In recent years, manufacturers of passenger vehicles have heavily incorporated electronics in their vehicle lineups. These electronics of course include the in-car “infotainment” systems, but more important is the manufacturer’s tendency to rely on built in electronics, computers, and sensors to monitor the systems and alert the owner or the diagnostics team to what may be happening under the body work. While failure of in-car electronics such as GPS, radio, or even seat warmers do not spell disaster in terms of vehicle reliability and drivability, those units that monitor and control the functions of the engine, transmission, throttle, and in some extreme cases steering and braking, could show to be otherwise and possibly even be fatal.
RTI was requested to investigate why an owner’s brand new vehicle would constantly drain the battery and refuse to start even after multiple replacements of the said battery, and, to top it off, across two model years of the vehicle: specifically 2011 and 2012. Thankfully, no personal injuries or property damage was associated with the litigation and the vehicle was still under warranty. Time and inconvenience were factors that drove the owner to seek reimbursement for the purchased vehicle. Is it too much to ask that a brand new vehicle performs its duties without flaw before its first oil change?
The said vehicles both had keyless entry and engine start features that required the owner to merely have a fob on person within a certain radius of the vehicle for it to start. In the early iterations of the keyless entry and start systems, if the keys were stored within that sensing radius, some electronics in the car were continuously energized to a “ready” state. Naturally the owner was suspected of storing the keys too close to the vehicle at home causing the battery to drain without taking into consideration that the keyless entry and start systems have long evolved from its early predecessors. The diagnostics personnel at the dealership attempted to reproduce the conditions and noted that the vehicle would automatically switch off the electronics fully after some time had passed with the key within sensing range. Suspecting a faulty battery, the mechanics replaced the battery and returned the vehicle to the owner who after some time, began to experience the same issues even with the new battery. This cycle continued through a few batteries, recharges, and a next-year model vehicle replacement, which still suffered from the same failure.
RTI examined the vehicle in its own laboratory in a controlled environment under multiple conditions. The battery was instrumented to monitor voltage and passing current. Truly, the electronics would fully shut off dropping the drain current at the battery within acceptable limits some time after the keys were left within the sensing range. In fact, the vehicle would automatically turn off ALL of the electronics including the radio and the headlights when it sensed the battery charge drop below a set point. At this point it became necessary to determine if any odd interference was present at the owner’s home that may be keeping the vehicle powered. Similar tests were run at the owner’s garage to RTI’s controlled environment but the vehicle performed satisfactorily.
However, during the controlled tests at RTI, we found an uncommon electronic device connected in-line with one of the battery terminal cables. Upon further investigation we learned that the “black box” was in fact a battery monitor. It was not a simple monitor in that it also allowed for the control of the charge level of the battery through means which would certainly be a great bed time story if told in detail. The monitor functions by assuming the charge level of the battery based on initial programming, or “learning”, performed by the shop. This determines the battery’s initial charge and calculates the instantaneous charge based on the current passing through the monitor throughout use. Over time, the monitor has the capability to recognize, and correct for unaccounted changes in charge. The subject monitor did not exhibit the proper ability to correctly monitor the voltage, for reasons beyond the scope of this study, and thus, if not “re-taught” when a new battery was placed, or a current battery recharged while disconnected from the vehicle, it would allow the battery to be over or under charged and over time, diminish the battery’s capacity to store charge. By the same token, it is stated in the owner’s manual to NOT use the battery terminals to recharge the battery or jump the car. Instead, the manual instructs to use the built in remote terminal since using the battery terminals directly would successfully bypass the monitor. It was then determined, that the battery monitor and associated hardware and software were poorly designed and implemented on the specific model and the end users or mechanics could easily overlook the peculiarities of the said systems. Overseas, a recall was issued for similar models which were experiencing a no-start condition due to low charge levels of their batteries which addresses the battery monitors and associated hardware and software.
Reliance on electronics to improve safety and function of passenger vehicles is a great step in the evolution of the automobile, but it also introduces interesting problems and unforeseen failures. At RTI, we maintain a close watch on trends of technology to be able to successfully diagnose and investigate failures resulting from various factors and resolve a matter with certainty.
- Electrical Engineering
- Forensic Investigation
- Mechanical Engineering
- Product Liability
- Recall and Product Safety
- RTI News