No cell voltages appear (Orion Jr. BMS)

Common Causes:

  • Incorrect Cell Population Settings
  • BMS is configured with default settings (default settings will show no cell voltages).
  • Cell wiring harnesses not connected to the BMS
  • Cell tap wiring error
  • Internal damage to the BMS

Note: If the BMS has been damaged by previous wiring errors, do not continue to use the BMS. Contact Ewert Energy for evaluation and repair options.

Note: If the “Live Cell Voltages” tab in the BMS utility is grayed out (unable to be clicked), the utility needs to connect to the BMS (press the “Connect to BMS” button or select “Connect to BMS” from the File menu). For help troubleshooting connection problems, see the the troubleshooting guide here.


Resolving the issue:

Step 1. Ensure that the LED on the BMS is not flashing red rapidly.

If the LED is rapidly flashing red, immediately disconnect the cell tap connector from the BMS, as this indicates that the unit may be getting damaged from incorrect wiring.

Step 2. Verify that the cell tap wiring harnesses are connected to the BMS.

The cell voltage tap connector must be connected to the BMS to be able to measure cell voltages.

Step 3. Ensure that a settings profile has been uploaded to the BMS.

Until the Orion Jr. BMS has been programmed using the PC software, the BMS will assume no cells are connected. If no profile has been uploaded to the BMS, please create a settings profile and upload the settings to the BMS. Follow the steps in the “Profile Setup Wizard” to generate and upload a basic profile. Reset the power on the BMS and check cell voltages again. After settings have been transmitted to the BMS, we recommend downloading the settings profile from the BMS unit by pressing the “Receive Current Profile From BMS” button in the Orion Jr BMS utility. This will ensure that the exact settings on the BMS are the ones being viewed (as in Step 4 below).

Step 4. Verify that cells have been properly populated.

Download the settings profile from the BMS unit by pressing the “Receive Current Profile From BMS” button in the Orion Jr BMS utility. This will ensure that the exact settings on the BMS are the ones being viewed. Next, under the “Cell Settings” tab, click the “Configure Which Cells Are Connected (Populated)” button. Ensure that cells which are connected have a check in the “Populated” box. If changes need to be made, the profile will need to be sent to the BMS by clicking the “Send Profile Changes to BMS” button.

Step 5. On the same Cell Populations Settings dialog, look at the “Current Voltage” column.

If cell voltages appear correctly here, but not on the live cell data tab, the problem will be a configuration issue. If the voltages also appear as 0 volts here, the issue is likely in hardware.

Step 6. Measure the actual voltage of the cells and the battery pack.

Using a multimeter, measure individual cell voltages and the total pack voltage of the actual pack to ensure proper voltages. If cells are reading 0 volts because they actually have become fully discharged, consult with the cell manufacturer about whether it is safe to charge them back up. Many lithium cells cannot be charged safely once they have been over-discharged.

Step 7. Test the cell tap wiring using either a multimeter or the cell tap validation tool.

If using the tap validation tool, connect the tool to the wiring harness and ensure that the tool finds the correct number of cells and that no “X” marks are present. If using a multi meter, carefully place the multimeter black probe onto the negative terminal of the most negative cell in the pack. Then, being very careful not to arc pins, measure the voltages of the individual pins on the cell tap connector. Start with cell 1 – (black wire). This wire should read 0 volts. Then measure the voltage of cell 1+ – this should read the voltage of the first cell. Then proceed to cell 2 which should read the voltage of cell 1 + cell 2 and so forth.

Hint: While there are other possibilities, the most likely wiring issue to result in all cells reading 0 volts is if the harness has been wired backwards starting with the most positive cell rather than the most negative cell first.

The cell tap validation tool can be rented by the week (US only) or purchased. Rentals can be made here.

Step 8. Check the BMS’s total pack voltage measurement.

The total pack voltage is sensed differently than the individual cell voltages. Checking the total pack voltage value and comparing it to the voltage measured with a multi-meter may yield clues if there is a wiring issue. Please include this information if contacting Ewert Energy.

Step 9. Try using a different BMS unit (if available).

If possible, attempt to swap out the BMS with another working unit. If the problem remains even after switching the BMS unit, the problem is very likely with the cell tap wiring. If the problem is resolved by changing the BMS unit, it is likely that there is an internal fuse that has blown inside the BMS unit or that there is another issue with the unit. Blown fuses most commonly result from previous incorrect wiring or if the battery pack was altered while the BMS was still connected to it. Information on why internal fuses on the BMS may blow can be found here. If this is the case, proceed to contact Ewert Energy to evaluate / repair the unit.

Step 9. Contact Ewert Energy for an evaluation of the BMS unit as there may be internal damage or another fault.

Copyright (C) 2015 Ewert Energy Systems

Ewert Energy Systems, Inc
161 East St. Charles Rd
Carol Stream, IL 60188

Phone: (630) 868-3173
Fax: (866) 657-5667

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