Three Good Options

Guides / Battery

Battery maintainers

Prices and specs checked October 8, 2026

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Concern
A car, truck or motorcycle sits for a few weeks, and the battery is dead when you need it.
Cause
Even when they're off, modern vehicles draw a little power for things like the alarm, clock and computer memory. Over weeks that drains the battery, and cold weather leaves it with less strength to start with.
Correction
A smart battery maintainer, sometimes called a trickle charger, plugs into a wall outlet and keeps the battery topped up without overcharging it. You can leave it connected for the whole season.

The three options

Your pick

For most cars and trucks

NOCO GENIUS5

$69.95 list price at NOCO

Output
5 amps, for 6-volt and 12-volt batteries
Battery types
Lead-acid (flooded, AGM, gel, maintenance-free) and lithium-ion
Cold weather
Adjusts charging for temperature from -4°F to 104°F
Dead batteries
Force Mode can charge a battery down to 0 volts

Pick it if

You have a car or truck that sits, especially in an unheated garage. At 5 amps it also recharges a run-down battery much faster than a 1-amp maintainer.

Skip it if

You only need to keep a motorcycle or mower battery topped up. The GENIUS1 does that for less than half the price.

GENIUS5 on NOCO's site

Your pick

For motorcycles, mowers and small batteries, on a budget

NOCO GENIUS1

$29.95 list price at NOCO

Output
1 amp, for 6-volt and 12-volt batteries
Battery types
Lead-acid (flooded, AGM, gel, maintenance-free) and lithium-ion
Cold weather
Adjusts charging for temperature from -4°F to 104°F

Pick it if

You want to keep a motorcycle, ATV, mower or healthy car battery topped up while it sits.

Skip it if

You need to bring a flat car battery back. At 1 amp that takes a long time. Get the GENIUS5 instead.

GENIUS1 on NOCO's site

Your pick

For heated garages and large lead-acid batteries

CTEK MXS 5.0

$119.99 regular price at CTEK; on sale for $99.00 when we checked

Output
4.3 amps, for 12-volt batteries
Battery size
Charges up to 110Ah, maintains up to 160Ah
Battery types
12-volt lead-acid only: wet, maintenance-free, Ca/Ca, AGM, EFB and gel
Extras
Reconditioning mode and temperature compensation
Works in
41°F to 122°F (+5°C to +50°C)
Warranty
5 years

Pick it if

Your vehicle sits in a heated or attached garage, you maintain a larger battery such as an RV or truck battery, and you want a long warranty.

Skip it if

Your garage drops below 41°F, or you have a lithium battery. Either way, the GENIUS5 is the better fit.

MXS 5.0 on CTEK's site

Side by side

GENIUS5GENIUS1MXS 5.0
Best forMost cars and trucksSmall batteriesHeated garages, large batteries
Price checked$69.95$29.95$119.99 ($99.00 on sale)
Output5 amps1 amp4.3 amps
LithiumYesYesNo
Cold ratingAdjusts down to -4°FAdjusts down to -4°FOperates from 41°F

Also worth a look

The Battery Tender Junior Multi-Chemistry is a long-running 1-amp maintainer for 12-volt lead-acid and LiFePO4 lithium batteries, with a 5-year warranty. It was $52.95 on sale at Battery Tender when we checked, which is more than the GENIUS1, so it's a good choice mainly if the longer warranty matters to you.

From the service counter

  • Check your battery type before you buy. Many newer cars, especially ones with engine start-stop, use AGM batteries, and the charger should list AGM as supported.
  • Follow the connection order in the charger's manual and your owner's manual. Some cars want the negative clamp on a ground point rather than the battery post.
  • If a battery won't hold a charge even on a maintainer, it's likely worn out. Most auto parts stores will test it for free.
  • A maintainer keeps a good battery good. It won't revive one that's failing, so a battery that's three or more years old deserves a test before winter.

Sources