Deltran Battery Tender Junior 12V Charger, 021-0123

What To Expect

A dead battery at the start of riding season usually isn’t a defective battery — it’s one that sat too long without a proper maintenance charge. The Deltran Battery Tender Junior (model 021-0123) solves that. Its microprocessor-controlled circuitry monitors battery state in real time, charges to full capacity, and then switches to a safe float maintenance voltage that holds the battery ready without ever overcharging it.

Unlike a standard trickle charger — which pushes constant low-level current regardless of battery state and eventually causes sulfation damage — the Battery Tender Jr automatically stops charging when the battery is full and restarts only when voltage drops below the maintenance threshold. The result is a battery that lasts longer and starts reliably every time, even after months of storage.

4-Stage Charging Program

The Battery Tender Junior uses a 4-step charging program which in most cases extends your battery’s useful life by at least 50%.

Uses & Compatibility

The Deltran Battery Tender Junior 12V Charger is designed for 12V lead-acid batteries in flooded (wet cell) or sealed maintenance-free configurations, including AGM and gel cell types. It is not designed for lithium batteries.

Common applications include motorcycles, dirt bikes, ATVs, UTVs, personal watercraft, jet skis, classic and collector cars, lawn tractors, snowmobiles, and other seasonal or powersports vehicles. The 12’ output cord and included quick-disconnect ring terminal harness make it easy to leave the connector in place and simply plug in when needed — no need to remove the battery.

Deltran Battery Tender Junior Specs & Performance

• Output Current: 0.75 Amps
• Output Voltage: 12V
• Input Voltage: 120 VAC
• Frequency: 60 Hz
• Maximum Operating Temp: 50° C
• Weight: 2 lbs
• Model: 021-0123

Battery Tender Jr LED Indicator Light Guide

The most common question about the Battery Tender Junior is what the indicator lights mean. Here is the complete breakdown:

Product Features

Common Questions

Can I leave the Battery Tender Jr connected all winter?
Yes — that is exactly what it is designed for. Once in float mode, the charger monitors battery voltage and pulses a maintenance charge only when needed, drawing just milliamps. It will not overcharge or damage the battery with indefinite connection.

Will it work on a car or truck battery?
The 0.75A output is best suited for batteries up to approximately 30Ah. For larger automotive batteries (typically 40–100Ah), the charger will still maintain them in float mode — it will simply take longer to bring a deeply discharged battery back to full from scratch.

Is this the same as the Battery Tender Junior 800?
No. The 021-0123 is the standard 750mA Junior. The Battery Tender Junior 800 (model 021-0128) outputs 800mA and adds selectable lithium battery compatibility. If you are charging a lithium motorcycle battery, the 800 is the correct model.

What is the difference between this and a regular trickle charger?
A basic trickle charger delivers constant low-level current regardless of the battery’s state of charge. Over time this boils off electrolyte, causes sulfation, and damages the battery. The Battery Tender Jr monitors voltage, stops charging when full, and restarts only when the battery actually needs it.