Hi Kathy,
I've read the manual and am now trying to boil it down in terms of what to add to my POH/checklist. If I understand correctly the possible scenarios are these?:
Flashing light, <12.8 V = voltage too low (undercharging/discharged)
Flashing light, 13-14.6 V = cell imbalance
Flashing light, >14.6 V = voltage too high (overcharging but will not disconnect but instead block the excess voltage coming in up to 40V but still allow voltage out to run equipment)
Solid light = BMS fault
It would appear that the appropriate pilot action in the undercharging scenario would be to reduce electrical load, and in the overcharging scenario to turn off the alternator. In the other two scenarios the battery should be disconnected (master switch off)?
I also understand that the BMS will shut the battery off by itself if there is less than 5% charge remaining (approx. 11.5 V), or if the charging circuit rises above 16 V. I'm not sure though what if anything the warning light does in those cases?
thanks
Hi Alan,
Excellent questions and observations. I am going to copy directly from the EarthX manual:
In the event of a charging system failure where the voltage increases to above 15.2V, the resistance to charging current increases, and above 16V
the charging current is completely blocked. This design offers charge voltage protection up to 40V, exceeding the requirements of RTCA?s performance specification DO-311.
The discharge current (current out of battery) is unaffected in this situation.
The battery?s micro-controller monitors all failure modes, and reports failures with a built-in LED indicator and discrete output. The discrete output for external fault monitoring is a single wire connection with ?? quick connect terminal. The output is a ?current sinking? type circuit (see diagram below) that can handle 100mA (connects the discrete output to battery ground if a fault is present). This output can be connected to an external 12V LED or general purpose discrete input of an EFIS. The fault output has two states; slow flashing (5 second cycle time) or solid.
The slow flashing fault can indicate an improper state of charge or a problem with the cells internal to the battery. If the battery voltage is outside the normal range of operation, 12.8V to 14.6V, the battery is over-discharged or over-charged, most likely the result of an issue with the electrical/charging system. If the battery is less than 13.0V, you simply need to charge. If the voltage is greater than 14.6V, then the charging system should be investigated.
If the battery voltage is within the normal operating range, with a slow flashing fault, it is indicating an abnormal condition with a cell, such as one cell?s state of charge is very different as compared to the other cells (high cell charge level imbalance).
The slow flashing fault may come on briefly during or following periods of high current charging, and is not a concern. But if the fault persist, comes on consistently during changing, or remains (charging or not), the battery will need to be replaced.
The solid fault indicates a BMS hardware failure. For example, if the micro-controller fails the fault indication output is activated (on solid). If the fault persist, comes on and stays on, the battery will need to be replaced.
A sustained fault can indicate a serious issue with the battery or vehicle charging system that requires immediate attention. Discontinue use until the issue is resolved and the battery no longer indicates a fault. Continued use of a faulty battery can result in a cell rupture, the release of flammable vapors, smoke and or a fire.
Flashing light, <12.8 V = voltage too low (undercharging/discharged)
Flashing light, 13.28V-14.6 V = cell imbalance (this could be temporary while the cells come into being balanced)
Flashing light, >14.6 V = voltage too high (overcharging)
Solid light = BMS fault
The battery will disconnect when it is about 98% drained as there is nothing left in it anyway. You would have a fault light from your alternator that it isn't charging and a fault light from the EarthX battery that it isn't being charged and being drained.
For over charge, you should have a fault light from your alternator saying it is over charging, and you will see a fault light from your EarthX battery saying it is being attempted to be over charged. The battery will continue to have discharge current and block up to 40V coming into the battery. In this scenario, you should disconnect your alternator as soon as you know it is faulty and trying to over charge.
I hope this helps explain things in better details.