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May 13, 2008

Season’s Change –Understanding your battery


Power to the people???


The long winter has ended and motorcycles are uncovered and dusted off ready for a new riding season. You check the oil, hit the button and..click, not much happens. The battery has died. Maybe it can be recharged? If it is a conventional lead/acid battery (the type with yellow or red caps that can be removed and translucent case that lets you see the acid level), you may be able to recharge it with your trickle charger if it has not become too sulfated.

Sulfation is the crystal formation of sulfuric acid salts on the battery plates and is usually seen as a white deposit inside the case. It forms if the battery charge becomes low or if the plates are exposed to the air due to low acid level. The sulfation affects the activity of the affected lead plate area and the battery begins to lose life.

bat1.jpgMost modern motorcycles have Maintenance Free (MF) batteries which should more correctly be called Absorbed Glass Mat (AGM) type. These are identified by having (mostly) a black case and no easily removable caps. They are called MF because it is not necessary (or advisable) to check the fluid level inside. The fluid is installed when the battery is first activated and becomes absorbed by a special fiber material (similar to blotting paper), which holds the electrolyte against the plates.

The main advantages of this type of battery are greater power for smaller size, slower self-discharge, tougher against knocks and vibration and reduced chance of spill. But these advantages come with a cost. The recharging of a discharged MF battery must be performed with special equipment. The MF battery plate will start to sulfate very quickly after discharge and this resists the electrical voltage from a regular charger. To get the charge into the battery, the voltage must be raised until the sulfate salts become broken down by electrolysis. It may take 18 or 20 volts to break through the resistance, but when it does break through, that voltage will quickly cause the plates to become hot. The heat can distort the plate and damage it or it can dry the electrolyte from the AGM. Therefore it is important to lower the voltage again to prevent the damage. Once the battery begins to accept the charge, we must keep constant amperage flowing to completely recharge the plates.

Your automobile charger will not vary the voltage sufficiently, nor will it maintain constant amperage but will usually lower the amps as the battery resistance to charge increases. (In conventional batteries, this increased resistance indicates the battery is nearing full charge).

Most quality repair shops for motorcycles will have an automatic constant amp charger which will recover a discharged MF battery but keep inbat2.jpg mind it can be a long process requiring at least a day and possibly longer. But even if you go to the parts counter and buy a new battery, it will still require an initial charge on the same automatic charger. Give the mechanic time to do his job. His charger probably cost him in excess of $600 and he made that investment to provide you with proper service.

And ask your dealer about a storage charger that you can connect to your battery while your bike is in hibernation to prevent the dreaded click”….

Cheers

DS


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