Alternator heat, Regulator Controls, Small Engine Mode

[Craig Illman]

Stu - I was just wondering if the case design of the Balmar's give better air flow than the alternators built with Delco or equivalent cases.

I'm going to try to pay more attention on my next few outings, but don't expect to get in a multiple night excursion in the immediate future. I guess I could get "inverter crazy" and run the microwave, LCD & coffee maker, all in the same evening!

Craig

[Stu Jackson]

The Balmars have external cooling fins, which is why they get in the way of the bracket and necessitate the "shaving" of the bracket to install Balmars in many instances.

The fins on the Blue Circle, like the old Motorolas, are behind the flat cover plate forward of the fins.

I don't see much in the way of difference, because the Blue Circle moves the air very well.

I don't think it's the blades, it's the LOAD on the alternator from depleted batteries and the same would be true of a Balmar, I think, as noted by Jon.

[Jon Schneider]

Stu, I agree that it's the load (I guess that means that I'm agreeing with myself, which, as my wife points out, doesn't always happen).  One point of correction, the Balmar 6 series alternators have internal fans (two, front and rear) and are a perfect fit/replacement for M25-XP stock alternator. 

[Stu Jackson]

Jon's wife is right, Jon's point is well taken.  The Balmar alternator I was referring to was the older 912-75 unit.  The newer 6-series is a different configuration.

[Craig Illman]

A little data from this morning's trip back to the slip. To repeat, I have the four T-105's configured to a single house bank, a Balmar 712-80A alternator wired direct to the house bank (fused, of course) and a Balmar Max-Charge regulator.

When I started this morning, the Link showed a deficit of about 136Ah.

9:00 am, Idling at 1000 RPM, it started out charging at 65A
9:15 2000 rpm 61A
9:30 2000 rpm 63A
9:45 2000 rpm 64A
10:03 2000 rpm 42A  I think after an hour we had fallen into less than 20% discharged and into Absorbtion mode from Bulk mode
10:20 1200 rpm 25A

Sorry, I didn't track voltages.

Craig

[Stu Jackson]

Craig, occurs to me that voltage isn't important in this analysis, since the regulator is doing its 36 minutes routine.

NEW IDEA REGARDING AMP MANAGEMENT FROM REGULATORS

SMALL ENGINE MODE

This thread has summarized the issues related to smart regulator control of higher amperage alternators.

Here's something I just learned and installed from this thread.

Amp management seems to have been used by many skippers to reduce alternator output, for whatever reasons that have been mentioned and are quite valid.

The concept, basically, is to reduce alternator output and heat, engine load, and belt slippage when running at cruising speed after a night or two at anchor when the house bank is down and the regulator is instructing the alternator to max output.  Kyle's original start to this thread reported high alternator temperatures doing this, which I confirmed shortly thereafter.

We've discussed the fact that a good 400 AH house bank will have an acceptance rate of about 50A with a 70 to 100+++ alternator. 

There are, actually, TWO different ways to do amp management (with programmable regulators, such as our Balmar Max Charge MC 612).

1.  Use the program, which will require you to reprogram when you change your charging needs.  Needs to use the "magic wand" on the indicator lights.

2.  Use the SMALL ENGINE MODE.  This requires a toggle switch between alternator heat sense quick connect spades on the regulator board.  Switch in one position lets the full power signal to the alternator.  Other position is 50% of required output.

We tried it, it works.  360 AH bank, down -80 AH in a twenty six hour period at anchor.  2,450 rpm cruising speed, when ON: 50 A, when off 25A.  As noted above, the voltage is controlled by the regulator phases.  It also tells you how the alternator temperature sensor works:  it's simply a heat triggered switch, and what it does is cut the alternator output in half like the toggle switch; if you have an alternator heat sensor installed, you could still do this in series with it.

I figure when the alternator output hits (or gets down to) between 12 to 18 I'd flip the switch back to full and get 24 to 36 A.

We have the M25 engine, 2250 engine hours, a two year old Blue Circle 100 A alternator, Balmar Max Charge MC-612 regulator and a Link 2000.

Summary:

One simple toggle switch allows you to easily control the regulator's signal for alternator output.

No programming, or reprogramming, is necessary.  The "magic wand" reed switch is sometimes not the easiest "tool" to use.

Thanks to Jon Schneider and others for noting the amp management features, and suggesting that I [dare I say this??? ] actually read the manual!

If you haven't gotten around to do either of these yet, you could also turn the ignition key off once the engine is running.  That's like turning off the power to the regulator.  Down side of this is it turns the engine hour meter and tach off, too.

ANOTHER UNINTENDED CONSEQUENCE - DO THE MATH

Let's say you have a 400 ah house bank.  20% of that is 80 ah, about what we've found we use on one overnight stay with the fridge running (400 X .2 = 80).  That's enough "down" for the regulator to instruct the alternator to start pumping max amps as soon as the engine gets going.

However, that same 20% is the HARDEST of all to put back into the house bank, due to acceptance and that "last 20% is the hardest to replace without shorepower."  You can run your bank down to 50% and most cruisers use the 50% to 80% range of their house bank to minimize engine running time for charging.  Therefore, we can get two or three nights on the hook with that daily 80 A draw down (we have 360 ah in our house bank).

So, a "standard" night on the town at anchor uses just that 20% that's hardest to replace.  That said, I don't feel that bad about turning the amp manager or small engine feature ON.  While it reduces the alternator output, it keeps the alternator cooler and doesn't fry belts.

I go back to my earlier posts on this thread about acceptance and the fact that if you are going to motor all day, then use the lower output at first and then when the alternator output starts to drop because of battery acceptance as the bank begins to fill up, kick the system back to full charge capability.

It also reemphasizes the steadily diminishing law of returns previously noted.

Once you're out for MORE than one night, just charge, however you choose to (amp manager on or off) between the 50% and 80% of "C" and do the last 20% when you're plugged back in.

See this for a picture of the toggle switch:  http://c34.org/bbs/index.php/topic,4669.0.html

[jmnpe]

An interesting thread, Stu. Your final observation is very pragmatic and absolutely correct, particularly if you have flooded cell batteries and their lower acceptance rates due to higher internal impedance. If you are using AGM or even gel batteries, your "charge it back up at home" discharge level will be higher by about 10% or more, again because of the lower internal impedance of the newer battery technologies.

One point worth noting is that "hot" is very much a relative thing when talking about an alternator. It is not at all uncommon for alternators to regularly run with case temperatures in the 200 degrees F range, which is the temperature that Powerline and several other manufacturers use as their "hot operation" reference temperature. These temperatures will burn your hand/fingers pretty easily and make you think something is terribly wrong based upon your "damned hot to me" impression. As bad as that sounds ( or feels ), it is on par with other engine components found under the hood of a car, and well designed alternators will run for long periods of time at those temperatures without noticeable reduction in service life.

Most alternators that die from over-heating will do so from a slipping belt. At higher rotational speeds and high loads, the slipping belt will heat the pulley and rotor shaft to many hundreds of degrees. These elevated temperatures will cause the front bearings to fail first, which then causes the whole front case and rotor of the alternator to get even hotter. I have seen an alternator rotor that got so hot in this situation that the solder melted out of the slip ring terminations of the field winding. Needless to say, this sequence quickly becomes a catastrophic failure of the alternator.

While increasing air flow to the alternator is never a bad thing, the real killer is improper belt tension. If you are running a single 3/8 inch belt and a high output alternator, you need to watch your belt tension like a hawk. The nifty belt tensioner tool in a previous article will become your alternator's best friend, and make tensioning your belt easy enough that you will be without excuse. Got to get me one of those!

[Ed  Stu]  See: http://c34.org/bbs/index.php/topic,3667.0.html

Regards,

John
1988 C34 hull 728 "Otra Vez"

[Ray & Sandy Erps]

One point worth noting is that "hot" is very much a relative thing when talking about an alternator.

Bingo.

They're selling infra-red thermometers now for around $50.  Point it at an object with a laser sight, click the trigger and read the temperature.  I picked one up last month and it works well.  I haven't tried it on the alternator yet, but plan on getting a baseline temperature for the whole drive train for a reference point and log it in the maintenance manual.  That should help in future troubleshooting to determine if something is hotter than before.

[waterdog]

Excellent idea on the thermometer.   Don't limit your investigation to the drivetrain.  Pop open the engine panel and main electrical panel and any junction areas (mast base) and get baseline measurements on all of your electrical connections as well (turn on the loads).   If you have any that are on the warm side, its good bet that you have some corroded connectors with higher resistance on their way to becoming failure points.