Need a new alternator.... Should I get the 95 Amp

[lugbutz]

Hi
So... I am happily getting the car ready for the spring and at the point where I need to replace the alternator....Does it make sense to replace it with the 95 amp?


Any and all comments welcome..

[DieselSpider]

$200 + shipping for the 95 plus potential tinkering or pick one up at Oreilly's for $67.99 for the Marelli 55 Amp or $70.99 for the Bosch 65 Amp and its an OEM fit.

My leaning is to stay with the OEM. Mine has a Diesel Engine in it with a 2KW starter and the 65 Amp alternator that's in it works just fine keeping that big starting battery for the diesel engine charged up. I even have an electric defroster for the front windshield and the 65 is just fine.

Do you have anything that requires a 95 amp alternator in the car such as a 1.21 Gigawatt Sound System or Landing Lights from a Boeing Dreamliner? If your adding a lot of high wattage equipment that needs it that's one thing but most will not see any cost benefit.

[MattVAS]

$200 + shipping for the 95 plus potential tinkering or pick one up at Oreilly's for $67.99 for the Marelli 55 Amp or $70.99 for the Bosch 65 Amp and its an OEM fit.

My leaning is to stay with the OEM. Mine has a Diesel Engine in it with a 2KW starter and the 65 Amp alternator that's in it works just fine keeping that big starting battery for the diesel engine charged up. I even have an electric defroster for the front windshield and the 65 is just fine.

Do you have anything that requires a 95 amp alternator in the car such as a 1.21 Gigawatt Sound System or Landing Lights from a Boeing Dreamliner? If your adding a lot of high wattage equipment that needs it that's one thing but most will not see any cost benefit.

^^^^^ This........all of this
Also look up wire diameter to amp output in cars. This can all be found online about what needs to be used in cars for certain sizes of alternator.

[zachmac]

I have one of the higher amp output units in my car but pretty sure if I was doing it today I'd go with DieselSpider on this one. The Bosch 65 amp unit should be plenty. I've been doing a lot of electrical work and thinking on my car lately and looking at what exactly are the electrical load draws at any given time. I keep coming up with a 65 amp supply is more than enough! I think the whole high amp alternator thing began because people wanted what they thought might be a solution to dim headlights, slow wipers, etc. The problem is the solution of a higher amp output alternator doesn't fix those problems, large voltage drops across high resistance circuits. Save the dollars on the alternator and spend the savings installing realy kits for headlights, wipers, the starter etc. is my 2 cents.

I mean look at it this way, the total amperage ratings of all ten fuses in the fuse box is 88 amps. That would only come into play if your were at the point on every circuit simultaneously at which Fiat designers said you should be blowing fuses and stopping the current flow. Starting is the other big load but that is momentary and doesn't happen when the alternator is putting out anything. So why is 65 amps not enough?

[DieselSpider]

Indeed.

Some of the reasons newer cars require higher amperage is electronic control systems, heated seats, heated steering wheels, electric window defrosters, electric power steering, power windows, power seats, high powered sound systems, extreme HID lighting (LED systems can greatly eliminate this) and other high tech equipment that our cars may likely never have so it would be the rare person that would actually need to spend an extra hundred some odd on a bigger alternator when for far less they could actually fix the real problems instead of trying to mask them.

It may be more involved to go through the car and clean up those connections, put in relays, etc however it is the long term better solution the way I look at it.

Since I went the route of eliminating as many high draw electrical loads directly passing through the ignition switch my Spider has been daily driver reliable.

I recently found another root cause for my dim tail lights which is that a previous owner only put half the nuts back on that hold them in place and of course they left them off the mounting studs holding the light housings in place that the ground wires are attached to making it amazing that they worked at all. I found this since I started cutting out all the rust covered up by really bad Bondo and window screen that a prior steward of the car had slathered all over so while I was at it I completely removed the tail lights to address some rust spots near them. I have replaced all the Bondo I have found with welded in steel. In some places they just used masking tape behind the Bondo. They must have gone through gallons of the stuff. I am getting much better at shaping steel and welding sheet metal now.

[aj81spider]

I have no issues with the advice above. However I bought the 95 amp alternator for two considerations not mentioned.

1.) It's new and not remanufactured. The remanufactured units probably work great and will probably outlive lots of other components on the car. However I was spending a lot of money in other areas and in the end wanted a new unit.

2.) Although the car will never need 95 amps (see above), a 95 amp alternator has more head room and the components will be loaded to a smaller percentage of their rated capacity.

If you are interested in being cost effective neither of these are compelling reasons. However they tipped me over to buying the 95 amp.

[chrisg]

Adding to the last comment, a good, clean unhindered power supply to the ignition is a nice thing on pretty much any of our cars.

[MattVAS]

I have one of the higher amp output units in my car but pretty sure if I was doing it today I'd go with DieselSpider on this one. The Bosch 65 amp unit should be plenty. I've been doing a lot of electrical work and thinking on my car lately and looking at what exactly are the electrical load draws at any given time. I keep coming up with a 65 amp supply is more than enough! I think the whole high amp alternator thing began because people wanted what they thought might be a solution to dim headlights, slow wipers, etc. The problem is the solution of a higher amp output alternator doesn't fix those problems, large voltage drops across high resistance circuits. Save the dollars on the alternator and spend the savings installing realy kits for headlights, wipers, the starter etc. is my 2 cents.

I mean look at it this way, the total amperage ratings of all ten fuses in the fuse box is 88 amps. That would only come into play if your were at the point on every circuit simultaneously at which Fiat designers said you should be blowing fuses and stopping the current flow. Starting is the other big load but that is momentary and doesn't happen when the alternator is putting out anything. So why is 65 amps not enough?

^^^^^ This....... this times 100000000000000

Your headlights and wipers won't get much better with just an alternator as they are powered through your ignition switch rather than a direct battery source. Relay kits resolve this! The way I explain the system is........ A Fiat ignition switch allows as much flow as a small creek behind your house. As you turn items on you need the flow of the Mississippi River and you ignition switch will simply never allow that to happen.

I can't say just how happy I am to see people posting true research and real science to this subject. Reading old-wives-tales for years about "big alternator make all better because i-said-so" was growing old.

This topic and its fact based post are awesome and just what is needed to make this hobby great!!! Keep it up guys.

[chrisg]

Definitely relays!

I gather that people may throw higher amperage at various typical Italian car issues (poor grounds, dim stuff, slow wipers, whatever) & that is NOT such a sound approach.

For so many years, I just had a stash of late alternators from AC-equipped cars (65amp) and those were nice for a variety of reasons (a little more than the 40a that came on most my cars, no external regulator & hey, they actually worked), but now my stash is finally close to diminished.

For people bent on non-oem alternatives (is that a pun?), I saw something on the farcebook about people using a single wire 60-70amp (ish) alternator that is spec’d for a Toyota forklift or Kubota tractor.

[JohnMc]

I am in the "relay" camp.
I have a 65 amp and have relays for headlights, starter and of course also on extra driving lights.

[VAS]

Lest there be any confusion, our 65 amp alternator, part number 20-1365, is new, not remanufactured.

[Turbofiat124]

Unless you have a kick-a$$ stereo system or your running some really bright lights, I would say no.

I actually had a Bosch rewound for 140 amps. I could not tell any difference. The wipers operated at the same speed as before.

For years the battery indicator would glow, the more circuits I turned on. After doing "the brown wire fix", the light no longer glows.

Also the 12 to 15 step wiper motor deal finally fixed my mediocre wipers.

[nyc124]

Unless you have a kick-a$$ stereo system or your running some really bright lights, I would say no.

I actually had a Bosch rewound for 140 amps. I could not tell any difference. The wipers operated at the same speed as before.

For years the battery indicator would glow, the more circuits I turned on. After doing "the brown wire fix", the light no longer glows.

Also the 12 to 15 step wiper motor deal finally fixed my mediocre wipers.

What is the "brown wire fix"? My battery indicator is also always flickering and/or on.

[spider2081]

Personally I believe the Bosch 55/65 amp alternators are a great alternator. They were physically and electrically a quality product. I have taken a number of them apart cleaned and painted and reassembled them. They are a simple design and if the voltage regulator/brush assembly is removed and inspected?replaced periodically they will last forever.

If your car has a Bosch alternator, have you removed the voltage regulator and visually inspected the brushes? I would replace the requlator/brush assembly as they are the primary cause of the Bosch alternator failures.

The Bosch alternators were part of the Fiat engineering of the Spider. Yes the cars wiring is also part of the overall design mating the alternator to the car. I have seen a few car with the alternators output wire that connects to the starter battery post with melted insulation. I think this happens when the cars require a jump start to run on a dead battery. the alternator puts out max current to charge the battery and the wire overheats. I think that one wire would be better if it was #6 gauge.
For a while I had an amp meter installed in my 1981 stock Spider except for additional front driving lights and a radio. The amp meter never exceeded 50 amps. This is within the 80% safety rule for alternators.
I have converted a few mid 70's over to the Bosch alternators. This includes removing the original remote voltage regulator and battery warning light relay. I think this is a great upgrade for these cars.
Just my thoughts, no proven data.

[18Fiatsandcounting]

A few thoughts from me since my other hobby is electronics. The 55 or 65 or 95 amp rating on an alternator is simply that: a maximum rating, meaning that the alternator can supply that current while still maintaining the specified voltage and not overheating or the like. It does NOT mean that the alternator always puts out this current.

The current is determined by Ohm's Law, or V=IR. Voltage must equal current (amps) times resistance (ohms). So, if your alternator puts out 13 volts (just as an example), and the overall current draw is 40 amps, then the resistance that the alternator is "seeing" is 0.325 ohms. As you turn on more electrical items in the car, which are essentially all in a parallel circuit arrangement, this resistance drops and thus the current must go up to continue to satisfy Ohm's Law.

Note that the best source of large amounts of current in any car is the battery itself, and this can be hundreds of amps. The problem is that the battery can only supply this current for short periods of time. However, if you have a momentary need for a lot of current, such as that killer drum solo on your megawatt stereo system, your battery can supply this peak load for a while, and then get recharged afterwards. In essence, the battery and alternator work in tandem to meet the electrical loads.

-Bryan