Blog - Battery Monitoring

FAQ: RT-BMS power-on and settings after STAND-BY

FAQ: RT-BMS power-on and settings after STAND-BY

07.Oct 2012
| Blog - Battery Monitoring

FAQ: RT-BMS power-on and settings after STAND-BY

Question: At the general power on (+12V) all the contactors are connected for short time. Is it a normal operation?

Answer: Yes, this is a safety checkup of all contactors and signal lights. This is to confirm that all of these outputs are working properly.

This logic is the same in your car:  when you turn on the starting key in your car,  all important signal lights on the dash board will light briefly to confirm that the signalization is OK (like airbags, EPS, motor oil and other lights)

Question: After the power-on, the unit performs a sort of scan of the system. The numbers of 01.00 to 01.63 (02.00 to 02.63, and 03.00 to 03.63) was displayed. This behavior is also present if we set a number of 4 cells on the system. Is it a normal behavior?

Answer: Yes, this is normal. After power-on the Master unit scans all possible combination (3x 64) to locate any CBU on the data line bus. This is for safety reason to confirm that the communication with all CBU is regular. Also it can help to locate any CBU that would be miss-addressed.

In regular operation the RT-BMS Master should be powered all the time and only to be turned-on/off by means of the stand-by mode.

This logic is like your TV with DVB-T tuner:  you plug the TV on the socket for the first time and it will scan all possible channels.  Following that you keep the TV always ON, and you only use the STAND-BY mode (but it is powered 365 days/24hrs).  Of cause if you disconnect the TV from the main power, and re-connect, it will scan all the channels again.

Question: After the power-on, the system always activates the load contactors (PO1) and  the charging contactors (PO3 and PO4). Why is this so?

Answer: This is a correct function. The contactors are turned on by the setting values of the RT-BMS.  When you power-on the BMS-System and the cells are at regular voltage level, the RT-BMS will check the voltage levels and if the voltage levels are OK, it will turn on the contactors.  When the cells are at 3.3V, you can either discharge them or charge them. That is why all contactors are ON.

The charging contactors will disconnect only when the voltage increase above the levels set in the management software. They will re-connect when the voltage drops down again. Or they will reconnect after the power-on.

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