Subtopic: I.C. engine systems – fuel, cooling, lubrication, ignition, electrical, intake and exhaust
Question Statement:
A $12\text{ V}$ lead-acid tractor battery has a rated capacity of $C = 90\text{ A}\cdot\text{h}$. During cold-weather cranking, the starter motor draws a steady current of $I = 250\text{ A}$ from the battery. Neglecting internal resistance voltage drop and Peukert capacity reduction, the theoretical maximum continuous cranking time the fully charged battery could deliver in $\text{minutes}$ is ________ (round off to 1 decimal place).
Answer Key:
21.6
Step-by-Step Solution & Explanation
```
Battery Cranking Discharge:
Capacity C = 90 A*h
Current I = 250 A
Time t = C / I
```
**Step-by-step Calculation:**
1. Discharging time in hours:
$t = \frac{\text{Capacity } (\text{A}\cdot\text{h})}{\text{Current } (\text{A})} = \frac{90\text{ A}\cdot\text{h}}{250\text{ A}} = 0.36\text{ hours}$
2. Converting to minutes:
$t = 0.36 \times 60\text{ min} = 21.6\text{ minutes}$