Batteries died at 46%

[groetschel]

Hi group.
We took our airstream out for the first time after the full renovation.
We tried boondocking for two days but the batteries thwart the calculation :-(

Here is my setup:
4 dc house 100ah batteries
Me2012 2000w inverter
Victron smartshunk 500a

Because it is the first time out with this configuration I was quite paranoid and reviewed the victron smartshunk almost every 30 min :-)
We started first day at noon (100% charge)
Evening of the first day (96% charge)
Morning of second day (93%)
Noon of second day (83%)
Evening of second day
- we forgot to turn off the 12v water heater (74%)
- cooking food on induction cooktop, some tea and some heater action going on (55%)
At 9:30 pm voltage went to 9.5v, I checked the victron smartshunk and it showed 46%. A minute later everything was dead…
Why? The smartshunk showed 46%…
I don’t get it.
Thanks for any advice or feedback.
Regards
Gunnar

[Rolind]

Are you sure your batteries were fully charged when you began boondocking?
I think the smart shunt will automatically assume 100% charge if the power to the shunt is disconnected which may have happened during your renovation. Once you fully charge the batteries ,it will then begin reading correctly
A state of charge reading of 46% should have a higher voltage than 9.5v if not powering anything on the dc side.
The other possibility is that your batteries need to be replaced.
I would hook up to shore power and make sure your batteries are fully charged, ie very little current going into the batteries and then remove shore power and follow battery voltage vs state of charge reading on the shunt and see if the readings match up to to a SOC table for your battery type. Battery voltage readings are not reliable to determine SOC while there is a significant draw on the batteries. Once the draw is removed for an hour or so, the SOC and battery voltages should be close to the manufacturers table values,
Hope this helps!

[groetschel]

Thanks for your response. The batteries were fully charged. We were connected to shore power for a few days before.
I think what you suggest makes perfect sense and it is a great idea. I will do this when I am back home.
Regards
Gunnar

[ITSNO60]

The Smart Shunt cannot figure out the charge level, it only counts and keeps track of watts. It needs to be told the total watts the batteries hold and it needs to be told when the batteries are full. From that point it will keep track of watts in and watts out and let you know where you are at. If it starts with erroneous numbers it will be inaccurate.

As Rolind said, first make sure the batteries are 100% charged. If the shunt doesn't say 100% but they are fully charged it can be synched.

The other problem that can happen is circuits that did not get wired through the shunt. Everything must be wired through the shunt, if there is anything that bypasses the shunt it won't see the watts used (or watts added if it's a charge circuit like solar) and it won't be accurate. Watts can escape and the shunt doesn't see them, so it says you have more than you really do.

There is also a setting in the Victron app that you can set to remember the last charge level when disconnecting/reconnecting or you can set it to sync to 100% after a disconnect/reconnect. (The setting that automatically syncs to 100% is intended for applications like boats where the batteries are regularly removed for charging and re-installed fully charged)

[3OnOurWay]

There is a setting on smart shunt to have it reset and learn power or hold last power. One idea.

You mentioned:
4 dc house 100ah batteries

What type of battery do you have ?
I’m guessing if it registered 9.5 v dc not lithium?
If not lithium your usage would be about 50 when batteries have given all there useful life

[Wazbro]

You say 4 100AH batteries what kind? and how are they wired?
There is a thread about killing lithium batteries because they weren't wired properly, though that took a year to happen. Depending on how they are wired you might have a bad connection and not getting power from 2 of the batteries.

[groetschel]

Brand new lifepo4 batteries… connected in series to create a 12v battery bank with 400Ah.

[groetschel]

Originally Posted by ITSNO60

The Smart Shunt cannot figure out the charge level, it only counts and keeps track of watts. It needs to be told the total watts the batteries hold and it needs to be told when the batteries are full. From that point it will keep track of watts in and watts out and let you know where you are at. If it starts with erroneous numbers it will be inaccurate.

As Rolind said, first make sure the batteries are 100% charged. If the shunt doesn't say 100% but they are fully charged it can be synched.

The other problem that can happen is circuits that did not get wired through the shunt. Everything must be wired through the shunt, if there is anything that bypasses the shunt it won't see the watts used (or watts added if it's a charge circuit like solar) and it won't be accurate. Watts can escape and the shunt doesn't see them, so it says you have more than you really do.

There is also a setting in the Victron app that you can set to remember the last charge level when disconnecting/reconnecting or you can set it to sync to 100% after a disconnect/reconnect. (The setting that automatically syncs to 100% is intended for applications like boats where the batteries are regularly removed for charging and re-installed fully charged)

Thank you very much. Good input… I will review the setup keeping your input in mind.

[3OnOurWay]

Good luck, an idea is to make sure all 4 batteries are connected and fuses etc have continuity.

[DKB_SATX]

Each individual one of your batteries is what, a 3V battery for a 12v series?
Or you have 4 6v batteries in a series/parallel combo?
Or you have 4 12v batteries in parallel?

While I AM being a little pedantic, it makes a difference. 4x 3v 100ah batteries in series would get you 100ah at 12v. 4x 100ah 6V batteries in series/parallel will get you 200ah at 12v, and 4x 100ah 12v batteries in parallel will get you 400ah at 12v.

I'm not really a betting man, but I'd bet you have a combination of 2 issues. With 4 brand-new lithium batteries, you may not have started out at really-really 100% state of charge, and I'd guess the smart-shunt hadn't fully "learned" your new battery array either.

Another possibility based on reports I've read on the Forums is that, depending on exactly how you have the batteries connected, possibly just one of the batteries had an issue and its BMS shut it down, but that took out the the whole array because there was an open circuit at that point. I think that's why people use bus-bars with these batteries.

How many amp-hours did the Victron tell you had passed through the shunt by the time the batteries shut down?

[uncle_bob]

Hi

Since the batteries are brand new, did the trailer have lead acids before they went in?

Are they lithiums or lead acid? I'm assuming they are lithium. If they are lead acid, 50% on the smart shunt is the "stop using / they are empty" point.

If this is a new lithium conversion:

1) The charger needs to be reprogrammed for lithium. Lead acid settings will not work.

2) The smart shunt needs to be reprogrammed for lithium. Again, the lead acid settings will not work properly. (It also needs to be correctly installed).

3) If you have solar, that also needs to be adapted for lithium. This is only a big deal if you want to get the most out of your solar setup.

4) The charge wire on the 7 pin connector needs to be addressed.

There are lots and lots of threads that dive into each of these items. The only point here is : did they get addressed?

As noted in several posts above, the Smart Shunt can only do just so much. At 9.5V your batteries are most certainly dead.

They should get to above 14.4 V when charging and stay there for at least 30 minutes (hopefully longer ...). On a properly programmed Smart Shunt, it sees this and "resets to full". If it's set for lead acid, it resets at a much lower voltage.

After charge, your batteries should "rest" at above 13.5V. If the shut thinks they are "full" and you are at 13.0V ... you need to go back into the Victron App and check the settings on the shunt. One or more of those settings is wrong.

Based on the info I can see on the web, the ME2012 cannot do what's needed in point 1 above. It came out before folks really got into lithiums. It is a "lead acid only" device. Is there a later model? Maybe. If so the manufacturer's web site does not seem to know about it. Simply put: It's not going to charge your batteries to "full".

Bob

[SunchaserV]

Some great observations here. I take it the OP does not have a portable genset. Having spent decades on the water and sometimes days from shore power, battery issues are nicely supported by a standby genset.

[Wazbro]

If your batteries are 12v each they must be connected in parallel and power to system needs to connect positive to battery on one end and negative to battery on other end like this picture or all positives to a terminal block with same length wires and all negatives connected to another terminal block with same length wires.
All loads must go through the shunt.
Your charger must be set to properly charge lithium batteries or it will only charge the batteries to 55-80%.

[billrector]

Originally Posted by groetschel

Brand new lifepo4 batteries… connected in series to create a 12v battery bank with 400Ah.

Hopefully, you mean parallel. Series would give you 48v and only 100 ah.

[Vlamgat]

Originally Posted by 3OnOurWay

There is a setting on smart shunt to have it reset and learn power or hold last power. One idea.

You mentioned:
4 dc house 100ah batteries

What type of battery do you have ?
I’m guessing if it registered 9.5 v dc not lithium?
If not lithium your usage would be about 50 when batteries have given all there useful life

This is correct and something that escapes most users. Lead/Acid whether or not AGMs do not function below 50% with any load. And every time they are discharged to that level they are damaged and/or sulphated and their ability to hold charge is reduced. Also the discharge rate increases as the S0C decreases so a Victron stating 75% after 3 hours of a specific usage profile at a specific ambient temperature will not last another 3 hours before hitting 50% but possibly as little as half that amount of time depending on how many time the discharge has been taken below 50%.

I service aircraft batteries and the above is based on my training by Gill and Concorde that make AGM cells and batteries for aircraft. Their construction uses better quality than the sh1t that we purchase as consumers (no recycled lead for one thing) but otherwise its the same battery with a lot of CCC for their size and weight.

[JohnTF]

If you were reading the monitoring system every 30 mins , then you should be giving us the watts consumed ?
With a bunch of heating items being used ?
It is possible [ without having all the data ] you just used 54% capacity ?
Do you have any kind of charging , besides shore power ?

To live off batteries , the 2 worst uses are heating & motors .

[groetschel]

Originally Posted by DKB_SATX

Each individual one of your batteries is what, a 3V battery for a 12v series?
Or you have 4 6v batteries in a series/parallel combo?
Or you have 4 12v batteries in parallel?

While I AM being a little pedantic, it makes a difference. 4x 3v 100ah batteries in series would get you 100ah at 12v. 4x 100ah 6V batteries in series/parallel will get you 200ah at 12v, and 4x 100ah 12v batteries in parallel will get you 400ah at 12v.

I'm not really a betting man, but I'd bet you have a combination of 2 issues. With 4 brand-new lithium batteries, you may not have started out at really-really 100% state of charge, and I'd guess the smart-shunt hadn't fully "learned" your new battery array either.

Another possibility based on reports I've read on the Forums is that, depending on exactly how you have the batteries connected, possibly just one of the batteries had an issue and its BMS shut it down, but that took out the the whole array because there was an open circuit at that point. I think that's why people use bus-bars with these batteries.

How many amp-hours did the Victron tell you had passed through the shunt by the time the batteries shut down?

You guys are awesome… I think we found the problem. Neither my inverter nor my solar charge controller are made for lithium batteries. This makes it impossible to know the charge level. I will buy a new charger/inverter and solar charger. Fuel up the batteries and test again. Thanks for your valuable insights!

[uncle_bob]

Originally Posted by groetschel

You guys are awesome… I think we found the problem. Neither my inverter nor my solar charge controller are made for lithium batteries. This makes it impossible to know the charge level. I will buy a new charger/inverter and solar charger. Fuel up the batteries and test again. Thanks for your valuable insights!

Hi

If you are headed out to "buy stuff", the hybrid inverter / charger comes first. I would suggest that something better than the Magnum might be a good idea. Victron is one option, Xantrex is another.

For the solar, Victron is pretty much the "go to" source. They make a *lot* of versions. The ones with built in Bluetooth are a really good idea. That way you can use their app to monitor things.

If you plan to go even more crazy with fixing things up, an "all Victron" approach would let you network things together. No, that's not something you *must* do. It's very much an optional part of this.

If you do not already have a DC/DC converter, either you need to get one or you need to disconnect the charge wire from the 7 pin adapter. Your TV cannot deal with lithium's directly. You either need to break the circuit between them (disconnect the wire / no more charging from the TV) or put in a DC/DC. Again, Victron is a "go to" source. Again, one of the programmable versions with Bluetooth is a really good idea.

One other caution: It's best to get this stuff from somebody local. That makes the "see it before you buy it " process possible. If that's not practical then the next choice would be somebody (in country) that you can talk to on the phone / who knows the stuff they are selling. Last choice is some random dude on Amazon with no apparent support for the products ....

I tend to buy from an outfit that is about 3 hours away. That's not a quick drive, but it is doable. It would be a bit more of a drive from Calgary .

Fun !!!

Bob

[DCPAS]

Originally Posted by uncle_bob

If you do not already have a DC/DC converter, either you need to get one or you need to disconnect the charge wire from the 7 pin adapter. Your TV cannot deal with lithium's directly. You either need to break the circuit between them (disconnect the wire / no more charging from the TV) or put in a DC/DC.

Bob: You can correct me if I'm wrong. One of the cool things you can do with a bluetooth equipped batter is look at the charge going to the batteries. I left my 7 pin charge win connected. The highest charge rate I have seen while driving was 3.3 amps. I am not seeing how cutting off a charge in this amount is going to do much to my alternator. Thus far, it seems to have no ill effect.

[uncle_bob]

Originally Posted by DCPAS

Bob: You can correct me if I'm wrong. One of the cool things you can do with a bluetooth equipped batter is look at the charge going to the batteries. I left my 7 pin charge win connected. The highest charge rate I have seen while driving was 3.3 amps. I am not seeing how cutting off a charge in this amount is going to do much to my alternator. Thus far, it seems to have no ill effect.

Hi

There is zero chance of ever damaging an alternator with 7 pin charging. That simply is not now and never has been a problem. It is not why this is an issue. The various videos you see taking about alternator issues are *not* talking about the setup we have here. Not even close.

Why do you see those videos? They are dramatic and alarming. They get you worried. All this makes for lots of views. The fact that they are (in this case) totally wrong, has no impact on that. Exciting always wins.

So:

What is the issue?

1) The lithium battery needs a higher voltage to charge than a lead acid does. Your TV electrical system simply is not set up for lithium voltages.

2) The wire running from your TV battery all the way back to the trailer has resistance. Running lithium *or* lead acid (yes, either one) this results in very modest charge currents.

--- so --

You aren't getting any benefit from that 7 pin charge wire.

But:

Since the lithium is higher voltage than the TV ... hmmm ... You could be *discharging* the trailer into the truck. Net would be less charge on the trailer batteries than when you started your journey. That's not a good thing.

Also since the lithium is a higher voltage, you just might muck up the trucks electrical system. No, this isn't common. Might it happen? Who knows.

Bottom line:

Since there is no advantage to having the wire connected (it does not charge) and some disadvantages (blowing out that controller on the truck that costs $500 to replace ...), you just pull the wire.

Alternate:

(this is true with either lead acid or lithium)

Put in a DC/DC converter and get some real charge current into the batteries while you are driving down the road. With modern compressor fridges, this is a *really* good idea.

Make sense?

Bob