sorry...I do not have a shunt kit. have been using voltages/direction from BB to try to run this down.
my "unsolvable problem"
- Thread starter olmz
- Start date
I would suggest getting one of these :
I use that clamp meter to know how much is being drawn all the time. With it you will know how much power is actually being drawn from your batteries and you can use it to actually track down what is using the power be it the inverter or another drain from the rv's 12v stuff.
Uni-T B4Q094 UT210E True RMS AC/DC Current Mini Clamp M W Capacitance Tester: Amazon.com: Industrial & Scientific
Uni-T B4Q094 UT210E True RMS AC/DC Current Mini Clamp M W Capacitance Tester: Amazon.com: Industrial & Scientific
www.amazon.com
I use that clamp meter to know how much is being drawn all the time. With it you will know how much power is actually being drawn from your batteries and you can use it to actually track down what is using the power be it the inverter or another drain from the rv's 12v stuff.
thank you kindly. a moderator here ("boondocker") who has been so gracious...as have so many....in guiding me, suggested the same thing, gave me a link for one which he felt would work....making sure it measures both AC AND DC voltages.....I ordered and received it....and am now reading instructions on using it.
I have a fluke VOM and believe in them, and thought I needed some expensive piece of equipment to do this, too...but he suggested not, and the piece came in yesterday.
thanks for the suggestion!
fyi and fwiw, this is the one:
WindWizard
Solar Enthusiast
Now that you have the clamp meter then put it over your wires and put it on DC amps and show us what you measured and where you measured it and possibly we can figure this thing out.
Just an FYI, I've got (2) MS2812 with LFP batteries.
I often see that the inverter voltage and the BMK voltage are different with the BMK. The BMK is much more accurate to what I actually measure at the batteries themselves.
I have mine set to CC/CV and finish based on end amps. I don't rebulk until the back is around 10-15% charge and I don't float at all.
rebulk in magnum settings is really just restarting the full charge cycle.
I think you have 2 issues you are dealing with here:
I think your wiring is drawing down one battery before the others and that's leading to a lot imbalance on the low end.
I also think your batteries themselves are never getting fully charged, and are themselves imbalanced both internally and compared to the others in the group.
I often see that the inverter voltage and the BMK voltage are different with the BMK. The BMK is much more accurate to what I actually measure at the batteries themselves.
I have mine set to CC/CV and finish based on end amps. I don't rebulk until the back is around 10-15% charge and I don't float at all.
rebulk in magnum settings is really just restarting the full charge cycle.
I think you have 2 issues you are dealing with here:
I think your wiring is drawing down one battery before the others and that's leading to a lot imbalance on the low end.
I also think your batteries themselves are never getting fully charged, and are themselves imbalanced both internally and compared to the others in the group.
i am looking at the documentation now...and within a day or two, expect to take the measurements and report in. many thanks
Now, that is very interesting.
First, I am about to change to CC/CV to see what, if anything that does. I expect to have that done, if not tonight, by tomorrow. I would love for that to be the issue.
as to your comment about "wire", would you be so kind as to say "why" you think this. just about everyone I have heard from ....even at BB.....does not think there is any problem with the wiring.....and perhaps you saw here that I posted a graphic, never mind actual photos of the wiring, that I got from BB and used to wire the batteries.
Indeed, when I can get my tech back here (he is unwell, himself), I am going to have two victron busbars mounted on the side of the compartment and then try the wiring though those, as I have been concerned about one terminal....the positive terminal on the battery in my photo to the right of the compartment as you are facing it through the photo...the one "closest" to the compartment door on the right as you look at the photo.....as even though it is as per the instructions, there is a lot going on on that one terminal and it has made me wonder.
yet, so many have suggested that that is not an issue....so I am not challenging you, but I sure would like to know why you think this, PLEASE...and what you think the alternative should be....and if it is two busbars whether or not you think that solves this.
at the same time *why*, please, do you think that the batteries are not being fully charged? same reason?
many thanks.!
ps what BMK do you use?
PPS because I usually believe in overkill in crucial matters, and insofar as I intend to vastly increase the number of batteries in the near future, I chose wires that are larger than what was needed. "nobody" had any problem with any of that. indeed, the comments were always that there is a problem with "too small" but not "too big". do you agree with this?
again, thanks.
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Sojourner1
Itinerant
Without a shunt you are chasing your tail with voltage. LiFePo4 need a shunt for coulomb counting for the SOC of the batteries, I find it hard to believe that BB didn't say this but it is mentioned in their battery monitor section but use Victron stuff. Magnum has the ME- BMK. So you are saying that there is no shunt that is communicating/ interacting with the charger/ inverter? I believe this is your problem and not getting the full functionality of the charging/ inverting system.
After charging the lfp batteries they will always drop in voltage to their resting voltage if you have no loads on them but an rv will always have some sort of 12v loads. You have something that is drawing 12v draining the battery even slighly. Co detector, fridge, fans for fridge, maybe landing gear but something is drawing power and that is what needs to be found.
Edit... wiring batteries especially 8 of them, something to read and think about. BB batteries have a lot of small cyclinder cells making up 1 100ah battery now multiple by 8.
http://www.smartgauge.co.uk/batt_con.html
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ok.....let me try to ask this in a way that I can be sure I get it all.
first, are you saying that without a shunt, the batteries are not even charging properly or that I am simply being deprived of a better way to measure capacity?
next, i certainly do have a few things drawing on the electrical system, albeit these days, while always hooked up to shore power. are you saying that such as, say, a large residential fridge (or an airxcel AC...that the fridge being the only things drawing any appreciable power under most circumstances), even with shore power, is drawing enough power to make an immediate difference such that they will lower a fully charged battery bank within 20 minutes to a voltage level which BB's own charts show to be a heavily depleted battery?
I do have big foot struts, so to say, but once down they are off.........and other than small LCD tvs and lights, I have no clue what else would be drawing enough power, especially on shore power, that I would lose...at least based on voltages which BB says represent a huge drop in capacity...........such large amounts every single time...with the system automatically going back into another charge cycle each time. do you have any thoughts about that?
also, just to be sure, as you mentione 8 batteries. I HAVE 8 batteries, but it is only material in terms of having tried two separate groups of 4 while I sort this out. are you saying what you are, thinking I have all 8 hooked up at one time?
I have previously had, as mentioned, 2 sets of batteries....both AGMs.....one a no name Chinese set of 4 (6 volts wired serially) and the second set, Lifelines...great batteries but for a variety of reasons, I decided to move to BBs..........neither set of AGMs produced this "oddity" with voltate dropping precipitiously. why would that happen "now"....all my equipment is the same.....same fridge, same ACs and so on......and not for 7 years prior? this literally happened the minute I "dropped" these in.
I am getting a lot of input from a lot of people and I am grateful for it, but my head is spinning from some of it and I need to be better understand all this. if you would be so kind as to answer the above in as granular a fashion as you can, I would much appreciate it.
many thanks1
Sojourner1
Itinerant
I'm guessing and correct if wrong you do not have bluetooth on the BB batteries to see their individual voltages? Whether you have 4 or 8 batteries hooked up they need to be balanced and wired evenly for this to happen. Read that link that I posted.
If you had a shunt you would be able to see what you dc draw live time on the batteries.
If you had a shunt you would be able to see what you dc draw live time on the batteries.
The shunt would tell you if current is going in or out and how much. In your case, the shunt would not limit how much the batteries get charged.
WindWizard
Solar Enthusiast
Until you hook up your clamp meter over the wire from your red positive battery cable and let us know how many amps you are using out of your battery, then it is only speculation whether you have bad batteries or a large current draw.
S Davis
Solar Enthusiast
- Joined
- Sep 25, 2021
- Messages
- 607
Have you determined that none of the batteries BMS are tripping or tripped and you are not running on less than four batteries? With four hooked up in parallel you will see proper voltage even if only one battery is operational.
If you have a clamp on amp probe run the system and get it to finish charging where it has the voltage drop and check each individual battery for amp draw, if you had three of your batteries BMS tripped and were running on one I would bet when finished charging the load would pull the surface charge off rapidly causing the voltage to drop and the charging to start again depending on you settings.
I might be totally off base here but it is simple to rule it out.
If you have a clamp on amp probe run the system and get it to finish charging where it has the voltage drop and check each individual battery for amp draw, if you had three of your batteries BMS tripped and were running on one I would bet when finished charging the load would pull the surface charge off rapidly causing the voltage to drop and the charging to start again depending on you settings.
I might be totally off base here but it is simple to rule it out.
WindWizard
Solar Enthusiast
This implies that there is something wrong with the BB's
MisterSandals
Participation Medalist
Or how they are being charged.
I'd try running with 2 BBs and then with the other 2.
thank you. I have just purchased a clamp DC meter, am reading the instructions and by this weekend, will have measured this very thing and will report back.
thank you.
that thought has occurred to me and by process of elimination, I will get there if nothing else manifests itself, too. I do keep coming back to having had no apparent problems with any of 8 batteries and a victron ip65 in terms of fully charging each by iself and determining that no battery manifested any drops in time periods much longer than it is taking for this to show up now.
I know less than anyone, but am suspecting some kind of wiring issue, especially as I am not aware of any odd current draws going on (I get that there may be one and I am not seeing it...such as, perhaps, with, say, the water heater.....and that with the same equipment for 7+ years, I have never had this experience before with other batteries....but I see now that there is a list of things to eliminate, and that the clamp charger is a big one....so that is next.
thanks!
got it. thank you.
i did read the link and understand. presently, the batteries are no more than 4 at one time (nor has there been more than 4 throughout this whole matter) and it is clear that the next move is to measure dc current at certain times...and I do now have a clamp based meter to make that test, which assuming it is not heavy raining and thunder, etc....which we have had in the last few days, if not tomorrow, by the weekend I plan to make those measurements.
many thanks for staying on this !
i thought i had answered this just now but don't see it.
well, the answer was that this is on my list of process of elimination.
I am hoping that measuring DC current with the clamp will make that moot, but I get that my list is pretty long until it isn't.
also, I sure hope there is no draw and that this is a wiring issue somehow, never mind that I followed instructions, although another poster here sent a very helpful link showing even two more ways to do this............but whatever it is, I understand that there is only an elimination process so I am steeling myself for it all (if I were ten years younger I would actually be enjoying this, although I am learning a lot!....and I do enjoy that...just wish it were more academic and less tied to a problem.
again, thanks so much!
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