just a simple electrical diagram.   Of course drawing does not indicate X26 is inside SAM.  

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Yeah, considering how difficult the altenator is to RE&RE, no.

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= difficult.  I can do my 404 alternator in three minutes flat.

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