Why has my motorcycle battery gone flat and what can I do about it?
There are several reasons why a motorcycle battery can go flat but it is very rarely the battery that is at fault unless it's getting really old.
In some cases the battery can be recovered to good working order. The cause of the loss of charge should be identified quickly otherwise it will just keep going flat and letting you down.
1. The most common cause of a flat battery is the battery self-discharging during a long period when the bike gets very little or no use at all. All batteries gradually lose their charge at a slow and steady rate and this is quite normal, but after a few weeks it can mean that your battery may not have enough power left to start your bike. If the bike is fitted with an alarm or any other accessories this will happen even more quickly.
2. Another common reason is if there is an additional load on the battery such as leaving the lights or some other equipment switched on, or if there is an electrical fault which puts more load on the battery than normal.
3. The other main reason for a flat battery is if the battery is not being re-charged correctly while the engine is running. This can mean that even if you start a journey with a fully charged battery it will gradually go flat while you are riding because the lights, ignition, instruments etc. gradually take power from the battery and it is not being replaced by the bike's charging system. This means that at the end of your journey your battery might be nearly flat and will not re-start, or it might even run out completely while you are still riding causing the engine to cut out and not re-start.
Before you start checking for the cause of the problem the first thing to do is to re-charge the battery.
If it is a good quality battery then it should re-charge without a problem as long as it hasn't been flat for more than a few days. However if it has been flat for much longer than that or it is a poor quality battery then the chances of recovering it get smaller.
1. Connect the battery to a 12v charger with an output current in the range recommended for the battery and switch the charger on, or if it is an automatic charger check that it starts on its own.
2. If the charger does not start up then this might be because the battery voltage is too low for the charger to recognise that it is connected to a battery. If this happens then it is likely that you will need to buy a new battery.
3. Depending on how flat the battery was it may take anything from a few hours to several days to fully charge. You may also need to restart the charging process periodically if the charger "times out" during charging.
If your battery is still going flat unexpectedly and all the above possible reasons have been ruled out, or if the battery will not charge up at all, then it may need replacing from the range in our shop or on our website.
Click here to find a new Yuasa battery for your motorcycle