A battery charger sitting on a garage shelf requires you to open the hood, dig out the charger, connect the clips, and reverse the process when done. That friction — small as it seems — is exactly why most people do not maintain their batteries consistently. The driver who truly protects battery life is the one for whom connecting the charger takes 10 seconds: plug a quick-disconnect into the pigtail already installed on the battery, and it is charging.
Battery Tender® has pioneered smart charging technology for over 60 years, and proper charger installation — whether a simple ring terminal pigtail on a car battery or a fully integrated WaveCharge system on a boat — is central to making that technology useful. This guide covers installation options from the simplest to the most comprehensive.
Installation Option 1: The Ring Terminal Quick-Disconnect Pigtail
This is the most popular installation for cars, motorcycles, ATVs, and any vehicle where the battery is accessible. It takes 10 minutes and requires only basic tools.
What You Need
- Battery Tender ring terminal accessory cable or quick-disconnect pigtail
- 8mm and 10mm wrenches or socket set (for battery terminal bolts)
- Dielectric grease
Installation Steps
- Identify the positive (+) and negative (-) battery terminals. The positive terminal will have a red cover or a plus (+) symbol; the negative terminal will have a black cover or minus (-) symbol.
- Loosen but do not fully remove the positive terminal bolt. Slide the red ring terminal from the pigtail cable over the terminal post, under the existing battery cable clamp.
- Tighten the positive terminal bolt, securing both the existing cable and the red ring terminal together.
- Repeat for the negative terminal with the black ring terminal from the pigtail.
- Apply a small amount of dielectric grease to the terminals before reassembling to slow future corrosion.
- Route the pigtail cable to a convenient, protected location — under the hood lip, through a rubber grommet, or to an accessible spot where the quick-disconnect plug will be easy to reach.
- Tuck and secure any excess cable with cable ties, keeping it away from moving parts and hot surfaces.
The quick-disconnect end of the pigtail mates directly with the Battery Tender charger connector — just plug and charge. The pigtail can be left installed permanently; it does not draw any current when the charger is unplugged.
Shop the Alligator Clip and Ring Terminal Combo with Quick Disconnect (SKU: 081-0180) — includes both connection methods.
Installation Option 2: Extended Ring Terminal for Hard-to-Reach Batteries
Many modern vehicles, particularly European sedans and performance cars, locate the battery in the trunk, under the rear seat, or in a location that makes terminal access difficult or impractical during charging. For these vehicles, an extended ring terminal cable routes the quick-disconnect plug to a more accessible location — typically under the hood near the jump-start posts that most manufacturers provide.
Installation for Vehicles with Under-Seat or Trunk Batteries
- Install ring terminals on the battery as described above.
- Use the extended-length 4-foot pigtail to route the cable from the battery to a panel opening, under carpet, or through existing wire channels to reach the engine compartment.
- Secure the cable routing with cable ties every 12-18 inches.
- Terminate the quick-disconnect plug in an accessible location — typically clipped to an existing wire harness near the jump-start posts or strut tower.
- Label the plug location so it is easily found during the next charging session.
The Battery Tender 4-Foot Extension Cable with Quick Disconnect (SKU: 081-0148-12) extends reach from difficult battery locations.
Installation Option 3: Onboard Marine Charger (WaveCharge or WaveCharge Pro)
Marine onboard charger installation is the most involved of the three options — the charger mounts permanently in the boat and connects permanently to the battery system, with AC power provided through a weatherproof shore power inlet. Once installed, charging is as simple as connecting a single shore power cord at the dock.
What You Need
- WaveCharge or WaveCharge Pro multi-bank marine charger
- Shore power inlet (if not already installed)
- Appropriate gauge DC wiring (typically 10 AWG for runs under 10 feet to each bank)
- Marine-grade ring terminals and heat-shrink butt splices
- Inline fuse holders and appropriately rated fuses for each bank
- Cable ties and conduit for wire management
- Drill and hole saw for mounting
Charger Mounting Location Considerations
- Mount in a dry, ventilated compartment — never in the bilge where it may contact standing water (though IP67-rated WaveCharge units tolerate splashing).
- Minimize DC wire run length to each battery — every foot of wire adds resistance and reduces charging efficiency.
- Ensure the mounting surface is structurally adequate for the charger weight plus vibration loads.
- Allow adequate clearance around the charger for airflow — at least 2 inches on all sides.
DC Wiring Each Bank
- Run positive and negative wires from the charger output to each battery bank independently.
- Install an appropriate inline fuse on the positive wire within 18 inches of each battery — typically 15A for a 6A bank charger.
- Terminate all connections with marine-grade ring terminals — crimp connections are more reliable than solder-only in vibrating marine environments.
- Apply heat-shrink tubing to all connections for moisture protection.
- Verify polarity (positive to positive, negative to negative) before connecting to the battery.
Shore Power AC Wiring
AC wiring for a shore power inlet should be handled by a certified marine electrician if you are not experienced with marine AC systems. Marine AC wiring involves specific standards for cable routing, connection methods, and safety equipment that differ from residential electrical work.
Shop the WaveCharge and WaveCharge Pro lines for multi-battery boat systems.
Frequently Asked Questions
Can I leave a ring terminal pigtail permanently installed on my car?
Yes — permanently installed ring terminal pigtails with the quick-disconnect plug hanging free draw zero current and cause no harm. The convenience they provide far outweighs any cosmetic concern. Many enthusiasts install them the same day they buy the vehicle.
Is it safe to charge through the ring terminal pigtail with the vehicle on?
Battery Tender smart chargers can remain connected while the vehicle is on without damage. The charger's smart technology monitors battery state and adjusts output accordingly. For safety, it is best practice to charge with the vehicle off.
Do I need a professional to install a WaveCharge onboard charger?
The DC side of a WaveCharge installation is within reach of any competent DIYer comfortable with 12V wiring. The AC shore power inlet and wiring should be handled by a certified marine electrician. Many owners install the charger and DC wiring themselves and call an electrician only for the shore power portion.
What gauge wire should I use for a ring terminal pigtail?
Battery Tender OEM ring terminal pigtails use 16-18 AWG wire rated for the charger's output current. For automotive and powersports applications, this is appropriate. For the DC wiring of a marine onboard installation handling 6+ amps per bank over longer runs, use 10-12 AWG to minimize voltage drop.
Conclusion
The best battery charger is the one that actually gets used — and permanent installation of a ring terminal pigtail or onboard charging system eliminates every barrier to consistent maintenance. The 10-minute investment in a simple ring terminal pigtail yields years of effortless battery maintenance and a battery that lasts measurably longer than one that only gets charged reactively.
For boat owners, an onboard WaveCharge system converts the dock connection into a complete battery maintenance solution for every battery in the system simultaneously.
Shop Battery Tender charger accessories and installation hardware at batterytender.com.
