How to set up the BMV or SmartShunt monitor for lead and lithium batteries

Digital Skipper |27/05, 2022

We previously wrote a blog post where we explain the concepts for, among other things, State of charge, Time remaining, Discharge floor etc. however, there is a quite a few questions about basic settings and how they differ between Lead (Lead, Gel, AGM etc.) and Lithium.

Before we get into the details, we first have a brief overview of battery monitoring a little more generally.

Batteries have a number of different areas of use, mainly to store energy for later use. But how much energy is stored in the battery? It is not possible to determine this by just looking at; the battery. The lifespan of batteries depends on many factors. Battery life can be shortened by under charging, over charging, excessively deep discharges, excessive charging or discharging current and high ambient temperature.

Regardless of you have a boat, motorhome, caravan or an off-grid accommodation & monitoring the battery with an advanced battery & monitor is important soå that corrective actions can be taken if necessary. This extends the life of the battery and the battery monitor quickly pays for itself.

Installation is usually simple and builds regardless of which manufacturer you choose; the same principle, namely that you let the current pass through a "shunt" which, together with some battery-specific settings, makes it possible to calculate the remaining capacity, time, etc. . The battery monitor also shows the "net" current that passes through the shunt, which means that you can easily see how much charge you are getting from, for example, your generator.

< strong>Who are there? the most common settings and how do they differ between a Lead and Lithium batteries?

Setting	Lead-Battery	< strong>Lithium Battery
Battery capacity	This parameter is used to tell the battery monitor how big the battery is. The setting specifies the battery or battery bank capacity in ampere-hours (Ah)	This parameter is used to talk about foundö r battery monitor how big the battery is. The setting indicates the capacity of the battery or battery bank in ampere-hours (Ah)
Charged voltage	The battery voltage must be above this voltage level for the battery to be considered fully charged. As fast as the battery monitor sensing that the battery voltage has reached the “charged voltage” and the current has dropped below the “tail current” set the charge status to 100%. Normally set to 0.24V under the battery charger setting for "Float Voltage". In a 24V system it is 0 instead ,4V and in 48V 0.8.	The battery voltage must be above this voltage level for the battery to be considered fully charged. As fast as the battery monitor sensing that the battery voltage has reached the “charged voltage” and the current has dropped below the “tail current” set the charge status to 100%. Normally set to 0.24V under the battery charger setting for "Float Voltage". In a 24V system it is 0 instead ,4V and in 48V 0.8.
Discharge floor	The ”Discharge floor” parameter is used to calculate the remaining time. The battery monitor calculates the time remaining until the set The "discharge floor" has been reached. It is also used to set the default value for charging status. Set it to 50%. For lead-acid batteries.	The parameter "Discharge floor" is used to calculate the remaining time The watchdog calculates the time remaining until the set "discharge floor" is reached. It is also used to set the default value for charging status alarms. br> Set it to 95-99% for Lithium batteries, depending on how close to maximum discharge you want to meet.
Tail ström	The battery is considered ”fully charged” when the charging current has dropped below the fixed parameter for ”Tail current”. The parameter for ”Tail currentöm” is specified in a percentage of the battery's capacity. Some battery chargers stop charging when the charging current drops below a preset value. In these cases, the tail current must be set enter the default value. As soon as the battery is charged, the monitor detects that the battery voltage has reached the "charged" parameter. the voltage” and the current has dropped below the”tail current” for a set time, the battery monitor will set the charge status to 100%. Default The value of 4% works well for most batteries and if you want to see the exact value for your particular battery, wait until the charger goes to "Float" and has been dead. is for at least 5-10 minutes and then you read how much current goes into the battery and put it in relation to the total size of the battery bank.	The battery is considered ”fully charged” when the charging current has fallen below the fixed parameter for ”Tail current”. The parameter for "Tail current" is specified as a percentage of the battery's capacity. Some battery chargers stop charging when the charging current drops below a certain value. In these cases, the tail current is set higher than the default value. As soon as the battery the monitor senses that the battery voltage has reached the "charged voltage" parameter and the current has dropped below the "tail current" for a fixed time, the battery monitor will set the charge status to 100%. The default value of 4% works well for most batteries and if you want to see the exact value for your particular battery, wait until the charger turns to " Float" and has been there for at least 5-10 minutes and then read how much current is going into the battery and put it in relation to the total size of the battery bank. >
Charge detection time	This is the time when ”Charged voltage and ”Tail ström” must be met for the battery to be considered fully charged. Normally the value does not need to be changed.	This is the time when ”Charged voltage and ”Tail ström” must be met for the battery to be considered fully charged. Normally the value does not need to be changed.
Peukert exponent	Set the Peukert exponent according to the battery specifications. A value on 1.00 disables Peukert compensation. Peukert value for lead batteries can be calculated. For further information on Peukert extraction, battery capacity and Peukert exponent, see separate blog post. If the Peukert exponent is not set, set it to 1.25 for lead-acid batteries.	Set the Peukert exponent accordingly with the battery specifications. A value on 1.00 disables Peukert compensation. Peukert value for lead batteries can be calculated. For further information on Peukert extraction, battery capacity and Peukert exponent, see separate blog post. If the Peukert exponent is not available, set it to 1.05 for lithium batteries.
Factor for charging efficiency	”The charging efficiency factor” compensates for the loss of capacity (Ah) during charging. A setting on 100% means that there are no losses. Efficiency of a charge på 95% means that 10 Ah must be transferred to the battery to bring 9 Ah actually occupied by the battery. A battery's charging capacity depends on; battery type, age and usage. The battery monitor takes this phenomenon into account through the charging efficiency factor: The charging efficiency of a lead-acid battery is almost 100%. as long as no gas formation takes place. Gassing means that part of the charging current is not converted into chemical energy that is stored in the battery's plates, but is used to split water into oxygen gas and hydrogen gas (highly explosive). The energy stored in the plates can be extracted during the next discharge, while the energy used to split water is wasted. Gassing can easily be observed in liquid-filled batteries. Note that ”oxygen only” at the end of the charging phase in closed (VRLA) gel and AGM batteries alsoå resulting in reduced charging efficiency. The default value is set to 95% and you reduce the value if you only use a small part of your battery between charges or when the battery becomes äolder and less efficient to charge.	”The charging efficiency factor” compensates for the loss of capacity (Ah) during charging. A setting on 100% means that there are no losses. Efficiency of a charge på 95% means that 10 Ah must be transferred to the battery to bring 9 Ah actually occupied by the battery. A battery's charging capacity depends on; battery type, age and usage. The battery monitor takes this phenomenon into account through the charging efficiency factor: The charging efficiency of a lead-acid battery is almost 100%. as long as no gas formation takes place. Gassing means that part of the charging current is not converted into chemical energy that is stored in the battery's plates, but is used to split water into oxygen gas and hydrogen gas (highly explosive). The energy stored in the plates can be extracted during the next discharge, while the energy used to split water is wasted. Gassing can easily be observed in liquid-filled batteries. Note that ”oxygen only” at the end of the charging phase in closed (VRLA) gel and AGM batteries alsoå resulting in reduced charging efficiency. The default value is set to 95% and you reduce the value if you only use a small part of your battery between charges or when the battery gets older and less efficient to load.
Ström threshold	Nä if the measured current falls below the value for ”Current threshold” it will be considered zero. With this function it is possible to exclude smearing; currents that can adversely affect the long-term state of charge resolution in highly disturbed environments. For example, if the actual long-term current is 0 ,0 A and på due to disturbances from outside or lubrication; deviations in the battery monitor indicate -0.05 A, the battery monitor in the long run can an incorrect way to indicate that the battery is empty or needs to be recharged. When the current exceeds the threshold in this example, set to 0.1 A counts battery & the monitor with 0.0 A soå that the errors are eliminated. The default value is 0.1A and rarely needs to be changed.	When the measured current falls below the value of ”Current threshold” it will be considered zero. With this function it is possible to exclude smearing; currents that can adversely affect the long-term state of charge resolution in highly disturbed environments. For example, if the actual long-term current is 0 ,0 A and på due to disturbances from outside or lubrication; deviations in the battery monitor indicate -0.05 A, the battery monitor in the long run can an incorrect way to indicate that the battery is empty or needs to be recharged. When the current exceeds the threshold in this example, set to 0.1 A counts battery & the monitor with 0.0 A soå that the errors are eliminated. The default value is 0.1A and rarely needs to be changed.
Average period & remaining time	Average where the period for remaining time specifies the time window (in minutes) that the moving average filter works with. A value for 0 disables the filter and provides an immediate (real-time) trigger. However, the values for remaining time shown can fluctuate greatly. Selection of the longest time (12 minutes) ensures that only long-term load fluctuations are included in the calculation of the remaining time. The default value ä is 3 minutes and rarely needs to be changed.	Average period for remaining time specifies time management; the number (in minutes) that the moving average filter works with. A value for 0 disables the filter and provides an immediate (real-time) trigger. However, the values for remaining time shown can fluctuate greatly. Selection of the longest time (12 minutes) ensures that only long-term load fluctuations are included in the calculation of the remaining time. The default value ä is 3 minutes and rarely needs to be changed.
Synchronized battery start	Battery's charging status becomes 100% when the battery monitor has been supplied with power. When it is PÅ the battery monitor will consider itself synchronized at startup, which means the charge status will be set to 100%. If it is OFF, it will consider itself unsynchronized at startup, which means the charging status is unknown until the first real sync. Think about; that certain situations may arise; you should make some considerations before setting the function to PÅ. Such a situation can arise; in systems where the battery is often disconnected from the battery monitor, for example in a boat. If you leave the boat and disconnect the DC system with the main DC switch when the batteries were charged to 75% e.g. When you return to the boat and plug in; The DC system again will the battery öwatcher thereå to show 100%. It gives the false impression that the batteries are fully charged when in reality they are partially discharged. There are two; way to solve this, one is to not disconnect the battery monitor when the batteries are partially discharged and the other is to turn off the function “Synchronized battery start” . When the battery monitor is connected to again the charging status will show ”---” and only shows 100% when the batteries have been fully charged. Note that if you leave a lead-acid battery in a partially discharged state for a long time, it will lead to damage to the battery. the battery. The default setting is "På" and if the above scenario occurs in your usage, it is recommended to set it to "Off".	The battery charge status becomes 100% when the battery monitor has been supplied with power. When it is PÅ the battery monitor will consider itself synchronized at startup, which means the charge status will be set to 100%. If it is OFF, it will consider itself unsynchronized at startup, which means the charging status is unknown until the first real sync. Think about; that certain situations may arise; you should make some considerations before setting the function to PÅ. Such a situation can arise; in systems where the battery is often disconnected from the battery monitor, for example in a boat. If you leave the boat and disconnect the DC system with the main DC switch when the batteries were charged to 75% e.g. When you return to the boat and plug in; The DC system again will the battery öwatcher thereå to show 100%. It gives the false impression that the batteries are fully charged when in reality they are partially discharged. There are two; way to solve this, one is to not disconnect the battery monitor when the batteries are partially discharged and the other is to turn off the function “Synchronized battery start” . When the battery monitor is connected to again the charging status will show ”---” and only shows 100% when the batteries have been fully charged. Note that if you leave a lead-acid battery in a partially discharged state for a long time, it will lead to damage to the battery. the battery. The default setting is "På" and if the above scenario occurs in your use, it is recommended to set it to "Off".
Charging status	This setting allows you to manually set enter the charging status. This setting is only active after the battery monitor has been synchronized at least once. Either automatically or manually. Normally this setting does not need to be changed.	With it In the setting, you can manually set the charging status. This setting is only active after the battery monitor has been synchronized at least once. Either automatically or manually. Normally this setting does not need to be changed.
Sync state of charge (SoC) to 100%	This option can be used to synchronize your battery monitor manually. Press the The "Synchronize" button to synchronize its battery monitor to 100%. This should only be done if you are sure of that your battery is fully charged.	This option can be used found ;r to synchronize your battery ömonitor manually. Press the The "Synchronize" button to synchronize its battery monitor to 100%. This should only be done if you are sure of that your battery is fully charged.
Zero current calibration	If the battery monitor shows a non-zero current even when there is no load and the battery is not charging, this may option is used to calibrate zero current resolution. Only perform this process if the battery monitor shows a current when you see full charge. ker på that no current is actually flowing. The only way to know for sure is to physically disconnect all cables connected to the SYSTEM MINUS side on the shunt. You do this by unscrewing the shunt bolt and removing all cables from that side of the shunt; the shunt. The alternative, which is to turn off all loads or chargers, is NOT accurate enough, as it does not remove smudges; standby currents. A zero current calibration is (almost) never required and only performed after review as above.	If the battery monitor shows a non-zero current even when there is no load and the battery is not charging, this option can be used to calibrate zero current resolution. Only carry out this process if the battery monitor shows a current when you are absolutely sure of; that no current is actually flowing. The only way to know for sure is to physically disconnect all cables connected to the SYSTEM MINUS side on the shunt. You do this by unscrewing the shunt bolt and removing all cables from that side of the shunt; the shunt. The alternative, which is to turn off all loads or chargers, is NOT accurate enough, as it does not remove smudges; standby currents. A zero current calibration is (almost) never required and only performed after review as above.

Good luck!

/Digital Skipper