Thanks Charlie, Ill answer your questions below and look forward to any feedback..
I suspect (based on SG) that your batteries are sulfated because of poor charging. I presume that the SG reading was taken at full charge of course.
I bet that the root cause can be corrected without spending any money
. In order to confirm and correct the root cause in the best possible way that can you please provide the following info (or at least whatever you can provide now) ?
I know these are lots of questions, but the fact of the matter is that this systems are typically sold as very smart but in fact they are only as smart as the dumber of its many settings!
- Exact battery model (eg 4DMDC, but that is a 160 Ah model)
multifit DUAL ER660 660Wh 140Ah 750A(EN) 12V
These batteries are dificult to find online details for. I think they may have been branded for Benetau or Lagoon
but the one information sheet I have found online shows the charging parameters as set out in my original post
Absorption Charge with 14.8V - 15.0V limit for 12 to 24 hrs or when current drops below 1% of the C20 rating (example; C20=100Ahr, the low current shut off is 1%x 100 or 1A).
Float 13.5v - 13.8
- Do you have 6 of those in parallel?
- What was the SG of the batteries at full charge when you bought them?
I think it was close to or above 1.25. I didnt record
my initial SG readings
- Do you know what is the manufacturing date of those batteries or what is the date code marked in the case?
The code stamp says in large font - 14A and below in smaller font - 981AB406 - The boat was delivered new in May 2014
- How many controllers you have (one connected to the 6 batteries?)
One solar controller connected to all solar and batteries
- What is the exact model name of the solar controller (something like "BlueSolar MPPT 100/30")?
BlueSolar charge controller MPPT 150/85
- Please send a photo
of the controller because there is at least one model name that corresponds to to different pieces of kit.
Let me know if you need this as internet
is very slow here for sending photos. It should be found online fairly easily.
- What are the dip-switch settings of the controller?
It doesnt have dip switches. Set points are programed into the LED screen
. My settings 14.8 abs for 12 hrs, 13.8 float 16.2 eq. Eq is set to manual rather than automatically on a set date. I have been attempting to equilize for one hour the last day or two but the highest voltage I am seeing is 15.5. I may need to try for a longer period.
- How you used the Victron software
to program the controller? What settings did you enter?
- What is the cross section and length of the cables between the solar controller and whatever they are connected going towards the battery (shunt or whatever)? What is the cross section and length of the cables between that point and the batteries?
I think its 7mm and approximately 6m from panels
to controller. I did check at the installation
and it was adequate. The controller shows amps going in on the LED display and it usually seems correct. I am currently seeing 34A going in. The battery monitor
is showing me 24A going in and the difference is appliances
and fridges drawing 10A. I have seen as much as 60A going in at the controller LED
- How you actually measured the voltage across battery terminals at the beginning of the absorption stage? What was it?
I have measured with a multimeter across the terminals. Its currently in Abs mode. At the battery measures 14.36
At the panel reads 14.4 on the basic panel readout, and 14.24 on the Mastervolt Easy BM which has the more detailed information and runs directly from the batteries via the Mastervolt Mastershunt
- What is the current going into one of those batteries (measured with a clamp around all the cables that go into one of the terminals) after a typical day of solar charging at 14.8V and before voltage starts to drop because the sun went down or because the controller moved to float?
I dont have a clamp on ammeter but when they are full or close to full I usually see around 10A going in at around 14.4V
- Are you saying that your solar controller only moves to "float" after 10 continuous hours at 14.8V? Does it actually move to float every day then?
Im not sure but I think it rarely moves to float at all. Its set for 14.8V for 12 hrs but thinking about it now, it usually seems to be closer to 14.4V for most of the day
- How does your battery monitory "synchronize" ie realize that batteries are 100% full? Do you do it manually (based on what criteria) or does it do it automatically (based on what settings?).
Im not sure but I believe it syncs when the amps going in reach 99% and are below a set point of around 1-2% of total bank. ie, It is currently showing 98% with 20A going in. Its showing capacity consumed as 18Ah. When the Amps drop to around 10 for an hour it might go to 100%. It has never mysteriously jumped to 100% after being tricked by the controller under certain conditions. I usually see a maximum amps in of 10-12A for at least 2 hrs before it will show 100%
- What battery monitor do you have?
Its a Mastervolt Easy montor connected to the Mastervolt mastershunt. It seems reliable and fairly accurate. I have it displaying SOC, voltage, Amps in/out, Capacity consumed and battery temp which ive only ever seen 22-24 degrees C
- Can you please confirm that the 1.20 SG reading was taken at full charge (or as full as you can charge them).
- What do you mean "We use around 10ah at anchor and 20Ah underway". What is the time period over which you add up those amp-hours? Are you referring to net amp-hours (ie consumption
by loads minus charging)?
Sorry for the terminology, We draw 10 Amperes constantly at anchor and 20 Amperes underay, so a total of 240Ah at anchor and 480Ah underway per day. It may be a little less than this but close enough.
- If you disconnect one battery after fully charging it an dlet it rest 24 hours. What is the voltage across its terminals?
I havent done this but I can if it helps.
- Where do you get the voltage warning from? What was the voltage across the battery terminals when you got that warning?
I get the warning on the Masterview BM. I havent checked the voltage at the terminals at that time.
- Is the main panel with the house loads (fridge, etc) connected to the LOAD terminal of the solar controller or to some point in between the BATTERY terminal of the controller and the batteries?
No I believe the solar panels
go directly to the controller and then the controller goes directly to the batteries.
That was about the underlying root cause. Now letīs worry about your current batteries. If the 1.20 SG reading was taken at full charge then IMHO the best you can do is to equalize and hope you can get some of that sulphur back into solution to do its job. In my not so humble opinion it is a waste of time to try to equalize with solar directly, but if you have a good charger that can do equalization the way Exide wants it and your inverter (and 5 of the batteries) can handle it then go for it! Otherwise you may have to go to a marina. Note that equalization may not help much if the sulfation has been there for a long time.
Thanks again Charlie. I am wondering about a couple of things now. The Abs stage is set to 14.8V, but as I said it rarely seems to reach or stay at 14.8V
And also the Eq stage hasnt gone over 15.5V when it should be reaching 16.2. Its 1pm and the BM is showing 99%, 14.48V 20A going in, 13Ah consumed. The solar controller is showing 25A in, which seems a bit low considering its full sun now and theres no shading.
I just checked on the controller and its showing Pv current 8A, Pv Voltage 33V, Pv Power 270W. Thats in full sun, so it would appear the input it much lower than it should be. The panels
are 4x 280W. Im assuming the readings shown on the controller are actual readings and not the readings after the controller has reduced the amounts for the battery to accept...
OK that was strange/confusing. I just boiled the kettle to draw some amps and noticed the Amps in on the panels rose to 55A and now dropped back down to 12 again on the solar controller so I guess the reading is actually the controller output and not the solar panel output...