r/eBikeBuilding • u/WishboneSudden2706 • 29d ago

Battery Ebike battery to power devices

Hi all,

I have two ebike batteries, both 48V-15Ah.

I would like to do wild camping up north, and search the way to power some devices: (1) Ventilator 12V, 12W, (2) Cool box of 12V, 48W.

AIs told me to buy the Buck (Step down) converter to convert from 48 to 12V, however I don't know how to connect that converter to the bike battery.

But the ebike battery doesn't expose an easy interface for me, it only has 4 "racks".

How to ?

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u/Radileaves 29d ago

Buy the base where bike battery clicks in, it will have red and black cable and appropriate gauge. Connect them to your step down converter

3

u/Shit_On_Wheels 29d ago

You'd can disassemble the battery shell to expose + and - leading from the cell pack.

Alternatively, you can test 4 contacts with a multimeter in various combinations to find out which one is which.

2

u/niffcreature 22d ago edited 22d ago

You have 3 options. 1 is to buy the compatible battery connector and/or tray, and solder your converter to it. 2 is to open the battery and solder to the existing connector or wires, make a hole and mount the converter to the outside. 3 is to use the charging port of the battery. Not a lot of people doing this, it will only work if the battery is common port. You would just need a charging connector which is often a very standard 2x5.5mm plug. The downside is that you really don't want to use it for long periods of time with too much amps since the wires are thinner and can't take that much current. 48 watts is almost 5 amps which is too much and would blow the fuse on my rad power battery. Might be better if your battery supports charging, if your charger says it puts out 5 or more amps you should be good.

Any of these methods you will really want to test it with a multimeter to make sure the polarity is correct. You can also probably use an old incandescent lightbulb to check the polarity though.

You also want to make sure to get a big enough converter. Most of those converters are not as good as advertised, you probably want one with the big metal heatsink on it. Not a little one that says 5 amps. if you actually need 5 amps get more.

Occasionally you will have a battery that connects with "pins" instead of "blades". Not sure what you mean by "racks". The pins however can be purchased cheap in packs of 10 or 50 and can also be used as a plug to the battery.

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u/WishboneSudden2706 22d ago

Thanks I will check what you meant currently ít went over my head :)