Yuasa Motorbike battery YB4L-B (DC) 12V 4Ah

The Yuasa YB4L-B is the absolute industry standard for 50cc scooters, mopeds and smaller motorcycles. As part of the proven YuMicron series, this 12V lead-acid battery offers reliable starting performance and long service life. It is the first choice for countless vehicle models, from classic Vespa scooters to Simson models (with 12V system) and modern scooters from Yamaha, Peugeot or Piaggio. Thanks to “Dry Charged” technology, the battery can be stored indefinitely before first use.

Highlights at a glance

• The scooter standard: Proven millions of times in 50cc scooters and mopeds – offers exactly the right balance between compact size and starting power.
• YuMicron technology: Uses special glass mat separators to reduce internal resistance and thus delivers up to 30% more starting power than conventional batteries.
• Sulphate Stop: Chemical treatment of the plates slows sulphation, increasing lifetime, especially when the scooter stands idle for longer periods in winter.
• Dry pre-charged (DC): The battery is supplied without acid filling. In dry condition, it can be stored for a long time and is only activated “fresh” by filling with acid.
• Robust & Durable: The case is heat-sealed and resistant to vibration, oil and petrol.
• Easy maintenance: Classic design with transparent case (or markings) and plugs for easy checking of water level.

Features

FAQs for Yuasa YB4L-B

For which vehicles is this battery suitable?

The YB4L-B is the standard battery for almost all 50cc scooters (2-stroke and 4-stroke) of the Piaggio (Vespa, Zip, TPH), Yamaha (Aerox, Neos), Peugeot (Speedfight) brands as well as for many 125cc motorcycles of older years. It is also frequently used for Simson S51/SR50 (when converted to 12V).

What is the difference to the YB4L-A?

The difference usually lies in the position of the venting and partly the pole arrangement. The YB4L-B has the vent on the right side (at the positive terminal). As the path of the venting hose is predetermined in the narrow battery compartments of scooters, it is important to select the correct version (A or B). The YB4L-B is the much more common variant.

Is the battery maintenance-free?

No. This is a classic lead-acid battery. You must check the acid level regularly (min/max markings on the case) and top up with distilled water if necessary. This ensures a long service life.

Do I need to charge the battery after filling?

Yes. After filling with acid and a rest period of approx. 30 minutes (“outgassing”), the battery has voltage but not yet its full capacity. To avoid starting problems and shortened service life, it should be fully charged with an appropriate charger (low charging current, e.g. 0.4 - 0.8 A) before installation.