3 hours ago, The Terrible Triplett said:

The controllers I mentioned are more stable with less fluctuations, even with clouds, and therefor the BMV may be able to get a more stable reading

My Axpert charge controller charges my batteries 100% without fluctuations. If I charge my batteries for only 5 hours and go to batteries at 23h00 at night, my tail current is less than 1.0 amp at that stage. If I charge my batteries for 12 hours, my tail current goes all the way to 0 amps. It will jump up to 0.1 amps for 2 seconds, then back to 0 again for between 1 and 2 minutes. I don't think you can get more stable than that. Victron decided to set the lowest setting on the tail current at 0.5%. That is 2.5 amps on my system and I have a problem with that, because for me that is too high for my system. Now my batteries jump anything from 96-98% to 100%. That is with a detection time of 50 minutes. I cannot set it any lower to go gradually go all the way up to 100%. 

4 hours ago, ebrsa said:

In the video the example battery has an absorption voltage of 14.4V and a float of 13.4V. If you look from the 2.50 minute point it is suggested that the BMV charged voltage be set at 13.1 as per you posts but immediately afterwards the presenter says that in the case of solar systems or systems with fluctuating charge currents, the parameter should be set at 14.1V or 0.3C below the absorption voltage which is in fact, to my knowledge the end of charge voltage, as at that point chargers drop to the float voltage.

That to me was just a stupid comment to make as there no difference between charging a car battery and charging a solar battery. The BMV does not know the difference. The BMV looks at volts and amps over a certain period of time. If the values stay true during that time, it goes to 100%.There is no little block where you select the little block and a green tick mark comes up to say this is a solar battery, so now use absorption voltage. The bottom line is the Charged Voltage setting needs to be less than the Float Voltage. You should set the Charged Voltage on your BMV to 53.7 Volts. If you don't believe me, phone Victron tomorrow, they will tell you the same thing. 

 

4 hours ago, ebrsa said:

I have last night set the BMV charged voltage at 58.2V or 0.2V below maximum and will see what happens today.

The SOC will get stuck somewhere between 90 and 96%. Tell me tomorrow where it got stuck. It will go up to a level and even if you go to grid, will refuse to increase any further. Your batteries will be unable to go to 100%. 

 

4 hours ago, ebrsa said:

So all I am trying to do is find a solution that will give the best results before I buy some more unsuitable equipment.

I would not get a standalone charger at 24 volts. That just becomes messy, disconnecting strings once a month or whenever required, do one string and then the next day do the other. I would suggest you get a MPPT Controller that can do that voltage.  

1 hour ago, Don said:

That to me was just a stupid comment to make as there no difference between charging a car battery and charging a solar battery.

 Sorry Don, you just lost me for we all know a car battery cannot be used in solar applications and a solar battery has difficulties in a car because of their differences in design and application and that by default stands to reason their charging patterns differ.

The fact that you are changing your BMV so drastically, make no sense to me at all, even if you explain it as well as you do.

I am wondering:
- Already mentioned the MPPTS - see below.
- Could the parallel Axperts have an impact / factor into your SOC value not being reached as expected? Can you test for that?

Don, if I was you, as a test, borrow a Victron controller (make a plan beg borrow steal or try before you buy) and run it for a few days and measure it thoroughly as you are doing at present because ...

1 hour ago, Don said:

I don't think you can get more stable than that.

If you have done the comparison and post your experiences and data back here, we can settle this once and for all AND maybe, your BMV is back to basic settings. 

One thing I have learned this week was that monitoring Batteries isn't nearly as straightforward as what I though. 

1.  You need to make double sure that your settings is correct. The BMV rely HEAVILY on the users input and that in itself is a major concern for me. This make the device a subjective rather than objective device. If you are over confident and you are wrong then it will be a costly mistake.
2. The BMV used , the way I understand it , two methods to determine if the soc is 100% 

• The battery voltage - flout , bulk charge and all of that  
• The coulomb counting - ah consumed vs ah charged 

If the parameters were met , that the user setup , then it will go to 100% or if the ah consumed goes to 0 then it will also go to 100%. In what I have seen you can tweak the time it takes to detect that the batts is in float in order to get the AH consumed to 0. Then you should not get the "jump".
In most solar applications you will get some days that the panels will "jump" up and down and this will result in the battery volts and therefore it uses the ah consumed method as well. 

When any one now asks me something about the BMV first thing I would say is "Make sure that it measures 0 when there is NO load on the batts" as this will have a MASSIVE influence on how the BMV measures the batteries. 
Jus as a test look at the difference between the BMV and the Axpert battery amps readings.

 

 

 

 

 

 

 

 

 

 

 

 

 

There is quite a difference between the two so much that I had another check  today , just to make sure , that If there is NO load in the batts that the BMV still measures 0 and it did. So now I wonder which one of the two readings is correct as the difference is constant? 

Maybe the rest you guys can post some comparative graphs so that we can confirm if the difference stays the same or not. 

 

1 hour ago, The Terrible Triplett said:

 Sorry Don, you just lost me for we all know a car battery cannot be used in solar applications and a solar battery has difficulties in a car because of their differences in design and application and that by default stands to reason their charging patterns differ.

I have no idea what you are referring to. When did I say I wanted to use a car battery in solar application? I did not make the distinction between a "battery" and a "battery in solar application"!

 In the video, the presenter talks about charging a "battery" and how to set the parameters, then right at the end throws in a thing when you get to "solar battery applications", set the values as follows. That to me is just stupid. So what was the first battery she referred to? A camper deep cycle battery or a yacht deep cycle battery or a car battery? To me it goes about the amps and the volts, IRRESPECTIVE of what type of battery it is and WHAT it is used for.

You charge your battery for 12 hours and it should be fully charged if you use it on a daily basis or 24 hours when you don't use it that often. You check the float voltage and the tail current going into the battery at that time as it should be fully charged. You set the Charged voltage to below the Float Voltage at that time and the Tail Current going into the battery to above the Amperage going into the battery at that time and it will go to 100%. It is simple. I cannot understand why people cannot get it? 

2 minutes ago, Don said:

That to me is just stupid. So what was the first battery she referred to?

Remember that Victron was build/designed for ships originally and therefore have excellent AC chargers and the inputs volts does not go up and down during bad weather days. Solar power could have an impact on how the BMV reads the SOC.The "stupid" remark made by the lady from Victron is most likely aimed at the WORST case scenario where it could very well "trick" the BMV into thinking that the batts is fully charged.  

Lots of traffic since I last read this.

About the charged voltage. This simply has to be a voltage that indicates "charging is presently happening". A fully charged 12V battery standing at rest might sit at 13.2V. It's full, but it is clearly not presently being charged. If you applied any charging current the voltage would immediately rise to at least 13.5V, and probably even more.

So if your 48V bank is siting at 54V (and it is otherwise in good shape), you can know current is presently flowing INTO it.

All the BMV wants to know is a voltage that's above the "rest" voltage, with a corresponding current. The two are related of course. In my batteries, when they are full, they accept 1.5 ampere at absorption voltage but only around 300mA at float. So I could (for my 24V bank) set a condition of 28V and 1% (of 200Ah). Then it will only synchronise during absorb below 2A.

But this would be a bad idea, because I frequently drop to float around 90% SoC, while the batteries still accept quite a bit more than 2 ampere. So my charged voltage has to be slightly lower than float, not absorb, and I have to set my tail current to be lower (0.5%) because I'm dealing with syncing at float voltages.

In the end, you have to play with the three parameters until it works more or less how you want to.

Then you have to periodically check the chart and if you see a rising edge on the chart that is a bit too pronounced, you probably need to intervene and do a manual full charge.

The BMV will go all the way to 100% if you put enough current in, even if it never meets the exact criteria (eg, you have some large loads causing blips so your detection time is never reached).

My BMV hardly ever does an auto-sync, but it still periodically goes up to 100% simply because I end up putting enough in there.

It's not an exact science... but it is better than the alternative.

9 hours ago, The Terrible Triplett said:

Could the parallel Axperts have an impact / factor into your SOC value not being reached as expected? Can you test for that?

No, only when you set the wrong values it has an impact.

 

9 hours ago, The Terrible Triplett said:

Don, if I was you, as a test, borrow a Victron controller (make a plan beg borrow steal or try before you buy) and run it for a few days and measure it thoroughly as you are doing at present because ...

Why, there is nothing wrong with my controller. My batteries goes to 100% daily, just to fast because the Victrom BMV set values are not allowing me to fine tune my setup. My problem is the Victom BMV.  Victron assumes I sit with batteries that will require at least 2.5 amps when fully charged. Well Victron got it wrong, my batteries actually goes down to 0 amps. 

 

9 hours ago, The Terrible Triplett said:

If you have done the comparison and post your experiences and data back here, we can settle this once and for all AND maybe, your BMV is back to basic settings. 

I don't need to set them back to basic settings, basic settings are for worn batteries. If I set my batteries to those settings according to the video, my a SOC would probably jump from 90% to 100%, because it is a very easy target for my batteries to achieve. I just checked, the BMV would jump to 100% while I am halfway in absorb and sitting at a SOC of 93%, it would jump to 100%. 

7 minutes ago, Don said:

Victron assumes I sit with batteries that will require at least 2.5 amps when fully charged.

I've never really thought of this. Lithium batteries also charge right down to almost zero (very little current) and I know the BMV is used with the lower-end 12.8V batteries (not the higher end 24V ones that use the Lynx BMS). It would be odd to think they don't work as intended. Oh well... I generally prefer it if it gets there without syncing.

I would prefer it if the BMV had settings for it it to go all the way to 100%, without taking a 4% leap in the process. Unfortunately the settings does not allow that.

22 minutes ago, Don said:

Well Victron got it wrong, my batteries can go down to 0 amps

@Don just out of pure curiosity when you say your batts goes to 0 amps. Does this mean that your batts can not accept any more amps when charged or the bmv showing 0 amp , other words no amps going in or out of the batts? 

8 minutes ago, PaulF007 said:

Does this mean that your batts can not accept any more amps when charged

Yeah that's a little strange to me too. A lead acid will always accept some charge (even if milliamps) if you take it up to float voltage. Float-voltage is a "gassing" voltage, tiny bits of electrolyte is converted to hydrogen (and turned back into water in most sealed bats)... that is to say almost the entire float process after 100% SoC is simply wasted energy... but it is there.

Lithium is different, those really do go down to almost zero.

Are these your batts Don? http://www.bsbpower.com/pdf/BSB Solar Series.pdf - the 250ah BSB batteries?

13 minutes ago, PaulF007 said:

@Don just out of pure curiosity when you say your batts goes to 0 amps. Does this mean that your batts can not accept any more amps when charged or the bmv showing 0 amp , other words no amps going in or out of the batts? 

The charging amps go down to 0 amps. If you put one more amp into them, they would puke I think.

5 minutes ago, The Terrible Triplett said:

Are these your batts Don? http://www.bsbpower.com/pdf/BSB Solar Series.pdf - the 250ah BSB batteries?

Yes, those are my batteries. Blady Super Batteries (BSB) for short. 

1 minute ago, Don said:

The charging amps go down to 0 amps. If you put one more amp into them, they would puke I think

LOL all that acid ,, eish.

Looking at your graph do you charge the batts with the grid as well? I notice that the batts drop form almost 40a to 2a between 18hoo and 19hoo . Then there is no negative amps. So I can only assume that your batts is in flout all the time?

8 minutes ago, PaulF007 said:

Looking at your graph do you charge the batts with the grid as well? I notice that the batts drop form almost 40a to 2a between 18hoo and 19hoo . Then there is no negative amps. So I can only assume that your batts is in flout all the time?

This is a normal day for my batteries. They start working hard from about 8h30. My lowest SOC is just before the sun sets. I don't get to fully charge them with solar power, they work to hard. Their resting time is when the sun sets. I basically only charge them on grid. Then they cruise along from 23h00 or 24h00  until the next day, then I hammer them again.  

Here is another example. My batteries goes above 100 amps at least twice a day. Depending what I am busy doing, for the last week I have been welding and spraying with a large compressor, the inverters would go to grid 2-3 times a day because of excessive amps drawn from my batteries or excessive load when the compressor stars up. They charge for 5 hours, then they are ready for action again. At 21h00, my batteries are sitting below 1.0 amps 

My batteries were lying in a box for a year before I started using them. When I started logging my Charge efficiency in December 2016, they were siting at 90.5%. My batteries are improving daily, currently my charge efficiency is around about 91.4% and my Battery Midpoint = 0.01%.

Just now, Don said:

I basically only charge them on grid. 

Ok so your batteries is not exposed to a solar charge application but rather a grid charge application. Then the MPPT charge won't "really" apply to your batteries as you sort off use them as a "buffer" for high loads during day time and then charge them at night. That's almost as a car using a lot of amps from the battery to start and then gets recharged during the drive. .

1 hour ago, Don said:

then right at the end throws in a thing when you get to "solar battery applications", set the values as follows. That to me is just stupid. 

Considering that you don't really charge your batteries via solar may I suggest you review your statement as the setup being  "stupid"?

(All in good sport mr!!)

7 hours ago, PaulF007 said:

Considering that you don't really charge your batteries via solar may I suggest you review your statement as the setup being  "stupid"?

No, it stays a stupid comment, as charging a car battery, RV battery or solar battery, the settings remain the same. That happens when you have someone reading a script and have no idea what they are talking about. She explained it perfectly and until she started talking about solar applications, then she stuffed it up, because you don't get different settings for solar applications. They must call the guy that wrote the script to tell me how to set my settings depending whether I charge a car battery or a solar battery and I will prove him wrong. It is simple:

1.) The Charged Voltage need to be below the float voltage.

2.)The Tail current need to be above the current going into your batteries.

3.) Detection time - How long those values need to be true.

You cannot change the settings. There are not different setting for charging different types of batteries. There is also no different settings for charging from grid or for charging from solar.   

To prove it, I will charge my batteries to 100% on solar tomorrow morning, with exactly the same settings.

 

9 minutes ago, Don said:

To prove it, I will charge my batteries to 100% on solar, with the same settings.

Cool would be interesting if you run your batts "normal" , in other word use them at night so that the soc drops to whatever you prefer and then charge them to full on solar only in the day time. It might take a day or so to to get a full "normal" cycle. I love these types of data! 

PS. the word "normal" is used very cautiously as we still need to determine what is normal  .

12 hours ago, ebrsa said:

@Don  what I don't quite understand is that one would assume that charged voltage refers to absorption and not float voltage. The description in the manual is therefore somewhat confusing. Only solution would be to get advice from Victron I suppose. @Chris Hobson is the Outback charger you mentioned an MPPT charger. I have found a Ctek MXT 14 24V at Communica for about R7000 VAT included with an equalising voltage of 31.6V which is only 0.8V below the T105 voltage of 32.4V for a 24V bank. Perhaps I could equalise in banks of 24V if I disconnect from the Axperts. The specs look very good. Does anyone have experience of these chargers.

Hi Ed 

JIp it it is a MPPT charger. I have a Ctek 12V charger which I love but is is not sophisticated enough for equalising set whether you charging a bike battery or automotive battery and away you go.

13 minutes ago, PaulF007 said:

Cool would be interesting if you run your batts "normal" , in other word use them at night so that the soc drops to whatever you prefer and then charge them to full on solar only in the day time.

I see tomorrow we have a lot of clouds, but I will do it in any case. If I run on batteries from 24h00, my SOC when the solar kicks in, is about 88-89%. If I run on batteries from about 23h00, the SOC is closer to 83-85%. I will run on batteries from 23h00 tonight. I will use a bit more power tonight and hopefully I can get them down to 80% SOC.

Hi Don

Just a comment that actually deals with another post. If you are working you batteries so that their lowest SOC is early evening you not going to see the SCC voltage overshoot during the day as your large battery bank has space for the extra energy whilst your MPPT backs off due to variable load or sudden appearance of the sun from behind a cloud.

40 minutes ago, Chris Hobson said:

Just a comment that actually deals with another post. If you are working you batteries so that their lowest SOC is early evening you not going to see the SCC voltage overshoot during the day as your large battery bank has space for the extra energy whilst your MPPT backs off due to variable load or sudden appearance of the sun from behind a cloud.

I still see them once in a while, just over 60 Volts. Not lately however, but on the other hand I have not really been looking at it for a while.