Estimate parking AC runtime from usable energy divided by average electrical demand. Use a measured demand for the conditions you expect. The lowest advertised current or the cooling-output rating is not an adequate basis for an overnight promise.
Start with energy, not amp-hours alone
For a simple planning estimate, nominal battery energy in watt-hours is nominal voltage multiplied by amp-hours. Two banks with the same amp-hour number can store different amounts of energy if their voltages differ. Use the battery maker's rated watt-hour value when available and check its operating limits.
Not all nominal energy is available to the AC. The permitted discharge range, reserve, battery condition, temperature and conversion losses can reduce the usable amount. The installation's protection settings may stop cooling before the energy estimate is exhausted.
A transparent eight-hour illustration
The following inputs are hypothetical planning assumptions, not Vethy product specifications or a field result:
| Input | Illustrative value |
|---|---|
| Battery nominal voltage and capacity | 24 V × 200 Ah |
| Nominal stored energy | 4,800 Wh |
| Assumed usable fraction after reserve and losses | 80% |
| Assumed energy available to all loads | 3,840 Wh |
| Other loads over eight hours | 40 W × 8 h = 320 Wh |
| Remaining allowance for AC | 3,520 Wh |
| Average AC input permitted by that allowance | 3,520 Wh ÷ 8 h = 440 W |
If the AC averages 600 W instead, eight hours requires 4,800 Wh for cooling alone, plus 320 Wh for the other assumed loads. That exceeds this example's available energy. The same battery label therefore cannot establish both outcomes.
Replace assumptions with a route test
Measure a complete rest period, including the initial cooldown. Record starting battery condition, ambient temperature, humidity, solar exposure and cabin setpoint. Log other electrical loads rather than attributing the whole battery discharge to the AC.
Recent parking-cooler launches, including Cooltronic G3, give buyers reasons to compare new configurations. They do not remove the need for this installed-system energy check. A cooling-capacity claim should not be substituted for measured electrical input.
What the result means
This calculation is a screening tool. It does not size cables, protective devices or charging equipment, and it does not guarantee comfort. Use it to identify whether the proposed energy budget is plausible, then confirm the full installation and the required operating period through the supplier's documentation and a representative trial.
Next step
Compare the available configurations in the Vethy product catalog, then request the current model-specific documentation before selecting a unit.
Sources and method
- Eberspächer — New generation Cooltronic · 2026-05-11