Yuasa Powersports Batteries Technical Manual

About Yuasa

Yuasa Battery, Inc. has been a leading manufacturer of batteries in the U.S.A. since 1979. They are a major supplier of batteries for motorcycles, ATVs, utility vehicles, snowmobiles, and personal watercraft, supplying more powersports OE manufacturers than all other competitors combined. Their manufacturing facilities adhere to rigorous quality processes, ensuring high standards.

This manual is designed for both professional technicians and powersports enthusiasts, offering in-depth information on battery operation, activation, maintenance, installation, and testing. Key information is highlighted in Bold Text, and important points are summarized at the end of each section.

Battery Basics & Safety

What Does a Battery Do?

Batteries perform three primary jobs:

1. Provide electrical power to start the engine: This is the battery's main function, with requirements determined by engine size and application. Key ratings are Amp-Hour (AH) for extended current delivery and Cold Cranking Amps (CCA) for starting in low temperatures.
2. Supply additional current when the charging system can't keep up: Batteries supplement the charging system when electrical demand exceeds its capacity, such as with added accessories or at low engine speeds.
3. Act as a voltage stabilizer for the charging system: Batteries absorb voltage fluctuations and spikes, protecting sensitive electronic components.

The Lead Acid Battery

A typical lead-acid battery consists of cells, each producing approximately 2.2 volts. A 12-volt battery has six cells, totaling 13.2 volts. The cells contain alternating positive and negative lead plates separated by insulators. These plates are immersed in an electrolyte solution (sulfuric acid and water). When a load is applied, a chemical reaction occurs, producing electrical energy.

Battery Construction Features:

• Patented Sealed Post: Prevents acid seepage, reduces corrosion, and extends battery life.
• Heat Sealed Case To Cover: A bonded unit providing greater strength and protection against seepage and corrosion.
• Polypropylene Cover and Container: Offers resistance to gas and oil, and withstands higher impact in extreme weather conditions.
• Special Separator: Makes the battery spill-proof, with a valve-regulated design that eliminates water loss.
• Thru-Partition Construction: Provides a shorter current path with less resistance for increased cranking power.
• Safety Valve/Flame Arrestor: Relieves excess pressure and minimizes explosion risk.
• Special Active Material: Compounded to withstand vibration and prolong battery life.
• Special Grid Design: Withstands severe vibration and ensures maximum conductivity.

Battery Chemistry

Batteries convert chemical energy to electrical energy. They store chemicals, not electricity itself. During discharge, ions move between plates, and the sulfuric acid to water ratio changes, increasing water content and lowering specific gravity. Lead sulfate forms on plates, reducing surface area and capacity. Timely recharging reverses this process. Discharged batteries are susceptible to freezing, which can cause permanent damage.

Battery Safety

Handling batteries requires caution due to explosive gases (hydrogen) and corrosive sulfuric acid. Key safety precautions include:

• No smoking, sparks, or open flames near batteries.
• Ventilate charging areas and loosen vent caps on conventional batteries.
• Stop charging if the battery feels hot to prevent damage.
• Remove red sealing caps from vent elbows on conventional batteries and never replace them.
• Connect charger leads correctly (positive to positive, negative to negative) and unplug the charger before connecting/disconnecting.
• Wear eye protection, gloves, and protective clothing.
• Clean acid spills immediately with a water and baking soda solution.
• Ensure work areas are well-lit and acid containers are clearly marked. Seek immediate medical attention for acid ingestion or eye contact.

Battery Discharging & Charging

Battery Discharging

Discharge is the process where chemical energy is converted into electrical energy. When an electrical load is applied, sulfate ions move to the negative plates, releasing electrons. This electron flow creates DC current. As discharge progresses, the electrolyte becomes more water-rich, and lead sulfate forms on the plates, reducing the battery's capacity. Prolonged discharge can lead to sulfation and freezing.

Reasons for Self-Discharge

Batteries lose charge over time even when not in use. Self-discharge rates increase with temperature. Modern polypropylene cases do not cause discharge when stored on concrete.

Battery Charging

Charging reverses the discharge process by converting electrical energy back into chemical energy. Chargers provide higher voltage than the battery's open circuit voltage to push current into the battery. This process increases the electrolyte's specific gravity. It's crucial to use the correct charging rate (typically 1/10th of the AH rating) to avoid overheating and hydrogen gas production. Always turn off the charger before connecting or disconnecting terminals to prevent sparks.

Charging Times

Charging times vary based on battery type, state of charge, and charger type (trickle, taper, constant current). Tables provide approximate charging times.

Charging a Deeply Discharged Battery

Batteries with an open circuit voltage below 11.5 volts may require special chargers or procedures. If a battery does not show an increase in voltage after initial charging attempts, it may need replacement.

Points to Remember

• Prolonged discharge causes sulfation and damage.
• Discharged batteries are prone to freezing.
• Short trips may not provide sufficient charging.
• Verify battery state-of-charge after charging.
• High temperatures damage batteries during storage.
• Never exceed 3 amps when charging small batteries.

Battery Selection & Activation

Selecting a Battery

Choosing the correct battery is vital for customer satisfaction. Sources for correct battery information include the Yuasa Battery Specifications & Applications guide (available at yuasabatteries.com) and original equipment (OE) microfiche or parts look-up data. When replacing a battery, ensure it's the correct type or the same issues may recur.

About Sensors

Some powersports vehicles with conventional batteries use sensors that indicate low electrolyte levels via a dashboard warning light. These sensors are specific to the battery and must be replaced with the battery. AGM batteries do not use sensors.

Activating a Battery

Yuasa batteries are either Factory Activated (FA), filled and charged at the factory, or shipped dry with an acid pack. Factory activated batteries have a limited shelf life. Dry batteries must be activated before use; failure to do so can lead to plate oxidation and difficulty charging.

Choosing a Battery Charger

Battery chargers restore battery capacity by sending DC current into the battery. Types include Trickle/Taper, Constant Current, and Smart chargers. Smart chargers monitor battery state-of-charge and switch between charging and maintenance modes. For powersports batteries, charger output should not exceed 3 amps. Using high-amperage automotive chargers can damage smaller batteries.

Activating AGM Batteries

Activating AGM batteries involves filling them with electrolyte from a dedicated container. The process requires careful handling of the electrolyte and ensuring complete filling. After filling, the battery needs an initial charge.

Activating Conventional Batteries

Conventional batteries are sealed at the factory and have a long shelf life. Once unsealed, they must be activated and put into service. The process involves filling with electrolyte, allowing a stand period for electrolyte to permeate the plates, and then charging the battery to 100%.

Points to Remember

• Newly activated batteries require an initial charge.
• Yuasa Smart Chargers are recommended for activating and maintaining batteries.
• High-rate automotive chargers can damage powersports batteries.
• Never remove AGM battery caps to add water or electrolyte.
• Remove the red sealing cap from conventional battery vent elbows before activation.

Installation, Testing & Maintenance

Battery Installation

Batteries should generally be mounted in an upright position. If a different orientation is required, a "non-spillable" "Factory Activated" battery must be used. Yuasa assumes no responsibility for damage if a battery is mounted in a position other than its original OE mounting.

Inspecting a Battery

Before testing, inspect the battery for cleanliness, terminal condition, and case integrity. Clean terminals and apply dielectric grease to prevent corrosion. Check for cracks, leaks, warping, or discoloration, which may indicate overheating or overcharging.

Battery Testing — Hydrometer

Hydrometers measure the specific gravity of the electrolyte in Conventional batteries to determine state-of-charge. A fully charged battery typically has a specific gravity between 1.265 and 1.280. Readings are temperature-dependent. Floating ball hydrometers use colored balls to indicate charge levels.

Battery Testing — Voltmeter

AGM batteries, being sealed, are tested using a voltmeter for open circuit voltage. A fully charged AGM battery typically reads 12.8 to 13.0 volts. A surface charge must be removed before testing. A voltmeter can also check the vehicle's charging system.

Battery Load Testing

Load testing determines a battery's ability to start an engine. This can be done with a dedicated load tester or by using the vehicle's starter motor. Cranking voltage should not drop below 9.5 volts (at 70°F) during the test.

Yuasa Digital Powersports Battery Tester

This tester measures internal resistance, allowing it to test batteries regardless of their charge state. It provides information on open circuit voltage, state-of-charge, and battery health.

Battery Maintenance

AGM Batteries: Check every three months or three months from activation. Keep fully charged to prevent self-discharge and ensure longevity. Never open an activated AGM battery.

Conventional Batteries: Check monthly if not used regularly. Add distilled water as needed to maintain electrolyte levels. Clean terminals and ensure vent tubes are clear.

Battery Storage

For infrequent use, disconnect the battery cable. Check batteries monthly (Conventional) or quarterly (AGM). Recharge if the state-of-charge is low. Store in cool temperatures (below 60°F or above 80°F may require more frequent checks).

Sulfation and Freezing

Sulfation

Sulfation occurs from continuous discharge or low electrolyte levels, forming lead sulfate crystals on battery plates. This reduces capacity and can lead to permanent damage if not addressed promptly. Yuasa's YuMicron and AGM batteries use "Sulfate Stop" to mitigate this.

Freezing

Discharged batteries, with a higher water content in the electrolyte, are prone to freezing. Freezing can cause internal damage and crack the battery case. Fully charged batteries can withstand much lower temperatures before freezing.

Electrolyte Freezing Points

A table shows that as the specific gravity of the electrolyte decreases (indicating a lower state of charge), the freezing point increases. A fully charged battery (SG 1.265) freezes at -75°F, while a discharged battery (SG 1.050) freezes at +27°F.

Glossary

Key terms related to batteries are defined, including:

• Acid: Sulfuric acid used as electrolyte.
• AGM: Absorbed Glass Mat, a type of sealed battery.
• CCA: Cold Cranking Amps, measures starting power in cold.
• Electrolyte: Diluted sulfuric acid and water solution.
• Hydrometer: Device to measure specific gravity.
• Sulfation: Formation of lead sulfate on plates due to discharge.
• VRLA: Valve Regulated Lead Acid, a sealed battery type.

Professional Shop Products

Yuasa offers specialized products for professional use:

• Yuasa MB-2040 Battery Charger: A 4-amp charger with high output and voltage, suitable for all battery types, featuring automatic shut-off and reverse polarity protection.
• Digital Battery Tester (YUA00BTY01): Tests battery status in seconds using single load dynamic resistance technology, compatible with charged and discharged batteries.
• 10-Bank Battery Maintainer: Maintains up to 10 batteries simultaneously with a 5-stage maintenance/float charge cycle.