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What you need to know about batteries.

You can make your own simple wet-cell storage battery with only two lead plates. Submerge them in an electrolyte solution (64% water and 36% sulfuric ac is standard), apply direct current and watch as the positive lead plate develops a brown coating of lead peroxide and the negative plate becomes sponge lead. Remove the voltage source and put a voltmeter across the plates and you'll find approximately 2.1 volts, regardless of the size. The larger the plates, the longer the battery can supply this voltage. Combining six cells can make a 12-volt battery (12.6 volts) TADA you've got a 12V battery!

When we ask the battery to produce current flow by putting a load across its terminals, the plates and acid solution undergo another chemical transformation, causing both lead plates to change into lead sulfate, consuming the acid and producing water as a by-product.

Gradually the electrolyte becomes increasingly watery and the plates more sulfated until the battery either dies or we reverse the process by returning current to the battery by charging it. The basic chemistry hasn't changed for a hundred years.

Motorcycles don't have the room that cars do for large batteries. Since even a smooth-running motorcycle subjects the innards of a battery to much greater vibration than a car, the motorcycle battery's case will be a tighter fit to prevent the lead plates from rattling to pieces. But it's still generally true that a motorcycle that vibrates a lot will have a shorter battery life, because the plates themselves are more fragile than you might expect. They are constructed of highly active but very soft lead pastes applied to waffled supporting grids, which provide greater surface area for the chemical reaction than simple flat plates. The paste is porous to allow full penetration of the electrolyte, and the pastes on both the negative and positive plates begin as the same substance; a mixture of lead oxide, dilute sulfuric acid, water and special binders like plastic fiber that produce a material about the consistency of firm mud. Recently we've seen some batteries coming out of China that are using recycled wood and cardboard as binders, these break down WAY too quickly. We've seen Chinese scooter batteries that have failed in as little as 30 days.

To make the battery more rugged for motorcycle applications the plate grids must be made of a harder lead alloy, usually lead-antimony. Anywhere up to 12% antimony is typical, with higher antimony mixtures making for tougher plates but shortening the sitting life of the charged battery. The big drawback to lead-antimony is that gradual corrosion of the positive grid releases the antimony, which may then form tiny hairlike bridges between the plates. These bridges are actually short circuits that gradually increase the current necessary to recharge the battery, causing increased electrolyte loss. Therefore, an older battery needs it electrolyte level checked more often.

Most bikes and scooters ship with sealed, maintenance-free batteries now use calcium instead of antimony to strengthen the plate grids, since calcium does not produce internal shorts. By giving the battery box a slightly larger volume to hold an extra reserve of electrolyte, incorporating sulfation-retardants and some even use a gas-recombinant technology (GRT a special glass mat or AGM surrounding the plates which helps the hydrogen and oxygen recombine rather than escape from the battery as a gas, do not confuse these with Gel Cell ), the manufacturer can eliminate the filler caps. However, all these batteries are not truly sealed, but may incorporate almost invisible safety vents around the perimeter of their tops. Do NOT routinely tip them upside down!

As advertised, the maintenance-free battery does have a natural resistance to overcharging and water loss. But unfortunately, they are also not as resilient as the old lead antimony (drain tube) style when deeply discharged (considered to be the loss of 80% capacity) and can be killed by such things as leaving an electrical load on for a long time (alarm systems, immobilizers etc.) while a lead-antimony battery might still be saved. Some of the new high-tech "smart" battery chargers often claim to be able to restore even a deeply-discharged maintenance-free battery by increasing the initial charging voltage to as high as 20 volts to overcome the internal reisistance. This has had mixed results, car batteries are usually large enough to handle this kind of heat, where motorcycle batteries will usually melt down internally in the process. This usually puts the final nail in the coffin for a battery that was on its way out anyway.


Even a battery disconnected from its cables slowly self-discharges over time, typically at a rate of around 1% of total output per day for the refillable lead-antimony battery, or up to .3% per day for the maintenance-free lead-calcium type. It's therefore prudent to charge your bike's battery every two to four weeks if the bike is not being used, more often if accessories are drawing power.

Battery Tenders (and their like) this chore a thing of the past. Internal circuitry monitors the battery's condition and applies voltage only as necessary so your battery is always ready to go when you are.

Try glueing a penny to the top of the battery as a sacrificial anode to minimize corrosion of the terminals. We laughed at this when we first read it, but a lot of these scooters have batteries that are BURIED in the bodywork (X9, BV500 etc.) this will greatly reduce the amount of corrosion you'll deal with.

The discharge rate is also temperature-dependent. Hot weather greatly accelerates self-discharge (at 95º, it's twice as fast as at 77º, and 130º is considered lethal) and cold weather slows it, so it stands to reason that charged batteries are best stored in a cool (and dry) place. However, very cold weather can actualy turn electrolyte to jelly or even freeze it solid. And since a discharged battery contains a greater percentage of water, it freezes sooner than a fully charged one. Just a frosty 27º can be enough to jellify a weak battery, but a fully charged battery will resist freezing down to a -75º. Also, don't attempt to jump-start a very cold battery without letting it thaw out first.

Routine battery inspection can be the ounce of prevention that saves many pounds of new lead cure. Periodic checks of the electrolyte level in a Lead Acid Battery will allow you add distilled water before the level drops below the tops of the plates. Should this happen, contact with the oxygen in the air will cause the sulfation, which is actually crystalline, to grow until it will bridge the plates and short them out permanently. And distilled water is an absolute necessity in a motorycle battery. The second worse thing you can do to hurt a battery is use tap water to top it up.

Simple corrosion of the battery terminals can drastically reduce the battery's ability to supply, receive or hold voltage. Plus, the gradual buildup of acid fumes, dirt and grime into an electrically-conductive film on the case between the terminals can greatly accelerate self-discharge. Baking soda mixed with warm water is the perfect tonic to cure these problems. Sponging this mixture over the area around the battery is a good idea too. Keeping the top of your battery clean is more important than you think.

It's wise to occasionally disconnect your battery cables and clean the connections even if they don't look bad. The surface you can't see is where the contact corrodes first. Brushing the soda solution on the corrosion produces a satisfying rapid white foaming as the crusty stuff is neutralized. Just apply until the foaming stops, dry the pieces and burnish the terminals with a wire brush or fine sandpaper to ensure an excellent connection.

CHARGING - Wow! We finally got to charging!

The proper trickle-charging rate for a motorcycle battery is one-tenth of the A/H rating for as long as 10 hours, depending on how discharged it is. Charging faster than 2 amps causes overheating which can warp and even melt the battery case if ignored. High-rate charging also speeds up internal corrosion, and its visible sign is sediment buildup under the cells, which if it reaches high enough, will also permanently short out the battery.

Too high a charging rate can also result in a battery that does not hold a charge because too-rapid transformation of the lead sulfate may actually trap sulfate under a surface coating of rejuvenated lead, producing a battery that can test okay but fails quickly. We see this WAY too often. If you're using a "Smart Charger" that is designed for automotive applications 2/10/50 amp, you're probably already a victim of this. If you've ever dropped your battery off at a AutoZone or NAPA or other car shop, this is probably how they charged your battery.

Both the taper-rate and trickle chargers supply only a fixed voltage. However, the lead-antimony battery should be charged at 14-15 volts.

The lead-calcium type needs 15-16 volts to reach full charge. What's the voltage of your charger? Does it match your battery type?

Constant current chargers like the Oxford or Battery Tender brands are called smart chargers because they can vary the charging voltage to keep current constant and charge a battery much more quickly.

Visually inspect the side of translucent cases for proper electrolyte level, check its bottom for sediment buildup and take a look down the filler holes for evidence of extreme sulfation, which appears as a white crusty substance. Since the cells are connected in series, only one cell needs to short for the battery to be ruined.

Proper charging is the next step. The vent caps should be unscrewed and merely resting in their holes to allow positive venting without acid spattering from the bubbling electrolyte. During charging, a good battery's cells should all begin gassing (bubbling) together. If one cell begins rapid gassing before the others, it is likely to be a bad cell.

Because charging creates what's called a surface charge at the top of the plates that can give a false indication of voltage strength, a charged battery should be installed in the bike and the headlight's high beam turned on for about three minutes to eliminate the surface charge. A voltmeter connected across the terminals of a conventional lead-antimony battery should show between 12.3 and 12.6 volts on a 12-volt battery. If the result is below these numbers, charging has been insufficient or you've got a bad battery. An even more reliable test can be made with a load on the charged battery. Turn on the ignition and headlight but don't start the engine, and check the voltage across the battery terminals. With this load the battery should show at least 11.2 volts on a 12-volt battery. If the result is below 10 volts you've got a bad cell and will have to replace the battery.


For a conventional wet-cell vented battery, take the vent caps off and charge the battery (see above) at the recommended rate (C/10 or lower) until all cells are gassing. A battery tender may well take longer than 6 hours, but a C/10 charger will be about 3 hrs. Allow it to rest for an hour then top up with deionised (distilled) water if necessary (it rarely is) and replace the vent caps.

Without giving this initial forming charge a newly filled battery won't have the electrolyte properly and evenly mingled with the plates, and the cells won't be equalised. If such a battery is subjected to the full starting current the plates can warp, and also if not then fully charged on a run or on a charger sulphation will set in right away. It'll probably suffer with a shorted cell within a few months.


While the above is going on remove the old battery. Unattach the negative (black) cable first, and tuck it out of the way. This ensures you don't short out the positive (red) connections with your screwdriver or wrench.

Detach the clear plastic vent-hose, take out the old battery. Check that there is some foam or other padding underneath, and put the new battery in. You may have to wiggle the vent-hose on at the point, make sure that when the battery is in place this hose isn't under any tension or otherwise liable to come adrift. You do not want drops of acid on any nearby components.

Attach the positive (red) cable first, then the negative (black) one.

Ensure the battery retaining strap is in place, or whatever your scooter uses to prevent the battery moving - particularly up and down.

OK, there you have it...I'm sure the pocket-protector-types out there will have input to add to this post, please do, every bit helps!

Phil Waters
Pride Of Cleveland Scooters
Last Updated Sat, 28 Nov 2009 21:11:47 +0000

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