Author Topic: VEC 300 72V with 5000W QS Motor and 72V 85Ah battery - Configuration help needed  (Read 12151 times)

Offline Wildbeats

  • Confirmed
  • New Member
  • *
  • Posts: 11
Without knowing what the maximum current rating of the battery's BMS is, it's impossible to say whether it will cut out or not.

If your battery is supposed to provide 14400W (or 18720W) peak power to your scooter, it should not cut out under a 200A load.

The BMS is designed to protect the battery by cutting the power being delivered if its maximum current limit is exceeded, and when this happens, it should either reset automatically when the load is removed, or reset manually by turning off the power and turning it back on again.

Alan

If I see peak power in manufacture of standard model is 200A this is for a battery of 93A, then doing calculations for my battery of 85a peak power can be 182.79A, I try 180A, what do you think?

Offline Bikemad

  • Global Moderator
  • Professor
  • PhD. Magic
  • ******
  • Posts: 5,553
If I see peak power in manufacture of standard model is 200A this is for a battery of 93A, then doing calculations for my battery of 85a peak power can be 182.79A, I try 180A, what do you think?
Unfortunately, it is not quite that simple, as a battery's discharge current will vary tremendously according to the discharge rate of the actual cells used as well its total Ah rating.

This 5Ah pack has the ability to discharge current at 325A constant and 650A peak:



If your pack was built using the same 65~130C nano-tech cells it would theoretically be able to deliver 5525 Amps (397.8kW of power) constantly and 1050 Amps (795.6kW of power) in short bursts!

At the other end of the discharge scale you can find packs that are claimed to be a 28Ah capacity using Panasonic cells that only have a continuous discharge current of just 18A and a maximum instantaneous discharge current of 36A.



If your pack was built using these cells it would only be rated for 55 Amps constant and 110 Amps max!  ;)

Unfortunately, the only way you will know whether your battery can produce the required output is to put it under load and see what happens. If the battery voltage drops below 60V under heavy load (or the BMS cuts the power), then the discharge current is too high for the battery.

Alan