Drawing Power From Battery Charging Port

[Art]

I own an EM3ev 52V 17.5 Ah battery, and was trying to power a new set of 10-60V front/rear lights for the bike.

I was planning to either a) Tap the current by soldering up a pair 12 gauge silicone wires into the existing 4mm bullet connectors by creating a 2" bullet connector "Y" adapter...or b) Utilize the battery's charging port to power the lights.

I am unsure whether the charging port, which obviously feeds into the BMS, can be utilized in this way.

Any advice would be appreciated.

 

[fechter]

Yes, you can draw power from the charge port. The only catch is if you forget to turn the load off, it could drain the pack beyond the low voltage cutoff point and damage the cells.

 

[Alan B]

I think EM3EV said they use 2 port BMS's. If that's the case the charge port is just in parallel with the discharge port, they're not different. So the BMS is still in between both ports and the pack and there would be discharge protection on both ports. My Bioenno 12V packs are that way.

If it is a 3 port BMS then there's no discharge protection on the charge port unless they have a blocking diode in there in which case there's no discharge current available from the charge port (which generally is not done).

3 port BMS's are cheaper because they require fewer FETs. So most packs likely use them.

 

[Art]

Thanks so very much for the insight and advice :thumb: