question

solseekerssolar avatar image
solseekerssolar asked

Battery fire - manufacturer says caused by Smart Solar sending PV voltage to battery

We experienced a battery fire last week. I am curious of others thoughts on this situation.


We installed 4x LiFePo4 batteries in parallel in February 2023. We also added 2000 watts of solar run to a Victron 150/70 (2s3p) and a Victron 100/50 (2s2p). The system has been performing well since installation.


For sake of detail the panels are Rich Solar 200 watt panels, specs:

20.4 VMP

9.8 IMP

24.3 VOC

10.2 ISC


It is very clear that the fire was coming from one of the four batteries. This battery is now very swollen and has significant damage to the case from the fire. It was hot enough that the battery was stuck to the battery next to it and had to be pried apart.


I contacted the manufacturer, they responded pretty quickly. The very first response from them was the Victron mppt caused this issue. They also immediately offered to replace the battery. They went on say the Victron mppt’s should be swapped for Epever mppt’s. Their explanation is that the mppt sent pv voltage to the battery damaging the bms and causing it to start fire. He stated that the 100/50 in particular is "poorly" designed and not recommended. We have used Victron mppt's extensively with excellent results.


I am having difficulty accepting this as the cause. I am not surprised they want to shift the cause away from their product, but immediately blaming Victron without further details seems suspect. They are also stating the other three batteries are fine and we shouldn’t worry about them.


Has anyone experienced anything similar? I would be very interested in any thoughts on this explanation, particularly if anyone from Victron could weigh in.


Thank you,

Scott

MPPT SmartSolarovervoltagefire
6 comments
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jjbond avatar image jjbond commented ·

Another huge thank you to @Guy Stewart (Victron Community Manager) for sharing that document. It caused me to discover a feature (page 22, short relay) one of my 250/100's has that I had no idea existed, one of my serial numbers are too low but my newest one has that feature in VictronConnect....thank you again Guy..

https://www.victronenergy.com/live/mppt_pv_short_relay_reset

Jen

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snoobler avatar image snoobler jjbond commented ·
Dagnabbit! Mine is too old for it too... :(
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jjbond avatar image jjbond snoobler commented ·
Maybe @Guy Stewart (Victron Community Manager) will see this and setup a trade in / upgrade option for us... LOL
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kevgermany avatar image kevgermany ♦♦ commented ·

If there was excess voltage it would be recorded in the MPPTs. They keep a daily max battery voltage which you can see with Victron connect.

Your dealer can test the MPPTs.


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snoobler avatar image snoobler commented ·

As @Guy Stewart (Victron Community Manager) indicated, if the MPPT sent full PV voltage to the battery, the MPPT would be in a permanent state of failure, i.e., it would no longer function.


If the MPPT is operational, another possibility is that the BMS cut the battery out of the circuit under heavy charge, and the MPPT couldn't clamp down on the output quickly enough to avoid a voltage spike. I've seen spikes on the order of 22V on a 12V system, so if the BMS aren't rated for higher than 12V system voltage, they will pop. If the batteries say that can be put in series for 24V, 36V or 48V, they should be able to handle that spike. If they say they can't be put in series, the BMS likely isn't rated for operation in series strings, and it popped due to the elevated voltage.


This last scenario is not a fault of the MPPT, but a fault of an imbalanced battery and a very cheap, low quality BMS that is either under-spec or just plain failed. Given that they readily volunteered to replace the battery, I would strongly suspect it is due to battery issues.


If it was the fault of the MPPT, it likely would have cooked ALL attached batteries.


An EPEVER or any other brand of MPPT would have done exactly the same thing.







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jjbond avatar image jjbond commented ·
Totally agree with @snoobler I was experiencing incredibly high voltage spikes on BMS disconnect on some Battleborns till I got them balanced enough. Sound like their crappy BMS inside their drop in isn't working properly as to internal balancing, with 4 in parallel obviously it's not external balancing. Please share the name of the battery manufacturer, this is still America, you have a right to speak, they sure did about Victron (frankly I see grounds for a lawsuit if they were really spewing off like that about blue product, buy an Epever instead of Victron, that's ridiculous and clearly shows the total lack of knowledge about the topic.
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5 Answers
Paul B avatar image
Paul B answered ·

Its VERY Very unlikey to be the MPPT , as long as it was setup with the correct voltage settings has been done.

There are many reasons/possibilities for this sort of failure

However as the battery's BMS in your case (from what you have said) controls the cells and manages the battery if there was a overvoltage or undercharge then the BMS would disconnect that battery, as thats its job. in a stand alone battery

Personally having 4 multi stand alone batteries that are all having internal BMS with internal shut off in the battery - in a system is not a good way to go, you should be having a intergrated BMS that works with the power systems and advises all systems on when to reduce change or to stop or reduce loads.

using a battery system thats integrated into each battery means that a battery can turn off and you will never know - unless you check them manually on a regular basis.

Your failure is more than likley a battery thats disconnected because of a low cell voltage and stayed disconnected and the cells voltage has continued to drop lower and lower until it swells and smokes, or it was NOT correctly cell balanced from the very start.

If a overcharge did occur then all cells would more than likley be damaged in that battery.


However saying the above really depends on your complete setup and what style of battery's you have,


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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @solseekerssolar

To be straight up with the potential, it is possible for the Victron MPPTs (excluding RS models which are galvanically isolated) to connect PV voltage directly to battery voltage in the unlikely event of a particular type of fault.

It is rare, but it can happen. It is not a transitory failure, if this fault has occurred the unit would now permanently be in that state.

If you're concerned about the MPPT, please take it to your Victron dealer and ask them to perform a pre-RMA check on it. That procedure will test to see if this is occurring.

The procedure to test is step 6 of the MPPT pre-RMA check and is described here - https://www.victronenergy.com/upload/documents/Pre-RMA_bench_test_instructions/114199-Pre-RMA_bench_test_instructions-pdf-en.pdf


There are 100,000's of Victron 100/50 MPPTs in the field, they are a workhorse model and there is no specific variation in their design, or statistical failure rate compared to the rest of the range. To give the claim the benefit of the doubt, because there are so many of them, anecdotally they might see more of them and presume there is some problem with that model.

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jjbond avatar image jjbond commented ·

Thank you for sharing this PDF @Guy Stewart (Victron Community Manager) , very handy to have in the collection of notes. PS: You need to do another pair of videos with Glen from the Smart Energy Lab, the Cerbo one you both did was epic, I want to see him chewing on the new baby to the family (Ekrano), like he did the Cerbo (LOL)... While I have you, why'd you name it something so close in pronounciation to a product you pickup at Woolies to unplug your sink? LOL


1692149578881.png


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1692149578881.png (237.1 KiB)

lol, yes I might get the chance to catch up with Glen again for the AllEnergy event.

The Victron product naming process is an illusive and mysterious art, I’ve tried several times to have an influence in pre-release product names without success yet - but I won’t give up!

They usually grow on me over time.

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seb71 avatar image seb71 jjbond commented ·

I want to see him chewing on the new baby to the family (Ekrano), like he did the Cerbo (LOL)... While I have you, why'd you name it something so close to a product you pickup at Woolies to unplug your sink? LOL

In a few languages ecran or ekran means screen / display.

Ekrano is a GX device with an integrated display.

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kevgermany avatar image kevgermany ♦♦ seb71 commented ·
My immediate thought when I saw the name was Ekranoplan. But we digress.
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klim8skeptic avatar image
klim8skeptic answered ·

@solseekerssolar Further to what has already been written, it might be an idea to review the way the batteries have been paralleled, and fusing requirements.

Recommended ways to parallel 4 batteries from Wiring Unlimited.

parallel-batts-x-4.png

It would also be a good idea to fuse each battery on the positive batt post. This will ensure that if one battery has a failure, the other 3 batteries don't gang up and set fire to the battery having a bad day.


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kevgermany avatar image
kevgermany answered ·

Reading the replies reminded me that a friend's had exactly the same problem on his boat. Battery was 4 cells in series, external BMS. BMS faulty, was fixed, failed again, supplier didn't fix. Failed BMS overcharged one cell which failed with short circuit when it swelled up. Other cells then split the charge voltage between them. All wrecked.

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snoobler avatar image snoobler commented ·

The issue here is that no BMS in the market can handle being exposed to PV voltage.

Sequence of events for LFP:

  1. PV shorted to battery.
  2. BMS triggers over-voltage protection and isolates battery.
  3. BMS exposed to PV voltage @ BMS terminals.
  4. BMS pops and the FETs fuse closed.
  5. Full PV voltage/current sent to batteries.
  6. LFP cells exceed 4.2V for extended period.
  7. Electrolyte degrades, outgasses
  8. Cell(s) swell and potentially ignite.

The only resolution is:

  1. "Canned" BMS manufactured to handle 150VDC+ (HAH!)
  2. External monitoring system that triggers a suitably rated relay to open if total volts exceeds a predetermined limit. This won't prevent BMS death, but it could prevent cell damage.
  3. ??


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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ snoobler commented ·

The Victron Lynx Smart BMS has an integrated relay contactor that will open if the battery voltage gets too high.

It also has an alarm, which can trigger a push notification to your phone if connected to a GX device and internet. That is quite a robust solution.

https://www.victronenergy.com/battery-management-systems/lynx-smart-bms

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kevgermany avatar image kevgermany ♦♦ snoobler commented ·
Yes, was a no name cheapie BMS bought online. One module per cell, plus control module.
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kevgermany avatar image
kevgermany answered ·

Reading this thread again reminded me of something. I used to live in an area with high incidence of lightning strikes. Electric gate failures due to lightning were a regular problem. Didn't even need a direct strike.

A friend made quite a good income fixing the gates and protecting the circuitry with electronics that would safely conduct the spikes to earth. It should be possible to design something to do the same for PV systems. Sadly I've lost contact with my friend, so no way of finding out what he did. But mine never failed. But I guess it's a rare enough occurrence that would not justify the effort of product development..

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Related Resources

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