Victron 712 Monitor Settings

[eric1514]

There was another thread on this subject but it ran off course so I'd like to start a new one.

I have 420Ah of batteries, a PD converter and a Victron 712 monitor. As Booster noted in this thread, https://www.classbforum.com/forums/f...ing-10753.html, the default settings are not very good. Over the course of a day I ran the batteries down 29Ah. The monitor showed the state of charge as 94%. Close.

I plugged in the van, forced the charger into boost mode and 30 minutes later I was only down 20Ah and at 95-95% SOC. Again, close. Then suddenly I was at 100%. What tripped it? The converter is still showing 12+ amps and falling, battery voltage is 13.99 and climbing and I still have roughly 2 hours to go in boost mode.

The batteries are not full, but I'm not sure what parameter I should change to get a more realistic reading. My settings are Charged Voltage=13.2, tail current 2%. Actually the default tail current is 4%. I changed it because that's where my Trimetric is set. But the Trimetric is also set for a charged voltage of 14.3. Any recommendations?

[booster]

Originally Posted by eric1514

There was another thread on this subject but it ran off course so I'd like to start a new one.

I have 420Ah of batteries, a PD converter and a Victron 712 monitor. As Booster noted in this thread, https://www.classbforum.com/forums/f...ing-10753.html, the default settings are not very good. Over the course of a day I ran the batteries down 29Ah. The monitor showed the state of charge as 94%. Close.

I plugged in the van, forced the charger into boost mode and 30 minutes later I was only down 20Ah and at 95-95% SOC. Again, close. Then suddenly I was at 100%. What tripped it? The converter is still showing 12+ amps and falling, battery voltage is 13.99 and climbing and I still have roughly 2 hours to go in boost mode.

The batteries are not full, but I'm not sure what parameter I should change to get a more realistic reading. My settings are Charged Voltage=13.2, tail current 2%. Actually the default tail current is 4%. I changed it because that's where my Trimetric is set. But the Trimetric is also set for a charged voltage of 14.3. Any recommendations?

I am assuming you have AGM batteries? if so, the setting that is generally too conservative is the tail current (return amps, ending amps, float transition amps).


The recommended setting for tail current will normally be in the .5 to 1%C for regular AGM and may be as low as .1%C for TPPL, so you need to see what the manufacturer of the batteries recommends.


What you are seeing on the Victron is that they appear to be resetting to 100% full on the up cycle of the charging, so while charging. As soon as it hits the tail current setting while at absorption voltage it resets to full. If the tail current is set too high it happens before the batteries are full. Trimetric and others don't reset until you start to discharge the batteries, but will light the fully charged light, which IMO is a better way to go because it allows you to see your overcharge amps hours in the amp hours in/out screen to see if they are in the ballpark (5-15% normally over used amp hours).


4% is way high for AGM batteries and will leave them quite undercharged, and even 2% will not get totally full.


I would check the manufacturer site for what the tail current should be for their batteries. Lifeline in .5%C for instance. Set that and set the absorption voltage to a bit under whatever your PD charger runs at in absorption (boost in PD terms IIRC). I think you will see hugely different results and charging from 30 AH down, which is really too small for a good test, should take a lot longer and use about 5-10% more AH than was used. Of course, because of the monitor settings, you probably were not full to start out so need to do a complete charge with correct settings first to know for sure. I like to go 50% down on charge for testing as it is an easy place to visualize and deep enough to see what is going on. With a small charger, PD is 45 or 60 amps?, it will take something in the 10-12 hours to charge to full with the good settings on AGMs, I think. You will probably need to force the PD back to boost 2 or 3 times during the process as I think it will only run 4 hours per reset before going to prefloat.

[eric1514]

Thanks, Booster.

The batteries are 6 volt Interstate GC2s. I have 4 for a total of 420Ah. Getting info for them is tough right now so in the mean time I can use Trojan T-105 specs.

1)Trojan says charging rate should be 10%-13% of total 20hr Ah capacity. I have 420 so my 45 amp charger is right there in the low-middle.

2)They say absorption voltage should be 14.7. I'm at 14.4, not even close, but I can't change that.

3)They say finish current should be 1%-3%.

So, if I take your advice, I should set my fully charged parameters at 14.3 volts and perhaps 1% tail current. That certainly make more sense than the defaults. I try that.

[booster]

Originally Posted by eric1514

Thanks, Booster.

The batteries are 6 volt Interstate GC2s. I have 4 for a total of 420Ah. Getting info for them is tough right now so in the mean time I can use Trojan T-105 specs.

1)Trojan says charging rate should be 10%-13% of total 20hr Ah capacity. I have 420 so my 45 amp charger is right there in the low-middle.

2)They say absorption voltage should be 14.7. I'm at 14.4, not even close, but I can't change that.

3)They say finish current should be 1%-3%.

So, if I take your advice, I should set my fully charged parameters at 14.3 volts and perhaps 1% tail current. That certainly make more sense than the defaults. I try that.

The T105s are wet cells so would have totally different charge parameters compared to AGMs. 14.4v vs 14.7v is not a big deal in most cases. If yours are wet cell GC2s, I would do a test to see what the tail current should be by setting the tail low, like the 1% you mention and going at boost voltage until it is not changing anymore. The set the tail a couple of tenths of an amp higher than that.

I think if you change to the settings your mentioned, you will be much better off and taking better care of the batteries, but if you have wet cells, the 1% will likely be a bit low. Wet cells are generally stated at 1-3% tail current, that changes with age to the higher, but the best I ever saw with our Trojans was about 1.2%. Thus the above test is a good idea.


Won't Interstate give you the information if you call them or the ask for the manager of the local store? If they won't, I find that pretty poor service, put very gently....

[eric1514]

Originally Posted by booster

The T105s are wet cells so would have totally different charge parameters compared to AGMs. 14.4v vs 14.7v is not a big deal in most cases. If yours are wet cell GC2s, I would do a test to see what the tail current should be by setting the tail low, like the 1% you mention and going at boost voltage until it is not changing anymore. The set the tail a couple of tenths of an amp higher than that.

I think if you change to the settings your mentioned, you will be much better off and taking better care of the batteries, but if you have wet cells, the 1% will likely be a bit low. Wet cells are generally stated at 1-3% tail current, that changes with age to the higher, but the best I ever saw with our Trojans was about 1.2%. Thus the above test is a good idea.


Won't Interstate give you the information if you call them or the ask for the manager of the local store? If they won't, I find that pretty poor service, put very gently....

My batteries are wet cells and it's too early in the morning to call Interstate. I'll try later today. In the meantime, I'll do the test you described.

Thanks again.

[eric1514]

As an aside, the batteries were in "normal" mode (PD lingo) all night with these numbers-13.64 volts and .12 amps showing on the Victron. I just forced it into Boost mode and the numbers are 14.41 and steady volts and 1.14 amps and falling. I think you're right. The parameters should be slightly lower than the 14.4 volts, say 14.3, and the tail charge should be 1.5 to 2%.

It's kinda funny that we're arriving at the same numbers that Bogart Engineering considers the starting point for their Trimetric.

[booster]

Originally Posted by eric1514

As an aside, the batteries were in "normal" mode (PD lingo) all night with these numbers-13.64 volts and .12 amps showing on the Victron. I just forced it into Boost mode and the numbers are 14.41 and steady volts and 1.14 amps and falling. I think you're right. The parameters should be slightly lower than the 14.4 volts, say 14.3, and the tail charge should be 1.5 to 2%.

It's kinda funny that we're arriving at the same numbers that Bogart Engineering considers the starting point for their Trimetric.

yep, Bogart knows their stuff, although they also have backed off on defaults because most chargers can't do the charging well enough. It is too bad the charger folks haven't improved things for wet and AGM charging, and now with all the emphasis on lithium, they probably never will.


Is the 1.14 amps at 14.41v a typo? That's less than you had at 13.6v.

[booster]

Originally Posted by eric1514

As an aside, the batteries were in "normal" mode (PD lingo) all night with these numbers-13.64 volts and .12 amps showing on the Victron. I just forced it into Boost mode and the numbers are 14.41 and steady volts and 1.14 amps and falling. I think you're right. The parameters should be slightly lower than the 14.4 volts, say 14.3, and the tail charge should be 1.5 to 2%.

It's kinda funny that we're arriving at the same numbers that Bogart Engineering considers the starting point for their Trimetric.

yep, Bogart knows their stuff, although they also have backed off on defaults because most chargers can't do the charging well enough. It is too bad the charger folks haven't improved things for wet and AGM charging, and now with all the emphasis on lithium, they probably never will.



I expect you will probably wind up at somewhere a bit under 7 amps if the batteries are in decent shape, after a the current tapers to near not changing any more. If that is the case, setting at 7 amps or so would be appropriate as it will vary a bit with temps and such.



If the 1.14 amps at 14.41v a typo? That's less than you had at 13.6v.

[eric1514]

Originally Posted by booster

yep, Bogart knows their stuff, although they also have backed off on defaults because most chargers can't do the charging well enough. It is too bad the charger folks haven't improved things for wet and AGM charging, and now with all the emphasis on lithium, they probably never will.



I expect you will probably wind up at somewhere a bit under 7 amps if the batteries are in decent shape, after a the current tapers to near not changing any more. If that is the case, setting at 7 amps or so would be appropriate as it will vary a bit with temps and such.



If the 1.14 amps at 14.41v a typo? That's less than you had at 13.6v.

No, that's not a typo. It started out at about where the readings were for 13.6v but instead of leveling off, it has steadily declined. I'm at .56a now.

When you say 7amps do you mean about 1.5-2% of the 420Ah I have?

[booster]

Originally Posted by eric1514

No, that's not a typo. It started out at about where the readings were for 13.6v but instead of leveling off, it has steadily declined. I'm at .56a now.

When you say 7amps do you mean about 1.5-2% of the 420Ah I have?

Yes that is what I mean. .56 amps is like .1% which is way low for wet cells. What shunt and settings do you have in the Victron?


What model # batteries are they?

[booster]

i dug around some and it appears that Interstate uses some non normal chemistry in at least some of the deep cycle batteries. They talk about 14.4v bulk and then 15.5v absorption, then 13.2v float. 15.6v equalizations. It is said to match what lead calcium batteries call out which may be what things like forklifts use.


Chargers that will charge that high are rare, and personally I would not put that much voltage on the coach or van electronics.


This may be as a way of trying to get better life in golf carts and such that get daily deep discharges and only have overnight to charge back to full and disulphate. The 14.7 volts Trojan gives is similar based on what they told me when talked to them a long time ago. The high voltage is better for deep recovery and to get done in time. For not deep every day stuff like RV, they list a normal charge profile at 14.4v. Total range given was 14.1-14.7v but they didn't like below 14.3v plus temp comp.


I couldn't find any tail current info, though which makes sense as they state bulk to 80% SOC at 14.4v then absorption at 15.5v to 95% and then float at 13.2v to 100%. I have no idea how you would ever control that cycle by the time you put charge efficiency and temp comp into it. And you would have to reset the monitor based on the float charge amps. Very weird compared to other batteries.

[eric1514]

Truthfully? I don't know what model Interstate batteries they are. They are what the local Costco is selling now for $89.99. I bought 4 of them last week.



I'm using the shunt that came with the Victron 712 Smart. All settings thus far are factory except for the 2 we've discussed. Now I have set the charged voltage at 14.3 and the tail current at 1.5%.

[eric1514]

Here are some numbers from a test I just performed. I ran the batteries down about 10% or 43Ah. Not a lot, but I'll do a longer test later. SOC was 90%. Trigger points on meter were 14.3v, 1.5% tail current and both for 3 min.

After 2 hours:
SOC was 98%
14.05v
11.27a
down 6.6Ah

After 2 hours 30 min
SOC was 99%
14.2v
7.05a
down 3.8Ah

After 2 hours 40 min
SOC was 100%
14.29v
4.31a
down 2.7Ah

After 2 hours 45 min
SOC was 100%
14.34v
2.93a
down 0.0Ah (it just suddenly jumped from -2.7 to 0)

After 3 hours
SOC was 100%
14.38v
1.69a
down 0.0ah

At around 4 hours the charger went into "normal" mode
SOC was 100%
13.64v
.19a
down 0.0 Ah

I expect it will remain there for 23 hours at which time it will drop the voltage to 13.2.

I'm OK with what it shows now. There's a few weird things but overall, I think I'm way closer than I was yesterday.

Thanks, Booster.

[booster]

Originally Posted by eric1514

Here are some numbers from a test I just performed. I ran the batteries down about 10% or 43Ah. Not a lot, but I'll do a longer test later. SOC was 90%. Trigger points on meter were 14.3v, 1.5% tail current and both for 3 min.

After 2 hours:
SOC was 98%
14.05v
11.27a
down 6.6Ah

After 2 hours 30 min
SOC was 99%
14.2v
7.05a
down 3.8Ah

After 2 hours 40 min
SOC was 100%
14.29v
4.31a
down 2.7Ah

After 2 hours 45 min
SOC was 100%
14.34v
2.93a
down 0.0Ah (it just suddenly jumped from -2.7 to 0)

After 3 hours
SOC was 100%
14.38v
1.69a
down 0.0ah

At around 4 hours the charger went into "normal" mode
SOC was 100%
13.64v
.19a
down 0.0 Ah

I expect it will remain there for 23 hours at which time it will drop the voltage to 13.2.

I'm OK with what it shows now. There's a few weird things but overall, I think I'm way closer than I was yesterday.

Thanks, Booster.

Do you have a charge efficiency programmed in to the Victron? You should expect to always see more amps back in than were taken out due to the inefficiency of charging. On a very low discharge like you had, you were in the very low charge efficiency range as it varies with SOC. At 10% down I would expect you could actually need to put in 20% more than you took out. That would put you needing to be about +8 AH on the counter to actually be full. That is the bummer on the Victron as it appears to reset to full and zero amp hours while charging, so you can't see your overcharge %.

[eric1514]

Charge efficiency is set at 95% and "Peukert exponent" is 1.25.

The Trimetric, in my opinion, is a better monitor. I went with the Victron because it is smaller and less industrial looking but more importantly, it has blue tooth. If the Trimetric had blue tooth I might have put up with it's antiquated looks knowing what I know now about the functional differences between the two. Oh well, it'll be OK. Besides, when I get home from travels, I always plug in and I would think, the Ah I'm short when the meter says full will be made up eventually while the RV sits on it's pad.

[booster]

Originally Posted by eric1514

Charge efficiency is set at 95% and "Peukert exponent" is 1.25.

The Trimetric, in my opinion, is a better monitor. I went with the Victron because it is smaller and less industrial looking but more importantly, it has blue tooth. If the Trimetric had blue tooth I might have put up with it's antiquated looks knowing what I know now about the functional differences between the two. Oh well, it'll be OK. Besides, when I get home from travels, I always plug in and I would think, the Ah I'm short when the meter says full will be made up eventually while the RV sits on it's pad.

My guess is that for a big battery bank like yours the charge efficiency may be a bit high because you will be in the inefficient slow charging range much of the time. Setting the efficiency may be your best way to get the best reset to 100% accuracy. You have wet cells so have the luxury of being to directly read SOC with a hydrometer, assuming the Interstate chemistry tests the same as other batteries. Just check the specific gravity when the meter resets and if it is not to fully charged state, lower the charge efficiency setting. The Victron is probably using the setting in the amp counting going up. If you put in a 100ah it would only show you put in 95ah.

Personally, I always leave Peukert at 1.0 on our monitors as I think that the whole idea of Peukert is misapplied to RV use patterns. Peukert is fine for knowing how long a battery will run a fixed load, but IMO, pretty much useless if your loads vary over the discharge period. This is particularly true if you use short bursts of large loads, like microwave runs.

Trimetric does have a Wifi model now, but not Bluetooth. I also think the Trimetric is a better monitor, but clunky. The newer model has one very big feature for solar users, though, in that the add on solar controller is controlled by the monitor amp hour counting settings so you can get perfect charging. Downside is that it is a PWM controller and not MPPT so a bit less efficient on higher voltage panels.

[eric1514]

Getting back to the charge efficiency setting just so I understand a little better, let's say I run my batteries down 43Ah but to bring them back to 100%, I need to replace not only the 43Ah but maybe 7 more for a total of 50 because, well because that's how batteries are. So a charge efficiency of 86% would accomplish that, right? 43 is 86% of 50. I'm not going to do that right now, I'm just trying to learn what the adjustment does.

[booster]

Originally Posted by eric1514

Getting back to the charge efficiency setting just so I understand a little better, let's say I run my batteries down 43Ah but to bring them back to 100%, I need to replace not only the 43Ah but maybe 7 more for a total of 50 because, well because that's how batteries are. So a charge efficiency of 86% would accomplish that, right? 43 is 86% of 50. I'm not going to do that right now, I'm just trying to learn what the adjustment does.

That is the basic premise for sure. The problem comes from the depth of discharge before recharging because the charge efficiency will change as the battery fills so the overall efficiency has to be an integrated calc of that curve, which is not an easy thing. In reality you will have a different overall charge efficiency for every cycle unless the cycles are identical. This is why you should never go be the AH recovered on a monitor because it will either be actual put into the battery or adjusted by whatever arbitrary charge efficiency is programmed into the monitor. All of this is the reason the good monitors and the battery manufacturers use the tail amps to determine if the batteries are full, as it is about the only way to know for sure, beyond the specific gravity for wet cells.


If the Victron is resetting to full 100% based on the charge efficiency modified amp hours returned, it is better than if they just went to 100% returned, but not a good as not resetting to 100% full until tail amps are reached and you start to discharge the batteries. At this point I don't think we can tell from your experience, but it might say how they do it somewhere deep in the manual for the monitor.



Our average off grid recharges off the solar are in the range of 40-70 amp hours each day and I let the Magnum charger with monitor do their automatic averaging of charge efficiency to set the efficiency. We usually come close to AH in, adjusted, matching the out, but never right on and if we get a deeper or shallower discharge we can be way off. I normally only look at the charging amps to get an idea how close to full we are, which is always repeatable for us.

[tgregg]

Originally Posted by booster

If the Victron is resetting to full 100% based on the charge efficiency modified amp hours returned, it is better than if they just went to 100% returned, but not a good as not resetting to 100% full until tail amps are reached and you start to discharge the batteries. At this point I don't think we can tell from your experience, but it might say how they do it somewhere deep in the manual for the monitor.

I have a Victron monitor and I believe it resets to fully charged based on satisfying tail amps AND charged voltage for time specified. So if the tail amps are set too high or the charged voltage is set too low it may reset prematurely.

I believe it uses charge efficiency to increase the indicated SOC during partial charges. So if the charge efficiency is set too high the indicated SOC may rise quicker than the actual charge of the batteries.

[booster]

Originally Posted by tgregg

I have a Victron monitor and I believe it resets to fully charged based on satisfying tail amps AND charged voltage for time specified. So if the tail amps are set too high or the charged voltage is set too low it may reset prematurely.

I believe it uses charge efficiency to increase the indicated SOC during partial charges. So if the charge efficiency is set too high the indicated SOC may rise quicker than the actual charge of the batteries.

It really should reset on tail amps and voltage, as that what matters. It was interesting though that appeared to reset when it 100% in the example given. The defaults in the Victron are way off and too conservative for good battery life at 4% and 13.2v. What we don't know is where they should be set for the Interstate that appears to want much higher charge voltages.


Normally, a monitor will not adjust amp hours out as such, just when charging. The setting actually reduces the amount added to what is in the battery compared to the AH put in. This makes it so the discharges, if discharge only, are accurate for what has been removed from the battery but when recharging, because charge efficiency is variable with SOC, the amp hour count may or may not be accurate at any given time. The more up and down cycles you run without getting full and generating a calibration synchronization, the further you will be off going up and down. If the charge efficiency happens to be spot on for any given recharge, the battery will be full and when it resets on tail amps and voltage, the amp hour counter will read zero. It rarely happens that way, though.



I just looked at the manual for the unit and it explains it all very, very poorly and seemed to imply that it adjusted it on the downcycle which would be odd. It also implied it adjusted the amp hours out based on the Peukert setting, which I think is a bad idea if you have variable loads.



For instance, if Peukert says that at 5 amps you will get and hour of run time out of the battery before it hits 10.5v which is the cutoff for rating capacity, but that if you use 10 amps you only get 20 minutes it would indicate that you got 5ah out of the first case and 4ah out of the battery in the second case before it hit 10.5v. Where did the missing ah go? Nowehere, IMO, as it is still in the battery. Peukert does not predict total energy out, only when the battery will get to 10.5v at any given load. If you let that battery sit and recover for an hour or two, the voltage would rise and you could discharge at 5 amps for another 12 minutes, using the missing ah, that was there all along.



In an RV, at least ours, we get lots of variable loads on the batteries, from 1.4 amps when nothing is on but the detectors and monitors to near 100 amps when the microwave is running. As long as the high drains aren't at the near end of capacity of the batteries, they both use the same amount of capacity as a direct calc will give you. Amps times volts time duration equals watt-hours of capacity used (better than amp hours as it takes into account battery voltage changes under loads and and SOC change).