Can i tap charging lead to draw small power for light?

I was wondering if it would be possible to connect a small load (.5a) to the charging lead to draw power for a light? It will be much easier to tap into cables of that size as everything else is 10 gauge and pretty tightly secured. Part of me says yes, but part of me isn't sure if it will cause any problems with the BMS . Have the bike under the knife right now, So thanks in advance!

That will depend on the BMS. If it is a "2 wire" BMS then it won't matter since the charge and discharge leads some from the same spot on the BMS board.

If it is a "3 wire" BMS; I wouldn't tap into the charge leads because the charge circuit may not have discharge protection for the cells.

pwd said:

That will depend on the BMS. If it is a "2 wire" BMS then it won't matter since the charge and discharge leads some from the same spot on the BMS board.

If it is a "3 wire" BMS; I wouldn't tap into the charge leads because the charge circuit may not have discharge protection for the cells.

Click to expand...

Thanks, that is sort of along the lines of what I was thinking. If it's regarding the fact that someone could leave the circuit on and over discharge the cells I'm not terribly worried as it would be used very rarely when my wife commutes with it and stored on the porch...plus she never really rides below 50% battery anyway. the lamp draws about 18w

I use the charging input on my pack to run my electric air pump. As mentioned above, there would be no protection against over discharge and the maximum current you can pull will be in the ballpark of what the charger puts out. 18w should be no problem.

Thanks guys, this made my day. Would've literally been extra couple of hours to do it in a more conventional way because the guy I bought this thing from used so much frocking industrial Velcro It's literally impossible to get the battery out from the seat without damaging the pack. The pack is sitting over the controller wires so to get the controller out so there's enough slack I would have to pull the battery as well. Options were either this, or some cutting and soldering on the discharge end But it's much easier and cleaner to do it this way

I would think that the charging port would not run if any cells were overdischarged. That safety feature should always be enabled. Well I've never had occasion to test it.