140A -> 250A alternator upgrade

[fekillix]

Hello folks.

I have my HPFP out for refurbishment and I've noticed how good access I now have to the alternator, it is usually sandwiched between the HPFP and the AC compressor.


The 250A alternator appears to me to have the same size pulley, same connector and power terminal (albeit placed differently on the back).

The 250A appears to have a bit more junk in the trunk, but the mounting points to the engine case look to be the same.

I've seen a lot of talk about it here but has anyone done the upgrade? My alternator has 220K km and is 14 years old, so I thought spending €200 on a younger 250A unit isn't a bad idea as it could potentially power one heck of a DC/DC charger for a secondary battery in the future, and then I know it won't fail in a few years time being a cumbersome job to replace. I have a CAAC engine T5.1.

Best regards

 

[fekillix]

After more research, I've discovered the connector is different. The 250A unit uses LIN communication while my 140A does not.


So although the 250A unit appears to bolt in (I found a spec sheet with the dimensions), I suppose I'd get dash messages.

The 180A unit from the T6.1 part 03H 903 026 uses the same connector as the 250A and LIN.

So my conclusion is that the 250A upgrade is only possible on the T6.1 unless someone makes a LIN->DFM adapter.

 

[meza]

Go with the 140a and spend the difference on as much solar as you can cram on your roof?

Good research on the plugs.

 

[fekillix]

Go with the 140a and spend the difference on as much solar as you can cram on your roof?

Good research on the plugs.

I am a bit stubborn. There are no good second hand DFM alternators available. I suppose I could buy a new quality 180A for €250-300.

For barely used 3-5 year old sub-10K miles VW LIN alternators there are plenty available from €100 (180A) to €200 (250A) from crashed VWs.

I am going to do a bit more research. My van is neither Bluemotion nor does it have start stop, so it might only use the "LAMP" cable. If so, a LIN alternator might be possible as after some googling, LIN alternators should work fine without LIN BUS, they just won't do recuperative braking or signal for start/stop. I need to learn a bit more about the LAMP signal before buying a 250A unit and checking if my alternator plug has one or two pins.

 

[Stefan]

I’m considering too to upgrade my 180A alternator to an 240A one. This is on a eu5 T6 bluemotion with auto start stop CAAC engine. Wondering if its a straight swap so i can have it done while the cambelt work going

 

[fekillix]

I’m considering too to upgrade my 180A alternator to an 240A one. This is on a eu5 T6 bluemotion with auto start stop CAAC engine. Wondering if its a straight swap so i can have it done while the cambelt work going

The fool proof way to check would be to unplug and look at the communication connector on your current alternator, or look up the part number of your alternator and see what it has. I would be surprised if you have the newer LIN communication but it is uncharted territory.

There is also the possibility of replacing the LIN regulator on the 250A alternator for a DFM regulator from a regular 180/140A, if both are made by the same OEM they might be interchangeable (research required).

I ended up replacing the regulator (with brushes) and pulley on my alternator. They say the alternator brushes are good for about 250K km and I think that's not far off. Mine had about 30% of the original brushes left at 220K km.

 

[Stefan]

The fool proof way to check would be to unplug and look at the communication connector on your current alternator, or look up the part number of your alternator and see what it has. I would be surprised if you have the newer LIN communication but it is uncharted territory.

There is also the possibility of replacing the LIN regulator on the 250A alternator for a DFM regulator from a regular 180/140A, if both are made by the same OEM they might be interchangeable (research required).

I ended up replacing the regulator (with brushes) and pulley on my alternator. They say the alternator brushes are good for about 250K km and I think that's not far off. Mine had about 30% of the original brushes left at 220K km.

 

[fekillix]

Very interesting. Looks lin LIN to me. Only one pin in the connector and the key looks right. The pulley diameter is different so the 250A spins faster but that's intended. Looks to be the same amount of teeth.

Also, I don't know if I said it or not but removing the alternator out the top was a real pain in the ass. Going the bottom route looks way easier in the videos I've seen.