Battery problems

Charging and voltage checks

This free guided diagnosis asks up to 6 questions about what the bike is actually doing and narrows it down to 6 possible faults, each with a safety call, what it costs to fix, and the guide that fixes it.

Start the guided diagnosis

What causes battery problems?

Charging system undercharging

Battery may be healthy but not receiving enough charge. Test stator and regulator/rectifier.

Ride with caution. Ride only where you could be recovered. An undercharging bike dies as soon as the battery runs down. Typical cost: $40-180 DIY, $200-500 at a shop.

Regulator/rectifier failing

Low charging voltage indicates the regulator/rectifier is not converting AC properly.

Ride with caution. Fix before your next long ride. The bike runs until the battery is flat, then stops wherever it happens to be. Typical cost: $45-160 DIY, $220-480 at a shop.

Battery at end-of-life

Capacity fades over time. Replace with quality AGM or lithium battery.

Safe to ride. Not dangerous, but replace it before it leaves you stuck at a fuel stop. Typical cost: $60-140 DIY, $150-260 at a shop.

Parasitic electrical draw

Aftermarket accessories may drain battery when parked. Test draw with multimeter.

Safe to ride. Not a safety issue, but it will keep flattening batteries until the accessory is traced. Typical cost: $10-60 DIY, $100-250 at a shop.

Internal short or relay issue

Battery drains without accessories. May have internal short or stuck relay.

Safe to ride. Trace it before it kills another battery. A stuck relay can also overheat its wiring. Typical cost: $10-80 DIY, $120-300 at a shop.

Sudden battery cell failure

Sudden failure indicates internal cell short. Battery needs immediate replacement.

Safe to ride. The battery is scrap. Check for a swollen case before you put a charger anywhere near it. Typical cost: $60-140 DIY, $150-260 at a shop.

Guides that fix these faults

Other symptoms