In a world where everything is claimed to be "best," what does "best" really mean?

If one looks up the definition of "best," it's clear that being best is not only subjective, but also tough to quantify.  So when we say a POWER-GATE battery isolator is the best battery isolator on the market, are we just being arrogant?  Are we just taking the same marketing liberties that we as the consuming public see day in and day out?  The "best" pizza in town.  The "best" battery money can buy.  The "best" window washing company.  The concept of "best" has become so commonplace that we've lost touch with what "best" really means.

So how does one define or measure the "best" battery isolator if every manufacturer claims to offer the "best."  From our perspective, it's very simple:  to measure the efficiency of  isolators (also known as rectifiers), you need to know what the voltage drop is at a given current level.  Many companies try to impress buyers by offering a zero or no-voltage-drop isolator.  This of course defies the laws of physics, but they hope the buyer doesn't know that.

At very low current levels, the voltage drop through any isolator will be very low.  But what is the voltage drop at 100 amps?  200 amps? or 300 amps?  The voltage drop at these elevated current levels is what truly makes POWER-GATE "best."  And we say that not because we are arrogant, it's because the numbers don't lie.

Perfect Switch, LLC owns the patent on a unique assembly process where the use of arrayed MOSFET's yields the absolute lowest resistance from the input to the output of a device. The resistance is so insignificant that heat sinking and airflow are not necessary.  So as you compare devices for your DC power management needs, if it looks like a giant heat sink, it does so for a reason....to dissipate heat.  If it were a "zero voltage drop" device, it would dissipate no heat and if it dissipates no heat, why does it look like a giant heat sink?  If it looks like a duck and quacks like a duck, you guessed it....it's a duck.

We've scoured the earth looking for competing technologies and we can say with absolute certainty that when you buy a POWER-GATE battery isolator, or you add a POWER-GATE solid state relay to your electrical system, you are buying the "best" that technology has to offer.

The ideal diode...how the POWER-GATE battery isolator became the best.

H. Frank Fogleman is a DC power management expert and the inventor of the internationally patented POWER-GATE arrayed MOSFET technology.  He resides in Rancho Santa Fe, California.

When George Westinghouse set up AC power transmission systems in America, he was primarily concerned with providing power to remote locations for lighting homes without using gas or kerosene lamps. That was going well, but people wanted to use the available power to recharge batteries powering radios and vehicles. Yes, there was the Baker electric car like the one that President Monroe had introduced to the White House; one catch, to convert the AC to DC, a rectifier was needed….. a rectifier to conduct during the positive part of the line voltage and block during the negative half of each cycle, making it suitable for recharging storage batteries.

The first wide-spread use of AC rectification was the use of mercury vapor tubes to produce Direct Current for the “Third rail” excitation for railways. The mercury vapor rectifier soon became deployed in room-sized units that remained in service for decades. There were much smaller units used in photography and metal treating facilities.              

Next came copper-oxide and selenium rectifiers for lower current applications

in the 1950’s.  Germanium diodes were used for low voltage ( 40 to 100 ) applications which only required current capacity in the fractional ampere range.

Then silicon diodes became available offering much higher blocking voltage ratings with a substantial increase in current capacity. The down-side was (and still is) the forward voltage drop which results in high heat dissipation in multi-amp applications. They are still in wide-spread use today mounted on extremely large heat sinks and often require additional air cooling fans. The Schottky diode hit the market in the late eighties with a lower voltage drop but a jump in cost and reduction in current capability.

At the end of the century, MOSFET rectifiers were introduced, but price and other factors prevented them from becoming the success developers envisioned.  That was when I found a need for a superior rectifier in DC power management applications. 

Looking at what was commercially available, I could see that the engineers using MOSFETS didn’t have thermodynamic experience.  At this point, a large array of MOSFETS was successfully engineered and the POWER-GATE concept was born. Patents were issued in countries around the world and Perfect Switch, LLC set out to market the arrayed MOSFET devices in the form of rectifiers, relays, and OR’ing devices. POWER-GATE devices are smaller, lighter, and more efficient than any other competing technology.  Early adopters of this new technology include tough vehicular applications including military and fleet utility, aircraft, marine, and communications markets.

Why POWER-GATE solid state MOSFET battery isolators over mechanical switches, relays, and solenoids

Why do people use mechanical relays, switches, and solenoids as battery isolators?

Very simply, they're cheap and easy to understand, but in no way should they be considered a battery isolator for high current DC applications.

A very common, old-school way of creating battery isolation is to install a starter solenoid (relay) between two batteries, and have that solenoid close the connection between the two batteries when the vehicle is running. When the vehicle is shut off, the solenoid will open creating "isolated" batteries. This works great on paper, but if one of the batteries is deeply discharged, when the solenoid is closed, the current transfer from the "full" battery to the "low" battery can exhibit very high inrush current creating a possible fire danger if the wiring, plugs, and/or the solenoid overheat. It's not uncommon for solenoids, relays, and/or switches to become stuck when mechanical contacts effectively weld closed under high current, high arc'ing conditions. This can lead to a situation where the user thinks that the mechanical disconnect is open when in fact it is stuck closed and therefore, no disconnect is occurring.

Another serious problem is when the engine is stopped shortly after starting. The two batteries have been connected during the cranking, starting, and running process just long enough to cause the cranking battery to discharge into the auxiliary battery and now the vehicle will not restart. If the auxiliary battery is of a low voltage potential, the main battery WILL

discharge into the auxiliary and the engine may have to be operated for a considerable period of time before it may be safely turned off. Many an engine has failed to restart because of this problem.

The constant opening and closing of mechanical disconnects also lead to high resistance, high heat connections.

When contacts are new and flat, they yield low resistance transfer of current which means little heat dissipated. However, each time the contacts open and close, an arc is generated. The greater the current and/or difference in voltage, the larger the arc. In short order, the contacts are no longer perfectly flat and are instead pitted and deformed. What was an efficient transfer of current has become poor conductor of current and the additional resistance yields heat which will be the ultimate demise of the mechanical connection. It's not a matter of if it will occur, it's a matter of absolute deterioration over time guaranteed to end in thermal failure.

MOSFET-based battery isolators, specifically the patented POWER-GATE single rectifiers and dual rectifiers have no moving or mechanical parts. There is no arc'ing and no deterioration in performance over time. Unlike typical silicon and Schottky diode isolators or rectifiers, POWER-GATE devices achieve ultra-low resistance....we invented and patented the technology to achieve the lowest resistance devices in the marketplace. There is no such thing as a "no resistance" isolator and until someone figures out how to defy the laws of physics, when it comes to advanced, solid state battery isolator technology, POWER-GATE is the ultimate choice for high reliability systems.