Battery Compatibility

Hey guys i just bought 3 batteries for a 3000w 80A kit. Im building 3 bikes from scratch. This whole time the guys i get my kits from have been selling me 80bms batteries. Ive built quite a few bikes already with an 80bms 72v battery and i have a new battery connect and they are telling me this will not work. i need a battery with a continuous current if 80 amps is this true? The 80bms seems like its been working fine. i also learned that the continuous current is usualy half the bms. The bike will rarely ever hit a full 80amps the average is around 60amps what do you guys think? 80a continuous current/ 160bms is very expensive and is being that extreme necessary? could i go with a 60a continuous current sense 60a for this kit is the norm? very rarely will it go higher than 60a plus the 60a continuous battery has a max current of 120a. i need advice i want to do the right thing.

Just bypass the bms negative side.
Battery + direct to controller
Battery - direct to controller

Charge + to battery +
Charge - to bms C-

This will allow this cells to balance charge and balance at rest but the discharge will be the battery maximum continuous amps and burst amps without overloading the bms

Hope this helps

Jonno

could you please elaborate on that?

He's suggesting that you bypass the bms so it is no longer protecting the pack while it is being used, and instead only protecting the pack while being charged.

If this were a personal build and you were willing to accept the risks involved that would be on you. If you're acting as a business and will be serving this up to a customer my advice would be to not do this. For a number of reasons.

Best case scenario:

Sooner or later (probably sooner as this is an Alibaba mystery pack) one group of cells will have their voltage fall well below the others before the controllers low voltage protection kicks in, resulting in an over-discharged group of cells. This will ultimately damage that cell group. When the charger is reconnected the BMS will likely refuse to charge the pack because of the low voltage in that group. So your customer will be dead in the water. That's best case.

Worst case scenario A:

Something fails while the bike is being used, the BMS should have cut power but was disabled, the pack catches fire/cells start exploding.

Worst case scenario B:

A group was over-discharged and damaged. The group is then recharged and catches fire/cells start exploding.

Do what you feel, but if you're doing this as a business I'd think on it a while and maybe speak with my insurer if I were you.

...and stop buying batteries from Alibaba. Seriously.