Alternator heat, Regulator Controls, Small Engine Mode

[Kyle Ewing]

Had a great race!  Will post more in the near future.

After nearly completely discharging the batteries (4 Trojan T105s) to 11.97 volts I was finally able to run the engine at cruise speed.  After several minutes I noticed a wierd smell.  We diagnosed it as the Blue Circle 100 amp alternator putting running at high capacity.  After running longer it continued to get hot, to the point of the alternator door being hot to the touch.

There were no signs of belt slippage (i.e. squeeling) and the belt tension was as it should be.  Is this hot an alternator normal when charging completely discharged batteries or might I have a partially slipping belt or other problem?

[Stu Jackson]

Kyle, I'd start by reducing the load on the alternator by using the amp manager feature on your regulator.  

{Ed. by Stu]  Or the Small Engine Mode ;  see page 2 of this topic.

The voltage may be down, but you didn't mention whether the bank was depleted, although I must assume you had drawn it down for the race without motoring.  I haven't had that problem with our Blue Circle 100 even with a drawn down house bank.  We use a 3/8 inch belt.  See if reducing output will work, and then I'd call Blue Circle and ask them.  Check to see if the alternator bearings are OK by taking the belt off and turning the alternator shaft.  Adding an alternator temperature sensor would do the trick, also. Let me know how that works and we can continue the forensics.

[Ed - Stu  9/20/2013 - Also read the Critical Upgrades topic - Alternator Pivot Bolts]

[Kyle Ewing]

Stu,

Thanks for the response.  I don't have a battery monitor but they were pretty low.  We'd been running the fridge, radar, instruments, lights at night, auto-pilot, etc for 4 days with 2 hours of engine run-time per day (1 hour twice day) to recharge.  We skipped a run so the alternator was trying to make up for 24 hours of load.

We disconnected the belt and the alternator spun free.  We motored for 10 hours yesterday with intermittent sailing and there was no heat build-up.  The batteries were charged when we left so the alternator wasn't working.  I'll call Blue Circle next week to see how much heat to expect.  As of now I'll consider the problem caused by heavy charging and lack of cooling.  I'll also add a temperature sensor to avoid the problem in the future.

Kyle Ewing
Donnybrook #1010

[Ron Hill]

Kyle : It would seem to me that the investment of $220 in a Link 10 battery monitor would be well worth the cost to protect your 4 Trojans, from being excessively discharged !!  You definitely cut down the recycle life by running them down to 11.97V !!
The Link 10 will tell you if your guess of 1 hr recharging is correct or not. 
Afew thoughts. 

[Stu Jackson]

MORE INPUT FROM A RECENT CRUISE - THE UNINTENDED CONSEQUENCES

Kyle, I have just experienced almost exactly the SAME conditions you just described.

To back up a bit, I believe we put larger alternators with external regulators into our boats to REDUCE engine charging times, and get as much amperage, as quickly as possible, within the 50% to 80 or 85% range of the house bank.

Accordingly, with house banks at around 400 Amp Hours and 70, 90, 100 and 125 amp alternators being installed, three things seem to be happening, which are THE UNINTENDED CONSEQUENCES of this "new" arrangement of charging:

(1)   The alternator works like a bandit when the engine first starts on the depleted house bank because the regulator is telling it to charge.  The voltage is low at the bank, and the voltage begins to rise as the regulator tells the alternator to pump in maximum amperage with the rising voltage.  This usually lasts between 23 to 36 minutes on the Balmar Max Charge we have on Aquavite.

(2)   The alternator gets really hot when the engine starts IF YOU'RE MOTORING AT CRUISING SPEED.  If you're idling at anchor (or motoring/cruising at a lower rpm) at 1,500 rpm it doesn't seem to be an issue.

(3)   The maximum output I've seen from our 100A alternator is 50 Amps when charging a depleted battery.  I am becoming convinced that this is the limit of the acceptance of a 50% discharged reasonably sized house bank of around 400 AH, maybe only based on wet cells, deep cycle, that we have on board.  AGMs will take many more amps.

This happened to us this past weekend:  two nights on the hook from a Friday arrival at 1800 to departure on Sunday at 1500 hours, no engine use at all.  Fridge on, some lights, radio, and inverter use for popcorn and the computer for DVDs.  The Link 2000 showed 11.97 V (sound familiar, Kyle???) and <–>170 AH on the house bank which is 360 AH.  We had essentially used just 50% of the house bank, which then needed to be recharged.

The alternator got very, very warm when we started motoring at cruising speed.  It was pretty amazing that it happened just after Kyle's original question on this subject, and I appreciate his input VERY< VERY< VERY much because it gave me a sense of comfort when it happened to me! 

Because we did not have to motor too long, I simply opened the alternator door to the head and let it vent.  If we had had to motor, as we do sometimes, for a longer period, and we did need to replenish the batteries, I would have made the decision to utilize the amp manager feature of the regulator to simply reduce the load, ON THE ALTERNATOR, and NOT on the engine!

That's what so crazy about this arrangement: Even with a good sized alternator which is way above the acceptance rate of the house bank (110A over 50 Amps max charge rate at a rising 12+ volts to the bulk voltage of 14.5 in the program's algorithm) the alternator is putting out so much it heats up.  Which is contrary to exactly what we're trying to do by pushing lotsa amps in as short a time as possible.  The next step is the REDUCE the alternator output using the Amp Manager, which would make the charge period even longer!!!  Another option would be to run the engine for an hour each day to reduce the drain on the house bank by pumping in 30 to maybe 50 amps at 1,500 rpm for an hour.  This is exactly what we've been trying to AVOID!   Like a Catch 22!

I've had a discussion with a C36 owner from Connecticut on the "larger the better alternator", arguing the point that a huge alternator (125A) on an M25, even M25XP, is kinda overkill and could hurt the bearings on the engine.  He replied that the larger alternator didn't have to work so hard.  There is truth to that IF the acceptance of the reasonably sized house bank is the limiting factor.

So, now that we've put in the large house bank, the larger alternator, rewired the alternator output to the house bank avoiding the dumb 1-2-B switch, and installed a new regulator, we're almost in the same place as we were when we had the dinky old OEM 55A alternator with internal regulation and one house battery of Group 27 size [a marina hopper stuck out at anchor for a night – can you visualize this???], not to say "bank": run the bloody engine for an hour or two every day ANYWAY!  Oh joy, Oh rapture, back to the Dark Ages!!!

It's an interesting system balance, but it is very nice to know, first, that we are not alone in this, and second, it is a system issue that warrants careful consideration in actual day-to-day use.

I go back to my earlier reply recommending the amp manager feature, which is relatively easy to deal with.  That would be appropriate IF Kyle's and my recent experience required motoring at cruising engine speed right after a deep discharge. OR one could motor slower for the first hour.  OR both.  Reducing the input amps to the house bank from the alternator is just what we're trying to avoid.

I don't think it is the alternator from Blue Circle, unless just Kyle and we have these on our boats.  It would be interesting to hear from those with other alternators what their experiences have been in these situations. In 2004, before we put in our new alternator, the OEM 55 A Motorola with an AutoMac which had NO trouble amping back when we were motoring at cruising speed up in the Delta.  It was probably only putting out 25-30 amps.

It's all such a delicate balance...

A battery monitor, our Link 2000 (A Link 10 would do for you, Kyle) has shown me two important things:

1.   My energy budget numbers are almost exactly on target (see my post on that earlier) for amps being taken OUT

2.   My energy budget for RECHARGING  was WAY, WAY OFF.  It takes much longer to charge, even with a shorepower charger, than I had thought.  This is IMPORTANT to know for REALLY extended cruising. The "steadily diminishing law of returns" from my earlier post on that subject goes like this:

"Helpful Hints:  Electrical Systems:  For extended cruises for those with OEM stock alternators and no external regulation, there is inherently a steadily diminishing law of return in battery charging even if you motor a lot everyday.  If you do an energy budget, even if you motor for eight hours a day, you will be drawing down your batteries, regardless of how much you've increased your house bank.  You WILL need to stop and plug in every week or so.  Do the math.  If you really want to stay out "forever," add solar and a new high(er) output alternator and smart regulator.  We minimized use of electric lights with our lamp oil trawler cabin light and lamp oil anchor light hooked onto our Garhauer dinghy davit, but most of the energy use is from the fridge.  With our large 315 amp hour house battery bank and a separate start battery, we were very comfortable being out in two different situations.  The first was for a few days without motoring or plugging in.  We turned off the fridge at night, so we only used 30 to 40 amp hours a day and could go three or four days without running the engine.  The second was knowing we'd be motoring for at least five hours or plugging in at a marina.  So, before you go, make sure your electrical system is up to snuff so you can really relax and enjoy the peace and quiet without having to worry about your boat systems."

This now seems to be true also of the newer arrangement of larger alternators and external regulators if you use the amp manager feature to reduce alternator output.

{Ed. by Stu]  BETTER YET:  Use the Small Engine Mode ;  see page 2 of this topic.

[DaveM]

Stu
Interesting experience and observations.  I recently bought 100 amp Delco to replace the 55 amp on my M25XP.  The alternator mechanic told me that at most I would get about 60 amps out of it without burning it up.  For a 55 amp I figure this heat limit would be about 30 amps.  I am putting a Balmar Max Regulator on the 100 amp and plan to set it at about a 55 amp limit with an alternator temp sensor.  I am charging a house bank of 2 golf cart batteries and was thinking of going to 4 for the amp hours storage.  What I am hearing y'all experience on heat seems to approximately match what I was told.  The charging acceptance rate limit is an interesting perspective to all of this and looks like setting the regulator at that level will save the alternator as long as it is below the ~60% rating of the alternator.  Thought I would throw this out.  Will be listening and researching.  Will let y'all know what I find or experience.
Good Winds
DaveM

[DaveM]

Found this article:

http://www.glacierbay.com/1batcrg.asp

Interesting reading.  Together with what I was told and y'all are experiencing seems to start to fit together.
Good Winds
DaveM

[Ray & Sandy Erps]

Good article.  I found it interesting that they actually figured you got more amps out of the life of the batteries by discharging them a little more deeply instead of just running off the top 10%.

We have a 105 amp Leece Neville (sp?) alternator on our boat and we regularly get 100 amps out of it for the first five minutes or so before it starts tapering back a bit.  It's on a single belt and I have to be careful when I first start up the engine so I don't get excessive slipping when the alternator kicks in.  Openning up the side door like Stu suggested is a stategy that we used to use when we had our C-34 with the blue circle alternator.

[Jon Schneider]

The other "must-do" (at least for the sake of convenience) is to attach a temperature sensor to you alternator (if it will accept one) connected to your regulator (again, if you have the kind, such as any one from Balmar which will accept the input).  That way, you'll let the regulator do the worrying for you.  I have my Balmar 100a alternator tuned down to 50% all the time.  If I was going hook to hook for several days, I would probably risk it and go to 80% alternator output capacity, and rely on the temp sensor to keep it safe.

[Stu Jackson]

Jon's last post is important, because missing in almost all of the earlier discussions that I can recall is that folks have been setting their alternator outputs to less than 100%, with or without temperature sensors, usually on the alternator, if not on both the alternator and the house bank.

What this kinda confirms is my earlier suspicion that we're buying 100A alternators and limiting them to half their output due to over heating.  While this ends up with somewhat greater alternator output (40 to 50 amps compared to 25 to 30 amps from old OEMs), and has the benefit of smart charging with external regulators (compared to tapering automotive internal regulators), it sure doesn't get 100 amps out of a 100 amp alternator now, does it?  Kyle's and mine warmed up too much only putting out 50A.

Oh well, I guess some improvement, rather than a dramatic enhancement as promised by the manufacturers, is still better than nothing (the old dark ages).

Lessons learned:

1.  It's still way better to get a larger alternator with a smart regulator - you'll get more out of the alternator AND you'll get faster charging at the right voltages for your batteries

2.  Don't believe all the promises made by manufacturers of greatly improved technology

3.  Seriously consider temperature sensing of your alternator OR limit the output with the regulator's amp manager feature, OR The Small Engine Mode (see page 2 of this topic) OR ALL of them (which unfortunately reduces output just when you need it in the bulk stage!).  

4.  Either in conjunction with Item 3, or maybe to avoid it, run your engine for an hour every morning at 1500 rpm to avoid the high outputs required by a depleted, but certainly within limits, house bank.  Which only gets us back to where we started and what we were trying to avoid in the first place!  Drats!

[Craig Illman]

I wish this thread would have started last month. I would have paid more attention to my setup while on vacation earlier this month. I have a Balmar 80A alternator, a Balmar Max-Charge regulator, a Link 20 & temperature sensors on the alternator and batteries, 4 Trojan T-105's, and an Echo Charger for the start battery. I've seen 60A show on the Link going to the house bank. I didn't notice any excessive heating this past trip. I didn't do any logging of battery drain, but we had a couple days where we were down in the yellow zone (-100Ah consumed) and easily came back up to above 90% capacity with our motoring. There was only one day where I didn't let the spouse make coffee using the 120V coffee maker off the inverter.

Possibly, the Balmar alternator has a better cooling design than OEM alternators? or maybe more efficient turning rotation into electricity than heat? Maybe my #2 cabling from the engine to house bank does make some sort of difference?

my 2 cents....

Craig

[waterdog]

Craig,

We've found a solution to your intermittent electrical problem identified above. 

Get rid of the electric coffee maker. 

We picked up this little espresso maker I think from Ikea.  You put the water in the bottom, fire up the stove, and it boils up through grounds into the reservoir above.     Heat up a little milk in the microwave and you have a far superior coffee beverage for a fraction of the amp hours.  I think we are going to retire our percolator.   

[Craig Illman]

Steve - We have a press, it's just messy to clean. The electric is bulkhead mounted and the stainless carafe keeps coffee warm for quite a few hours. Coffee keeps the spouse happy. (along with ample Diet Coke in the reefer). The electric, through the inverter, only consumes 9Ah.

Craig

[Ray & Sandy Erps]

You know, we could have a problem here with the definition of "excessively hot".  An engine running at its typical 160 to 180 deg F is also too hot to lay your hand on.  Although it's only a layman's opinion, I think an alternator rated at 105 amps ought to be able to put out 105 amps for short periods of time and it's going to get hot.  De-rating it certainly will be easier on the alternator, but now you're running a $10,000 diesel at lighter loads for longer periods of times, which also has trade offs.

My recollection is that we ran our blue circle alternator for two seasons without de-rating it and it was still running great when we sold the boat.  I do remember openning the access door when it was pumping out the amps for short periods of time though.

Anyway, it would be nice to hear from an alternator guy just what kind of heat these things will put out and what they can withstand.

[Stu Jackson]

Craig, just a clarification:  Kyle and I both have new Blue Circle alternators, no longer the OEMs and both have external regulation.