Stupid Alternator Regulators Get Smarter…Finally

If an alternator voltage regulator is not connected to a shunt, it's not smart.

One of the biggest snow jobs in boat gear sales is the myth of the smart three-stage alternator regulator. In fact, the alternator voltage regulators that have been available to us cruisers for about the last 15 years are not that bright...OK, they're downright stupid.

They're so stupid that they can't even perform their primary function of charging our batteries properly until full.

I know what you're thinking:

John is saying that a piece of gear with tens of thousands of units installed (that's a guess) in boats, and thousands more sold every year, that's so fundamental to comfortable live-aboard life, does not even work. Clearly he has lost his grip.

I totally get your scepticism. Heck, when our old, and sadly no longer made, Link 2000-R regulator died—the last cruiser's alternator regulator that was actually smart—I bought the then, and now, most popular "smart three-stage regulator" thinking that it would work, too.

I settled down and read the whole manual looking for the fundamental capability that would make it usable on a liveaboard cruising boat, and got to the end to find...nada. So I figured there were pages missing...nope.

What Matters in Alternator Regulators

What's that fundamental capability? The ability to measure when our batteries are full and reduce the voltage output by the alternator to float.

Lead acid (liquid-filled, gel, AGM, whatever) batteries are fully charged when the current (amps) they are accepting at their specified acceptance voltage—typically about 14.4 volts at 70˚F (20˚C)—has dropped to about 0.5% of their total capacity measured in amp hours. (Check with the battery manufacturer, since these two numbers vary between brands, though not by much.)

Sounds pretty simple, right? And it is. All you need is a shunt in a cable to the house battery to measure that current—often already there on a cruising boat to support a battery monitor—and a bit of simple logic in the regulator to turn the charge voltage down to float (typically 13.4 volts) when the above threshold is reached, but not before.

Easy peasy. But since the death of the Link 2000-R, and a rather complicated regulator from Ample Power (no longer in business), there has been no alternator regulator available, at least that I have found, that could do that simple fundamental thing.

How Could This Be?

Why? Beats the crap out of me. Maybe because few boat owners really understand how batteries charge and, even more distressingly, very few technicians in boatyards do, either, so the industry got away with selling stupid regulators for years, and they even had the nerve to call stupid smart—the power of marketing.

Stupid Is As Stupid Does

Rather than making that simple required measurement, these stupid regulators guesstimate using a combination of time and how much the regulator needed to juice the alternator field coil to maintain the acceptance voltage. That's bad enough, since different alternators have different relationships between field and output current (amperage) and, of course, how long a battery will take to charge will depend on how much it was discharged...duh.

But wait...it gets worse. These stupid regulators have no way to understand how much of the alternator's output is charging the battery and how much is supplying loads—they truly operate blind.

Making Stupid Worse

The way the manufacturers of stupid regulators get around this fundamental weakness is by shipping the regulator factory programmed to chronically undercharge the batteries, to the point that the regulator will typically cut the charge current back to float in less than two hours, even though a lead acid battery bank discharged even just 25% will typically take at least four hours to fully recharge, no matter how big the alternator—if you don't believe that, see Further Reading.

Now this can be kind of fixed, in a klugy way, by reprogramming the regulator, which is what I did, and then wrote an article about it to help others, recently deleted since this new regulator makes it obsolete.

At Last, Real Smarts

But now, finally, we have, once again, a truly smart regulator. Let's take a look:

  1. One Simple Law That Makes Electrical Systems Easy to Understand
  2. How Batteries Charge (Multiple Charging Sources Too)
  3. How Hard Can We Charge Our Lead Acid Batteries?
  4. Cruising Boat Electrical System Design, Part 1—Loads and Conservation
  5. Cruising Boat Electrical System Design, Part 2—Thinking About Systems
  6. Cruising Boat Electrical System Design, Part 3—Specifying Optimal Battery Bank Size
  7. The Danger of Voltage Drops From High Current (Amp) Loads
  8. How Lead Acid Batteries Get Wrecked and What To Do About It
  9. 11 Steps To Better Lead Acid Battery Life
  10. 10 Tips To Install An Alternator
  11. Stupid Alternator Regulators Get Smarter…Finally
  12. WakeSpeed WS500—Best Alternator Regulator for Lead Acid¹ and Lithium Batteries
  13. Smart Chargers Are Not That Smart
  14. Equalizing Batteries, The Reality
  15. Battery Monitors, Part 1—Which Type Is Right For You?
  16. Battery Monitors, Part 2—Recommended Unit
  17. Battery Monitors, Part 3—Calibration and Use
  18. Do You Need A Generator?
  19. Efficient Generator-Based Electrical Systems For Yachts
  20. Battery Bank Size and Generator Run Time, A Case Study
  21. Battery Options, Part 1—Lithium
  22. Battery Options, Part 2—Lead Acid
  23. Why Lithium Battery Load Dumps Matter
  24. 8 Tips To Prevent Lithium Battery Load Dumps
  25. Lithium Ion Batteries Explained
  26. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 1
  27. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 2
  28. Q&A—Are Battery Desulphators a Good Idea?
  29. Renewable Power
  30. Wind Generators
  31. Solar Power
  32. Hydro Power
  33. Watt & Sea Hydro Generator Review
  34. A Simple, Efficient and Inexpensive¹ 12 or 24 Volt DC Electrical System
  35. 8 Checks To Stop Our DC Electrical System From Burning Our Boat

John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for 25 years, first in yachting magazines and, for the last 20 years, as co-editor/publisher of AAC.

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