Battery Types

Motorcycle Batteries come in four basic types: Conventional, Yumicron, User-Activated Maintenance Free and Factory Activated Maintenance Free. Each requires a slightly different commissioning procedure.

Battery Identification

  • Conventional and Yumicron Batteries can be identified easiest by the removable plastic plugs they have at the top of each cell, 6 plugs for a 12V and 3 for a 6V battery. Conventional batteries generally have part numbers starting with either 6N or 12N depending on voltage. The Yumicron batteries generally have part numbers starting with YB or CB depending on manufacturer and are only available as 12 Volt units. These types of battery are more common on older machines and usually have an overflow pipe outlet on one side.
  • User Activated Maintenance Free Batteries or more commonly just Maintenance Free are usually supplied with a 6 cell acid package and a single sealing cap strip which will seal all 6 cells of the battery simultaneously. This type of battery does not have an overflow pipe, the casing is normally opaque and the part numbers generally start with YTX, GTX, ETX or CTX depending on the manufacturer.
  • Factory Activated Maintenance Free Batteries or more commonly Gel Batteries are generally opaque and completely sealed. The part numbers of Gel Batteries are a little more varied starting with CT, CTZ, YT, YTZ amongst others. Note: Gel type batteries require a charging voltage of at least 14.0 volts as opposed to 13.8 volts for liquid electrolyte types, so if upgrading check that the charging system is suitable.

Battery Capacity

Battery capacity is important for calculating the amount of time needed for an initial charge up. Battery capacity is measured in Ampere-hours (Amp hours) and is abbreviated to Ah. This is normally approximated in the first set of digits in the part number (second in the case of conventional batteries). For example, in YTX9BS and 12N9-3B, the approximate capacity is 9Ah so theoretically the battery should be able to supply 9 amps for one hour or 1 amp for nine hours. These figures are usually very optimistic and allow for a large fall in output voltage, something modern ignition systems wouldn't be able to function with.

Commissioning Procedure

Introducing the Electrolyte

  • Conventional and Yumicron Batteries. Before they can be used these batteries have to be filled with electrolyte and charged. The electrolyte is dilute sulphuric acid so care must be taken when handling it. Wear latex gloves or similar and make sure you're not wearing your best frock as any tiny splashes on it will mean small holes the next time the garment is washed. It would also be wise to wear safety goggles as any splashes to the eyes will necessitate washing out the eye with copious amounts of water and a precautionary trip to the doctor. Small amounts of the acid on the skin may not be too harmful but should be washed off immediately as it may irritate later. In other words, it's probably a good idea to wear overalls. Acid bottles usually come with a small plastic tube which when nipped between thumb and forefinger can effectively control the acid flow. Once you are properly prepared remove the plugs from the cells, remove the cap from the overflow pipe if one is fitted, and carefully add the acid up to the 'max' line indicated on the battery to each cell in turn. Then leave the battery for a couple of minutes to settle. When you return to the battery you'll probably find the electrolyte needs topping up with acid to the line again. When you are happy with the electrolyte levels to replace the plugs, fit the tube to the overflow pipe and wipe away any spilt acid with generous amounts of water. Only use specific dilute sulphuric acid for conventional lead-acid batteries and do not add any water at the time of commissioning. After the initial filling, do not add any further acid to the battery, always top-up with distilled or deionised water.
  • Maintenance Free Batteries. These batteries are somewhat easier to fill. However, you are still dealing with dilute sulphuric acid so you would be advised to follow the precautions outlined above. Make sure the battery is on a firm surface as sometimes the acid packs need a little pressure to mate with the battery. First, remove the foil strip covering the cell openings on the top of the battery. Do not remove the foil caps on the acid pack, these will be pierced when inserted into the cell openings. Invert the acid pack so that the foil caps are pointing downwards, line up with the cell openings on the battery and push home. Sometimes you may find a gentle tap with the palm of the hand is necessary. The acid should now slowly trickle into the battery, it is important not to try and hurry this process as the acid has to be absorbed by the fibre matting between the plates. Sometimes one of the acid cells fails to empty, if this is the case try gently squeezing the offending cell or gently rock the acid pack to release the air trapped in the cell. Once all the acid has made its way into the battery place the cover strip over the cell openings and tap home with a rubber mallet.
  • Gel Batteries. These chaps come with the electrolyte already installed. Aren't you lucky?

Charging the Battery for the first time

Once you have the battery filled with electrolyte you'll need to charge it. Whilst it may be possible at this point to use the battery it is not advisable. The first charge you give a battery is the most important, and the future length of life of the battery will depend on it. When giving a battery a long charge it is preferable to remove the cell caps on conventional and yumicron batteries and perform the charging in a well-ventilated room. When initially filled with acid the battery is 'half charged', that is, 60 to 80% of capacity and you should now bring it up slowly to full charge. The best thing to use is an intelligent motorcycle battery charger, or failing that a battery charger with a 'motorcycle' setting. As a last resort you can use a trickle charger, but never use a car charger as these can supply too much current and damage the battery internals permanently. An intelligent charger will tell you when the battery is fully charged. With an ordinary charger, you will have to calculate the charging time yourself at half the Amp hour rating divided by the average charging current (usually about 1 Amp) in hours. If you're using a trickle charger it's probably best to leave at least 12 hours or even 24 depending on the size of the battery, trickle chargers usually supply between 150 and 500mA. This should be marked on it somewhere so you can calculate the necessary time using the formula above. Once charged the battery is ready to fit to the bike. After fastening the electrical terminals cover them liberally with petroleum jelly or grease to help prevent corrosion. Happy riding.

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