They fail all of the time due to excess heat, especially when charging a large bank of LFP batteries. In my case, I have a 560Ah LFP battery and I have the output on the 105A hot-rated alternator limited to 50A which means that it will be putting out 50A almost all the time that the engine is running. At that rate, the case temperature stays at about 90ºc or 190ºF. @Maine Sail suggests limiting the case temperature on this alternator to less than 200º. I would like to increase the output but cannot do that until i improve the cooling of the case. I have the bilge blower pulling air directly from the front of the alternator and plan to add a computer fan to blow air onto the back. With this increase in airflow, it seems that increasing the cooling surface area with heat sinks would be helpful in pulling more heat from the case.
I plan to add a blower to the back side but am hoping to increase the cooling surface area. This alternator case has very little in the way of air ports in the back end. I would love to figure a way to put a water-cooling jacket onto the case but that would be too complex and dry fin heatsinks should be easier. I know that I can get small format sinks that have adhesive thermal tape and could stick a bunch of them on, but it would be nice to find something that can be bent to fit the curve of the case.
...or an excessive LOAD.
Aha, now we know you have LFPs.
For the alternator you've got, your best approach is going to be to increase the fresh air flow through the engine compartment as much as possible. Larger bilge blower ? Two blowers working in parallel on the same suction hose ?
I'm afraid this would accomplish little to nothing as it's already like a hurricane inside your engine compartment with the alternator fan and V-belts whipping around. A technical analogy for the computer fan would be "like a fa_t in a wind storm."
Check what the current air temperature is inside the engine compartment. If there's much of a difference between the 190ºF casing and the air temperature, the glued on heat fins would be a good bet. When I was looking at cooling my alternator, I had an initial air temperature of about 150ºF.
Thanks for the link to the Ample primer. I had downloaded it years ago but lost it. I now have the pdf in my manuals folder. My house bank is a 560Ah LFP bank made from 280Ah EVE cells in a 2p4s configuration. I have my alternator throttled and thermally protected but am looking for ways to cool it better so that I can up the output.
The system I now have works very well but I know that I can make improvements' which is what I am in the research process of doing.
I realize that buying a new alternator is the easiest way to go but I have never been one to take the easy road. Until this one bites the dust, I am looking for ways to make it work as well as I can make it which not driving it to an early death. When it does bite the dust and go up in smoke, I will probably build my own replacement from selvage cases and build from there.
When the alternator is off, it will cool down to about 160-170 which is about the engine space temperature. My hope is that with the change from a 180 to 160 coolant T-stat, I can get that lower.
This is what I have found with the space being about 170º and the engine coolant being 180º. I have checked the exhaust mixing elbow temp with my infrared gun and it is about the same due to the thermal wrapping I have installed.
What effect will lowering the operating temperature have on the engine performance and combustion?
