This newbie has a dumb newbie question - duh!

[Nixodemus]

My aim is to build a straightforward, simple, low budget commuter/ gravel bike with e-assist. My legs & lungs are not as strong as when I cycled a lot in my youth. Now I'm in my low 70's.
I want a reliable, legal mid-drive: BC has a 500W max for street legality.
I'm quite experienced at fixing stuff (albeit v slowly) but I find it best to first understand the engineering design behind the object to be fixed.
I bought a used donor bike to convert - Kona Splice - seems suitable and has 68 mm b/b and hydraulic disks.
I've done some reading and talked to a local shop that sells conversion kits, does e-bike warranty work etc.
I think the Bafang BBS02 would be a good choice. This is rated as 750W, but I expect the actual wattage or power output varies with the battery voltage - right? Hence, if I choose this model, I won't need/want a 52 V battery, which appears to be the only way that Luna Cycle packages this motor in their conversion kits. If the motor can steadily draw about 14.5A, it delivers 750W at 52V or 500W at 36V. So do I buy it instead with a 36V battery and expect the motor controller/ display etc all to be ok running at this lower voltage or is this simply the wrong motor unit if I only want 500W? I expect that the low voltage cut-off for the motor controller can be programmed to operate on a 36V power source.
The bike shop said this would work fine, but I don't (yet) fully trust them and anyway they are trying to sell their hub motors to me.
I realize and apologize for this being a very rudimentary question for forum of e-bike experts!
Any advice before I make bad choices?

[ncmired]

Hi, and welcome to the forum. The BBS02 motor and related displays are designed for 48 volts, and Bafang doesn't support using 52 volt batteries.

Many of us use 52 volt batteries for the slightly higher speeds possible, and deal with some of the related display issues 52 volts causes, such as inaccurate battery percentage remaining indications.

Some of the motor settings are tunable (via a PC to USB cable), such as max current - often the way to get to your desired 500 watt ceiling. Motor longevity is also likely improved, although Bafang's BBS series have been found to be quite reliable at higher, stock currents.

Bafang's BBS01B motor was designed for 36 volts / 250 watts and are still available, but I'd stick with the BBS02(B).

As for the legalities, riding sensibly is the key - and if you're concerned about a constable flipping your bike over and reading the motor numbers there are aftermarket "BBS02B 500W" stickers available. I'm not advocating going the sticker route, as, in general, we've not (as a group) run into law enforcement issues with the math.

For complete 48 volt BBS02 kits from a reliable North America vendor, Electrify Bikes may have some inventory.

[73Eldo]

I'm not trying to sway you away from Luna but since you are in Canada anyway maybe check these people out. I have not used them before

https://goldenmotor.bike/product-cat...id-drive-kits/

I think they are in Canada so that will likely make shipping faster and cheaper for you plus they seem to carry both the 36v and 48v 500w BBS02 models.

[ncmired]

I'm not trying to sway you away from Luna but since you are in Canada anyway maybe check these people out. I have not used them before

https://goldenmotor.bike/product-cat...id-drive-kits/

I think they are in Canada so that will likely make shipping faster and cheaper for you plus they seem to carry both the 36v and 48v 500w BBS02 models.

Thanks, 73Eldo - vendor Golden Motor is likely a much better fit for the OP's location - I hadn't looked at/over them in a long time.