Is your motorcycle battery flat or worn out? How to read the signs, charge it properly and choose a battery maintainer, lithium batteries included.
You press the starter and the engine turns over slowly, or all you hear is a click. A flat motorcycle battery is one possible cause, but before buying a new one you need to know whether it simply lost charge while the bike was parked or whether it can no longer cope with starting. A loose connection can produce similar symptoms.
A battery that went flat during a lay-up usually recovers with a full charge. If the bike still struggles to start, the battery should be load-tested in a workshop (or with the right tools, if you have them), together with the charging system. Mekainos keeps track of the motorcycle’s condition and its service history, so you know when the battery was last replaced.
how do you recognise a flat motorcycle battery?
A starter motor that turns with effort and a dashboard that switches off while you try to start are signs of insufficient power. A click from the relay can also point to the problem. Lights that come on only prove that current is getting through: starting the engine takes a much greater electrical effort. So look further: with the ignition off, first check that the terminals are tight and free of visible corrosion. Sometimes, and it has happened to me too, vibration loosens the cable.
However, if the casing is swollen or leaking, stop and replace the battery. Avoid insisting with repeated attempts when the engine struggles to turn.
is the measured voltage enough to decide?
A multimeter gives you a first answer. A battery manufacturer recommends charging a 12-volt lead-acid battery when its resting voltage drops below 12.45 V, and a lithium one below 12.9 V. A reading taken right after charging is unreliable: the same manufacturer advises letting the battery rest for at least 12 hours after charging. A correct resting voltage does not tell you how the battery behaves when it has to start the engine.
A deteriorated battery can show an apparently adequate voltage and then give up during starting. A workshop can run a test suited to the battery and check the charging system. If a warning appears on the dashboard, the article on motorcycle warning lights helps you interpret it before riding on.
how do you charge a motorcycle battery properly?
Read the label to identify the technology, and choose a motorcycle battery charger declared compatible with the battery’s capacity as well. The shape of the clamps is not enough, and neither is a generic mode on the charger. Follow the charger’s instructions together with the battery’s.
The manufacturer’s technical advice on charging stresses ventilation and checking the connections. Work away from flames and sparks. Sealed batteries must stay closed; topping up only applies to models that explicitly allow it.
Connect the charger with the mains supply switched off, respecting polarity. Whether you can charge with the battery fitted depends on the instructions for the bike and for the charger. If you have to remove it, follow the procedure in the manual, including any effects on the electronic settings. Wait for the charging cycle to finish. Before disconnecting the clamps, switch off the charger’s supply as its instructions say. If the charger shows an error, find out what it means before trying again: forcing a recovery mode without knowing whether it is compatible can damage the battery.
what is the difference between a charger and a battery maintainer?
A charger restores the energy available. A motorcycle battery maintainer keeps the charge topped up while the bike is not used, and is designed for long lay-ups. Many automatic units do both: what matters is which modes they actually support.
Before leaving a device connected, check that the manual allows that kind of use for the battery fitted. Check the permitted ambient conditions too. The marketing label on the front should be compared with the specifications, especially when you move from lead-acid to lithium technology.
how do you store the battery during a long lay-up?
Prepare the lay-up before the charge drops too far. A lead-acid battery left flat deteriorates faster; a compatible maintainer can help preserve it. If there is no socket available, plan checks and recharges according to the manufacturer’s instructions.
Check the motorcycle manual before disconnecting it: accessories powered during the lay-up can contribute to the discharge. Store a removed battery in a dry place and keep the terminals away from metal objects. Before refitting it, check its condition.
what changes with a lithium motorcycle battery?
With a lithium motorcycle battery you need to know the exact chemistry. The charger must support that technology; procedures for lead-acid batteries may be unsuitable. The technical precautions for lithium iron phosphate batteries warn in particular about desulphation programmes, which can damage them. The same manufacturer advises against charging them below 0 °C and recommends storing them between 15 and 25 °C, disconnected from loads and chargers.
Respect the temperature limits stated for charging and the storage requirements. The procedure after a deep discharge also depends on the model and the protections it has. If you are replacing a lead-acid battery with a lithium one, check that it suits the motorcycle’s electrical system.
how long does a motorcycle battery last, and when should it be replaced?
Battery life varies from one battery to another: what weighs most is the time spent sitting flat and the number of times it has run down completely. A lay-up with electrical draw can drain even a battery that is still in good health. If the problem comes back after a proper charge, the starting capacity should be tested and the electrical system checked before replacing it.
Mekainos S.r.l., Turin, develops a native app for Android and iOS designed for motorcycles of every make. The app reads the motorcycle’s data through a small device that connects to the bike. It helps you understand warning lights and faults and organises maintenance around the way you ride, with a service history, so charges and replacements are recorded together with the other jobs described in the guide to motorcycle maintenance by use.
Companies that make motorcycle electronics or accessories can contact us through the form on the for businesses page.
frequently asked questions about motorcycle batteries
Can I use a car battery charger?
Only if it is compatible with the technology and capacity of the battery fitted. Check in the instructions that it supports use on a motorcycle.
Do I have to replace it after it has gone flat?
An occasional discharge first calls for an assessment and a proper charge. If starting is still difficult, the battery and the electrical system need testing.
Can I leave the maintainer connected all the time?
Only if the instructions for that battery explicitly allow it. Check the installation conditions and make sure regularly that everything is intact.
To join the Mekainos beta, apply from the for riders page.