Up in Smoke - Not the movie, my alternator

[DavidWymore]

I was thinking about some simple heat shielding and air ducting.

 

[74M35A2]

It is not a radiated heat issue. It is a cooling air flow issue of self generated heat, combined with low temperature rated electronics. If you are heart set on keeping the stock alternator, the best you can do to maximize its life is to lessen its load to a minimum. Load test your batteries once a year, disconnect them and check open circuit voltage, and do a specific gravity measurement to confirm charge level, etc... If you already bought parts to fix it, OK, but for next time, pull it off and use it as a door stop. The deal from TM seems amazing. I don't think anybody else is offering lifetime warranty, free shipping, free brackets, and all for under $120.

 

[daytonatrbo]

It is not a radiated heat issue. It is a cooling air flow issue of self generated heat, combined with low temperature rated electronics. If you are heart set on keeping the stock alternator, the best you can do to maximize its life is to lessen its load to a minimum. Load test your batteries once a year, disconnect them and check open circuit voltage, and do a specific gravity measurement to confirm charge level, etc... If you already bought parts to fix it, OK, but for next time, pull it off and use it as a door stop. The deal from TM seems amazing. I don't think anybody else is offering lifetime warranty, free shipping, free brackets, and all for under $120.

Isolating the alt from engine heat would certainly help the issue. That, and the fact that the alternator picks up its cooling air from the BACK of the radiator. You are running a heat producing item, in a hot environment. If you cool the environment, the cooling capacity of the alternator might become sufficient.

If you really want to keep the stock alt, you could use some flashing to isolate the engine heat, block off the airflow coming from the radiator, and add an electric fan to draw air from outside the hood.

Adding a scoop like the coolant-fed cab heater uses might go a long way as long as you don't have a lot of stop and go driving.


The way that modern gasoline engines are run extra hot to scrub emissions is leading many manufacturers to relocate the battery and even water cool the alternator because the engine bay is just becoming too hot for these items.

 

[rustystud]

Isolating the alt from engine heat would certainly help the issue. That, and the fact that the alternator picks up its cooling air from the BACK of the radiator. You are running a heat producing item, in a hot environment. If you cool the environment, the cooling capacity of the alternator might become sufficient.

If you really want to keep the stock alt, you could use some flashing to isolate the engine heat, block off the airflow coming from the radiator, and add an electric fan to draw air from outside the hood.

Adding a scoop like the coolant-fed cab heater uses might go a long way as long as you don't have a lot of stop and go driving.


The way that modern gasoline engines are run extra hot to scrub emissions is leading many manufacturers to relocate the battery and even water cool the alternator because the engine bay is just becoming too hot for these items.

That's basically what the new buses are using. A fan draws in outside air to cool the alternator. Our older buses used engine oil to cool them, but they where big bulky cast-iron monsters !

 

[74M35A2]

Isolating the alt from engine heat would certainly help the issue. That, and the fact that the alternator picks up its cooling air from the BACK of the radiator. You are running a heat producing item, in a hot environment. If you cool the environment, the cooling capacity of the alternator might become sufficient.If you really want to keep the stock alt, you could use some flashing to isolate the engine heat, block off the airflow coming from the radiator, and add an electric fan to draw air from outside the hood.Adding a scoop like the coolant-fed cab heater uses might go a long way as long as you don't have a lot of stop and go driving.The way that modern gasoline engines are run extra hot to scrub emissions is leading many manufacturers to relocate the battery and even water cool the alternator because the engine bay is just becoming too hot for these items.

False. Todays engines still run 198F thermostats in them. They now minimize the amount of coolant the engine block can hold, to allow faster warm up to reduce cold start emissions faster, and increase passenger comfort sooner. They also are now using electric controlled thermostats and water pumps to help facilitate this. Cold start ignition timing is also retarded to faster increase converter light off by raising EGT. Dual VVT is used as a self induced EGR without the need of an EGR valve. Fast initiating upstream wide band O2 sensors allow near immediate closed loop control of A/F mixture. Water cooled alternators were tried on a few BMW's and such, but most have reverted back due to the unnecessary cost, complexity, and increased temp rating of later available electronics. I currently work for one of the worlds largest OEM alternator manufacturers. We supply alternators to nearly every vehicle maker in the world. All are air cooled, and now capable of handling under hood air of over 200F while under full electrical charging load at a vehicle stand still (worst case condition). Our largest brushless heavy truck alternator is 200A, rated for 1 million miles, and our largest current conventional brush type automotive alternator in production is 240A, both air cooled. The latter uses square wire with a hairpin type stator to maximize copper wire density per allotted area, and clutched/de-coupled driven pulleys to eliminate belt squeal with todays fast shifting automatic transmissions. Our stock MV alternators are absolute garbage. They are allowed to over-volt at loss of reference voltage (incorrect shut down on M939 series), destructing the ABS module on it's way (another silly design, shouldn't happen), and a lot of members here are scared to let the alternator charge their weak or dead batteries, because they have heard so many horror stories of the alternator committing suicide if asked to do so. Ummm, isn't that the alternators job? No way would this type of behavior be accepted by anybody in todays market on a newly purchased vehicle, and we don't have to accept it either, there are a lot of improved options available now. As Rusty said, there were oil cooled Delco units hung on the gear driven accessory drive of 2 stroke Detroit Diesels for decades, known as 50DN's, I think they kicked +200A or more @ 24V for buses back then. Our original MV alternators would be better served smelted down into shiny Christmas ornaments. Both 2.5T and 5T threads are full of alternator failures, that is a factual non-opinionated data collection.

 

[daytonatrbo]

Complaints about alternators failing when attempting to charge a dead or weak battery are common across many applications at least up through he 90's.

And a 198° thermostat is still hotter than the 180 and 170° that was common when these trucks were built.

But it I get your point.

I'll also start making sure I kill the engine before switching off the main switch.

 

[DavidWymore]

Is there a chance some sort of fuse or something could be retrofitted into the alt so as not to melt itself?

 

[daytonatrbo]

Is there a chance some sort of fuse or something could be retrofitted into the alt so as not to melt itself?

I suppose you could put a Klixon type device in the winding or regulator housing and have it interrupt the field current. It would be easier to just kill the exciter, but from what 74m35 is saying, that might actually cause the voltage to spike.