How to Test a Motorcycle Battery
Having starting issues with your Motorcycle or ATV battery? This brief article will show you how to test your motorcycle battery the right way and hopefully get you back on the road quickly!
To test your motorcycle battery's health, there are a few tips and tricks that will help you get going. For tools, you will need a multimeter, and a trickle charger to help diagnose.
In case you are wondering how to check a motorcycle's battery with a voltmeter it is actually simple. Find the DC voltage setting on your meter and set it to the proper resolution. We use the 20 DC setting for our voltmeter, which means it will show voltage up to 20 volts DC.
Once the meter is set, touch the positive lead (red) to the positive terminal on the battery (+). Then, touch the negative lead (black) to the negative terminal on the battery (-). The voltage will be seen on the meter, and the current voltage of your battery will be shown.
It's crucial to check the battery voltage before charging. A healthy, fully charged lead acid (flooded / AGM / GEL) motorcycle battery battery should read 12.7 - 13.6 volts. This initial check will give you a clear picture of your battery's current state.
Checking the voltage prior gives you the current state of charge and lets you know if you need further action. If the voltage is within this specified range, your problem might still be the battery or the issue may reside elsewhere.
For your reference, we have the following chart that indicates a battery’s current state of charge by voltage:
| Charge | 6 Volt | 12 Volt |
|---|---|---|
| 100% | 6.37 | 12.73 |
| 90% | 6.31 | 12.62 |
| 80% | 6.25 | 12.50 |
| 70% | 6.19 | 12.37 |
| 60% | 6.12 | 12.24 |
| 50% | 6.05 | 12.10 |
| 40% | 5.98 | 11.96 |
| 30% | 5.91 | 11.81 |
| 20% | 5.83 | 11.66 |
| 10% | 5.75 | 11.51 |
If your voltage is below 12.7 volts, you should use a smart charger and recharge the battery. Before charging, we recommend disconnecting from the application as it eliminates parasitic draws and focuses solely on the battery’s health.
Once charged, disconnect the battery from the charger, wait 30 mins, and see what the voltage off the charger drops to. Then wait another 12 hours to see where your battery’s voltage falls after the remaining residual charge has dissipated. This will be a good indicator of your general battery’s health.
Will a motorcycle start with a weak battery?
It is possible on a battery that was just charged, so we like our customers to wait 12 hours after the charge to let any residual charge dissipate.
As flooded and AGM batteries age, they sulfate which can be seen by a slight reduction in their standing voltage after charge. This reduction in voltage is normal and expected. However, once the battery drops below 12.5 volts, you might notice a weaker start under load. This might be a good indicator to use a desulfating charger to restore the battery to an earlier state.
The next step is to re-attach the application’s leads to the battery. Once hooked up, use a voltmeter to monitor the battery’s voltage during an engine start. A good battery will hold a voltage above 9.6 volts while cranking and recover into the 12-volt range once the cranking has been stopped. If it does not quickly rebound, your battery is suspect and may be due for replacement.
You can also use the multimeter to check the health of your charging system. A faulty stator can lead to a false diagnosis of a failing battery.
What should a motorcycle battery read while running?
At idle, you will not see much of an increase over the base voltages you saw earlier. We recommend you rev and keep the engine to about 4000 RPM to check the charging system properly. At this RPM, the stator should be put out full or near full power, and your battery voltage should jump up into the mid-14-volt range.
Testing a battery in this way will help you determine if there is a battery problem, mechanical problem, or if the battery was discharging from lack of maintenance or accidentally leaving a key or accessory on.
To sum it up, there are four easy steps to check a motorcycle battery:
- Check the voltage of your battery while the bike is not running.
- Check the voltage of your battery after recharging.
- Check the voltage of your battery while attempting to start the engine.
- Check the voltage of your battery with the bike running above idle.
Once you have completed these easy tests, you will have a much better idea of what is going on with your battery, charging system, or starter. If you gather this data but are still unsure what to do with it, you can write it down and call or email our tech department for further analysis.
