Electrical
Battery
The battery stores energy to crank the engine and powers the car when the alternator cannot.
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Starting & charging flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Supplies cranking current (hundreds of amps)
- Smooths electrical spikes and acts as a buffer
- Powers the car for a short time with the engine off
When it fails
- Slow cranking on cold mornings
- Dims lights when idle
- Dashboard warning lights or electronics reset
- Battery swollen or terminals corroded
How to diagnose
- Check rest voltage: 12.6 V+ is fully charged
- Load test the battery with a proper tester
- Measure parasitic drain with an ammeter
- Test the charging system — the alternator must keep it full
Maintenance
- Clean and protect the terminals
- Recharge after long parking periods
- Replace every 4–6 years depending on climate
- Never let it discharge completely
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.
Related part
Alternator
The alternator converts mechanical engine power into electrical power to run the car and recharge the battery.