Posted on 4 Comments

New BMS current ratings

TLDR: 175 Amps

We are in the process of testing prototypes of the new Nomad and Pathfinder BMS to find the thermal limits and current ratings. (The current rating is determined by temperature limits)

In this test we have a constant current flowing thru the BMS main board. The target temperature for the advertised current rating is 50c, while sitting flat on the test bench at an ambient room temperature of 23c.

The BMS has a temperature sensor in the center of the MOSFET array (in addition to 2 external probes to measure cell temperature), and it will have a default cutoff temperature of 85c to protect the BMS. The BMS hardware can operate safely up to this temperature limit, so there is considerable headroom over the base current rating to account for higher ambient temperatures or temporary surge currents.

In this thermal camera photo, the temperature has stabilized at 50c with a constant current of 175 amps.

Tentatively, based on this testing, the base model Pathfinder BMS will be advertised with a 175 amp constant current rating. The Nomad BMS will be offered with fan cooling, which can as much as double the free-air current rating!

As this testing program continues we are gathering data for derating (and up-rating) curves based on ambient temperature and duty cycle.

4 thoughts on “New BMS current ratings

  1. Cannot wait to get my hands on the new bms.

  2. Sounds great- eager to get a couple. Please update us on when we can purchase. Thank you very much

  3. We built (3) 16s-48v battery banks in service now with the old Overkill BMS, works great.
    We have 48 more cells ready to top balance & put together.
    Like the specs of the NOMAD with the cooling fan.
    We will take 3 when they are ready!

  4. Will have all 48 EVE 3.2v-280ah cells top balanced this weekend.
    Ready for 3 new Pathfinder BMS’s.
    Hope they are available soon!!!!

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