Installation Tips

What you will find, if you decide to search through the on line automotive forums, is that Delta products are well known for both their reliability and flawless performance. The majority of these systems were most likely installed per the instruction sheet, so arguably, the best advice regarding installation is to follow the directions. There is no benefit in an attempt to reinvent the wheel, given this proven reliability and performance.. Following these directions also includes using the pieces supplied with the kit, as the supporting pieces were chosen for a specific function, and the substitution of these pieces, regardless of the intended result, does nothing but lower the odds of success. The products here are designed to tolerate severe conditions and broad variances in their application, there are, however, a number of things that can be done in order to maximize the life span of the product.

Failure rates follow what's called a bathtub curve and can be divided into three timeframes, an infant failure term, a constant failure term, and a wear out period . The infant failure rate starts when the unit is first turned on and drops significantly over the first few minutes of operation, these failures are from either workmanship or defective parts and are essentially non existent in the field, as the infant failure rate is low to begin with and the units are burned in here prior to being sent out. Once the infant failure period is over, the failure rate is at its lowest and fairly constant through most of the products life, and finally, the wear out period occurs, where the failures rise exponentially. The MTBF is the point where 63% will have theoretically failed.

What actually happens over time is that the P/N junction of a transistor, which is formed by accurately contaminating the silicon over a specific area, degrades as the contamination continuously migrates out of that area until finally the part falls out of specification and fails to function. This migration is dependent on temperature in that it doubles in rate for every 10 degrees Celsius, so the failure rate can be predicted by the operating temperature. Likewise, the filtering capacitors degrade over time by the same process of chemical migration and follow the same rate of migration with respect to temperature. What is interesting about this number is that it’s near universal, whether the subject is rusting metal, degrading transmission clutches, drying paint, or spoiling milk, what ever is going to happen will usually happen at twice the rate for every 10 degrees in Celsius that the temperature is raised, it’s a matter of molecular electron rotational energy and the resulting increase in the odds of forming new chemical bonds.

The two components in the control unit that operate at the highest temperature are the high-side switching transistor, and the input filter. The high-side switching transistor is rated at 50,000 hours @ 175 C, but operate at a very conservative 125 degrees Celsius at full load and maximum environmental temperature, so the MTBF of this part is roughly 1.6 million hours. The input filter rating from the manufacturer is marginally useful, as it is virtually impossible to rate the part for each and every form of signal that may be presented to the part, and so they are factory rated using a simple sine wave. For the control units, accelerated testing is instead performed in lieu of utilizing the factory supplied rating, and have shown the filter life to exceed 20,000 hours. Although this number is far surpassed by the life span of the high-side switching transistor, it far exceeds the life span of the factory cooling fans, which tend to have spans of two to three thousand hours. Moreover, as the filter degrades, the control circuitry automatically shifts the load from the input filter to the high-side switching transistor by softening the rise and fall ramps of the output pulse.

Two points can be drawn from this. First, reducing the running temperature of the unit will increase the life span of both the high-side switching transistor and the input filter. This can be accomplished by increasing airflow, mounting the unit in a cooler area of the engine compartment, or heat sinking the control unit to a cooler surface. What needs to be realized is that the term cooler is relative, and given that the maximum allowable running temperature of 125 degrees Celsius equates to 257 degrees Fahrenheit, most of the airflow or mounting surfaces found in an engine compartment will serve well to cool the unit.

Secondly, the load on the filter diminishes by a factor of four if the lead length from the controller to the battery is halved, so if possible, the high current run from the battery to the unit should be kept within five feet. Also, keeping the positive and negative feed wires from the battery to the control unit in proximity to one another provides for mutual inductance and will reduce the effective length of the wire run.

About the only other point to be made is that all of the connections to and from the controller should be secure, as 35A of current will generate a tremendous amount of heat through a poor electrical connection.

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