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Just 'discovered' this thread, so uncertain where you stand. But . . .

So many comments about multimeters with virtually no discussion of the powerful tool for monitoring batteries - - the Victron shunt-based (a Victron 712?) you have. We see the shunt on the wall, but there's no RJ cable connected! Why? For us, this is the starting point. Not only does this instrument provide accurate (after calibration) State of Charge information, but it provides instantaneous insight into the current into, or out of, the battery pack. You say you have a solar charger, a B to B charger . . . well, the Victron will confirm that these 'chargers' are actually charging. The Victron will reveal how much current is being consumed when you run your inverter and cooktop. It will also alert you to unexpected loads. Seems you're finding your batteries discharged . . . why? The Victron is you best tool for detecting unexpected problems. Also, set the multimeter aside, the Victron includes a good voltmeter (for actual battery voltage).

Incidentally, we would relocate the shunt much closer to the negative terminal of the battery. By doing this you will be avoiding the voltage drop (during high charge/discharge currents) of that long negative wire from the battery to the shunt which, in turn, will make the Victron's voltage measurements more accurate.
 

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Just 'discovered' this thread, so uncertain where you stand. But . . .

So many comments about multimeters with virtually no discussion of the powerful tool for monitoring batteries - - the Victron shunt-based (a Victron 712?) you have. We see the shunt on the wall, but there's no RJ cable connected! Why? For us, this is the starting point. Not only does this instrument provide accurate (after calibration) State of Charge information, but it provides instantaneous insight into the current into, or out of, the battery pack. You say you have a solar charger, a B to B charger . . . well, the Victron will confirm that these 'chargers' are actually charging. The Victron will reveal how much current is being consumed when you run your inverter and cooktop. It will also alert you to unexpected loads. Seems you're finding your batteries discharged . . . why? The Victron is you best tool for detecting unexpected problems. Also, set the multimeter aside, the Victron includes a good voltmeter (for actual battery voltage).

Incidentally, would would relocate the shunt much closer to the negative terminal of the battery. By doing this you will be avoiding the voltage drop (during high charge/discharge currents) of that long negative wire from the battery to the shunt which, in turn, will make the Victron's voltage measurements more accurate.
I agree with you & love my Victron BM712

I did see an RJ connected in one photo - so not sure,,,

Networking cables Electrical wiring Bicycle handlebar Circuit component Line
 

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Just 'discovered' this thread, so uncertain where you stand. But . . .

So many comments about multimeters with virtually no discussion of the powerful tool for monitoring batteries - - the Victron shunt-based (a Victron 712?) you have. We see the shunt on the wall, but there's no RJ cable connected! Why? For us, this is the starting point. Not only does this instrument provide accurate (after calibration) State of Charge information, but it provides instantaneous insight into the current into, or out of, the battery pack. You say you have a solar charger, a B to B charger . . . well, the Victron will confirm that these 'chargers' are actually charging. The Victron will reveal how much current is being consumed when you run your inverter and cooktop. It will also alert you to unexpected loads. Seems you're finding your batteries discharged . . . why? The Victron is you best tool for detecting unexpected problems. Also, set the multimeter aside, the Victron includes a good voltmeter (for actual battery voltage).

Incidentally, would would relocate the shunt much closer to the negative terminal of the battery. By doing this you will be avoiding the voltage drop (during high charge/discharge currents) of that long negative wire from the battery to the shunt which, in turn, will make the Victron's voltage measurements more accurate.
You are right, but it is challenging to use the SOC monitor when the basic 12 volt portion isn't operational.
 

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Hopefully Dekkars is correct that the 0.6 volts was due to an open-circuit/BMS intervention. Otherwise the batteries are toast. But this doesn't tell us why the BMS kicked-in.

Is there a regular battery charger? Maybe a combo inverter/charger? In any event, a BMS reset, full recharge (possibly manual and supervised), set the Victron SoC to 100% . . . then start watching . . . the problem and hopefully answer should reveal itself.
 

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But this doesn't tell us why the BMS kicked-in.
This was suggested

"Inverter start up example:
In order to be stable, inverters and chargers have a fairly large capacitor on the DC input. These capacitors have essentially infinite ability to absorb current until they are filled up.

When the battery is connected to this (turn on breaker) , a fairly massive current flow will flow from the battery to these capacitors on a cold start up. Far higher than any practical van battery pack can sustain without tripping the internal BMS of a Li battery. With an AGM battery, the battery will self limit, but with Li, the effect is to trip the BMS. This is completely normal and happens all of the time with pretty much every LiFe battery on the market."
 

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2) Current output limits

There is a lot of marketing done by Li battery companies because it is so competitive about how much current can flow before it starts to be faster than the BMS or internal cell design can handle.

The reality is that there are only a handful of commercial BMS circuits used by LiFe battery companies and most of them will only run reliably at 50 - 75 amps continuous. A few high end ones will run more, but still very few can really sustain 100 amps continuous before they get too hot and trip.

The battery that you have purchased is being sold as a "deep discharge" battery, and the example of how it is being used on the amazon photo is of a low current / deep discharge usage.

No matter which LiFe battery that you purchase as a typical consumer, you need to accept that each one can only supply ~ 50 amps / 600 watts per battery to the load.

In your use case of a 2000 watt inverter,

(2000 watts) / 600 watts per battery = 4 batteries

This is how many batteries you need to run your electrical setup.

That is why in all van electrical builds that I do, a 2000 watt inverter is paired with 4 batteries. That is what it takes to be reliable and stable.

Having high capacity batteries - for the most part - doesn't change this basic number.

Really the same is true for most batteries, regardless of chemistry. 50 amps per battery load is a good target design for a van power system.

____

Your batteries may or may not be working as well as can be expected - I don't know.

Try to use them with a smaller inverter load - like a power drill and see if that trips them.
Hey @HarryN

Your posts #30 & #31 👍

Thank You !! Makes sense.

I consider you a very valuable Member of The Forum “especially when it comes to electrical”. Your knowledge coupled with professional experience & your willingness to post IMO very well written and educational material is extremely helpful.

You & I have some similar perspectives in design & in particular not asking “things” to provide 100% @ 100% of the time. Just because something has a maximum does not mean it is best practice to “redline” the equipment. On the flipside, it is not good to “idle” an engine for its lifetime as well.

I never installed an inverter in my 2018 & I do not know if I will have one in my new build. IMO a 12v to 120v inverter is a big deal electrically & I think with “normalcy bias” this type of equipment is sometimes tossed into van electrical without full consideration of the energy flow. Then there is how the equipment is used.
 

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Discussion Starter · #50 ·
Hey @HarryN

Your posts #30 & #31 👍

Thank You !! Makes sense.

I consider you a very valuable Member of The Forum “especially when it comes to electrical”. Your knowledge coupled with professional experience & your willingness to post IMO very well written and educational material is extremely helpful.

You & I have some similar perspectives in design & in particular not asking “things” to provide 100% @ 100% of the time. Just because something has a maximum does not mean it is best practice to “redline” the equipment. On the flipside, it is not good to “idle” an engine for its lifetime as well.

I never installed an inverter in my 2018 & I do not know if I will have one in my new build. IMO a 12v to 120v inverter is a big deal electrically & I think with “normalcy bias” this type of equipment is sometimes tossed into van electrical without full consideration of the energy flow. Then there is how the equipment is used.
I am learning this all as I go. I wish I didn't need an inverter because without it everything works great. But microwave and induction cooktop along with TV's and Xbox mean I need 110v. This will be my home for months at a time, so I have to figure this out to work with an inverter. I agree and appreciate all the help from everyone. I am kind of stuck right now and haven't had a chance to work on it. I used to be big into sound systems. Is the idea of putting a big capacitor in-between the batteries and inverter a stupid idea? We used to do that for when the amps and subs drew too much power on an intense audio system.
 

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Discussion Starter · #51 ·
Now nothing is working. Do we have any trusted contacts or members in the Michigan area that might want to help a fella like myself out. I am so busy with work tinkering with this is eating me alive. I would be happy to pay for the mentoring or work being done. I looked up electrical near me and it's all residential and commercial.....No van lifers😂.I will drive to get this fixed also.
 

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Now nothing is working. Do we have any trusted contacts or members in the Michigan area that might want to help a fella like myself out. I am so busy with work tinkering with this is eating me alive. I would be happy to pay for the mentoring or work being done. I looked up electrical near me and it's all residential and commercial.....No van lifers😂.I will drive to get this fixed also.
Fortunately, a van auxiliary electrical system is reasonably similar to a boat / marine application and Michigan is full of lakes and boats.

Look for a local marine electrician with inverter experience - either associated with a boat store or independent. Craigslist is a good place to look as well.

As far as the big caps - I don't really think that is the right path for this situation.
 

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Discussion Starter · #53 ·
Fortunately, a van auxiliary electrical system is reasonably similar to a boat / marine application and Michigan is full of lakes and boats.

Look for a local marine electrician with inverter experience - either associated with a boat store or independent. Craigslist is a good place to look as well.

As far as the big caps - I don't really think that is the right path for this situation.
Great idea! Thanks so much. I will do that :)
 

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I am having issues running power off my solar set up. Is there a common list of items to troubleshoot for campervan electrical systems on the forum or out on the web? It is difficult finding answers for a custom built system. Thanks in advanced for the help!
If I understand correctly the issue has been diagnosed as a problem with the inverter start up drawing too much current for the BMS so the bms shuts down.
Is that right?
Is that what you think @HarryN ?

Would it be feasible to build a switched bypass circuit that is current limited to 'prime' the inverter.
Maybe push a button, turn on inverter, let go of button and then turn on main power to the inverter?
 

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If I understand correctly the issue has been diagnosed as a problem with the inverter start up drawing too much current for the BMS so the bms shuts down.
Is that right?
Is that what you think @HarryN ?

Would it be feasible to build a switched bypass circuit that is current limited to 'prime' the inverter.
Maybe push a button, turn on inverter, let go of button and then turn on main power to the inverter?
I am really not sure. Might be more than one thing going on.

For example:
  • The labeled input / output voltage numbers for the Victron component shown in the photo are not what I would expect.
  • The other components are ones that I don't normally use and are more "weekender van / local / occasional use" than "needs to be reliable for living in" decisions.

It is possible that one or more of the battery BMS have tripped and not turned back on.

It is going to require separating out / testing each section and component to see what needs to be replaced - and that is a hands-on sort of thing.
 

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Discussion Starter · #57 ·
Sorry I have been gone! Great news I ordered 2 SOK batteries. One came today. I unhooked the expert power batteries and hooked up the 206 ah SOK battery. Guess what? Everything worked like a champ! On an also positive note.....expertpower has sent me two shipping labels for each 200 ah hour battery and will be refunding my money on their batteries, due to the BMS issue. It was a huge hassle and I appreciate everyone helping me. I will hopefully be able to be on the road soon!
 

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Sorry I have been gone! Great news I ordered 2 SOK batteries. One came today. I unhooked the expert power batteries and hooked up the 206 ah SOK battery. Guess what? Everything worked like a champ! On an also positive note.....expertpower has sent me two shipping labels for each 200 ah hour battery and will be refunding my money on their batteries, due to the BMS issue. It was a huge hassle and I appreciate everyone helping me. I will hopefully be able to be on the road soon!
Bravo, and kudo's to Expert Power for taking care of you.
 
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