55 amp or 65 amp alt?

[willlyons]

So I've searched to no avail...now here's my question oh helpful people...
After all of my electrical problems and checking things out on the car, I think my alt. is shot. I am going to get it tested tomorrow, but just out of curiosity is there any reason I should get the 65 amp alt. over a 55? My car is non-turbo and only has power windows in the front. Everything else is manual, but it does have a "normal" aftermarket radio. Doesnt' seem like the windows/radio would draw much, so should I be good with the 55 amp? That's what discountmbparts.com recommends for an older ('80) 300TD w/o a turbo.
I took the (new) voltage regulator out and everything inside looked normal, or at least not extremely worn. Thanks a lot, I've found tons of useful info on here so far.
Will

[t walgamuth]

if you are going to exchange it anyway, i recommend the 65 amp. of course the regualtor/ brush combo is the usual culprit and can be changed in 15 to 20 min. if you can reach the screws. the last set i bought was about $16, so if you're not sure what is wrong with it i would change that first. good luck.

i find that the 45 a in the 240 d is inadequate on a long trip running the air and will slowly drain the battery. 55a may not, but the one i upgraded i went to the 65 a like is on a 300dt.

[Hit Man X]

I'd go with the 65A if you have to pull it. More amperage is always a good thing.

Have you seen the 115A Saab unit? I was nosing about the local boneyards and I think a Volvo unit will work too... it was 100A I believe. Mounting ears seems the same on a quick look.

[Ganaraska]

I'd use whatever the factory put in. If it's 55 get a 55. Usually the larger alt goes with air conditioning.

There is NO benefit to using a larger alt unless your car requires it.

[rg2098]

The 65 amp also requires a new bracket. I have no issues with my 55 amp, it runs all the electronics in the car as well as my laptop charger.

[t walgamuth]

we didnt have to modify anything when putting a 65 amp on the 83 300 non turbo that i have. it is a euro motor. well, i paid for a 65 amp anyway.

[jayb79]

From what i have seen, mounting is the same for ALL benz alts.

The only things that are differant is the pullys and the wires on the back(flat pulley on newer models and a stud to the charging wire on anything more than 70amps).

You can bolt up a direct replacement up to 70 amp with only a pulley change.

The cost differance should be very small $5-$10 at most.

I would go for a junkyard 70amp unit from a 190 and change the pulley.

[Old300D]

Originally Posted by Ganaraska

I'd use whatever the factory put in. If it's 55 get a 55. Usually the larger alt goes with air conditioning.

There is NO benefit to using a larger alt unless your car requires it.

And if you are installing an electric fuel heater for your vegoil conversion, you need a bigger alternator.

[Jimmy Joe]

Originally Posted by Old300D

And if you are installing an electric fuel heater for your vegoil conversion, you need a bigger alternator.

Amen. I am not convinced the stock alt is more than barely adaquate to begin with. My car has the AC disconnected, and when I hit the heater or defroster, it is an obvious heavy load. Yikes.
Would love to get one of those beefy Saab alts, if I fine one for a reasonable price...

More amperage is a good thing. In older cars when wires age the resistance goes up. In other words, it takes more power to run things than when the car was new

[phantoms]

Most rebuilders can rebuild your alternator to put out in excess of 100amps without any problems. Check around with local starter/alternator rebuilders.

[hughet]

I just replaced the 55 amp alternator with a 65 amp alternator in my 84 300SD. It is a Bosch premium with a 2 year roadside warranty that I got from Phil.
The 65 seems to be a little larger and was harder to install then the 55 would have been. That makes me think that cars originally fitted with the 65 may have a different bracket.
The bottom line is that you can use a 65 but it is harder to install and with the 65 in, the bracket is butted right up against the hose which comes out of the water pump. That means the hose will be a little harder to change.

[Ganaraska]

Your alternator puts out enough power to charge the battery and handle the consumption of whatever electric things are turned on at the time. There is NO benefit to putting on a larger alternator.

UNLESS you have extra electric loads, such as air conditioning, or an electric waste oil heater. For most extra loads such as fog lamps and big stereos the extra consumption is within the capacity of the stock alternator.

You can calculate the load in amps by multiplying wattsXvolts. Your 55 watt alternator would handle 55X12= 660 watts. Add up the lights wipers radio whatever else is on and until you have 660 watts worth on all at the same time you are fine. After that the battery will cover the difference until it runs down.

[Hit Man X]

Originally Posted by Jimmy Joe

Yikes.
Would love to get one of those beefy Saab alts, if I fine one for a reasonable price...

I looked and can't find any Saabs junked out here... I did see a Volvo alt that looks like it may work. Same dual V-belt pulley and appeared to be the same mounting ears on a brief examination. It was 105A I think.