Battery question 2018 T@B 400 with solar

Deb55 · October 2022

We have a 2018 T@B 400 with 2 6-volt AGM batteries, a 190 watt solar panel on the roof, and a Victron battery monitor. We brought it for service a week ago and picked it up today. Unfortunately, I didn't think to turn off the battery at the cutoff switch, and the battery was quite run down. With a full day of sun and driving, the monitor now reads 11.5, but at the same time reads 100% SOC. I admit that I don't understand this. 11.5 is, to my understanding, clearly not 100%, so we're boondock camping with out using battery currently. What's going on here? I've already tried turning off the battery switch and turning it on again after resting it for a half hour, but it still said 11.5 and 100% charged.

pthomas745 · October 2022

Show us a picture of your Victron controller if you can. Did you take a look at the Victron when you had the battery switch turned off? That would have given you a "rested" battery reading, which would be more accurate than the reading you are getting in the trailer now, with the switch on and items running in the trailer. (What is running in the trailer?)

If you have time: turn everything off in the trailer, and turn off the battery switch. Wait a few minutes and then have a look at the Victron and see what the voltage readout is.

Deb55 · October 2022

Everything is off in the trailer except for the heat, which is on propane (but I guess uses a small amount of battery). The monitor reads 11.51. It's kinda cold and very windy, so I don't think I'll go outside right now to turn off the battery again, but I've done that several times and the Victron shows a range of about 11.49 - 11.7. It also says 100%SOC, which puzzles me. Is it OK, or low? I know 11.51 is very low, and I don't expect it to say 100% charged-- more like 30%. I usually feel pretty confident about my victron battery monitor readings, but not today!

Deb55 · October 2022

pthomas745 · October 2022

This is the smart shunt, which I missed on your original post. The "Consumed Ah row" is showing 0 amp hours used, so something has obviously gone wrong here. It is also showing some sort of power coming in...and it is obviously dark, it would seem to me. So...something has gone wrong here, and until you can get a good look at the battery connections and the connections at the shunt, it will be hard to figure out. Sounds like you have a lot of experience with the Victron...but I don't see how you can trust most of these numbers at this point. If the Victron persists at showing the Current and Power numbers, it may be you need to reset the Victron controller and start over.

The Alde...will keep working until the Alde senses the battery is down to 10.8 volts I know this is not much consolation, but if the Alde works for another hour or so and then shuts down due to low voltage...that means the Victron voltage is correct. If your Alde makes it through the night..then the Victron needs to be looked at.

What service did you have done? Did it involve anything electrical?

Deb55 · October 2022

We had bearings repacked, new tires installed, and the Alde fluid exchanged. Nothing electrical.

Deb55 · October 2022

How would I reset the monitor? Thanks...

pthomas745 · October 2022

Except for pulling the power wire from the Shunt, I honestly don't know.

Another thing: this morning my Android phone had a group of updates, and the Victron Connect app was at the top of the list. The update was released Oct 13.

Sharon_is_SAM · October 2022

@Deb55 - I recently helped a TaB 320 owner with this same problem. His battery had been depleted several times, then he got the Victron battery monitor. It kept coming up with a lower voltage that did not correlate to the high SOC %. I read somewhere that is an indication of an unhealthy battery. He would recharge fully, resync and it would start all over again.

Deb55 · October 2022

@pthomas745 I checked, and the version of Victron Connect that I'm using is up to date, so it's not that.

@Sharon_is_SAM the batteries are original 2018, so I guess they could be nearing the end. We've only let them run lower than is healthy twice, though, and we don't get out all that often. I'll try to plug in on Monday when we're back home and see if they fully charge. Until then, we're stuck with whatever the sun will give us!

Thanks!

pthomas745 · October 2022

@Deb55 this is the perfect situation for a multimeter. The Victrons and the Apps and all the stuff we love about them are only as good as what they are attached to. If the battery is failing, the Victron won't tell us explicitly, so an actual hands on test with a meter will be the fallback.

I'm curious if your Alde kept working all night!

DenisP · October 2022

@deb55 our battery(s) on our 2018 400 failed while on a long trip this spring. Our BMV alarmed overnight with low voltage while boondocking. We were on a 42 day cross country trip which we had both electric and non-electric sites. Once diagnosed with NuCamp’s help, I replaced the 2-6v batteries with BattleBorn heated batteries. I replaced one while on the road and finished the installation once I got home. Our tabs are the same age and probably the same battery lot.

Deb55 · October 2022

@pthomas745 our Alde worked like a champ all night! Right now we're on the road, and the battery has charged back up to 12.41 (from a low this morning of 11.16). I know that's not enough for lights tonight, but it's better than nothing. We'll be home tomorrow so I can plug in.

Deb55 · October 2022

@DenisP we might need to replace the batteries. We don't do anywhere near as much traveling as you, but, our campers are the same age and this was a pretty serious discharge. I don't know if we'll go with lithium because we're thinking of selling in a year or two to get a slightly larger camper. We find the 400 tight quarters with a dog sharing the space--plus we'd like bigger tanks.

Denny16 · October 2022

Replacing the old batteries with lithium, would be an added sale feature when you are ready to sell it on. The 2018 batteries are nearing end of life. Ours Jan 2018 had the last single 200 amp hr. AGM factory install, the following month, nüCamp went to two 100 amp hr AGM batteries. The single AGM failed two years ago, and was replaced by an Interstate 200 mp hr AGM. It fit in the original battery space. Next time round, we are converting to Lithium.

Cheers

DenisP · October 2022

@Deb55 our decision to bite the bullet and go with lithium was multi factorial. We plan on keeping the 400 for the foreseeable future, we were 2000 miles from home and could arrange for the batteries to meet us in Moab. The AGMs lasted four years which was ok but with several long future trips planned, I decided on the long term benefit outweighing the huge upfront cost.

In your case, I would also be reluctant to spend the $$$ on lithium.

Denny16 · October 2022

The 100 amp hr Battleborn Lithium batteries are now around $900, other brands are available for less.
Cheers

pthomas745 · October 2022

@Deb55 There are many options on Lithiums that sell for well under the Battleborn price, and have very good reviews. Many of these batteries, despite the hype....are mostly the same. (Even the Battleborn prices have dropped in the last year.) Will Prowse reviews many batteries, and he has recommendations in several price points, and his video reviews will show you what you are buying. "In the long run...." lithiums are quite worth it. Owners here have the Battleborns, the SOK's, and the AmpereTime. Each one can fill a different price point, and have good reviews. ( I have an AmpereTime.)

https://www.mobile-solarpower.com/lithium-batteries.html

Your 12.41 charge (as long as it holds when you get parked and "rested" of course!) is a fairly good state of charge. If the Alde worked all night, and didn't stop when it hit the "10.5 volts" lower limit, it would seem your batteries might have a bit of life left. A state of charge chart would show a 12.41 to be about 80 percent.

Image: https://us.v-cdn.net/5021717/uploads/editor/5w/5l90of3epmtk.jpg

Deb55 · October 2022

Now that we've been home for a few days, I've fully charged the 2 6-volt AGM with shore power and solar. I then unplugged the shore power and turned off the battery. When the sun is fully out, the charge reads 13.89. When the sun goes down, it drops. Last night it went to 13.11 overnight. I realize that's still a good 100%charged battery, but does that drop point to batteries that are aging out?

pthomas745 · October 2022

No, that "voltage going down" like that is perfectly normal. The number you are seeing with the sun out, and some solar charging going into the battery (the 13.89v number)...is only showing what is going to the battery, not the actual state of charge. Sun goes down...no charging going to the battery, the battery settles down. If you plug your trailer into shore power, and look at the voltage reading, it would read only whatever the WFCO converter is sending to the battery. Any voltage reading with charging going to the trailer is a "false capacity" reading

With the battery switch off and the sun down, that 13.11 voltage reading is reasonably accurate. If you want to see if the battery will hold that charge level, you might try to turn off the solar charging through the App ( on the settings page) and see how the batteries react. Over 24 hours the battery voltage might settle a bit lower, but if you see the voltage slipping into the 80 or 90 percent range in only a few days, that might indicate a "fading" battery. My old, retired 2016 original battery will show 12.6 after charging, but in just a few days slips down to about 12.46. It will hold that charge for a long time, but it indicates for me an older battery that has a reduced capacity. Still works, but I've lost some amp hours from it.

You also have the shunt, which is counting your actual amp hour use. When you saw the 13.11 number, did you note the "Consumed AH" number?

Deb55 · October 2022

@pthomas745 the consumed reading is 0, and has been for this whole week. I haven't actually used the camper without it being plugged into shore power, and that was to run the pump for winterizing. I'm not sure if this indicates a problem.

pthomas745 · October 2022

You have a big set of batteries. The small amount of pump usage probably didn't even add up to an amp.

You could: turn the solar charger off. Turn the battery switch on for some set period of time, say, 12 hours. Even with nothing on in the trailer, the "parasitic" drains will take out some amps (I know there are commenters who have measured the parasitic drain for the 400.) You could probably use 13 ah before your battery voltage would indicate "90 percent" on that voltage chart above.

Deb55 · October 2022

UPDATE: we are currently mooch docking with our now winterized camper. The battery and the smart shunt seem to be working as they should. I fully charged the battery at home on shore power, then at night, unplugged with no solar coming in, resynchronized the Victron monitor. We now have heat going, the refrigerator on, watched about an hour of a DVD, and used a minimal amount of lights. The battery reads above 12.5 while the fridge is cycling on, 12.74 without the fridge or heat cycling on, and state of charge says 97%. Consumed amp hours reading is also a number other than 0. I think I'm probably getting correct readings at this point. I also still suspect that the 5 year old AGM batteries might need replacement by next camping season.

Dutch061 · October 2022

The reason the SOC resets to 100% when the voltage is so low is because it is not configured properly. This is a common issue due to the "auto sensing" voltage set up in the BMV-712. If you do not change the default settings, it will never be correct.

There are 4 main things that need to be properly configured to prevent this from happening.

Battery capacity - matches the Ah of your battery bank (Harris AGM is 224 Ah)
Charged voltage - Victron suggests that is set to the "Absorption voltage level - which is 13.6 volts", but I set mine to 14.2 with AGM
Tail current - Minimum setting is .5%, which is where I had mine set
Charged detection time - default is 3 minutes, I suggest 5 minutes.

The SOC is reset to 100% when the following conditions are met.

When the Charged voltage reaches the level specified with a charge current that is less than the Tail current setting for the amount of time specified in the Charged detection time setting.

So, using the numbers that I used, the voltage has to reach 14.2 (or higher) with a Tail current of less than .5% (.005 x 224 = 1.12 Amps) for a period of at least 5 minutes. When those 3 things are met, that is when the SOC resets.

I think the defaults are as follows

Charged voltage - 13.2
Tail current - 4% (which is 8.96 Amps)
Charged detection time - 3 minutes

Using these settings and the same logic statement I listed above; you can easily see why the SOC resets to 100% long before the battery is 100% SOC. I had this issue early on with the BMV-712

Victron has some of the best (if not the best) stuff in the market, but their USA support is less than good.

Hope this sheds some light for all you "Tabbers and Victron users". As I mentioned before; I am going to miss this forum and the people on it but since I am no longer (okay in 10 days) a TAB owner, there isn't a reason to lurk

Brad

Sharon_is_SAM · October 2022

@Dutch061 - going to miss your Victron expertise! Thanks!

@Deb55 - it took me a while to understand the nuances of the BMV. As much as we want a “plug and play”, we do need to understand that the equipment needs to be tweaked from time to time. I have had residual current that was stuck on the monitor that required a reset. The Tail current concept is important. As Dutch61 noted, the Tail current (positive amp value) is one of the things that tells the BMV that you have reached your charging goal and the monitor can label the Charged voltage as 100%. This value and the Charged detection value can be impacted by changing cloud coverage - a cloud shades the panel, drops the Amps and if the time value is too brief, it will prematurely call it 100%. I read some marine articles that were very helpful in understanding the settings.

DenisP · October 2022

@Deb55 A bit more detail on the signs of failure of our AGMs. We left on our trip and the batteries were showing full charge and at our second stop a boondock cool rainy night the BMV alarmed low voltage around 2am.The refrigerator was sounding differently, cycling frequently and not a full cycle. We travelled to our next 5 stops had electric hookups and the battery voltage was normal. The refrigerator continued sound off but the temps were within normal limits. I called NuCamp from the road and they suggested the battery was the issue.

Long story short, once the battery was replaced, the refrigerator was rebooted and it has been normal ever since. As noted in the forum the Alde and the refrigerators are sensitive to low voltage.

Denny16 · October 2022

Yes, the Alde and fridge, are 12VDC devices, and do not like voltages below 11.8 or so volts.
Cheers

BrianZ · November 2022

I'd like to echo @Sharon_is_SAM's thanks to you, @Dutch061. I too will miss your depth of knowledge, Brad, in all things electronic within our T@B, including your latest suggestion about the Victron battery monitor settings.

I found the following section on synchronizing in my Victron manual, which also explains tail current..

There was also this section on measures to deal with fluctuating charge currents in solar systems, as Brad explained..

I reviewed our settings and then made the following changes to ours, from the previous settings which I've noted below in red..

As Brad suggested, I've increased the "charged voltage" and "detection time", and decreased the "tail current" & "efficiency factor".

Of course, my next consideration was "Is this going to work for us?", both for normal usage with charging either from an external smart charger & with the converter/charger, as well as while using our solar panel. Some additional testing will need to be done, but we probably only use our solar about once a year, so that test may take a while. However, I can share the results of my first test using our NOCO genius 7200 charger, as well as why I also changed the Peukert setting - more on that below.

First, in order to run the battery down so I could test the typical kind of charging that I might do, I simply disconnected shore power and turned on our fridge using 12V power. After about 5-1/2 hrs, it took our 150AH battery down to 70% state of charge, which seemed like enough for a good charging test (so, the 12V mode on the frig is good for something afterall!)..

That also tested the low battery alarm that I had set up in the settings.

Below is a graph of the entire charging cycle that was automatically captured by the Victron monitor, and which I was viewing the next morning after it finished..

In order to view this in my phone app, I had to select to display both Volts & Amps, then pinch the screen with 2 fingers multiple times to shrink the time-line to fit the whole 12 hour cycle on the screen. Then, I could clearly see what was going on. At the end of the cycle, I could see the top point on the voltage graph was at 14.3V, and by expanding the graph I could see that the previous point was at 14.2V and that they were 5 min apart on the time-line, exactly what my changed settings defined as the end point for charging! Meanwhile, the tail current was also low enough to meet the end point setting. So, this test of the settings worked exactly as it should. Nice when things work!

About the Peukert setting that I changed.. When discharging the battery for the test, I noticed when it got down to 78% charge, the voltage was very close to exactly 12.50..

I recalled that my battery spec sheet showed that 80% charge was equal to 12.50V, plus I knew from previous experiments that the Peukert setting directly affects the displayed state of charge percentage. So, when the charge dropped to 12.50V I increased the Peukert setting from 1.12 to 1.16, where it gave a reading of 80% state of charge..

Then I continued the discharge to 70% for the charging test.

And finally, after recharging the battery and letting it sit isolated for 24 hours, it showed the following charge level, looking like a fully charged battery..

I consider these new settings a successful verification of the charging parameters. I'll still need to see how it performs using solar, or with the converter.

Thanks again to Brad, and also @Sharon_is_SAM for your insights on this issue.

Deb55 · November 2022

@BrianZ thanks for posting all your work, and settings. I admit to not really understanding it, but I made some changes to my victron shunt settings based on your post. I now have the following settings for my 6 volt Harris AGM batteries with a 190 watt solar panel on the roof :

224
14.2
50%
2.0%
5 min
1.16
90%
.10 amps
3 min

Is this what I should use for my settings to get a correct reading?

Right now, my camper is plugged into shore power and the battery switch is on, so I assume I'm fully charged. Should I do anything else or change any of those settings? This is a bit beyond my technical knowledge, but I'm obsessive enough to want to know what my correct SOC is when we're on a trip. Thanks!

Denny16 · November 2022

Deb, if you are not using the trailer’s DC systems whilst it is plugged in at home/storage, you should turn off the battery switch once the Battery is completely charged. Leaving the battery connected long term to the WFCO charger can overcharge the battery, over a extended period of time.
Cheers

pthomas745 · November 2022

@Deb55 look up in the thread and find that "State of Charge" chart. If you can rest your battery for a few minutes, it will get you a pretty good idea of your state of charge.

As noted up in the thread, your Smart Shunt counts the amps going in and out of the battery, and is a much better representation of your "status" in how much power you have left.

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