WS500 48V renogy lifepo4 derate or amp cap


  • Trying to fix a problem where the amps are going over 105 which triggers the bms cutoff and a constant start stop cycle of charging, if I put a load on the system it never cycles, reading the config guide it says the amp cap is a uncommon factor on setups where the shunt is on the battery, should I just lower the derate values and not use the amp cap setting?


  • The problem with capping the amps out of the reg is that you are not actually metering that value. but in your situation it may actually work in your favor as you are not trying to cap your output but rather your input to your battery pack, which is where your shunt is located.  For instance if you have your solar dumping in 40 amps you really only want 55-60 amps out of your alternator to avoid a hard trip, and your battery shunt will measure the sum of all loads and charger instances. I have not played with the value much but it may be worth setting it to something like 75amps and see how your battery amps responds to a multi-charger situation. Let us know how you made out.

  • But changing the derate normal value would actually meter the output?  I\'m not sure I understand the amp cap parameter

  • as I recall that just limits the field output.  Check out the BMS capacity rating setpoint from page 55 of the manual BMS Amp Cap: <WHOLE NUMBER ( 0 2500 ) > BMS Amperage Capacity (<BMS Amp Cap>) issued to
    define a global system limit in a like way that <System Watts Capacity>. BMS Amp Cap defined the maximum
    charge amperage the BMS is defined to support. If the battery $CPB MaxAmps (aka, C rate) allows current to
    exceed the maximum allowed BMS current, the regulator will restrict current so as to not over-load the BMS
    rating. BMS Amp Capacity is clipped to 10A increments, so a defined value of 258A will be saved as
    250A

    If BMS Aggregation is enabled, the total BMS current allowed will be increased to match that of the
    total recognized online and active BMS’s.

    If a RBM is controlling the charge cycle, sending in goal battery current limits, BMS Amp Cap will be
    ignored.

    Set = 0 (Default) to disable BMS Current Limit

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