How Long Does a NOCO Genius1 or Genius2 Take to Charge?
3 lessons in this series, 7 min in total
- How Long Does a NOCO Genius1 or Genius2 Take to Charge? 2 min read
- Which NOCO Genius1 or Genius2 Mode Should You Use? 2 min read
- NOCO Genius1 vs Genius2: Which Charger Do You Need? 3 min read
Times come from NOCO’s user guides and data sheets for both chargers; the metric conversions are ours. See how we research.
Charge times by battery size
Amps (A) measure how much current a charger sends into a battery, and amp-hours (Ah) measure how much charge the battery holds. The Genius1 puts out 1A (15W max) and the Genius2 puts out 2A (30W max). More amps into the same Ah means a shorter charge.
NOCO’s user guides give these times for a battery at 50% depth of discharge, meaning about half empty, from the 12V column:
| Battery size | Genius1 (1A) | Genius2 (2A) |
|---|---|---|
| 8Ah | 6.0 hours | 3.0 hours |
| 12Ah | 9.0 hours | 4.5 hours |
| 18Ah | 12.0 hours | 6.75 hours |
| 24Ah | 18.0 hours | 9.0 hours |
| 30Ah | 22.5 hours | Not listed |
| 40Ah | Not listed (above its rating) | 15.0 hours |
Why some rows don’t add up
Most rows are exactly half. The 18Ah row isn’t: 12.0 hours against 6.75, and the Genius1 guide’s own 6V column lists 13.5 hours for the same battery. Treat these figures as rough guides, not promises.
The data sheets add a 20Ah row: 15 hours for the Genius1 and 7.5 hours for the Genius2.
NOCO’s data sheet lists about 60 h for 80Ah, though it rates the GENIUS1 to charge only up to 30Ah. The same data sheet lists about 30 h for 40Ah and about 75 h for 100Ah. We go by the rated capacity, so the table leaves those GENIUS1 figures out.
Charge vs maintain: the 30Ah and 40Ah limits
Charging means bringing a drained battery back up. Maintaining means keeping an already-charged battery topped up while a vehicle sits. NOCO rates the Genius1 to charge batteries up to 30Ah and the Genius2 up to 40Ah, but rates both to maintain any size.
So read the Ah figure on your battery’s label first. A Genius1 can maintain a charged car battery, but if the battery is above 40Ah and dead, neither charger is rated to recharge it. The general rule is that a charger’s charging rating should cover the battery’s Ah, and is a 1-amp charger enough for a car battery explains it.
What makes a charge take longer
NOCO calls these reference times only. Battery condition, depth of discharge and temperature change them, so a battery drained below 50% takes longer.
The guides say each charger’s amp rating is its bulk current, the steady current of the main charging stage, above 32°F (0°C). Both chargers are rated to operate from -4°F to 104°F (-20°C to 40°C), and both guides say not to charge a frozen battery.
To plan a charge, start from your battery’s row, then allow extra time for a deeper drain or a cold garage. Next, check which Genius mode to use, then which Genius fits your battery.
