Charge N Start 4120 — 4 Amp Battery Charger & 1200 Amp Jump Starter

The most capable unit in the Charge N Start lineup. The Battery Tender® Charge N Start 4120 combines a 4 Amp ISM smart battery charger with 1200 Amps of portable lithium jump starting power — four times the charging output of the CNS 1100 and 1120, same 1200 Amp jump starting power as the CNS 1120. Faster battery recovery for larger vehicles. Maximum jump starting power. The complete battery charger and jump starter solution in one portable unit.

Two Devices. Maximum Output. One Unit.

As a 4 Amp ISM smart battery charger and maintainer , it recovers and maintains larger automotive batteries significantly faster than 1 Amp alternatives. As a 1200 Amp portable lithium jump starter , it starts full-size vehicles with gas engines up to 6.0L and diesel engines up to 4.0L without jumper cables or a second vehicle.

How to Jump Start a Car — 1200 Amps Without Jumper Cables

Jump starting a dead car battery with the CNS 4120:

• Connect the red jump start clamp to the positive (+) terminal on the dead battery

• Connect the black jump start clamp to a ground point or the negative (−) terminal

• Spark-proof technology confirms connection — reverse polarity protection prevents damage from incorrect connections

• Crank for up to 5 seconds per attempt with 30 seconds between attempts

• Once running, disconnect and store

No second vehicle. No cable management. 1200 Amps handles the full range of passenger cars, trucks, and SUVs with gas engines up to 6.0L and diesel engines up to 4.0L.

How to Jump Start a Motorcycle, ATV, or Powersports Vehicle

The CNS 4120's 1200 Amp lithium jump pack is among the most powerful portable motorcycle and powersports jump starters available — more than sufficient for any 12V powersports battery:

• Access the battery — remove the seat or open the battery compartment

• Connect the red jump start clamp to the positive (+) terminal

• Connect the black clamp to a clean frame ground point or the negative (−) terminal

• Crank for no more than 3–5 seconds — small powersports batteries respond immediately to lithium jump pack power

• Once running, disconnect and secure the compartment

The CNS 4120's 4 Amp ISM charger is particularly well-suited for powersports applications where the battery is used infrequently and benefits from faster recovery after seasonal storage. Motorcycles, ATVs, UTVs, side-by-sides, personal watercraft, and snowmobiles stored for weeks or months are among the highest-risk dead battery scenarios — ISM maintenance charging at 4 Amps keeps them at full capacity and reduces the need for the jump start function over time.