FAQ
TL;DR: 100 mA parasitic draw can flatten a 55 Ah battery in ≈23 days; “12.3 V is almost an empty battery” [Elektroda, Xantix, post #16447391] Check resting voltage, charge to 14.4 V, then test current leak. Why it matters: Quick checks avoid needless battery swaps or breakdowns.
Quick Facts
• Healthy resting voltage: 12.50–12.90 V [Elektroda, wzielonymgaju18, post #16431872]
• Full charge voltage: 14.4–14.7 V [Elektroda, Strumien swiadomosci swia, #16432024]
• Parasitic draw limit: ≤300 mA; aim for <50 mA [Elektroda, wzielonymgaju18, post #16431872]
• 100 mA leak ≈2.4 Ah lost per day [Elektroda, vodiczka, post #16433901]
• Typical 55 Ah replacement battery: 14 kg, €60–€90 [“Exide spec sheet”, 2023]
What resting voltage shows my 12 V battery is still healthy?
A good lead-acid battery settles between 12.50 V and 12.90 V after 12 h rest [Elektroda, wzielonymgaju18, post #16431872] Read below 12.30 V and capacity is under 40 % [Elektroda, Xantix, post #16447391]
How long will a 100 mA parasitic draw drain a 55 Ah battery?
100 mA removes 2.4 Ah every 24 h [Elektroda, vodiczka, post #16433901] From full, voltage drops to the 50 % point in about 11 days and hits crank-failure (≈11 V) near day 23.
Is 13.1 V after charging enough?
No. That is only about 30 % charged [Elektroda, Strumien swiadomosci swia, #16431989]. Keep charging until terminal voltage reaches 14.4–14.7 V and current falls below 0.5 A.
How do I measure standby current safely?
- Switch car off and close doors.
- Insert multimeter (10 A range) in series with the negative cable.
- Wait 10 min for modules to sleep, then read draw. Pull fuses one-by-one to spot the circuit [Elektroda, wzielonymgaju18, post #16431872]
At what cranking voltage should I replace the battery?
If voltage under starter load drops below 9 V, the battery is finished [Elektroda, vodiczka, post #16435089] 10–10.5 V is borderline; plan a replacement soon.
Can a two-year-old battery already lose most capacity?
Yes. A single deep discharge below 11 V can sulphate plates and slash capacity by 40 % [BatteryUniversity, 2022]. The thread shows a two-year unit hitting 10.5 V after parking [Elektroda, DjAlcon, post #16431790]
What are common causes of excess draw in a Daewoo Lanos?
Frequent culprits: aftermarket radio wired to constant +12 V [Elektroda, Strumien swiadomosci swia, #16434516], trunk light staying on [Elektroda, Xantix, post #16434038], LPG controller memory, or alarm modules.
3-step test: battery or car?
- Fully charge to 14.4 V, then disconnect from car.
- Let it sit 48 h; voltage should stay above 12.6 V.
- Reconnect, measure overnight drop. Stable off-car but falling in-car means wiring leak [Elektroda, Xantix, post #16433924]
How much charge does a 14 km commute restore?
With a 50 A alternator and average 20 A net charge, 14 km (~20 min) returns roughly 6–7 Ah. That only replaces a small overnight loss, not a deep discharge [Bosch, 2021].
What happens if I keep letting voltage fall below 11 V?
Repeated deep discharges can cut cycle life to 30 % of rated cycles and may cause internal shorted cells—a failure seen as overnight voltage collapse [Elektroda, Ricoh_220, post #16447622]
How long should I charge a 55 Ah battery at 10 A?
Rough guide: hours = Ah/charging-A ×1.2. So 55 Ah/10 A ×1.2 ≈ 6.6 h. Finish when amperage tails below 2 A [“CTEK Manual”, 2022].
Does rear-window defrost affect radio reception?
Yes. Some cars use the defrost grid as the radio antenna. Energising the heater adds noise and can mute stations [Elektroda, Xantix, post #16434177]
