Setting my battery monitor parameters. Help please

[Oscarpop]

I have a bmv600s battery monitor.

The charged voltage can be set and I am trying to work out at what voltage to set it.

The battery monitor manual says to set it at a level where the batteries are considered "fully charged". It then goes on to say that "this is normally 0.2-0.3v blow the float charge of the battery charger"

However I am not connected to a battery charger and use wind and solar to charge the batteries.

The info on my Trojan batteries states that they are fully charged at 12.73 volts.

So do I set the parameter for " fully charged " to 12.8 v ?

Thanks

 

[pvb]

The info on my Trojan batteries states that they are fully charged at 12.73 volts.

So do I set the parameter for " fully charged " to 12.8 v ?

No, you need to set the "Charged voltage" higher. What Trojan mean is that a rested, fully charged battery will show 12.73 volts, but you couldn't get it to fully charged by applying 12.73 volts. Victron suggest 13.2 volts as the default Vc setting, and I'd suggest you use that setting.

For your battery monitor to reset itself properly, two conditions have to be met simultaneously. Firstly, the battery voltage has to be higher than the Vc setting; secondly the charging current has to be lower than the "Tail current" (Ic); and these two conditions have to be met for at least 4 minutes.

Victron suggest a default setting of 4% for Ic (ie 4% of your total amp-hour capacity), and this should work fine for most people.

 

[Oscarpop]

No, you need to set the "Charged voltage" higher. What Trojan mean is that a rested, fully charged battery will show 12.73 volts, but you couldn't get it to fully charged by applying 12.73 volts. Victron suggest 13.2 volts as the default Vc setting, and I'd suggest you use that setting.

For your battery monitor to reset itself properly, two conditions have to be met simultaneously. Firstly, the battery voltage has to be higher than the Vc setting; secondly the charging current has to be lower than the "Tail current" (Ic); and these two conditions have to be met for at least 4 minutes.

Victron suggest a default setting of 4% for Ic (ie 4% of your total amp-hour capacity), and this should work fine for most people.

I understand this fully. However in the absence of a charging current, for instance at night with no solar and the wind gen turned off, if my battery voltage is 12.73, the battery is fully charged (according to the Trojan data sheet)

I still don't understand if 12.73 is a fully charged battery, and assuming no load, why I cannot set the monitor to accept 12.8v as 100% charged?

This could just be me being thick . Thanks for patience and understanding

 

[pvb]

You have to look at the reason your monitor has these settings. The monitor's Ah counter only makes sense if it knows that the batteries were fully charged at the start. So it needs a way of detecting when the batteries are fully charged. It does this by making sure that they'vce reached a minimum voltage, and that the charging current has dropped down to a low level. When that happens, the monitor will reset itself to zero, then start counting the current you use on the Ah display.

If you set the "Charged voltage" lower than 13.2 your monitor probably won't give you any sensible information. Lots of people moan about battery monitors not giving accurate results, and often it's because the parameters have been wrongly set.

 

[Oscarpop]

You have to look at the reason your monitor has these settings. The monitor's Ah counter only makes sense if it knows that the batteries were fully charged at the start. So it needs a way of detecting when the batteries are fully charged. It does this by making sure that they'vce reached a minimum voltage, and that the charging current has dropped down to a low level. When that happens, the monitor will reset itself to zero, then start counting the current you use on the Ah display.

If you set the "Charged voltage" lower than 13.2 your monitor probably won't give you any sensible information. Lots of people moan about battery monitors not giving accurate results, and often it's because the parameters have been wrongly set.

Thank you . Makes sense.

Although, it means that using renewable energy, it will be almost impossible to get the batteries to 100%

 

[VicS]

Thank you . Makes sense.

Although, it means that using renewable energy, it will be almost impossible to get the batteries to 100%

You appear to want your monitor to read 100% when its as fully charged as your solar, wind or Watt and Sea can make it.

Therefore why not set it to 0.2 to 0.3 volt below the highest that any one of these three float at .

You may have to re-adjust the setting to a lower value, if that voltage is seldom achieved, to align with what you decide corresponds to fully charged.

 

[pvb]

Although, it means that using renewable energy, it will be almost impossible to get the batteries to 100%

Depending on the output of your solar panel and wind generator, there's no reason why they shouldn't be able to bring your batteries to full charge.

 

[VicS]

Depending on the output of your solar panel and wind generator, there's no reason why they shouldn't be able to bring your batteries to full charge.

OP's Sunsaver MPPT controller floats at 13.7 volts and his Watt and Sea Hydrogenerator floats at 13.8 volts . Unless his windcharger, the identity of which I have forgotten or simply don't know, floats at a significantly higher voltage then around 13.5 volts would seem to be setting for his BVM being approx the suggested 0.2 to 0.3 volts below their float voltages.

 

[pvb]

OP's Sunsaver MPPT controller floats at 13.7 volts and his Watt and Sea Hydrogenerator floats at 13.8 volts . Unless his windcharger, the identity of which I have forgotten or simply don't know, floats at a significantly higher voltage then around 13.5 volts would seem to be setting for his BVM being approx the suggested 0.2 to 0.3 volts below their float voltages.

If they float at those voltages, fine. Victron's default advice of 13.2 is no doubt based on the fact that many mains chargers float at 13.5v.

The tail current is probably the more sensitive setting for getting the monitor to reset its Ah counter properly.

 

[GHA]

Although, it means that using renewable energy, it will be almost impossible to get the batteries to 100%

Probably close to the truth for an awful lot of boats. If there's anyone onboard using them anyway.

 

[Oscarpop]

Thank you all.

I think that whatever the algorythm inside he monitor, it is easier to assume 12.8 is charged almost fully and 11.8 is discharged.
We do not have enough renewables to cope with our power requirements , so as some clever chap suggested the monitor will never hit 100%., as it is almost impossible to get to 13v floating .

The excercise is mostly about when we need to run the engine, as I don't want to do deep discharges.
Our current regime involves never dropping below 65% charge. So as long as the readings are accurate for values below 100% , I am happy.

 

[pvb]

Thank you all.

I think that whatever the algorythm inside he monitor, it is easier to assume 12.8 is charged almost fully and 11.8 is discharged.
We do not have enough renewables to cope with our power requirements , so as some clever chap suggested the monitor will never hit 100%., as it is almost impossible to get to 13v floating .

The excercise is mostly about when we need to run the engine, as I don't want to do deep discharges.
Our current regime involves never dropping below 65% charge. So as long as the readings are accurate for values below 100% , I am happy.

If you assume that, your monitor will reset to fully charged before your batteries are actually fully charged. Then if you discharge them until the monitor says 65%, you'll really be discharging them much more, thus shortening their life.

 

[macd]

If you assume that, your monitor will reset to fully charged before your batteries are actually fully charged. Then if you discharge them until the monitor says 65%, you'll really be discharging them much more, thus shortening their life.

Very true.
All the more reason for the OP to check them with a hydrometer when notionally fully charged. Then he'll know for sure.
(Assuming his Trojans are open lead acid.)