Hi all bafang G510/M620 owners,
This thread is to summarize and share knowledge about Bafang's most powerful mid drive (and possibly most powerful mid drive commonly available). Below information summary:

Manufacturer's website and specs
https://bafang-e.com/oem-area/drive-systems/drive-system/mid/m620-drive-system/
Programming UART version (till end of 2020):
http://frey-bafang.patransformers.com/2020/10/09/bafang-ultra-programming/
https://support.biktrix.com/hc/en-us/articles/360042301971-Stock-Ultra-settings-and-Programming-guide
https://endless-sphere.com/forums/viewtopic.php?t=99669
https://electricbike-blog.com/2017/11/23/i-void-warranties-hacking-the-bafang-ultra-max-mid-drive-ebike-drive/
Programming CAN version (2021 onwards)
https://lunacycle.com/bafang-besst-service-tool/
https://endless-sphere.com/forums/viewtopic.php?f=28&t=110876
Updated controller threads:
best available option, FOC controller - with efficiency close to Bosch and Yamaha, requires sending motor for upgrade (due to calibration)
https://innotrace-shop.de/produkt/motorenset-x1/
also known as
https://wattwagons.com/products/archon-x1-controller-only-upgrade-for-your-bafang-ultra
other:
https://endless-sphere.com/forums/viewtopic.php?t=95671
Spare part sources:
https://lunacycle.com/ultra-parts/
https://california-ebike.com/product-category/parts/bafang-ultra/
https://www.greenbikekit.com/bafang-8fun-spare-parts/ultra-g510-mid-motor-parts.html
https://mayebikes.en.alibaba.com/productgrouplist-814430431/Bafang_mid_motor_parts.html?spm=a2700.icbuShop.88.49.7f063b59p0Aid2
The last shop - I managed to purchase there small parts not listed on their website.
Most interesting applications:
http://www.frey.bike/
- AM1000 is one of best Ultra applications ever 21Ah Battery
- EX (sorry for being cruel) big dissapointment, serious design failures (details require a different article) 14/28Ah battery
- CC - brilliant idea - fast commuter with simmilar errors as EX, 14Ah battery
Ansbern Old - 21Ah battery, failed seat tube angle
Ansbern New - 17Ah battery
EXESS HP 180 - top of the linne, but is it discontinued?
https://endless-sphere.com/forums/viewtopic.php?t=94997
Luna Apex - sorry too ugly to add link,
others - many Fat bike projects - more ore less successful, I'm not a fan of fatbikes, especially if there are 3" tyres on std ebikes available.
I wrote the above to my best knowledge, to save others research time and hopefully start gathering all knowledge on the subject in the thread below. I had no intention to favour or discredit any brand/shop, producer, however if any statement is wrong from technical perspective or to harsh, pls let me know and I will gladly imrpoove the post.
This thread is to summarize and share knowledge about Bafang's most powerful mid drive (and possibly most powerful mid drive commonly available). Below information summary:

Manufacturer's website and specs
https://bafang-e.com/oem-area/drive-systems/drive-system/mid/m620-drive-system/
Programming UART version (till end of 2020):
http://frey-bafang.patransformers.com/2020/10/09/bafang-ultra-programming/
https://support.biktrix.com/hc/en-us/articles/360042301971-Stock-Ultra-settings-and-Programming-guide
https://endless-sphere.com/forums/viewtopic.php?t=99669
https://electricbike-blog.com/2017/11/23/i-void-warranties-hacking-the-bafang-ultra-max-mid-drive-ebike-drive/
Programming CAN version (2021 onwards)
https://lunacycle.com/bafang-besst-service-tool/
https://endless-sphere.com/forums/viewtopic.php?f=28&t=110876
Updated controller threads:
best available option, FOC controller - with efficiency close to Bosch and Yamaha, requires sending motor for upgrade (due to calibration)
https://innotrace-shop.de/produkt/motorenset-x1/
also known as
https://wattwagons.com/products/archon-x1-controller-only-upgrade-for-your-bafang-ultra
other:
https://endless-sphere.com/forums/viewtopic.php?t=95671
Spare part sources:
https://lunacycle.com/ultra-parts/
https://california-ebike.com/product-category/parts/bafang-ultra/
https://www.greenbikekit.com/bafang-8fun-spare-parts/ultra-g510-mid-motor-parts.html
https://mayebikes.en.alibaba.com/productgrouplist-814430431/Bafang_mid_motor_parts.html?spm=a2700.icbuShop.88.49.7f063b59p0Aid2
The last shop - I managed to purchase there small parts not listed on their website.
Most interesting applications:
http://www.frey.bike/
- AM1000 is one of best Ultra applications ever 21Ah Battery
- EX (sorry for being cruel) big dissapointment, serious design failures (details require a different article) 14/28Ah battery
- CC - brilliant idea - fast commuter with simmilar errors as EX, 14Ah battery
Ansbern Old - 21Ah battery, failed seat tube angle
Ansbern New - 17Ah battery
EXESS HP 180 - top of the linne, but is it discontinued?
https://endless-sphere.com/forums/viewtopic.php?t=94997
Luna Apex - sorry too ugly to add link,
others - many Fat bike projects - more ore less successful, I'm not a fan of fatbikes, especially if there are 3" tyres on std ebikes available.
I wrote the above to my best knowledge, to save others research time and hopefully start gathering all knowledge on the subject in the thread below. I had no intention to favour or discredit any brand/shop, producer, however if any statement is wrong from technical perspective or to harsh, pls let me know and I will gladly imrpoove the post.