I am also fairly certain that JBD=Overkill.
Overkill does not
equal JBD (as in they are not the same company), but the BMS's Overkill sells are JBD BMS's under their own brand name, which I think is probably what you mean.
They also put in the time/effort/money to write a manual for the specific models they sell. If you have the same model number, it should apply to you as well, if you have a different model number, it will still mostly apply, but some small and large things may be different (JBD has a lot of different models, and a few different lines I think).
Side note, Overkill Solar is a forum member, blanking on the name right now.
I found a photo of their BMS with the exact same model numbers except for the 'A4S'
With some careful study, I think you could probably learn to decipher the model numbers, from what I recall at least a good portion of the model number is pretty intuitive.
What is your model #?
I haven't yet found a user manual specifically for my model number.
Unfortunately there probably isn't one if its not one of the three Overkill sells.
believe the reason they wrote one is because there was no good documentation direct from the manufacturer. This is a great 'value add' from them, before that, I thought of them as just another reseller rebranding a ubiquitous BMS and selling to a western audience, but my opinion of them really changed when they took the time to write that up (or pay to have it done). Since then, I have come to see them as a reseller that adds considerable value to the community.