Your motorcycle battery keeps dying on you even after being fully charged. It just doesn’t make sense considering it is only a few months old. Read on to find out why your motorcycle battery keeps dying so fast. It really isn’t that complicated.
A motorcycle battery which dies every so often can be frustrating to say the least. If it is old and pretty much at the tail end of its lifespan, this eliminates the mystery because you know exactly what the problem is and what to do about it. You simply need to buy a new battery.
What if the battery is just a few months old? It means there is a problem in the electrical system and it must be found. The most common problems are a faulty battery, a faulty alternator or overload caused by too many accessories. Damaged wires and parasitic draw of power are also common.
How a Motorcycle Battery Works
Understanding how the battery and other components of the charging system works makes life a lot easier when you start investigating to find out why your motorcycle battery is dying fast.
The battery’s primary role is to provide sufficient current to start the engine. It works in conjunction with another key component called an alternator. It serves to recharge the battery so it is fully replenished when you need to start the engine again.
The alternator produces Alternating Current (AC) but it can only be utilized in the form of Direct Current (DC). Enter the third component of the charging system. The rectifier (or regulator). It converts alternating current into direct current. It also plays a regulatory role by checking the amount of current which finds its way into the motorcycle’s electrical appliances.
Why Your Motorcycle Battery Is Dying Fast
Here are some common reasons which could be causing your battery to die frequently even when it is nowhere near the end of its lifespan.
- A faulty battery
- A faulty alternator
- Damaged wires
- Too many accessories
- Parasitic draw
Faulty battery:
Yes, just because it’s new or newish, doesn’t mean it can’t be faulty. It could be failing to hold a full charge. The best way to confirm this is by using a multimeter. This is a small device used to measure current and voltage of the battery.
How to measure battery voltage: First make sure the engine is off. Also ensure the multimeter is switched to DC. Connect the multimeter’s negative leads to the battery’s negative terminal and the same for the positive leads and terminal.
You would be forgiven for assuming that a 12v reading from this 12 volt battery is a good sign. It is not. A 12v reading indicates that the battery barely has enough charge to power up the motorcycle. Ideally, a well charged battery should read at least 12.4v. If it is higher, at 12.6v or 12.8v, the better. It is rearing to go. If all you get is 12v, let the battery charge on a trickle charger for a few hours then try it again.
Once it has had sufficient charging time, get another multimeter reading. If it is now up to at least 12.4v, you can confirm the battery is in good condition. Cross it off the list of possible culprits and move to investigate the next possible problem.
A faulty alternator:
Now let’s find out if all is in order as far as power channeled from the alternator to the battery goes. Connect the multimeter leads at tick over speed. Normal readings should be at around 13.5v DC. Next warm up the engine for a few seconds then press on the throttle and maintain it at about 3000 rpm. The reading should rise to about 14.5v. Now try blipping the throttle. You should see a higher reading of about 14.8v.
These are approximate figures so don’t worry if your readings vary slightly…. Just slightly. Variations of about 0.2 volts are acceptable but not more.
Readings within these ranges mean the alternator is not sleeping on its job. If your readings are significantly lower or at zero, then you will need to do further investigation on the alternator as well as the rectifier and regulator (most modern bikes combine the latter two components into one unit).
Damaged wires:
It is not uncommon for certain sections of the wiring system to wear out as a result of rubbing against an adjacent surface or melting. When the wire casing is worn, the exposed wire comes into contact with the frame and this can drain power out of the battery to zero.
How to check for damaged wires. Unfortunately there is no shortcut. You simply have to check the entire length of every individual wire in the wiring harness. It is a tedious process but it has to be done and done methodically.
It does help to start by checking the most obvious areas which are at the steering head, near the exhaust system and under and around the seat.
Too many accessories:
There are so many cool motorcycle accessories out there. It is normal to want them all. Who wouldn’t want to have a heated vest, an mp3 player with all your favorite tunes? How about those auxiliary lights which make the bike look so much cooler?
As great as it would be to have all these and more, they come at a cost on the battery. The motorcycle already has basic electrical components like a headlight, a clock and perhaps a security alarm. All these draw power from the battery. When you add more accessories, you are putting strain on the battery. It can only support so much.
How to check battery overload: If you really must have some of these extras, consider adding a voltmeter into the system.
This way you can keep a close eye on the demands the accessories make on the battery and what it is able to put out. You may also want to invest in a more powerful alternator. It will supply more power to the battery so it can support the accessories without strain.
If the load is too high, shed some accessories for the sake of a healthy battery.
Parasitic draw:
Think of parasitic draw on a battery as a tick or some other parasite on an animal. Ticks can draw so much bool out of an animal that it becomes anemic and dies. In batteries, this concept refers to voltage being gradually sapped out of a battery by electrical components until it eventually dies.
Components such as the horn, lights, alarm, clock, GPS and so on draw a significant amount of power form the battery. If there is an abnormal draw of power by one of these components which continues even after the engine is switched off, the battery continuously loses power which is not being replenished.
How to check for parasitic draw: Remove the negative cable of the battery. Place a multimeter leads between the negative terminal of the battery and the negative cable. This measures the current draw and should be at zero. A reading of one amp or less is negligible. If the reading is one amp or more then you can confirm that you have a parasitic leak somewhere. Start instigating each individual accessory.
Conclusion
Figuring out why your motorcycle battery is dying fast takes a good understanding of how the charging system works and the most common causes of this problem. With this basic knowledge you can embark on a process of elimination.
Check how much current the battery is putting out and if that is fine check if the alternator is channeling enough to the battery. If both of these are fine, do a slow and methodical check of the wiring system. Lastly check if your accessories are putting too much strain on the battery or if one of the accessories is ‘secretly’ sucking power out of the battery.
