![]() This is enough information for me to figure out what is going on. Batteries of similar size and CCA ratings have a capacity rating of 50 Ah. I do not have a specification for its ampere-hour capacity, which is important when determining capacity. I will assume that the effective CCA rating is proportional to the Ah rating, which is illustrated in Figure 3.This temperature drop reduces the battery capacity to 60% of its charge at the specification temperature (77 F). The temperature had been in the 70 F (~25 C) range and now is about 18 F (-8 C) in the morning when the car is being started. In fact, cars brought in for service typically have batteries with 70% of a full charge. I will assume the battery routinely sits at 75% charge during normal use. I am guessing that the battery is never fully charge because of how it is started, driven a short distance and stopped. The car is only driven short distances. ![]() ![]() After October 30 th, the car has been driven sporadically. The car had been driven every day prior to October 30 th. His wife just had a baby and is on maternity leave.The car battery experiences the parasitic current drain for 5 days.This means that the total expected parasitic drain is ~100 mA = 70 mA + 30 mA, which is in rough agreement with reports on other web sites. Separate from the cell phone-based car starter parasitic current drain, the car itself has a parasitic current drain of 30 mA to support its onboard computer.Other folks report similar parasitic loads. The measured remote starter parasitic current drain is 70 mA – it is within specification for remote starter units with a cell-phone interface.His remote starter is rated to have a maximum parasitic current draw of 75 mA.Here is what I was able to find out about my son's situation: ( Source) Battery Capacity Versus Temperatureįigure 2 shows the impact of temperature on the capacity of a lead-acid traction battery.įigure 4: Required Car Cranking Amperage Versus Temperature. Battery charge capacity is usually rated in Ah. ( Source) Ampere-Hour (Ah) Capacity An ampere hour or amp hour is a unit of electric charge, having dimensions of electric current times time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3600 coulombs. This receiver current draw is parasitic current drain. In the case of a remote starter, the radio receiver must be powered so that it can receive the starter signal. ( Source) Parasitic Current Drain ( i P) Parasitic current drain can be defined as any electrical device that draws electric current when the ignition key is turned off. Background Definitions Cold Cranking Amps (CCA) Cold cranking amperes (CCA) is the amount of current a battery can provide at 0 F (−18 C). Even without a remote starter, the cars will discharge their batteries after about 3 weeks ( Appendix A). I should mention that all modern cars will discharge their batteries over time because their computer systems are always on – their nominal current drain is about 30 mA. In this post, I will discuss why this behavior is normal considering how the remote starter works and recent weather changes in Montana. He took the car into the Honda dealer, who told him that this is the result of the current discharge imposed on his car battery by his aftermarket remote start system (with cell phone interface, sometimes called a drone), which was verified to be within specification –the car was operating normally. However, this is a new car and under warranty, so I recommended that he just take it into the dealer. Unfortunately, I have had my share of car electrical problems and some of these problems have been hard to find. No starting problems had occurred prior to early November. Of course, the fact that it wouldn't turn-over is worrying in itself. Imagine if she had found herself in a car accident because of underlying problems? It would be unthinkable, but I guess we should be lucky that my son's wife had taken the time to read something like this safeco insurance review when it came to renewing her insurance policy, so at least she would be covered if something else were to happen. I'm just thankful that it was this problem we had to deal with and not something more severe. What do you expect to happen when it has been at a standstill for five days? The other side of me, though, thought that something more serious had to have been going on if something like this had happened in such a short amount of time. To be honest, there was a part of me that wasn't surprised in the slightest that the car wouldn't start. My Montana-based son mentioned that his wife's 2016 Honda CR-V (Figure 1) will not turn-over after sitting in the garage for five days.
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