Alternator Output Management with External Regulators [Small Engine Mode]

[Stu Jackson]

In a recent thread on "Excessive Alternator Heat" and followup answers regarding alternator output management (see Reply #20 on page 2: http://c34.org/bbs/index.php/topic,4454.0.html), [please read for important background] I noted that alternator output could be controlled two ways through a newer style external regulator:  reprogramming ("Amp Manager") or the "Small Engine Mode."

We installed the simpler Small Engine Mode switch on our regulator.  We did not purchase an alternator temperature sensor.  Jon Schneider noted that he installed the alternator temperature sensor which performs the same function but ONLY when the alternator gets "hot."  He ALSO noted he used the amp Manager at 50%, so:  he's got his amp output DOWN to 50% and THEN his alternator cuts back to 50% of that!  My concept is to get as MUCH out of my alternator as possible, but just lightly load it at first when starting up after draining the house bank down past 85% - like a night on the hook with the fridge running.

Attached are photos showing the toggle switch and wiring to the alternator temperature sensor taps on the regulator.

When the switch is open, the current from the alternator drops to 50% output.  When the switch is closed, the current from the alternator is full, based on the demands of the load requirement of the battery bank(s) being charged.

The wiring and discussion is on the other linked thread above, and included in the Balmar Max Charge MC612 alternator installation & instruction manual (which you can also find online through Balmar, www.Balmar.net).  

It works perfectly based on real life measurements with our Link 2000.  After a night on the hook with the house bank down, when we first start motoring I switch to 50%.  Once the amperage output drops to around 25 to 30 I switch it back to full and the alternator doesn't overheat.  More detailed discussion is on the linked previous thread.

[Ron Hill]

Guys & Susan : Another way to insure that your alternator doesn't overheat - is to purchase a hi output alternator (like a Balmar) that has 1/2 of it's diodes are mounted on a heat sync, not all on the case itself.  A thought

[Stu Jackson]

Good point, Ron.

Our system has:

Blue Circle 100 A high output alternator (recommended by Jim Moe in his excellent Projects and new wiki article)

Balmar Max Charge MC 612 regulator

Boat wiring diagram is posted elsewhere:  see reply #23  http://c34.org/bbs/index.php/topic,4623.15.html

When the house bank needs charging, the 100A alternator can get well over 60A output at 2450 rpm (engine rpm).  With the 50% small engine mode it drops back to 30A.  See longer discussion in the linked article and John Nixon's comments, too.

Everyone with a battery monitor must read the Gotcha Algorithm topic.  http://c34.org/bbs/index.php/topic,4922.0.html

[Randy and Mary Davison]

We love all that heat!  Living in a cool and damp place, it's great to take a time out in the head with the access door open and hot air blowing out.  The heat is part of our leaving anchor process too.  The batteries are usually down 200 AH or so after a few days, so we wait 40 minutes for the water to heat up, take turns in the shower, and then count on the hot air from the alternator to dry out the lingering water in the head.  Perfect synergy!

It's not so great in the summer but we can stand it for a month or so....

Randy and Mary
Seattle

[canuck]

On our 2004 we installed a Leece Neville 105 amp alternator with an Xantrex regulator mounted on starboard engine bulkhead. We have the two standard 4D and also a Trojan 27 starting battery housed under the head sink area. We glassed in 2X4 pieces and painted them same color as fibreglass. Very professional if I do do say so!  The stock Universal is a pos! A Link 10 was installed last January. Make sure you program the Link with the correct amp hour capacity available from the Exide web site. In position 2 we can charge all batteries at dock and then turn selector to ALL when starting and leaving the dock.
Has worked great since day 1, also I am anal in checking all batteries monthly and using distilled water.