Nuts About Bikes

Keeping Mr. Sparky Happy - Motorcycle Batteries

We ask a lot of that little motorcycle battery. And - considering the conditions under which it lives - it's pretty amazing how well it performs.

Your battery needs a bit of TLC to keep you on the straight and narrow. Now that spring is almost sprung, it's time to check Little Sparky to help him get you through the riding season.

By virtue of our lot in life, the motorcyclist is almost a textbook case of what not to do. Batteries are happy when they get charged regularly - at least once a month. Weather, lack of daylight and any other number of factors can sometimes keep us out of the saddle for weeks at a time - depriving the battery of the charge it craves.

Worse, winter really takes a toll. The combination of lack of charge and low temperatures can really wreak havoc on the battery's chemistry.

Batteries are also not keen on undue vibration, which tends to degrade the plates faster and decrease lifetime. Heat is a problem, too - and most of our bikes have the battery buried under seat, engine or gas tank - areas that can get pretty toasty when tooling down then Interstate in summer.

And with batteries, bigger is always better. The larger the battery, the less work it has to do - with extra capacity beyond the basic needs. Since we need miniature batteries - we tend to deprive them of that breathing room.

These are extreme conditions - it's no wonder our bike batteries don't last as long as our car batteries.

Here's Nuts About Bikes' spring battery tune-up report - tips to keep Mr. Sparky happy.

Safety first

Acid trip: Before we start tinkering down there, remember that batteries contain sulphuric acid, which is unpleasant when applied to skin and eyeballs. Though it's supposed to stay inside - there are conditions that will cause it to leak, including a cracked case, overheating and loose caps. Wear gloves and wash your hands well after handling the battery. Also keep the acid away from clothing you are fond of, unless you like a little extra ventilation. (The holes will magically appear the next time you run the item through the wash.)

Hindenburg reenactment: an active battery (one that's being used or charged) will vent pure hydrogen gas, which is on the explosive side. Don't smoke when working on the battery and be careful with chargers and sparks. Batteries explode on a routine basis. This is the reason for the "last connection to engine block" jumping routine. And don't apply or remove charger leads without first unplugging it from wall current.

Old style and new

There's a new mix of technology on the landscape - the old fashioned lead-acid battery and the newer style sealed "maintenance-free" variety.

The new style batteries produce a higher baseline voltage than the older design. With many more electronic components and gizmos, many newer bikes depend on this higher operating voltage. When the battery starts to go - the voltage drops - and gremlins could begin to appear.

Many riders have experienced this kind of strangeness. The battery seems fine - the lights work, the horn blows and the engine cranks. But little electrical problems start cropping up - like speedometer weirdness and other intermittent accessory issues. In many cases - these annoyances may be the result of the voltage drop on a dying maintenance-free battery.

This is also the reason you want to be sure to give your bike the right battery. You might save a few bucks by getting an old-style battery for a new bike - but you could pay the price when the lower voltage starts making trouble.

Say 'ahhhh'

How can you tell if your battery is heading south? First, grab a multimeter at your local auto parts store or Radio Shack. They are cheap and an essential tool in the garage.

Be sure your battery is fully charged but cool. (If you check voltage on a hot battery immediately after charging or riding, you may get an artificially high reading.) Set your multimeter to a scale that puts 12 volts DC somewhere in the middle, be sure everything on the bike is switched off and touch the leads to the battery terminals.

A traditional lead-acid battery should show a minimum of 12.6 volts. The maintenance-free varieties should produce at least 12.8 volts.

A healthy battery may show a higher reading - we've seen maintenance-free batteries as high as 14 volts. This high variance won't bother your bike. But if you see 12 or less - you are likely at the end of your battery's useful lifetime, unless you have a charging problem.

Not the end of the road.

Batteries are funny characters. Bad batteries often show healthy voltage. That's because the multimeter puts no load on the battery. A battery that's going to let you down could pass the multimeter test but fail under load. If your voltage is good but your battery seems troublesome, the only way to know for sure is to take it to a technician who can do a load test.

A word of warning here. We'd be loaded if we had a dollar for all the good batteries that are pulled from vehicles and thrown away each year. There is no shortage of mechanics and owners who do not understand the difference between a dead battery and a bad one. Arm yourself with some basic knowledge to avoid getting taken down this road, paved with wasted money.

The battery is basically a container that stores power for later use. It's not a NASA fuel cell that generates electricity by magic. You drain a battery, and it's dead. Leave the lights on overnight - crank without starting - ride without a functioning charging system - and you'll end up with a dead battery.

There are thousands of mechanics out there that will line up to sell you a new one when you show up with a dead battery. This is a crime of epic proportions. It's like shooting the cow when your milk glass is empty.

Here's the quandary: a dead battery may be good and a bad battery isn't necessarily dead.

The maintenance-free formula throws in another monkey wrench. In the old days, lead batteries could be charged relatively quickly with high charger voltage which made testing quicker. Those days are gone. Today's batteries need a slow charge for a long time - in some cases 12 hours or more.

You can't test a dead battery. So step one is to charge it up - however long that takes. This is where owners complicate matters - demanding their mechanics sell them batteries they don't need. Nobody wants to wait until tomorrow. Trouble is, if you put a new, good battery into a vehicle with an electrical problem, you are going to end up with another dead battery and a lighter wallet.

The charging will tell tales, too. If you charge a battery at say, two amps, for 24 hours and it's still reading under 12 volts, that's a pretty good bet that the battery's ready for recycling.

If it takes a charge and has good baseline voltage after charging - you might be OK. But if you are still having problems - you need to get it load-tested.

If the battery checks out but the bike keeps killing it - you have another issue in your electrical system. This could be anything from a failed component to a stuck relay. The battery is either being drained or denied a charge, so check it out.

Keeping it healthy

For the most part, you are at the mercy of your battery's useful lifetime. However, you can do a few things to keep it happy and perhaps buy yourself some extra time:

Check the fluid (old-style lead batteries.) The electrolyte should just cover the plates inside. If the battery is consuming fluid, your bike might be overcharging. Don't let the plates go dry - once that happens it's ready for the recycler. Don't overfill or you risk vent drainage when the battery heats up. Fill a charged battery with distilled water. You should never have to put acid into a battery unless it's new and has never been filled before.

Use a float charger when the bike is sitting. Keeping the battery cozy and charged is the thing, especially when the mercury drops. You can get a fancy charger-tender with a pigtail that stays with your bike and makes connection a breeze. Or save some cash with traditional alligator clips - this style can be had for under $10, like the ones they sell at Harbor Freight.

Keep the terminals clean: corrosion on the terminals will increase resistance and make the battery work harder. Keep 'em clean. Hot water and baking soda will break down the schmutz - but you'll want to do the bath away from the bike to protect your paint. A wire brush will send corrosion packing. A little is normal - but a lot could mean you have a charging issue or an acid leak somewhere. Coat the terminals with Vaseline after cleaning to prevent corrosion buildup.

Check the connections: make sure your cables and connections are in good shape and your battery bolts are nice and tight. But don't try to tighten the positive terminal without first detaching the negative. (When your wrench hits anything metal on the bike, you'll get a bit of Independence Day which is always a bad thing around batteries and hydrogen gas.) Here's the drill: 1) detach the negative lead; 2) inspect and tighten the positive; 3) reattach the negative and tighten.

Be gentle when charging: use a low-current charger, no more than an amp or two. (Technically, you should charge a battery at one tenth its amp-hour capacity rating. So if your battery capacity is 12, you'd want to use a 1 or 1.5 amp charger at most.) Be sure any charger you use is "automatic" - when the battery voltage comes up, the charger ratchets down to avoid cooking the insides. Keep an eye on the fluid level during charging - loosen the caps to vent gas and charge in a well ventilated area. To avoid sparks, NEVER apply or remove a charger without first unplugging it from wall current.

Replace or wait?

It's really up to you and your style of riding. With luck, you could go five years on a bike battery, but at some point it's going to give up the ghost and leave you stranded somewhere. (Unless you have a kickstarter, pretty rare these days.)

If you ride close to home or always with friends - you may feel comfortable riding until it dies. If you're the more paranoid type and your battery is more than a few years old, you might want to slap in a new one this year.

Also consider that jumping a bike can be tricky, with cramped quarters and tiny terminals. And unless your riding buddies are young and spry - getting a push could be a challenge, too.

Learn more: Here's a terrific battery FAQ from Yuasa USA.

Stay safe.

- Sal, Editor
March 2007