Battery basics and safety for motorcycle and Powersport Batteries
What Does a Battery Do?
Batteries have 3 main functions:
- Provide electrical power to start the engine
- Supply additional current when the charging system can’t keep up with electrical demand
- Act as a voltage stabilizer for the charging system
Battery Construction and Chemistry
A battery is a device that converts chemical energy to electrical energy.
What’s Inside the Battery Case?
The battery case is divided into sections (cells). A 12-volt battery has six cells that produce just over 2 volts each for a total of approximately 12.7 volts. A 6-volt battery has only three cells with a total voltage of just over 6 volts.
The size and number of lead plates within each cell have a direct relationship to battery capacity and the ability to start engines of various sizes. Cranking current performance increases as the plate surface area increases. The battery’s current producing capacity is directly related to the amount of active material (lead) on its plates.
During discharging or charging of a battery, ions (positively or negatively charged) are transferred from the positive and negative groups of cell plates. The plates are insulated from each other with a permeable, non-conductive separator which allows the transfer of ions. At the same time as the ions are moving from one plate to another, the ratio of battery acid to water is also changing. As the battery discharges, the ratio of acid to water changes causing the specific gravity (SG) of the electrolyte solution to reduce. SG can be used to measure a battery’s state-of charge. For example, an SG of 1.160 indicates a battery with only a 50% charge. This process is reversed when the battery is charged.
The SG becomes higher as the ratio of acid to water changes back to mostly acid. Measuring SG can only be performed on a Conventional battery because it has filler caps that allow access to the electrolyte.
When a battery discharges, and the SG changes to more water (less acid), lead sulphate is produced and starts to coat the cell plates reducing the surface area over which chemical reactions can occur. Although this process is normal within the battery during discharge, a timely recharge is required to reverse the process and increase the usable surface area of the plates. Without charging, the lead sulphate will continue to develop and can become impossible to break down. If the battery becomes too discharged, total failure of the battery is likely.
Besides sulphation, corrosion is also more prevalent inside the battery while in a discharged condition. This effect on the lead plates and connections within the battery is greatly increased due to the reduced specific gravity of the electrolyte. This results in a reduction in battery performance over time. Corroded connectors may have sufficient integrity to support low drain accessories, but may lack the strength to provide a pathway for the high discharge current required to start an engine. In extreme cases it may cause the inter-cell connectors and welds to fail, leading to sudden battery failure.
Another condition that frequently occurs in a discharged battery is freezing of the electrolyte. This will only occur in a deeply discharged battery due to the increased water content in the electrolyte. This is brought about by low specific gravity conditions. A fully charged Yuasa battery has a suggested operating temperature range between: -10°C to 60°C (14°F to 140°F).
Working with batteries poses multiple hazard such as potentially explosive gases, and corrosive sulphuric acid. The following 8-point safety list will help keep these hazards under control:
- No smoking, sparks (from static electricity or other sources) or open flames around or near batteries. Batteries can produce hydrogen gas that is highly flammable when combined with oxygen; if these gases ignite the battery case can rupture or explode.
- On Conventional batteries, loosen vent caps when charging and ventilate the entire charging area. A build-up of hydrogen and oxygen levels within the battery can pose a fire hazard.
- If a battery feels hot to the touch during charging, stop charging and allow it to cool before resuming. Excessive heat damages plates and can potentially rupture the case.
- On Conventional batteries, REMOVE THE RED SEALING CAP FROM THE VENT ELBOW. Never put it back on once it is removed. If left on, gases trapped inside the battery can explode. For the same reason, the vent tube must never be kinked or blocked.
- Properly connect battery chargers leads to the battery: positive to positive, negative to negative. Unplug the charger, or turn it off before connecting or disconnecting the leads. This will minimize the chance of creating sparks when connecting or removing the leads from the battery.
- Always wear eye protection, protective gloves and protective clothing when handling a battery.
- Clean up acid spills immediately, using a water and baking soda solution to neutralize battery acid (1 part baking soda to 10 parts water).
- Make sure acid fill containers are clearly marked and work areas are well lit. If acid is swallowed or splashed in the eyes, take immediate action. Ingesting or swallowing sulphuric acid can cause serious internal injuries or death.
Remedies for contact with sulphuric acid:
- External – flush with water
- Internal – drink large quantities of milk or water, followed by milk of magnesia, vegetable oil or raw, beaten eggs. Call a doctor immediately
- Eyes – flush for several minutes with water, seek immediate medical attention
Each Yuasa range of batteries has unique features that account for differences in price and performance. Yuasa manufactures two basic battery types; Conventional and Absorbed Glass Mat (AGM).
AGM batteries do not have filler caps and are sometimes referred to as maintenance-free batteries or VRLA (valve regulated lead acid) batteries.
AGM batteries are more compact than other types because there is no free electrolyte. This makes them more “volume efficient”. Because they are filled only one time during activation, a sealing plug permanently covers the filler ports. Also there is no vent tube. AGM batteries are ideal for long term storage on vehicles that include: riding mowers, personal watercraft, scooters and motorcycles that are not ridden in winter.
Yuasa’s AGM batteries do not vent gasses to the atmosphere during the charge/discharge process. Internal freed gas is recombined inside the battery so no vent tube is required. An AGM battery can be sealed because inside the battery the negative plates are never fully charged and therefore don’t produce hydrogen gas. The positive plates create oxygen during the discharge process but instead of the oxygen being forced out of a vent tube, it reacts with the charged active material on the plates to become water until the battery is charged and the water is transformed into acid. This process is called recombinant technology.
Inside an AGM battery, the separators between negative and positive plates are made of a special fibre that is resistant to heat and acid. This design makes the AGM battery less prone to spilling acid in that there is less liquid acid contained inside the battery. In addition, an internal safety valve is used in case of accidental overcharging. The valve also includes a flame arrestor disk that minimises the risk of explosion. Some of the benefits of an AGM battery include:
- No topping up with water or having to check the electrolyte level
- Reduced self-discharge because the plate grids are manufactured from a special lead-calcium alloy that holds a charge longer than other battery types
- Easy, instant activation using the “one-push” electrolyte acid container
Most Yuasa AGM batteries are available either “factory activated” (ready for install) or as a dry battery with an acid pack. The GYZ and YTZ series batteries are only available as “factory activated”. The part numbers for dry batteries end with “-BS” to signify “bottle supplied” (i.e. YTX14-BS, YTX20HL-BS etc.).
When considering upgrading to an AGM battery that was not original equipment on a vehicle, check to make sure the charging system has a regulated output between 14.0 and 14.8 volts. In general, older vehicles have a charging rate that produces lower voltages and a Conventional battery will be the only battery option for these vehicles.
Conventional batteries offer good performance and longevity but at a lower price point. Yuasa manufactures two designs of these batteries: Conventional (YuMicron) and High Performance Conventional batteries (YuMicron CX).
They have features in common that Yuasa uses for all their batteries. Sealed posts to resist corrosion, tough polypropylene covers and containers and heat sealed construction. In addition, they share design features like special separators and through-partition construction. Yuasa YuMicron batteries have more cranking power (up to 30%) than a standard Conventional battery. The plate surface area in the YuMicron is increased by the use of thin, high-tech separators that make room for extra plates within each cell.
The YuMicron batteries also use a special inter-cell connector that minimizes internal resistance and further maximizes starting capacity, plus a special glass mat that resists vibration damage. The difference between the YuMicron and the YuMicron CX is the material used in the plates. Conventional and YuMicron batteries both use lead antimony plates while the YuMicron CX uses lead-calcium. The use of lead-calcium technology provides increased cold cranking amps, reduced water loss (up to 66% when compared to a Conventional design) and has reduced self-discharge properties resulting in a battery that will hold a charge longer.
Powersports batteries are rated in Ampere-hours (AH) and/or cold cranking amps (CCA). A battery’s ability to discharge a given amount of current over a specific length of time is the AH rating.
The AH rating is based on a fully charged battery with an open circuit voltage of 13.0 that is considered fully discharged when the voltage reaches 10.5 volts at 25°C (77°F). The Amp hour ratings are printed on the battery case in two ways: 10 hour and 20 hour ratings.
The larger the battery plate area, the greater the ampere-hour rating. Temperature also has an effect on AH because low temperatures slow down the chemical reaction inside a battery. A battery will have a lower AH capacity in cold temperatures than in warm ones.
CCA rates how well a battery can be expected to produce current at low temperatures. Just like AH, the CCA rating depends on the number of plates and their total surface area. CCA represents the discharge load in Amps that a new, fully charged battery can deliver at -18°C (0°F) over a short duration. In general, as engine size increases so does the starter motor cranking current requirement and thus CCA battery requirements.