>>1082908>12v aux at 4a
It depends on your pack voltage - most dc-dc converters top out at 48v input. Ebikes.ca
makes a really small, potted unit that I use to power my LED lamps, a USB port, and microcontroller stuff. The larger potted aluminum ones used on golfcarts that say 48v I've tested up to 85V but they are quite a bit larger.>>1082918>mid drives and broken chains
Lots of folks running 7kw+ without problem on a chain (as high as 40kw with smaller reduction see Endless-Sphere user 'recumpence'). I've found 5kw at 20:1 reduction really reliable.
Chain breaks are usually the result of 4 things:
- chain angle
You'll want to optimize for whatever gear you spend time in. On an ebike this is usually the high gear. You'll also want at least >14 tooth gear else it wont hold and the chain will slip. This could be as benign as a 'popping' sound as it slips to fucking up your derailleur.
- chain bounce
Use a clutched rear derailleur - solves this issue. Without it you get oscillations in the chain that result in dropped chains that get broken as they bind up in your drivetrain.
- unsmooth/jerky starts cause breakage
Use high enough reduction and you will get a smooth preload. If <~20:1, you'll want to use a throttle ramping circuit inline with the throttle input. Google 'throttle tamer' and the throttle mapping feature of the Cycle Analyst. This was a big problem on my GNG kit running at 6kw.
- Shit Chinese hardware
Poor chain quality chain tensioners and excessive runout on reduction side jackshafts are usually to blame. Don't buy Chinese shit.