View Full Version : Alternator Question 90 , 120, 150 etc...

10-06-2013, 04:37 PM
My 2004 has destroyed its third alternator and battery apparently says dealer. They wanted $ 1850.00 to replace both. $1200 for alternator :bash:

I see reman Bosch alternators for like $200 with 3 year warranty. The thing I dont understand is each time I bought one from the shop they wanted to put the highest amp rated unit in.

This makes no sense to me as my white box has a radio and thats it. Are they specing the high amp unit because thats what came on mine..... perhaps shipped that way in case end dealer made a conversion van with lots of electrical needs or do I REALLY need the biggest alternator for my basic white box with radio???

Any thoughts greatly appreciated.

Any thoughts on brand or model to purchase also appreciated.


10-06-2013, 04:59 PM
NEW OEM Bosch 150amp alternator on Amazon for less than $200, no core return.
Mine has been going strong for years. I replaced the whole alternator instead of just the failing clutch pulley.
Half hour job to put on a new alternator, 5 minutes to put in a new battery ($100-150 at most parts stores, I recommend Interstate brand, my Bosch batteries have failed A LOT).

10-06-2013, 06:04 PM
Before replacing the alternator, do you know what in the electrical system is causing the alternator to fail?

I would not buy one from the dealer - their prices are inflated for reasons only they can explain.

You can buy new alternators online in the $200 - $300 range, depending on rating. Europarts is another source.
I replaced mine about 3 years ago, it came with a lifetime warranty. If you don't know what your Sprinter was originally equipped with, you can ask for a data card printout from the dealer, or post your VIN. Several forum members have subscriptions to MB EPC - with the VIN, it will display the factory build and you can find out what the original alternator rating was.


10-06-2013, 10:38 PM
I would love to know what size my alternator is, I can't seem to be able to see any writing on it and I'm about to install an auxiliary battery.
If someone could let me know, I'd appreciate it. And if it's possible to send me the factory build sheet, even better.
My VIN is WD0PD644065954964
Thanks in advance!

Aqua Puttana
10-07-2013, 12:24 AM
I can echo that the Bosch 150 amp alternator I purchased from Amazon has been working flawlessly. Over many decades I have had good luck with Bosch products, but I haven't ever purchased a Bosch battery. There have been some negative comments about those around here.

The thing I dont understand is each time I bought one from the shop they wanted to put the highest amp rated unit in.

This makes no sense to me as my white box has a radio and thats it. ...John
A 90 amp alternator should be plenty for what you describe. That said, in the T1N models any size proper Sprinter alternator can be installed. The amp rating of your alternator should have nothing to do with your failure history.

As has been said already, it sounds like you have other problems than the alternator proper.

The Sprinter alternator is not self exciting. There is an input voltage to the field to set the excitation in motion. As I recall, that voltage comes from the ECM via the IC Instrument Cluster so it has ultimate control.

The circuit has been discussed here on the forum. You might try this link for a start.


It points to another thread also. vic

10-07-2013, 12:47 AM
I've been having problems with EPC all day - I'll try tomorrow to find out for you.


10-07-2013, 01:12 PM
My used 02 2500 came with a 90a alternator. I changed that to the Bosch 150a when I did a diy rv conversion in 05. Chose that because commercial Sprinter rvs used that size. (My use was somewhat heavier due to drycamping with an electric kitchen and 4 house batteries.)

Many alternators fit the bolt pattern. My Net alternator expert thought some of the Japanese designs were the best back in 05. But the stock Bosch 150a has proven rugged enough to handle the somewhat heavy duty cycle I have put it through over the last 150k camping miles and 8 years use.

Just a data point. Pretty unlikely that any alternator spec'd for an expensive model would be subpar.

LuckyDawgz Jim
10-08-2013, 07:20 PM
I also bough a Bosch 150amp from Amazon to replace my stock 90amp.
It's still in the box as when I replaced my 90's brush/reg assembly awhile back, it's been working fine and I just did not have the time to swap out a working part.

As others have mentioned the Bosch will be a direct replacement and although a bit larger and heavier it will fit without modification.
Also note that the new one comes with a lifetime warranty (non commercial use) which is another good reason for me to swap out my working 90 for the new one... you always need a spare if you have to send one back for warranty replacement.

(New Bosch 150 amp $175.73 w/free shipping & no core)
Amazon link: http://www.amazon.com/gp/product/B000BZII30/ref=oh_details_o02_s00_i00?ie=UTF8&psc=1

FYI Amazon's part fitment drop-downs do not always tell the truth, or even know if that a year/make/model even existed... although it has been getting better with Sprinter fitments lately.