Selecting the Right CTEK Battery Charger

Automotive battery in vehicle

Sophisticated and electronically controlled, CTEK battery chargers provide superior battery-charging performance. However, because CTEK offers several models, each with many specifications, choosing the right charger can be confusing. Our reference table, below, compares features across models to help you select the charger that is best suited to your needs.

The following information also explains the functions of the different batteries and how CTEK chargers can help you get the most out of yours.

CTEK Battery Chargers
CTEK Multi US 7002 battery chargerCTEK Multi US 4.3 battery chargerCTEK Multi US 3300 battery chargerCTEK Multi URS 7.0 battery chargerCTEK Multi US 25000 battery chargerCTEK Multi US 0.8 battery chargerCTEK Multi UC 800 battery charger
Output Voltage12121212 and 1612126
Maximum Output
74.30.8 and 3.37 and 5250.80.8
Power Source110V AC110V AC110V AC110V AC110V AC110V AC110V AC
Battery Sizes
(Amp Hours)
14 - 2251.2 - 1601.2 - 12012V mode: 14 - 225
16V mode: 10 - 160
50 - 5001.2 - 1001.2 - 100
Automotive BatteriesXXXXX
Small BatteriesXXXX
Fast ChargeX
Soft StartXXXX
Bulk ChargeXXXXXXX
Pulse MaintenanceXXXXXXX
Cold Temperature

Breakaway kit battery

12V Lead-Acid Batteries

Battery Uses

Almost every gas- or diesel-powered machine uses a lead-acid battery for starting the engine. These include:

Starter batteries supply a high output for a short time - the few seconds needed to start an engine.

Batteries can be used as a power source to run electrical devices. These include:

Batteries used as a power source are designed to supply a lower output for a sustained period of time. Known as deep-cycle batteries, they typically charge and discharge at a slower rate than starter batteries.

What Happens Inside a Lead-Acid Battery

A lead-acid battery consists of lead plates suspended in a solution of acid and water. When the battery delivers power for some use, a chemical process occurs between the acid solution and the lead plates. This process deposits a material called "sulfate" on the lead plates. When the battery is charged, the sulfate is dissolved back into the acid solution.

The sulfate that collects on the lead plates of a battery can shorten its life. If the sulfate stays on the lead plates it may crystallize. This process is called "sulfation." Once crystallized, the sulfate won't easily go back into solution. The crystallized sulfate then interferes with the normal functioning of the battery, preventing it from charging fully.

Getting the Most Out of a Lead-Acid Battery

A lead-acid battery will last longest and perform best if it is kept fully charged. If not kept fully charged, a battery is subject to problems such as the following:

When Battery Problems Are Most Likely to Develop

Vehicles that are used only periodically or seasonally (like motorcycles, snowmobiles, boats, yard equipment and farm vehicles) are especially prone to battery problems because their batteries are often left for a long time without being charged.

When prepping a vehicle for longer term storage, such as during a military deployment, be sure to keep the battery charged. For longer periods of storage, it's a good idea for someone to occasionally check on the charger and battery.

Battery Chargers

Standard Battery Charger

To recharge a battery, an old-style battery charger or trickle charger simply supplies a set electrical current. The charger runs until you turn it off, leaving you to guess whether the battery is fully charged. And if you don't guess correctly, you run the risk of overcharging or undercharging. Undercharging a battery allows it to sulfate and overcharging it can lead to overheating and consequent damage.

CTEK Battery Chargers

Battery charger

CTEK battery chargers make it easier than ever to keep a 12V lead-acid battery charged and ready for work. The internal electronics in CTEK chargers get the best possible charge out of each individual battery, eliminating guesswork. Each CTEK charger features:

CTEK Advantages

Other features that CTEK battery chargers offer include:

Multi-Step CTEK Battery Charging Process

A CTEK charger goes through a multi-step cycle. By monitoring the battery's state, it can start and stop each stage at just the right time.

  1. Desulfation - uses pulses of electricity to break up sulfation (sulfate that has crystallized on the lead plates)
  2. Soft start - tests the battery to see if it can accept a charge
  3. Bulk charging - applies a strong charge to the battery to get it close to full charge
  4. Absorption - uses a lighter charge to fully charge the battery while avoiding the risk of overheating
  5. Analysis - makes sure that the battery can hold a charge
  6. Recondition - reduces the effect of stratification that could be caused by a deeply discharged battery. This is usually an optional mode that you can select on chargers that have this capability.
  7. Float/Supply - maintains the battery at 100% capacity for 10 days
  8. Pulse maintenance - keeps an unused battery in top shape for an extended period of time. It monitors the battery's condition and, when needed, gives the battery a pulse of current to maintain the charge.

Accessories for CTEK Battery Chargers

If you wish, you can get extra connect cables with either eyelets or clamps to connect to battery terminals. The eyelets are available in several different sizes. Some models of cables come with built-in battery health indicators that make it easy for you to monitor the state of your battery. See the table below to compare available cables.

CTEK Charger Cable Comparisons
CTEK Comfort Connect cable with 6.4mm eyeletsCTEK Comfort Connect cable with 8.4mm eyeletsCTEK Comfort Connect cable with 10.5mm eyeletsCTEK Comfort Connect cable with clamps and battery health indicatorCTEK Comfort Connect cable with 8.4mm eyelets and battery health indicator
Battery Connection6.4mm Eyelets8.4mm Eyelets10.5mm EyeletsClamps8.4mm Eyelets
Charger ConnectionComfort Connect plugComfort Connect plugComfort Connect plugComfort Connect plugComfort Connect plug
Battery Health IndicatorXX

Cigarette lighter or power outlet charge cable

Cigarette plug connect cable (CTEK56263) - With this cable, you can charge your battery through your cigarette lighter or power plug (which must be active even when ignition is off). The cable connects to your cigarette lighter or 12-Volt power supply at one end and to the Comfort Connect lead of your charger at the other.

In dash CTEK battery charger connector and battery health indicator

Dash-mounted charger connection and battery health indicator (CTEK56380) - With the in-dash monitor and connector installed permanently in your dash, you can easily stay informed of your battery's condition. And when your battery needs a charge, just connect your CTEK charger through the monitor's panel box right there on your dash. You won't even have to open your hood to charge your battery. The cables on this monitor connect to your battery with 8.4mm eyelets.

Written by: Raymond P.

Last updated: 7/6/18

Questions and Comments about this Article

Bart S.

Looking for a product recommendation. I need a battery float charger/maintainer that I can permanently mount on-board our school-bus. Output is for charging our VEHICLE battery bank. This is 3 x Interstate Battery 31-ECL batteries, wired in parallel. So the bank is 12v with 2100 amps. Input would be house 120v AC power, either from garage or in rare situations, the bus’ “House” electrical system when it is connected to shore power. My interest is primarily in maintaining the batteries when unused or under a light load. Example may be running the vehicle audio system without ignition running. Looking for a “smart” solution that does NOT require me to adjust modes, etc.

Etrailer Expert
Reply from Jon G.

Looks like you're needing a converter. Attached is a link to our selection that you can filter through. I really like the Progressive Dynamics options like part # PD9260C and then you can add the part # as well which gives you the ability to monitor and manually adjust the boost setting (as opposed to the smart system doing it) if the need ever arises.

Warren J.

This is all very interesting, but still a bit confused as to which one to buy. I have two deep cycle batteries for s fridge and a electric trolling motor as well as a starting battery for my boat. I need a charger that will maintain these batteries when not in use

Etrailer Expert
Reply from Chris R.

If you think you'll usually be charging up all (or at least two) of those batteries at the same time, I actually recommend the NOCO Genius # 329-GEN3 , linked below. This particular unit has a 3-bank setup so you can hook up and charge/maintain all your batteries at once. It provides 30 amps of output (10 amps per bank) and is compatible with your 12V batteries. We don't have any CTEK units that feature multi-battery banks like this.

Reply from Nick H.

@ChrisR What do you recommend for a lawn mower? I hear I am supposed to charge them over the winter months.

Etrailer Expert
Reply from Chris R.

@NickH Good question! A smaller charger like the NOCO # 329-GENIUS1 is perfect to maintain a mower's battery while it waits patiently through the winter months.

Reply from Bob J.

@NickH Make sure and trickle charge your marine batteries too



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