How to use Battery Tender Plus comes down to matching the voltage, connecting the clips in the right order and plugging in the AC cord last. The Plus line is sold as a charger and maintainer, so the same unit is meant for recharging and for keeping a battery topped up.
Setup differs between vehicle and bench use, and between 6V and 12V models, so learn how to use Battery Tender Plus for your case. Check the label on your charger and the manual for your part number before you connect anything.
Charging a lead-acid battery can release explosive gas, and a wrong connection can cause a short circuit. Wear eye protection, work in a ventilated area and follow the manufacturer’s instructions every time.
How to Use Battery Tender Plus: What It Is
Battery Tender is the brand on this charger. Its installation sheet is issued by Deltran Corporation, and the brand site describes Battery Tender as a Deltona Transformer brand. Its product listing for the Plus line names a 1.25 amp selectable 12V and 6V charger and maintainer, so the first step is knowing which model you own.
The charger is built to be left connected, but it still needs correct setup. The sections below explain how to use Battery Tender Plus step by step, covering voltage matching, cable length, the clip order, the plug-in step and the safety rules that prevent short circuits.
If your car battery is damaged, frozen or of an unknown type, do not start with the charger. Check the battery first, because the manufacturer’s rules for charging a battery apply before any clip touches a post.
Check the Voltage and Cable Setup
How to use Battery Tender Plus starts with the battery voltage. Deltran’s manual says not to use the charger unless the battery voltage matches the output voltage rating of the charger, so check the car owner’s manual or the battery label first. Learning how to use Battery Tender Plus correctly starts with that check.
When you learn how to use Battery Tender Plus, remember that a selectable 6V and 12V model must be set to the battery voltage before you connect the clips. Deltran also says the 6V model does not take the 12V extension cords, so keep the accessories that match your model. If you are unsure of the battery voltage, read the label on the battery before you connect the charger.
| Setup item | What Deltran lists | What it means for you |
|---|---|---|
| AC cord | NEMA 5-15 plug, about 6 feet | Use a grounded residential outlet |
| 12V DC cord | About 4.5 feet | Add an accessory of about 18 to 24 inches |
| Total run for 12V | UL-1236 calls for 12 feet from wall outlet to battery terminals | Plan the layout before you connect |
| Extension cords (12V only) | 25 feet (081-0148-25) and 12 feet (081-0148-12) | Do not use with the 6V model |
The table lists the cable details Deltran gives. Check the part numbers on your own cables, because accessories differ between the ring terminal, alligator clip and cigarette adapter kits.
How to Use Battery Tender Plus: Connect the Clips in the Right Order
Deltran’s manual says to connect the DC output clips only after the charger is off and the AC cord is removed from the outlet. Never let the two clips touch each other, because a spark near a battery can cause an explosion. Knowing how to use Battery Tender Plus safely means getting this order right every time. The Deltran manual also says to clean the battery terminals before you attach the clips.
If the battery is in a vehicle, most cars are negative-grounded. Deltran’s steps for that case are listed below.
- Check the battery posts. The positive post is usually larger than the negative post.
- Connect the red positive clip to the positive post of the battery that is not grounded.
- Connect the black negative clip to the chassis or engine block away from the battery.
- Do not clip to the carburetor, fuel lines or thin sheet-metal body parts.
If the battery is outside the vehicle, Deltran says to attach at least a 24-inch, 6-gauge insulated cable to the negative battery post first. Then connect the red clip to the positive post and the black clip to the free end of that cable, standing as far from the battery as possible.
How to Use Battery Tender Plus: Plug In and Disconnect Safely
The charger has no on/off switch, so plugging the AC cord into a grounded outlet is what starts it. That is why the clips should already be attached before the plug goes in. Once the clips are on, plugging in is the final step.
Battery Tender’s official site lists the brand and support contact. For manual questions, check the label on your charger for the exact model number. For questions beyond this guide, start with the manual for that number.
When you finish, reverse the order. Deltran’s steps say to unplug the AC cord, remove the clip from the vehicle chassis, and then remove the clip from the battery terminal.
Safety Rules That Prevent Short Circuits
Deltran’s safety sheet says like polarities must connect. Connecting opposite polarities causes a dangerous short circuit, so double-check the red and black clips before you plug in. The safety rules are part of how to use Battery Tender Plus, not an optional extra. Deltran also says to wear eye and clothing protection and to keep fresh water nearby in case battery acid reaches skin or eyes.
- Never connect the two quick-disconnect plugs together when both are attached to batteries. These cables are not jumper cables.
- Keep the charger out of rain and snow. Deltran says not to expose the charger to rain or snow.
- Never charge a frozen battery, and do not charge dry-cell batteries used in home appliances.
- Do not set the battery on top of the charger, and keep the charger away from battery gases.
Deltran also warns that a small 18 to 22 Ah motorcycle battery can produce hundreds of amperes or more when its terminals are short-circuited. That is why clip order matters more than speed.
Common Mistakes and Scope Limits
The most common mistake when people learn how to use Battery Tender Plus is plugging the charger in before the clips are attached. Because the unit has no on/off switch, the plug-in step starts the charge, so the clip order must be finished first. Because the charger is built to stay connected for long periods, also look over the clips and cords now and then for cracks, loose contact or corrosion, and replace any part that looks damaged.
This guide does not give a charge time, because Deltran’s excerpts for this model did not confirm one. Read the manual for your model and the battery capacity before you plan a charge.
Another common slip in how to use Battery Tender Plus is leaving the cable run to chance. Plan it before you start, because Deltran sets a total of 12 feet from the wall outlet to the battery terminals for 12V models, so measure the path first.
If you are unsure about the voltage, the cable run or the clip points, stop and ask a qualified technician rather than guessing. A short circuit on a battery is a fire and injury risk.
Related Guides
Frequently Asked Questions
Does Battery Tender Plus have an on/off switch?
No. Deltran’s installation sheet says there is no ON or OFF switch on the charger. Plugging the AC cord into a grounded outlet starts it, so attach the clips first.
Do I need to match the voltage?
Yes. Deltran’s manual says not to use the charger unless the battery voltage matches the output rating. Check the car owner’s manual or the battery label before you connect. Match the voltage before you connect anything.
Which clip goes on the positive post?
The red positive clip goes on the positive battery post. For a negative-grounded vehicle, the black clip goes on the chassis or engine block away from the battery.
Can I use an extension cord with the 6V model?
Deltran says the 25 and 12 foot extension cords will not connect directly to the 6 Volt model. Use only the accessories listed for your model, which is part of how to use Battery Tender Plus safely.
Can I charge a battery outside the car?
Yes, if you follow Deltran’s outside-vehicle steps. Use an insulated 6-gauge cable of at least 24 inches on the negative post, and keep the final connection away from the battery.
Before you learn how to use Battery Tender Plus, confirm the voltage, the clip order and the cable run. A wrong connection can cause a short circuit, so take the time to check.
