j 'ai vérifié dans une documentation technique les tensions sont bonnes.

infos données dans la notice d'atelier:

Charge feed check
• Remove the tail unit • Switch on the engine and run it at 2000 r.p.m. with
the light switch in the “ON” position and the selector on main beam Hl.
Measure the voltage between the positive (+) and negative (-) terminals of the battery with a multi-tester. If the tester indicates less than 12.6V or more than 14.3V the cause will be found in the generator.
N.B. When carrying out this check, ensure that the battery is fully charged.
Standard recharge voltage: 12.6 - 14.3V at 2000 r.p.m.

oui je suis d'accord , mais a la page 21 de la notice technique il ya ça:

Electrical system
A list of possible problems that could occur when the warning light is switched on.


With the engine switched on at approximately
2000 r.p.m. check the voltage of
the battery (all utilities must be switched
off and the regulator at 25°C.); the voltage
must be 14.5V ± 0.6.
N.B. At different temperatures the voltage
can be between 13V and 15.5V.

merci pour l'info