Smart charger / maintainer
NOCO GENIUS5 6V/12V 5A Smart Battery Charger and Maintainer
A 5-amp smart charger and maintainer for 6 V and 12 V batteries, with separate modes for flooded or maintenance-free lead-acid, AGM, and 12 V lithium (including LiFePO4) batteries that have a built-in BMS.
Best for
Keeping a car-sized 12 V battery charged during storage, whatever its chemistry
Specifications
| Charge current | 5 A DC |
|---|---|
| Battery voltages | 6 V and 12 V |
| Battery types | Wet, Gel, MF, CA, EFB, AGM, Lithium |
| Charge modes | 12V (14.5 V), 12V AGM (14.8 V), 12V Lithium (14.6 V, BMS-equipped batteries only), 6V, Repair, Force |
| Capacity | Charges up to 120 Ah; maintains all battery sizes |
| Dead batteries | Detects down to 1 V; Force Mode for batteries below 1 V |
| Protection | Spark-proof, reverse polarity, short-circuit, open-circuit, overheating, overcharge |
| Housing | IP65 |
| Operating temperature | -4°F to 104°F (-20°C to 40°C) |
| Input | 120–240 V AC, 75 W max |
| Warranty | 3-year limited |
Specifications as published by NOCO. Confirm against the current spec sheet before buying — manufacturers revise models without renaming them.
What's good
- A dedicated 12V Lithium mode as well as lead-acid and AGM modes, so one charger covers the chemistries an EV or generator might use
- 5 A charges a car-sized battery up to 120 Ah, and NOCO says it maintains batteries of any size, so it can stay connected for storage
- Spark-proof, with reverse-polarity protection that stops it from sending current until the clamps are on the right way
What's not
- You pick the mode yourself, and the wrong one is the wrong charge voltage. NOCO says the lithium mode is only for 12 V lithium batteries with a built-in BMS
- Repair mode drives up to 16.5 V and is for lead-acid only. NOCO says to disconnect the battery first, so never use it on a battery still connected to an EV
- It can't tell you whether your carmaker allows an external charger on the 12 V battery. Only the owner's manual can
Our verdict
This is the one to buy if the car will sit for weeks, whether that's a seasonal EV, a second car or a generator that only runs in outages. It's only useful once you know two things from the owner's manual: which 12 V chemistry the vehicle uses, and whether the maker lets you connect a maintainer, and where. Set the matching mode, leave it connected, and never use Repair mode on a battery still wired into the car.
Compare with the alternatives
- NOCO Boost Plus GB40 — waking a car with a flat 12 v lead-acid or agm battery without a second vehicle
- Battery Tender Jump N Start 1500 Amp Lithium Jump Starter (030-2020-WH) — a jump pack whose maker lists lithium 12 v batteries as compatible
- Battery Tender Junior Multi-Chemistry 12V (022-0199-DL-WH) — small 12 v starting batteries, such as a generator's, that sit between uses