Gnomeish

Battery not charging - alternator or something else?

17 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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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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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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