Cooling of Alternators

[merc240d]

AGM batteries have been getting alot of press in the forms over the last few years. Shore charging, regulator settings, batteries getting less than a full charge. What I saw in reading many of the threads was exceptional info of real life experiences dealing with the pursuit of a full charge in the short time a sailboat is running its engine. One point that has been mentioned has been the high temperature that alternators can get to when charging AGM batteries. I did not find many remedies other than opening a hatch to allow for more air flow to the alternator and regulator. I too have been thinking of this issue as I became disenchanted with the 4 1/2 years of life with my two golf cart lifelines connected as a house bank. With a little testing I found that my balmar 80A alternator was hitting 230° F, IR temp meter. I have been pursuing adding ventilation to blow cool outside air directly on the alternator. There have been several issues that have come up such as: water seperation, air for the engine, air balancing with exhausting air, and power robbed from charging to run blowers and controllers.

Admittedly this system is is abit envolved, and is more along the lines of a power boat. But as I have found we tend to motor way too much and such a systme may be needed. Besides I consider this boat to be a classroom and nothing ventured nothing gained.

My current system includes:
2 - Lifeline Golf cart battery house bank ( converting to 3 - Lifeline 31 house bank)
1 - Lifeline 27 starter/emergency
Balmar 70-80
Balmar ARS-4 regulator (still playing with settings, form threads have made me realize the short comings of the out of box settings)
Echo charger
Truecharge 40
Link 20 monitor
Adding ventilation

Any thoughts on cooling of the alternator?

 

[Maine Sail]

Any thoughts on cooling of the alternator?

Ventilation never hurts but alternator temp sensors are the key ingredient..

 

[Stu Jackson]

They do get hot. Here's an interesting discussion about modifying the basic settings on regulators, with links to other discussions that you should read, too.

http://www.sailnet.com/forums/elect...lmar-regulator-advanced-programming-long.html

The real issue, after all is said and done, is that we have tremendously increased the electrical loads on boats, primarily from refrigeration, which has put an increased burden on charging systems. Larger house banks are a good first step, but know that the next morning the alternator is still gonna be asked to provide the makeup power when you start your engine, unless you have other alternate charging sources, like solar, wind or a dock plug.

We're essentially where we may have been 20 years ago, with small alternators keeping up one or two batteries: now we have bigger house banks, with bigger loads, with bigger alternators.

That's what got me going on the Small Engine Mode, liked in that topic I included above.

 

[Rich Stidger]

I cooked my Fireboy compartment extinguisher- NOT GOOD

Yes, there is a need to ventilate. I have four golf cart wet-cell batteries and a 80A output Balmar alternator. I found out the hard way that ventilation is very much needed. With my batteries at 60% charged I was motoring when a loud bang sounded, followed by a whoosh. My engine was shutdown automatically by the Fireboy controller.

Long story short, my automatic heat-triggered extinguished was positioned directly over my new Balmar alternator. The heat from the alternator cooked the extinguisher and it fired off.

My corrective action was to buy and install a new extinguisher and located it near the rear of the engine compartment so that the alternator was not directly underneath it. I also installed an alternator temp sensor and wired that to my external alternator controller. Additionally I ran a 3" vent from directly above the alternator and sucked the hot air out of the engine compartment with an in-line blower. I used an existing cabin ventilation port in my stern near my batteries to vent the hot air.

I had found that my alternator was running at 230F when it was producing about 70A before I installed the temp sensor. With the temp sensor and the ventilation the alternator is dialed back and the case temp now runs about 170F. The compartment temperature doesn't rise above 135F so the extinguisher which triggers at 175F should not go off.