noelex
Well-Known Member
Ideally the load and charge systems should be controlled independently by the BMS.
Therefore, if there is a high voltage fault (the batteries are being overcharged) the BMS will disconnect only the charging sources. The loads are left connected. Not only does this help rectify the problem sooner than disconnecting the battery completely, but the boat functions normally. Unfortunately, the alternator may be damaged unless systems are in place to avoid this.
The opposite problem, is when a low voltage fault disconnects the loads and leaves the charging sources connected. In this case the yacht may lose all electrical systems (the boat goes dark). This can be a significant problem in some situations, but there is no danger to the alternator with this fault.
Unfortunately, this dual system is not possible with most reasonably priced drop in batteries. Most drop in batteries have an internal BMS and this will disconnect the battery terminals with either a high or low voltage fault. The load and charge buses cannot be separated.
The ultimate system is with seperate load and charge buses, combined with an external BMS that communicates with all the major sources. This is expensive and complex especially, as a retrofit.
Complex is not always sensible on a boat, but it can be an excellent system for those who want everything automated.
Therefore, if there is a high voltage fault (the batteries are being overcharged) the BMS will disconnect only the charging sources. The loads are left connected. Not only does this help rectify the problem sooner than disconnecting the battery completely, but the boat functions normally. Unfortunately, the alternator may be damaged unless systems are in place to avoid this.
The opposite problem, is when a low voltage fault disconnects the loads and leaves the charging sources connected. In this case the yacht may lose all electrical systems (the boat goes dark). This can be a significant problem in some situations, but there is no danger to the alternator with this fault.
Unfortunately, this dual system is not possible with most reasonably priced drop in batteries. Most drop in batteries have an internal BMS and this will disconnect the battery terminals with either a high or low voltage fault. The load and charge buses cannot be separated.
The ultimate system is with seperate load and charge buses, combined with an external BMS that communicates with all the major sources. This is expensive and complex especially, as a retrofit.
Complex is not always sensible on a boat, but it can be an excellent system for those who want everything automated.
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