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Rockstar Lighting Part 2


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I have good news and bad news. First the good. If you remove the plastic cover on the top left of the drive unit (3 Phillips screws) you will uncover main body of the M620 wiring harness. In it, you will find two blue and currently unused connectors; one is for the front light, the other for the rear light,  like so:

full

The next piece of good news is you can buy the pair of harness lead kit here: https://www.greenbikekit.com/catalogsearch/result/?q=Bafang+MAX+M400%2F+Ultra+M620%2F+M420%2F+M300+mid+motor+headlight%2Ftail+light+cables(a+pair) -- $7.95 plus about the same for shipping. I went ahead and ordered a set, but doubtful I'll ever bother. Which brings me to the bad news...

In my research, these Bafang output leads are for 6 volt lighting and it appears they are also only rated at 0.5 amp(!) load -- I have not confirmed that, but the only Bafang plug-in light I can find is rated as such. So first hurdle was finding a wired 6 volt system that will output adequate light, and frankly I've had poor luck. The one Bafang compatible unit I've found is a meek 300 Lumen front light with an el-cheapo wire loop for a threaded fork fender mount hole. There are a few for the Bosch system that look decent and 6 volt compatible, but only 500 Lumens which still seems too meager.  Most other lights I've found for pre-wired systems have fewer features and limited output and/or are also significantly more expensive than fuller-featured rechargeable units. This may in fact be why Sondors has not released a plug-n-play kit for us -- after all, it's not like we need to be overly weight conscious in our lighting choices -- and there is something to be said for not having to string any more wires 😎

So for now, I bought a relatively inexpensive USB rechargeable unit with remote power pack from Amazon: https://www.amazon.com/gp/product/B06XXKQ9RG/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1  I have not used it for an extended night ride yet, but tested it and it is actually quite nice. It has three brightness levels plus two flash modes and a neat little rear power display. They also make a self-contained unit for a few dollars more, but I chose the battery pack unit simply because it's lighter weight on the bars should keep it from bouncing around on rougher terrain and the battery pack will fit easily in my top-bar phone bag -- plus if I do ever happen to get the urge to splice into the Bafang light wiring, it will make for a clean install. (My hesitation on doing this is current draw and possible damage to the Bafang controller, which would not be worth the gains IMHO.) What I have not yet tried is recharging this light battery from my controller USB output, so stay tuned on that.

One minor upside is this Bafang system should more than adequately power any LED rear light. In my search of Bosch front lights, I also found this rear light which looks promising: https://www.amazon.com/gp/product/B0858Y9G1P/ref=ox_sc_saved_title_3?smid=ATVPDKIKX0DER&psc=1 But again, it has no features other than "on" which again is bringing me back to any of the fuller-featured and relatively inexpensive usb rechargeable units. FWIW, the rear light that comes with the front kit I linked to above is actually really nifty with 3 modes --on, fast and slow strobe-- but is not rechargeable and runs on two 2032 button cells which is disappointing. I probably could drill a hole and wire to the battery contacts, but with other wired or rechargeable rear light options this seems again not worth the bother. I'll use it and see how long those button cells last, but I'm not optimistic.  

That's it for now. 

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Quick update for thread posterity. The Bafang lighting leads arrived today so I was able to accurately test and confirm output voltages. In contrast to published specs I found:

1) The front light output is apparently 12 volts, though it actually floats a little between 12.4 and 13.7,  so this may open up some additional options I had not previously considered.  It's also very likely being transformed internally off the main battery as Li+ cells are nominally 3.7 volts each, so it's not a 3 or 4 bank tap. This could mean there is more power available here than I initially suspected, however the wires are small, like 22 ga, so I remain skeptical. *(See below -- and please correct me if my calculations are in error!)   

2) The rear light output is 3.7 volts -- which actually makes some sense, and is interesting in that it opens up the possibility or hard-wiring into almost any 2-cell or rechargeable rear LED.   

*22 awg can carry 1.5 amps, 1.5 amps at 12 volts is 18 watts, and 18 watts translates to around a 1200 lumen load for sustained LED output. 1000 would probably be safer and 1000 Lumens isn't really very much light... It could in fact be 20 awg that could carry nearly twice the 22, so maybe more light-viable... Regardless, it may ultimately make more sense to use this tap for one of the inexpensive 12v to USB (5v) converters to power an additional accessory or charger.  

As of now, I am relatively happy with my rechargeable battery pack front light, so will not likely head down this particular rabbit hole. 

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