Automotive · Head-to-head
NOCO GENIUS2 vs Battery Tender Junior Multi-Chemistry 12V 1 Amp Battery Charger and Maintainer
Which should you buy? Our verdict on both, pulled from our full The Best Battery Tenders: 4 Compared (and One to Skip) comparison.
The GENIUS2 wins because it publishes more of its own behavior than anything else in this group, covers both chemistries and both voltages, and NOCO's manual says outright that it can stay on the battery indefinitely. The Battery Tender Junior Multi-Chemistry is the runner-up and the better buy if everything you store is a powersports battery, because its chemistry selector and longer warranty cost less.
NOCO GENIUS2
Buy itThe most flexible small maintainer here, because it covers 6V and 12V, lead-acid and lithium, and NOCO states in writing that it can stay connected indefinitely.
- Publishes a charge voltage for every mode: 14.5V standard, 14.8V AGM, 14.6V lithium, and 7.25V for 6V batteries
- Rated up to 40Ah for charging and stated to maintain all battery sizes, so it works on a stored car as well as a bike
- IP65 housing and a back current drain under 0.5mA, which matters when it lives on a battery for months
- The user guide states plainly that the charger can be left connected to the battery indefinitely
- Three-year warranty is the shortest in this group
- The GENIUS2 manual lists no separate repair or desulfation mode, even though the product page markets the unit as a desulfator
- Lithium mode is restricted to packs with a built-in battery management system, and NOCO tells you to confirm with the battery maker first
Battery Tender Junior Multi-Chemistry 12V 1 Amp Battery Charger and Maintainer
Buy itA correct answer if the thing you are storing has a lithium powersports battery, thanks to a physical chemistry selector on the case.
- A manual lead-acid or LiFePO4 selector sets the right absorption and float behavior before any current flows
- ETL and CETL certified, with published spark-proof connection, reverse-polarity, and short-circuit protection
- Five-year limited warranty, longer than the NOCO
- Deltran explains what float actually means on its own site: holding the battery a tenth to half a volt above its resting voltage, well below the gassing voltage of lead acid
- Rated for 3Ah to 30Ah at 12V, so it is not intended for a car battery
- 12V only, with no 6V mode for older machines
- Deltran does not publish an ingress rating for it, so treat it as an indoor or sheltered-garage unit
Side by side
The 8 criteria below are the ones our full comparison judged every product on, narrowed to these two.
| NOCO GENIUS2 Our pick | Battery Tender Junior Multi-Chemistry 12V 1 Amp Battery Charger and Maintainer | |
|---|---|---|
| Our verdict | Buy | Buy |
| Best for | Someone with a mixed garage who wants one small unit that can sit on a car, a bike, or a 6V classic through the whole off-season. | Anyone tending a motorcycle, ATV, jet ski, or snowmobile battery, and especially anyone who has switched that machine to lithium. |
| Price tier | $$ · mid-range | $ · budget |
| Rated output | 2 amps | 1 amp |
| Battery voltages | 6V and 12V | 12V only |
| Chemistries listed | Wet, gel, MF, CA, EFB, AGM, lithium | Flooded, AGM, GEL, sealed MF, LiFePO4 |
| Battery size range | Up to 40Ah charging, maintains all sizes | 3 to 30Ah at 12V |
| Published charge voltages | 14.5 / 14.8 AGM / 14.6 lithium / 7.25 at 6V | Not published per stage |
| Maker on leaving it connected | Can be left connected indefinitely | Four-stage program ends in chemistry-matched float |
| Published protection | IP65 housing, reverse-polarity detection, under 0.5mA back drain | Spark-proof, reverse-polarity, short-circuit, ETL and CETL |
| Warranty | 3 years | 5 years |
Which one is right for you?
Pick the NOCO GENIUS2 if
someone with a mixed garage who wants one small unit that can sit on a car, a bike, or a 6V classic through the whole off-season.
Know before buying: three-year warranty is the shortest in this group.
Pick the Battery Tender Junior Multi-Chemistry 12V 1 Amp Battery Charger and Maintainer if
anyone tending a motorcycle, ATV, jet ski, or snowmobile battery, and especially anyone who has switched that machine to lithium.
Know before buying: rated for 3Ah to 30Ah at 12V, so it is not intended for a car battery.
The bottom line
Our overall pick is the NOCO GENIUS2 - The most flexible small maintainer here, because it covers 6V and 12V, lead-acid and lithium, and NOCO states in writing that it can stay connected indefinitely. Choose the Battery Tender Junior Multi-Chemistry 12V 1 Amp Battery Charger and Maintainer instead if anyone tending a motorcycle, ATV, jet ski, or snowmobile battery, and especially anyone who has switched that machine to lithium.
Want the full picture, including the other options we compared and the popular one we'd skip? Read the complete The Best Battery Tenders: 4 Compared (and One to Skip).