How Long Does a NOCO GB40 or GB70 Take to Charge?
2 lessons in this series, 5 min in total
- How Long Does a NOCO GB40 or GB70 Take to Charge? 2 min read
- NOCO GB40 vs GB70: Which Jump Starter Do You Need? 3 min read
Every figure below comes from NOCO’s user guides and data sheets for the two models, apart from one estimate marked as ours. More on how we research.
Charge times by power source
Watt-hours (Wh) measure how much energy a battery stores. The GB40 holds 24 Wh and the GB70 holds 56 Wh, more than twice as much. Both charge through a USB input rated 5V 2.1A, so on the same charger the GB70 simply has more to fill.
| Power source | GB40 | GB70 |
|---|---|---|
| 2A USB | 3 h | 7 h |
| 1A USB | 6 h | 14 h |
| 0.5A USB | 12 h | 28 h |
| 12V fast-charge input | None listed | 12V 3A, about 2-3 h |
“None listed” means the input doesn’t appear in NOCO’s GB40 documents.
Here is our own estimate, not a NOCO figure, of where those hours come from. A 2A source at 5V delivers about 10W, so 24 Wh would take about 2.4 hours and 56 Wh about 5.6 hours. NOCO’s 3 and 7 hours are both about 1.25 times those numbers, so the gap between the two packs comes down to battery size.
The GB70’s 12V fast-charge input
The GB70’s guide lists USB charging at up to 10W. It also lists a 12V fast-charge input rated 3A at 12V, which works out to 36W. NOCO’s guide says that input refills the pack in about 2 to 3 hours from a car’s 12V socket.
That 36W is about 3.6 times the 10W USB rate. With 7 hours on a 2A USB charger, the 12V input is the one to use when you need the GB70 back in service soon.
The GB40 has no 12V input listed in NOCO’s documents, so plan around its USB times. Its smaller battery makes up some of the difference: 3 hours on a 2A source is less than half the GB70’s USB time.
First charge
Both packs ship partially charged, and both guides say to charge them fully before first use. On a 2A USB charger, that means up to about 3 hours for the GB40 and 7 for the GB70, or about 2 to 3 hours for the GB70 on its 12V input.
How long to leave the pack on the charger after that is a separate question, covered in should you keep a jump starter plugged in. Charging is rated only between 32°F and 104°F (0°C and 40°C), which shapes the answer to can you leave a jump starter in your car.
Both guides also say an unused pack discharges over time and needs recharging before use, so it helps to know how long a jump starter holds a charge.
If you haven’t picked a model yet, compare engine ratings and weight in NOCO GB40 vs GB70: which jump starter you need.
