changing BionX aux jack from 6V to 12V

[sethoscope]

Hello, Endless Sphere!

On the BionX battery, there's an accessory jack for powering lights or other things. It defaults to 6V DC, and the manual claims it can be set to 12V. Is there anyone still alive who knows the secret rituals to accomplish this? Or failing that, could anyone recommend a decent 6V-12V converter?

I spent most of today searching, and it's looking grim. I found many listings of secret config codes, and the best such list was right here in this forum by Cephalotus, but using this I can only check the voltage, and according to that post, I'll need CAN bus tools if I want to change it.

(Weirdly, when I view the setting, it says 12, but the jack actually puts out 6.3V when turned on.)

I don't know much about CAN, but my understanding from what I read today is that it's a low level protocol, and you need to know what you want to transmit to get useful outcomes. I saw references (mostly in German) to CAN tools for BionX, and even this list of codes, but it doesn't list anything about switching the output voltage.

Plan B ought to be a step-up converter, but when I look on Amazon, everything is sketchy, and when I look on DigiKey, I'm not sure what to shop for. (I'd welcome advice on this.)

At this point, I'm nearly ready to give up and use a pack of AAs for my lights, but it's frustrating when I already have a big rechargeable battery that, in theory, can do exactly what I need if only I knew how to ask.

Thanks for reading all that.
Can anyone help?

 

[amberwolf]

I don't know how to change the existing system to provide the 12v, but you can get all sorts of DC-DC converters to output 13.6v (the usual voltage for "12v" lighting) from various ebike/EV battery voltages. Most have some input voltage range that can be fairly wide, but will probably work better in the middle of that range.

What is the battery pack voltage? (most I've seen posted are either 48v (13s) or 36v (10s).)

What is the actual input voltage range of the stuff you want to run from it?

You could instead run off the 6v and step up, but then you are limited to less than half the current the 6v port can make (because when you double the voltage, you halve the current available, because power must remain the same, *and* nothing is 100% efficient so the conversion itself wastes some power too, leaving that much less for your lights).

 

[sethoscope]

Thanks for your help.

The pack is 48V.

I don't know the acceptable input range of the lights (a 5m RGB LED strip). The AC-DC supply they came with puts out 12.4V. I'd be happy to give them 13.6V and see what happens.

That said, I just measured the current draw of the lights, and they max out at 1.2A (all white, max brightness). The battery pack manual says 1.5A max current for the port. I imagine that's independent of voltage. So it would be nice to switch the voltage from the pack, as I'll only get the lights to half power using 6V converted.

I don't really need more than half power (patterns of colors is prettier and looked more like 400-550mA, though probably with spikes higher; I could also turn the brightness down) but I'd rather it not be possible/likely to blow a fuse by playing with the light settings. I could solve that by cutting the strip shorter or shopping for less capable lights, and I could add my own fuse (easier to replace).

But... someone out there knows the sequence of bytes to broadcast on the CAN bus to double the power on the port. It's hard to settle for half power, knowing it's right there.

 

[E-HP]

https://www.amazon.com/XWST-Converter-Regulator-Waterproof-Transformer/dp/B0989Q7JPY?ref_=ast_sto_dp&th=1

Assuming 2A is good enough.

 

[amberwolf]

The pack is 48V.

I don't know the acceptable input range of the lights (a 5m RGB LED strip). The AC-DC supply they came with puts out 12.4V. I'd be happy to give them 13.6V and see what happens.

If they're like the random ebay find single-color strips I started out using on SB Cruiser, they'll work at up to 16.4V at least (4s pack charged to 4.1v each).

I suspect yours will work fine (just a bit brighter) at 13.6v; it depends on the driver chips they used. There are also 12.0v/etc DC-DC units; just the 13.6v ones can be had in sealed potted styles cheaply for vehicle applications. Random amazon link to one that should work per provided specs
https://www.amazon.com/SUPERNIGHT-Waterproof-Converter-Regulator-Module/dp/B01KV71MVM


There are sealed / potted PCB mount versions for low currents (a few amps) but may need a heatsink and/or fan when used near their rated powers. 12.xV versions are common, but ones that can operate from the ful 42v-54v range of a 48v battery pack are much less common. (I only found one for about a hundred bucks, for over 600w output capability https://www.mouser.com/ProductDetail/ABB/QBDE055A0B641-PHZ?qs=sPbYRqrBIVnUlzefw6y28g%3D%3D )

LED PSUs should also work, some are made for AC and DC input, or even just DC input.

Your original AC-DC converter (that came with the strips?) may even work from your battery, at least when near full charge. It might fail to start when the battery is low if it wasn't already running. You'd just connect it's AC input prongs to the battery + and -.

That said, I just measured the current draw of the lights, and they max out at 1.2A (all white, max brightness). The battery pack manual says 1.5A max current for the port. I imagine that's independent of voltage. So it would be nice to switch the voltage from the pack, as I'll only get the lights to half power using 6V converted.

I don't really need more than half power (patterns of colors is prettier and looked more like 400-550mA, though probably with spikes higher; I could also turn the brightness down) but I'd rather it not be possible/likely to blow a fuse by playing with the light settings. I could solve that by cutting the strip shorter or shopping for less capable lights, and I could add my own fuse (easier to replace).

At least you have some options available; I wish I knew where you could get the CAN commands, but I poked around and didnt' find anything useful other than the stuff you already found and linked originally. :/

 

[sethoscope]

Thanks. I guess I got drawn in by the tantalizing aux port and never thought of tapping into the motor power line, which after further reading I see is the usual approach. There's certainly plenty of power there.

I wonder what the voltage on the wire looks like during regenerative braking. I might hoist the bike up and measure.