Dark Start Guide
If your 48V Blue Ion ever gets to an extremely low state of charge, you may encounter a situation known as a Dark Start.
This situation arises when the inverter or charge controller settings are such that the battery is allowed to discharge below the voltage necessary for the Battery Management Unit (BMU) to restart without relying on an outside source of DC to “jumpstart” the system.
To be clear, there is little danger to the batteries or the BMU in this situation, however it can be mighty inconvenient for an installer and a project owner, much like allowing your truck to run out of gas on the side of the road.
Please follow these instructions to Dark Start your Blue Ion. And then adjust your settings in order to not fall into this situation again.
- Ensure there are no loads on the DC bus by turning off all inverter breakers and unplugging the LED lights in the cabinets.
- The breaker on the front of the Blue Ion needs to be on.
- Ensure the BMU "On/Off" button is in the "off" position.
- Remove the BMU/Battery Comm Cable from Module 0 (bottom right module)
- Using an adjustable 48-60 VDC Battery Charger (example product - note that this is a slow charging option) with alligator clips, attach the clip leads to the positive and negative terminal blocks respectively (located on the back of the upper shelf of the Blue Ion).
- Plug in the battery charger to an AC source.
- Turn the battery charger on.
- Turn the BMU on by pushing the "On/Off" button to the "On" position. The BMU should immediately turn on, no need to use the momentary “start” switch in this process.
- Allow the charger to charge the batteries for approximately 10 minutes.
- For DC coupled systems, the solar charge controller can be turned on at any point in this 10 minute period to allow the solar to help charge the batteries.
- For AC coupled systems you will need to turn on the battery based inverter to begin charging from the solar. Before turning the inverter on, ensure that all AC loads are turned off.
- Leaving the battery charger still connected, turn on the battery based inverter.
- For AC Coupled PV Systems, turn the AC Coupled inverter on, which will need to qualify the voltage for 5 minutes. This should allow the solar to charge the batteries.
- For generator only systems, ensure the generator input breakers are in the on position and begin charging with the generator.
- Once you have ensured the battery is charging from the preferred source, turn off, unplug and carefully disconnect the battery charger.
Recommended Settings
Once you are sure the BMU and batteries are behaving normally, please consider the following:
Install more energy resources: solar power, wind power, hydro power
upgrade to more efficient products that use less energy
change the set points to have the loads turn off sooner
change the set points to have the inverter turn off sooner
change the set points to have the generator/grid power charge the batteries sooner
Your system should reach 100 percent State of Charge (SoC) at a minimum of every 90 days.
A properly sized and implemented system will reach 100 percent SoC on a regular basis - perhaps as often as daily or weekly.
If the system does not reach 100% SoC every 90 days, the SoC indication may become inaccurate and the system may not provide full capacity.
Over long periods of time with no maintenance charge (several months or longer) the system may have trouble at lower states of charge and shut down more often, eventually needing extensive troubleshooting to recover and in some cases even replacement to bring the system back up to optimal performance.
This is avoided by charging the system to 100% at least once every 90 days.
Max Charge Time:
Your system is at maximum SoC when it has reached 55.2 VDC for 30 - 60 minutes.
Recommended Low Voltage Disconnect Setting:
48 VDC (~2-10% State of Charge)
BMU will power down the Blue Ion cabinet at ~44 VDC (<1% State of Charge)
Based on system discharge patterns, SoC and voltage correlations will vary.
We recommend you err on the side of caution with a higher LVD setting and adjust as necessary.
Advanced Generator Start Voltage Settings: 0.5 Volts above the LVD described above.
This recommendation is intended to allow for enough time to start the generator before the Low Voltage Disconnect engages. Adjust as your system design allows.
Legal/Disclaimer/Warranty
The information in this application note is provided “as is” without warranty of any kind, either express or implied, including, but not limited to, the implied warranties of fitness for a purpose, the warranty of non-infringement, or any warranties as to the information's accuracy or completeness. Blue Planet Energy reserves the right to make changes to the information available at any time and assumes no liability for applications assistance, customer product design or specific customer requirements. Nothing in this application note shall be construed as modifying any rights and obligations in the contract between the parties.