A question we often get asked is:

Do low coolant alarms cause electrolysis & should they use Alternating (A/C) or Direct Current (D/C)?


The simple answer is:

An electronic sensor must use some current & voltage.

They should use a microscopic amount at the lowest voltage possible & it should definitely be D/C current.

We at Engine Saver® did major research into the subject long before going into design & production almost 10 years ago.

As a result our units do not cause any damage to any cooling system or radiator.


Direct Current (D/C) or Alternating Current (A/C)

The most common industrial use of electrolysis is in the electroplating industry where they use D/C current because A/C damages the electrolyte.

In our case with D/C the electrolyte is the coolant, the anode is the probe and the cathode is the radiator and inside of the engine.
With D/C the transfer of metal is from the anode to the cathode (probe to engine)

Engine Saver® probes are high quality stainless steel and do not degrade and plate the cooling system due to their high quality and the extremly low voltage & current used so there is no transfer.

With A/C Current, the process is reversed as the polarity alternates and system damage will result if the current is high enough.

A/C will  damage the cathode (radiator & inside of the engine) and try to deposit it on the anode (probe)

So no A/C was the first parameter for our unit as it can damage the radiator, coolant & also produces hydrogen & oxygen as by-products which are undesirable in the hot, closed, pressurised cooling system.

Incidentally, the coolant is permanently connected to the battery earth via the cylinder head & block so in reality it isn't possible to make it positive and produce a true A/C alarm using the vehicles electrical system.

Next what current & voltage to use as some of each is obviously required to make an electronic warning system.

We evaluated existing designs that had been on the market for many years & found they were using about 170 micro amps.
Obviously they had been used continuously in marine & industrial non stop applications for many years with no adverse effect so we used similar values as a starting point.

Our original test vehicle a 1994 4 cylinder Mitsubish Magna has been continuously fitted with 4 of these original units with different, separate test probes for 9 years now & is still fine with it's

original radiator & thermostat housing so I have full confidence that the 170 micro amps which
competitors were using has absolutely no ill effect on a cooling system.
However some 6 years ago we totally redesigned our electronics and reduced our current to typically 45 micro amps at typically 1.8volts.
This is about a quarter of the current we were using previously!





Low Coolant Alarms generally have been spotlighted in recent years as a result of OAT coolants being introduced. 

The fact is in recent years many radiators have failed within 2 years of being installed & this is because the coolant was not properly flushed before new was put in.

Many modern coolants are not compatible with each other and the existing coolant in an engine.
When they are mixed, within a week or two they become acidic and then proceed to attack both the inside of the radiator and alloy parts of the engine.
A by product is formed which is borne around the inside of the cooling system by the coolant.
Fortunately for many of our customers, the Engine Saver is very sensitive to this layer which is formed and will give out a much longer test beep & led flash on it's start up test routine, indicating a problem.
The existence of this problem can be found  by wiping a finger around the inside of the radiator neck.
If this layer is present the finger will come away a dirty grey/black colour.

The cure is a drain, complete, thorough flush and refill with the coolant recommended by the vehicles manufacturer.

Also be aware that some OAT technology coolants will actually attack silicone sealants & hoses of some pre OAT vehicles as well as after market silicone hoses.


I hope I have put your mind at rest & answered any questions you have about electrolysis. 

Unfortunately there is some scare-mongering out there, mostly driven by commercial competitiveness but the reality is Engine Saver Low Coolant Alarms will not cause any damage to your vehicles radiator.


And for what it is worth.. I don't believe any other competitive units "A/C" or otherwise actually use enough current or voltage to do any damage at all to any cooling system.

David Jones


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