Re: Electrical System Frustration

Posted by HH56 On 2017/8/10 10:07:55

I am definitely no expert on the subject but I think it is a combination of things.

Different expansion rates of materials in the engine can cause tighter tolerances in some areas when hot. Hot oil is thinner and may run and not be covering all the surfaces as thoroughly or as evenly as when the engine is cool causing a bit more friction.

The bigger issue is electrical items are generally less efficient when hot. The starter motor, coil, and battery are particularly affected. In order for the starter to do the increased work of turning the engine and cope with its own loss of efficiency it needs to draw more current. If the battery is hot it has a harder time supplying the extra current. An added insult is if the battery cable is marginal in size it may not be able to carry the needed current easily and results in a voltage drop to the entire car. The lower voltage available to the coil makes the spark weaker.

Added all up, a hot engine needs more power to be turned but the items providing and using the power are at their least efficient states. On a 12v car there is extra capacity to help in all the requirements but on a 6v car there is not much room between barely enough and not enough. That is why the 6v electrical needs to be in top notch condition.