95 amp alternator conversion

[RoyBatty]

You need to check your battery condition.
This symptom tells me your battery may be weak or badly discharged.
You might have a bad cell.
Make sure the battery is fully charged and see if it acts the same.

[vandor]

You need to check what the voltage is at idle and also when this happens.

[DieselSpider]

I have read a few times that installing a 95 amp alternator without upgrading the wiring has caused a number of fires as the un-fused line going to the battery got hot melting its insulation and shorted to the body. Some call it the dangerous 95 AMP conversion due to those incidents.

We are talking about 30/40 year old wiring so due diligence should be practiced before hand to ensure the final results are less likely to be a fire. The battery cable goes from the starter through the firewall and then under the carpeting to get to the trunk if I understand correctly.

[spider2081]

The cable running from the starter to the battery in my 81 is a big wire something like an "0" size. I don't think it would over heat if a 95 amp alternator was putting out max current. The battery would have to be pretty dead to require this much current.
On the other hand the wire from the alternator to the starter and from the starter to the ignition switch are of a questionable size for 95 A alternator.

[vandor]

>I have read a few times that installing a 95 amp alternator without upgrading the wiring has caused a number of fires

Read it where? I have not heard of any fires, and sounds rather far fetched.

>as the un-fused line going to the battery got hot melting its insulation and shorted to the body.

Why would it get hot? There is not any more current in that cable with a 95A alternator than there would be with a stock one.
Sure, the wire can rub through in a 30-40 year old car, especially if a PO botched a repair, but it would have nothing to with the alternator.

>due to those incidents.

What incidents? Did you talk to the person it actually happened to, or just some hearsay being spread by a vendor that does not carry these alternators?
Thanks,

[DieselSpider]

>I have read a few times that installing a 95 amp alternator without upgrading the wiring has caused a number of fires

Read it where? I have not heard of any fires, and sounds rather far fetched.

>as the un-fused line going to the battery got hot melting its insulation and shorted to the body.

Why would it get hot? There is not any more current in that cable with a 95A alternator than there would be with a stock one.
Sure, the wire can rub through in a 30-40 year old car, especially if a PO botched a repair, but it would have nothing to with the alternator.

>due to those incidents.

What incidents? Did you talk to the person it actually happened to, or just some hearsay being spread by a vendor that does not carry these alternators?
Thanks,

Two different vendors that were promoting fixing the wiring and eliminating the need to upgrade the alternators. Just filed it mentally and did not save the links.

[DieselSpider]

The cable running from the starter to the battery in my 81 is a big wire something like an "0" size. I don't think it would over heat if a 95 amp alternator was putting out max current. The battery would have to be pretty dead to require this much current.
On the other hand the wire from the alternator to the starter and from the starter to the ignition switch are of a questionable size for 95 A alternator.

On my 78 it looks undersized especially considering the length of the run however I am not sure if that bright green cable is original or not in my Fiat with a Diesel transplant.

[vandor]

The large green cable does not have any common problems in Spiders, other than the battery clamp on the end wearing out.

[spider2081]

The large green cable does not have any common problems in Spiders, other than the battery clamp on the end wearing out.

If the battery clamp end wears out or needs replacing I suggest considering installing a good quality insulated standoff. Then purchase a short new battery cable to run from the standoff to the battery. Here is a link to a terminal standoff.

http://www.go2marine.com/product/247253 ... ctors.html

The stud size should be 3/8 inch for the size wire Fiat runs to the trunk mounted battery.

Most auto, marine and aviation electrical repair shops will have the proper crimper to install the ring terminal on the original battery cable.

Another option is to purchase a good quality battery cut out switch and mount it in the trunk using a short new battery cable. Either way a new ring terminal gets crimped onto the original battery cable.

[baltobernie]

For those of you embarking on a rewire project this Winter, a helpful tool for battery cables:
http://www.alpharubicon.com/altenergy/l ... nytoyz.htm
Large-diameter wire doesn't rotate easily, so make sure you have the terminal oriented correctly before crimping. I did several crimps in sito by placing the anvil on a stub of 2x4 near the ultimate destination, and whacking it there. Vendors that cater to the electric vehicle conversion market usually have very high-quality wire and components for the heavy gauge stuff.

[So Cal Mark]

Csaba is completely correct about the high amp alternator conversion. The fire myth is one concocted by VAS and distributed to their customers in an effort to curtail sales by competing vendors. They obviously don't understand how electrical circuits operate. It's a shame dieselspider is spreading this unfounded rumor. The alternator upgrade merely guarantees enough output to offset all of the accessories operating at the same time. An electrical item only draws the current it was designed to use. So if a circuit, say wipers, draws 8amps, that's all of the current in the circuit. The alternator doesn't force more current through the circuit.
So if you add up all of the current demands in the car, your stock alternator doesn't have enough output to prevent a discharge situation.
Remember, max output is calculated at about 6000rpm at the alternator. They won't put out max output at idle or lower speeds.

[spider2081]

I agree that the alternator only puts out the current a load asks for and it dose not push more current to a load than the load needs.
I also agree new is better and am not trying to talk anyone out of replacing an alternator.
The wire size I would question on early Spiders is the alternator output wire going to the starter battery terminal. I could be wrong but this wire looks to me about a #10 wire, which would have a max current rating of about 40 Amps. This kind of makes sense as the original alternator 55 amp or less. If the cars battery is discharged enough to need a jump start it could draw that high a current for a while. I don't think it would burn but I think it is marginal in size. I would replace this wire with a #6. On late cars it is a #8 which should carry about 60 amps.
Another issue is having greater current available could be looked at if any of the unfused wires were to accidentally short to ground. Example any wire between the alternator and the headlight fuses. Then their current rating could be exceeded. The chances of it happening are slim but food for thought.
I have experience with other vehicles where a 45 amp alternator was replaced with a 65 amp alternator as a fleet modification. The original alternators output had a 50 amp circuit breaker in its wire. The 50 amp was kept as part of the mod to protect the original wire sized for the 45 amp alternator. The circuit breakers began to fail. The cause was traced to the battery draw after the engine first starts.

[DieselSpider]

I agree that the alternator only puts out the current a load asks for and it dose not push more current to a load than the load needs.
I also agree new is better and am not trying to talk anyone out of replacing an alternator.
The wire size I would question on early Spiders is the alternator output wire going to the starter battery terminal. I could be wrong but this wire looks to me about a #10 wire, which would have a max current rating of about 40 Amps. This kind of makes sense as the original alternator 55 amp or less. If the cars battery is discharged enough to need a jump start it could draw that high a current for a while. I don't think it would burn but I think it is marginal in size. I would replace this wire with a #6. On late cars it is a #8 which should carry about 60 amps.
Another issue is having greater current available could be looked at if any of the unfused wires were to accidentally short to ground. Example any wire between the alternator and the headlight fuses. Then their current rating could be exceeded. The chances of it happening are slim but food for thought.
I have experience with other vehicles where a 45 amp alternator was replaced with a 65 amp alternator as a fleet modification. The original alternators output had a 50 amp circuit breaker in its wire. The 50 amp was kept as part of the mod to protect the original wire sized for the 45 amp alternator. The circuit breakers began to fail. The cause was traced to the battery draw after the engine first starts.

Exactly the problem one could encounter on an old car with a tired battery when a near to double output alternator is installed. If the batter runs down and pulls a 70 amp charge through wiring that when new was rated for 40 amps then yes we can have a problem. You would have to dot all the I's and cross all the T's so to speak and verify every wire going from the alternator to the battery at the least to ensure that there are no undersized wires or failing connections that could generate heat. I deal with this more in RV systems where folks put in a larger charger/converter going double without first verifying the wiring and are then troubled by smokey odors especially after a deep discharge situation. You just can't slap in that much larger an alternator without taking risk and you really need to follow best practice and verify the existing electrical system that you are connecting it to.

Some may feel the chances are slim and while its possible that no one within the confines of the small group of Fiat 124 owners on this forum have experienced it one can not ignore the possibility and follow best practice to prevent such an occurrence. Folks who skim and see a "Expert" or someone who should know better make statements seemingly contrary to following best practice will usually be the ones at greatest risk since they would unknowingly not be showing due diligence when preforming the upgrade.

Understand that I have a diesel which will draw as much as a large 8 cylinder engine running down a battery more quickly during a hard start event and having helped others deal with issues from this in other venues I am a bit more cautious.

[courtenay]

If I recall correctly, an original alternator is rated at 65 amps, so I would be very surprised if the original wiring from the alternator to the battery was only rated for 40 amps.
Regardless whether you have the original alternator or you install a 95 amp model, it is probably prudent to check your wiring to ensure it is in decent shape.

[nalle]

As spider2081 said new is always new, but if the existing 55-65A alternator is working fine why it should be changed?
Only reason for new alternator that I know is, that there is some new load in the car.
Maybe oversized headlamps, new suwoofer, electric heated seats or something else.

If our alternators (55-65A) has been working and charging battery over 30 years,
it can not be so that on year 2015 they will come undersized to our cars.
Or do we have a common problem with our cars?

There was said that alternator nominal current will be reached at 6000 rpm.
Yes. that is true.
But it is alternator speed not the engine speed.
There are 2 pulleys other in the crank shaft and the other in alternator,
so the 6000 rpm at alternator will be reached at much lower engine speed.
And the curve is not linear, it is logarithm.
Then we should check the operating curves between the 65A and 90A alternators, there are differencies.
I tried to find Bosch operating curve, but I did not find it.
Maybe somebody has a operating curve for those nwe alternators, it would be nice to see it.
Google search "alternator operating curve" shows basic alternator operating curves.
On the curves we can easily see the relationship between alternator speed and max. output current,
but only in common level.


I do not say that 90A alternator not good, I'm still wondering why.