I think you need to be careful on how much watts it will drain, and add that on top of your motor usage, if you are in turbo, it might ask for too much power than your battery can deliver.
Other than that, just check the voltage needed 🤷🏻♂️
I’ve seen that the charger sometimes is plugged but does not charge, you have to plug it again or turn it in order to have a good contact, maybe that’s the issue
I’ve used this converter:
Je viens juste de trouver cet incroyable article sur AliExpress. Jetez-y un coup d'œil ! 2,73€ | SZWENGAO-Convertisseur de puissance abati eur, tension de Sochi, 24V 36V 48V 60V à 12V l'autorisation pipeline 3A 5A DC, 15-80V à 12V Buck
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I can tell you that I have the magicshine me2000 and the build quality is good! Very satisfied with the product, I do not know about the monteer but is should be good!
Also, after few night rides, I came to the conclusion that the handlebar light on his own is not enough, I double it with...
Magicshine are great, there is the me2000 which will use 12W, so it should be ok.
Don’t go for the big ones if you want to use the internal light output, it’s useless as you do not demiver enough power
I've also bought one on Aliexpress, the M03 : 18.38£ 47% de réduction|Enquêter avant étanche pour vélo, 3000 lumens, éclairage de sauna, feux de route et de illeur, éclairage de vélo en alliage d'aluminium, feu de vélo VTT | AliExpress
I did a custom battery with spare cells and it's very bright!
I only have 2000 lumen! In complete darkness in the forest it was a bit scary 😃
I now use a 3500 lumen on my helmet in addition, I ran into a runner in the woods, I think he didn’t recover fully his vision yet 😂