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Post by Elcano on Sept 23, 2023 6:59:37 GMT
Hi, the readings of my different battery gauges do not make sense to me and I hope you can enlighten me on this topic. I have the following setup: 1. 400 Ah AGM house bank, 100 Ah AGM motor (C20), bought April 2023 2. Jeanneau gauge on the main panel 3. Victron BMV-702 4. 2x Victron Smart Solar 15/75 5. Victron Inverter 1200 VA Here are the problems: 1. The voltage on the main panel is different to the voltage on the MPPT controllers to the voltage on the BMV-702 2. The min voltage alarm activates (>12V) and the SOG shows 80% (the drawn amperage about 80 A); this happened after about 2,5 days after a full charge at the dock (only solar charge during the days). 3. See the history: it seems that the Victron does not record discharges(?)  4. Here are my battery settings in the Victron BMV-702:  I am not good in electrics, it seems to me that the SOG and the voltage do not fit together (I recon 12V is quite low). Is it possible that the inverter was installed in a way that all the gauges do not recognise the its usage? I hope you have some ideas so I can talk to an electrician. Will not tinker around by myself  . Cheers Thomas |
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Post by Charlie-Bravo on Sept 23, 2023 18:50:39 GMT
it’s a bit tricky, your system seems to recognise a lot of what is going on, but with odd blanks in the picture.
Various possibilities, all dependant on how the victron has been wired in, as to what it can read, but a little odd it would seem, from your screen shots displayed.
Of course with all this great tech, it can be that nothing is ‘wrong’ , just the app isn’t behaving as it should, and just leading you to thinking there is an error.
Discrepancies, between panel voltages displayed and the victron app are normal, the Victron is usually wired closer to the batteries, the panel sees a voltage drop from the length of undersized cables to them, but we are sailors, absolute voltage values should not be a great concern, as long as we know we are not putting ourselves in peril and flattening all the batteries.
Stage one, software update everything, TOTO everything,
Stage two , send your findings to Victron , it may enable a software update ‘fix’ , they may even offer advice on things to check.
Only after one and two above would I involve an electrician , and even then, choose the sparky familiar with the subject, many are just clever at getting a cable from one part of a boat to the other and connecting it up, a skill in its own right, but full understanding of these things seems to vary considerably in the trade here.
Not much help I know, but too many unknowns of your set up to add anything definite.
Good luck sorting it
CB
CB
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Post by zaphod on Sept 24, 2023 10:37:14 GMT
The Scheiber panels on Jeanneaus are known for reading low compared to battery monitors.
You cannot use voltage to determine state of charge unless the battery bank has been in a resting state with no loads on it for a while. When you are actively using the battery bank, the voltage will drop as more load is put on it. What kind of loads are you running when your voltage drops below 12v?
I'm not sure why you have blank data points on the app. That might be a question for tech support.
You do have to zero the monitor once in a while, when you know the batteries are fully charged, in order to keep it reasonably accurate.
The monitor doesn't know the health of your batteries. If the batteries have lost capacity due to being at partial charge for long periods, your resting voltage readings might indicate a lower state of charge than your monitor has calculated. Your batteries are pretty new, so hopefully that is not the case.
To me, the most useful information the monitor gives me is amps in and out and amp-hours consumed.
How deeply do you discharge your batteries? How long do you go without fully charging them?
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Post by Elcano on Sept 24, 2023 15:39:04 GMT
it’s a bit tricky, your system seems to recognise a lot of what is going on, but with odd blanks in the picture. Various possibilities, all dependant on how the victron has been wired in, as to what it can read, but a little odd it would seem, from your screen shots displayed. Of course with all this great tech, it can be that nothing is ‘wrong’ , just the app isn’t behaving as it should, and just leading you to thinking there is an error. Discrepancies, between panel voltages displayed and the victron app are normal, the Victron is usually wired closer to the batteries, the panel sees a voltage drop from the length of undersized cables to them, but we are sailors, absolute voltage values should not be a great concern, as long as we know we are not putting ourselves in peril and flattening all the batteries. Stage one, software update everything, TOTO everything, Stage two , send your findings to Victron , it may enable a software update ‘fix’ , they may even offer advice on things to check. Only after one and two above would I involve an electrician , and even then, choose the sparky familiar with the subject, many are just clever at getting a cable from one part of a boat to the other and connecting it up, a skill in its own right, but full understanding of these things seems to vary considerably in the trade here. Not much help I know, but too many unknowns of your set up to add anything definite. Good luck sorting it CB CB Thank you CB, will contact the Victron support. The firmware is updated on all devices, so it must be something else. At least I know now, that I the different voltages are not really unusual. Will go on a further hunt for the solution. Cheers |
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Post by Elcano on Sept 24, 2023 15:49:53 GMT
The Scheiber panels on Jeanneaus are known for reading low compared to battery monitors. You cannot use voltage to determine state of charge unless the battery bank has been in a resting state with no loads on it for a while. When you are actively using the battery bank, the voltage will drop as more load is put on it. What kind of loads are you running when your voltage drops below 12v? I'm not sure why you have blank data points on the app. That might be a question for tech support. You do have to zero the monitor once in a while, when you know the batteries are fully charged, in order to keep it reasonably accurate. The monitor doesn't know the health of your batteries. If the batteries have lost capacity due to being at partial charge for long periods, your resting voltage readings might indicate a lower state of charge than your monitor has calculated. Your batteries are pretty new, so hopefully that is not the case. To me, the most useful information the monitor gives me is amps in and out and amp-hours consumed. How deeply do you discharge your batteries? How long do you go without fully charging them? Thanks for your support zaphod, the highest load in my boat is the fridge I guess. I keep things simple and easy. Not to underestimate that all the little electronic gadgets in sum take also loads of energy. I understand what you are saying about voltage, but what I find kind of strange is that with only 80 amps taken out in total the battery voltage drops and stays under 12 volts even if no amps are drawn. Yeah I regularly zero the monitor, after being docked and attached to electricity for a longer time. In this topic I observed another thing I do not understand: The SOG is back to 100% quite quickly but the alternator or the solar panels still put significant amps in. I know that the AGM take a long time to be fully charged but the SOG metric does not show that adequately. My deepest discharge was 148 amps usually it is 80 to 100 amps (2 days on anchor). The batteries are fully recharged every week. Cheers |
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Post by zaphod on Sept 24, 2023 18:14:24 GMT
It sounds to me like your batteries are NOT getting fully charged every week. Are you by any chance still using the stock Cristec battery charger that came with your boat?
When I first bought my boat it was not very old, but the previous owner had already replaced the battery bank at least once, and, even though the size of the bank had been upgraded to 550ah, it didn't take long before the batteries were not lasting a long weekend off grid. That's when I embarked on a mission to learn about my battery system. My first step was to buy a battery monitor, a Victron BMV712, and monitor my amp draw. (Since Jeanneau was too cheap to even install a shunt to enable the ammeter on the scheiber panel!)
I, too, observed some anomalies once started studying the data the monitor was putting out. I discovered that the battery bank was wired wrong, and there was more than one negative connection to the battery bank. That meant that not all current flow was going through the Victron shunt. Once I corrected that problem, the information I got from the monitor started to make more sense, but I still wasn't getting the ah I expected out of my relatively large 550ah FLA bank.
The culprit was the Cristec battery charger. I had assumed that since the boat was plugged in at the dock when not in use, the battery charger would maintain the batteries at 100%. I was wrong. I read through the charger manual and discovered that the charger automatically switches to float mode after 4 hours, regardless of the acceptance rate of the batteries! 4 hours of bulk/absorption charging might be sufficient for the small bank that the factory installed, but it is woefully inadequate for even a modestly upgraded bank. So it turned out that the battery charger was keeping the batteries only partially charged, which is the kiss of death for a lead acid bank! It causes the plates in the batteries to sulphate, resulting in a permanent loss of capacity.
So, if you are still using the Cristec charger, you need to replace it! Fast! It will kill your batteries!
In the meantime, after your charger has switched to float mode, cycle the power to it, and it will go back to bulk charging for another 4hrs.
A good charger uses battery acceptance rate to decide when to stop charging and switch to float. Usually when the bank is only accepting 1 or 2 amps. The Cristec is not a good charger!
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Post by ForGrinsToo on Sept 24, 2023 20:37:54 GMT
What did you select to replace the Cristec?
Thanks,
Geoff
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Post by zaphod on Sept 25, 2023 1:12:41 GMT
What did you select to replace the Cristec? Thanks, Geoff When I replaced the battery bank I went with Firefly Carbon Foam AGMs, and those batteries like high amperage charging once in a while, so I ended up going with a Xantrex Freedom XC Pro 2000, which is a combination 100a charger and 2000w inverter. It was much cheaper than a stand alone 100a charger and in a much lighter, more compact package. |
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Post by Trevor on Sept 25, 2023 2:54:22 GMT
Hello Elcano,
The battery monitor tracks battery state of charge (SOC) by monitoring the current through the shunt and calculating how much has been used and how much has been put back in. In order to calculate this with any degree of accuracy various factors are taken into account like charge efficiency, peukert value and temperature tracking. At best it is an estimate based on best guess of those parameters.
One factor that resets the system though is when it is deemed to be 100% full. This is assumed when the voltage is at a certain level ( battery charged voltage) and charge current has fallen to a certain level ( tail current). The standard default for tail current is 4%. Yours is set below less than 1%. That is why you have never seen the batteries shown to be 100%. The charge current has never dropped low enough for the BMV702 to ever deem your batteries as full.
When charging the batteries the charge current will reduce and when the tail current reaches its preset value the SOC will show 100% and then the system is reset for another discharge. That way the Victron system is constantly resetting to reduce accumulated errors.
I suggest to reset tail current to 4% and test system again. Let’s know how that goes.
Regards
Trevor
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Post by zaphod on Sept 25, 2023 6:38:42 GMT
Hello Elcano, The battery monitor tracks battery state of charge (SOC) by monitoring the current through the shunt and calculating how much has been used and how much has been put back in. In order to calculate this with any degree of accuracy various factors are taken into account like charge efficiency, peukert value and temperature tracking. At best it is an estimate based on best guess of those parameters. One factor that resets the system though is when it is deemed to be 100% full. This is assumed when the voltage is at a certain level ( battery charged voltage) and charge current has fallen to a certain level ( tail current). The standard default for tail current is 4%. Yours is set below less than 1%. That is why you have never seen the batteries shown to be 100%. The charge current has never dropped low enough for the BMV702 to ever deem your batteries as full. When charging the batteries the charge current will reduce and when the tail current reaches its preset value the SOC will show 100% and then the system is reset for another discharge. That way the Victron system is constantly resetting to reduce accumulated errors. I suggest to reset tail current to 4% and test system again. Let’s know how that goes. Regards Trevor Except that Elcano isn't saying that his monitor never shows 100%, he is saying the opposite; it often says 100% when the batteries are still accepting a lot of current. |
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Post by Trevor on Sept 25, 2023 7:02:50 GMT
Oh, Yes, apologies for that......It is perhaps possible the inverter could be wired directly to the negative battery terminals instead of on the load side of the shunt. In that case the inverter current would not be registered on the battery monitor. If the inverter were used, that current would not be counted so the battery monitor would read a higher SOC than the reality.
The discharge cycles are zero. The discharge cycle for the Victron BMV 702 is when the SOC drops below 65% and rises above 90%. That represents one "cycle". The average discharge current is linked to the discharge cycles so if discharge cycles are zero so is the average discharge current. Those are preset and not adjustable. Maybe not very intuitive but nevertheless that is the case.
It is important for the negative feed to the inverter to be on the shunt connection opposite to the negative battery connection.
I hope this helps and sorry about earlier confusion on my part.
Trevor
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Post by Elcano on Sept 25, 2023 8:20:38 GMT
Thanks a lot for that helpful discussion.
Here are some answers to your questions:
- Helpful description Zaphod. I have a Mastervolt Chargemaster 12/50-3. I think the batteries should be full after a long charge. The guy who installed the batteries also changed the settings in the Mastervolt because I changed from gel to AGM. But, I will double check this.
- I read some good reviews about the Firefly batteries, could not find a dealer in Europe though, if somebody has a contact I would appreciate this. I was eyeballing the Victron carbon foam batteries for my next replacement.
- Good point with the wiring of the inverter and other "minus poles". Will check this.
Will keep you updated.
Cheers
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Post by moonshadow on Sept 26, 2023 11:01:07 GMT
Firefly seems to no longer be making batteries. They had a manufacturing problem that turned out to be horrible. Some of us received well made batteries which have been great! I know that Victron is selling carbon foam batteries and I don’t know much about them yet.
When I’m at a dock for a while I put the cristec chargers in storage mode at 13.3 v and that works. My solar and engine are set for higher voltage and seems to provide the high voltage occasionally that keeps the batteries happy.
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