Balmar alternators overheating

[Chief Engineer]

My Mentor told me that to get the correct tension....tighten the belt enough so you can't turn the alternator by hand. Don't go with that "deflection" thing. It will make the belt too tight.

[hellosailor]

There are belt tension gauges for v-belts. With the big shift to automatic tensioners in cars & trucks, they've become hard to find. There are some cheap new ones that aren't terribly accurate, and better classic ones that are always on eBay and other secondhand sources.

In theory you can measure tension by using a ruler and a deflection table, and with open access in the engine bay that might be good enough too. (In cars, there's usually something making the access problematic.)

CE, with all due respect "can't tighten by hand" violates all the advice from every belt maker AND every alternator maker. It might be better than nothing--but it isn't going to give you the optimum tension. On small engines (cat/truck/boat size) too much tension will ruin bearings and waste power. Too little will just waste power. Rule of thumb is great--when you've run out of chewing gum and baling wire, and thumbs are the only tool you have left in the inventory.[g]

I took my time and finally invested in a tension guage. For the same reason that I have a torque wrench, even though I know "this is fifty pounds" when I squeeze something.[g]

[courageous cat]

I'll put my two cents in. how about the battery? one bad cell in the group will keep the alternator working to bring it up when it can't because of that cell.

[Dedzaboy]

The batteries are good, no problems there. The last I heard from Balmar was essentially that these alternators do run hot, so live with it! I've rigged up fans to duct cool air onto the alternators and this has improved matters but not cured the problem completely.

[Jerry]

I have to purchase a new high output alternator. If not Balmar then who?

[gettinthere]

Originally Posted by Jerry

I have to purchase a new high output alternator. If not Balmar then who?

Good question; but you should specify Large frame or Small frame alternator.

I'm waiting for the answers too: Small Frame alternator to replace my 75 amp Balmar. Hopefully a direct drop in replacement that can work with my ARS. Prefer over 100 amps.

[zeppelin]

FWIW we have used a commercial style large frame alternator on our last two boats with excellent results. The alternator is a Leece Neville 150 amp unit, these are used extensively throughout the Pacific Northwest on fish boats and tug boats.

We put it in our first liveaboard when we replaced the engine on the advice of our mechanic. He said that the biggest problem with all the high output cruising alternators like Balmar is that the frame simply is not able to dissipate the heat and the alternators will not produce the rated output and they will tend to burn out.

I have several cruising friends who have gone through multiple high output alternators over the years, whereas the unit in our first boat was still going strong when we sold the boat after 6 years and our current unit is still working perfectly after 8 years, with full rated output, and never any problems.

The Leece Neville comes with a built in 2 stage voltage regulator which you simply remove and then connect the alternator to your 3 stage smart regulator. I also understand that there are other brands with similar industrial grade alternators available.

The downside to these units is they are quite large and heavy and require double belting, we had to beef up the brackets on the engine for it and not everyone will have enough room for one. On the plus side they are actually cheaper than the high output cruising units.

Wayne

[GordMay]

Large-Frame and Small-Frame refer to the diameter of the Alternator housing.

Small-frame alternators measure about 7" from their mounting bolts to the adjustment bolt on the opposite side. They are roughly 7" from front to back (deep). The small frame alternator primarily dissipates its heat through forced-air cooling. Special designs, such as dual internal fans in small frame units, will increase the airflow - but to ensure sufficient cooling, the small frame should be operated at higher RPM..

Large-frame models measure about 8" from mounting bolt to adjustment bolt, and are about 7" deep. Large-frame models are generally more efficient and run cooler than small-frame alternators. The larger frame designs have the advantage of increased metal mass that works as a heat sink. This makes these designs the most reliable solution for heavy duty charging in combination with lower RPM engines, such as marine diesels.

Painting of any alternator will increase it operating temperature, reducing it’s output.

[CorrinaCorrina]

I have seen this problem of overheating before as well as the Balmar alternator failing just after a year of use. Just recently I encountered a brand new Hylas 54 that went through 6 high output Balmar alternators in its voyage up the east coast of the US. After looking into it we found out that there was a considerable amount of flex where the alternator mounted onto the engine which ultimately caused the belts to slack and tighten. This was countered by strengtheing its mount and increasing the wire gauge going to the batteries direct. Now with the overheating problem, look into the the actualy temp sensor, it could be defective. Also arrange a blower to push air directly onto the alternator drawing cool air from outside. Simply connect the blower to your DC panel via circuit breaker and turn it on any time you crank your engine or have it come on when you key your ignition. Hopefully this will provide some help.

[Nauticatarcher]

Bosch 120 amp stock alternator, 1/3 the price of balmar, three years cruising no problems, say no more!

[Roy M]

I use the same technique as Hud, dumping the coolest air available onto the alternator, directly, and sucking the hot stuff out the top of the engine room and over the side. I'm using the Yanmar 3GM30F engine and the Yanmar package designed by Balmar - no problems. Also, the NAPPA green belts. I took extra care in installing the alternator to the engine to make sure the alignment to the belts was absolutely square, which can be a problem and lead to the black dust you are experiencing.

Originally Posted by blisspacket

Vasco, and all other Wizards
The alignment is visually proper, the v belt has those indents on the bottom side, the Balmar won't kick out more than 55 amps ever so infrequently, and there's black dust all over. what's happening???

What do you mean when you say "alignment is visually proper"? You can not align the pulleys "visually". You MUST use a straightedge laid across the pulleys. The pullys must be be square to the straightedge and in exactly the same plane. This is NOT something you can eyeball. Very small errors will twist your belt and turn it to dust.

As has been suggested by others in this thread, the mountings MUST be strong enough that they maintain this precise alignment when the alternator is drawing full power and really pulling hard on the belt.

[gettinthere]

Originally Posted by Nauticatarcher

Bosch 120 amp stock alternator, 1/3 the price of balmar, three years cruising no problems, say no more!

Could you give more details?

I did a google search and received an enormous array of automotive bosch alternators. Way too many to sort through.

Also, I want drop in capability in replacing my Balmar so I can keep the Balmar 75 as back up with quick replacement.

[GordMay]

Sorry it's upside down.
http://www.cruisersforum.com/gallery...r&imageuser=79

[Badsanta]

Originally Posted by Roy M

I use the same technique as Hud, dumping the coolest air available onto the alternator, directly, and sucking the hot stuff out the top of the engine room and over the side. I'm using the Yanmar 3GM30F engine and the Yanmar package designed by Balmar - no problems. Also, the NAPPA green belts. I took extra care in installing the alternator to the engine to make sure the alignment to the belts was absolutely square, which can be a problem and lead to the black dust you are experiencing.

I have the same 3gm30 and the balmar also. The alternator is not aligned right. Straight edge shows at least 1/16 off at the alternator. Lots of dust and frayed belts. I know it is off, but dont know how to correct it. Any suggestions?? many thanks