A 12V and USB charger to use on a Bosch e-bike to charge a phone or use an electric pump to inflate a paddleboard.

Supplies

DC - DC converter, 15A, 30-60V in, 12V out | aliexpress link
USB socket 60W PD with fuse and spade connectors (2PD1QCOR) | aliexpress link
Car cigarette lighter socket, 12V, 20A (15A might also work) | aliexpress link
2x XT60 connector | aliexpress link
Latch button (needs to handle 10-15A) | aliexpress link
1K ohm resistor | aliexpress link
2x 3 port wire connector | aliexpress link
2x 2 port wire connector (can also be 3 port)
2x male spade connector | aliexpress link
Splash proof container (here bike water bottle used)
Modelling paste (to make connector)
Wood cutouts (OPTIONAL, to mount DC - DC converter and give rigidity to container)
Cable tie (to hold DC - DC converter to wood cutout)
18AWG silicone wire (or thicker) | aliexpress link
Heat shrink tube | aliexpress link
Solder
Hot glue

Equipment

Soldering iron
Sharp knife
Hot glue gun
Drill (to make round holes if you don't want to use knife)
Belt sander (to make DC - DC converter fit in water bottle)
Laser cutter (to make wooden cutouts) | engraveme link

Other

Bestway 12V pump for paddleboard | bestway website | aliexpress link (might be found cheaper locally)

Step 1: Notes

IMPORTANT: this might damage your e-bike, battery or both. I'm not an electrician, things might melt, smoke, catch fire or explode. be careful when working with high currents! ⚠️

I have not yet found a way to directly connect to the battery because Bosch uses a proprietary communication protocol.

Step 2: Testing & Planning

Connect the DC - DC converter input to your bike. (this might spark)
Connect the DC - DC converter output to a 12V load.
Turn on the battery.
Turn on the load.
Check for smoke, fire or other damage, if none, proceed.
Check the distance from your bike output to where your container will be placed, this will determine the length of the wire you need to use

Step 3: Cut the Hole & Sand Down Converter

Cut a big enough hole in your container to fit the converter and all of the wires in.
If the converter does not fit in your container, sand down until it fits.
If you don't have access to a belt sander, use a metal saw or file instead.

Warning: this might get very hot, you might damage it and this will reduce the amount of heat that can be dissipated.

Step 4: (optional) Create Supports

Use (and modify) the svg to cutout supports for the converter/bottle, this will benefit the rigidity of the bottle.
Cut in 3mm mdf. (People living in Switzerland can use www.engraveme.ch to order the parts)
Attach the converter with a cable tie to the cutout.

bottleskeleton.svg
Download

Step 5: Wire It Up

Wire up according to the diagram and keep track of polarity. You don't need to use the wire terminals or XT60 connectors but it's easier to put everything together afterwards.

It's recommended to test if everything works after you connected everything.

Step 6: Mould the Bike Connection

!Make sure the wires fit trough the hole before moulding this!

Push the male spade connectors into the correct terminals of your battery (should be marked with + and -. Once they are correctly positioned, mould the paste around it until you are satisfied with the result.

Follow the instructions on the packaging for drying times etc.

Step 7: Put It in the Box

Attach the USB socket from the top. (you might need a big washer to clamp it firmly into the neck of the bottle)
Attach the button in trough a hole.
Attach the XT60 output with some hot glue to the outside.
Connect everything.
Put everything neatly inside.
Put the biggest disk-thingy in first.
Put the double thick half circle-thingy in second.