It worked for a couple of hours. I had turned off the breaker on the battery to check something then turned it back it on. When I did it went up in smoke. It was at 53.8v. The inverter breaker was off and not short. Later on everything else worked fine, but the shunt was burnt out and wouldn’t turn on.
It seems that the power source IC of the shunt (step down converter) is burnt.
It happens. You were not at fault.
Most likely a series was made with wrong parts, you should receive an improved version (warranty)
Several 300a shunts have gone up in smoke in recent weeks..
Just bought one of those 300A shunts, but I didn’t power it up yet…
Do you know the range (serial numbers) of the defective one? Or a reference somewhere?
Thanks in advance!
Indeed, it seems that it’s not an isolated incident…
Same issue here, where @guystewart asked for serial number of the affected units.
Hi @nolensb,
As mentioned please get in touch with your dealer for an RMA warranty replacement.
I am still collecting all the reports I can to help R&D investigate what is causing this issue.
If you could please post the serial number id appreciate it.
It made me curious and, before powering it up, I wanted to know which IC is there and if indeed will handle up to 55V, in my case.
It seems that it’s an LM5163, which, according with its datasheet, it supports up to 100V.
So I may be safe to power it up… 
Please @nolensb , can you carefully remove the resin on your chip and look at its part number to see if it’s the same?
You can use acetone for removing nail polish (from your lady) and use an ear cotton swab to carefully dissolve the resin.
It may take some time and patience, but the result is quite OK. Look below on my picture.
Don’t use sharp objects to remove the resin as you may damage the writing.
Thanks in advance.
LE:
Looking carefully at your picture, it may seem that below that resin could also write 5163 on the first row.
If this is true, then we may have a problem and maybe the chip batch could be defective…
Couldn’t find the message about the burned shunts maybe on a Dutch ess forum (Teaker.net)
@nolensb don’t open the shunt, you will lose warranty if you do so!
Too late for that… From where did you think he’s got that first picture on the first post? 
Come on… Loose warranty for taking a peek inside a failed product?..
If you say „breaker“ I assume you had a breaker on the positiv.
In a DC environment you never want to cut positiv side first as this will produce a big power spike and can/will fry your stuff. This is something any car technician knows but is not really common knowledge otherwise.
If you google for it you will find it right away. I also had to learn it the hard way and my first smartshunt had to pay the price.
Hope that helps a little.
Problem is some people damage things when opening. So viewing it from the other side its a chicken-egg story. Which came first?
A good rules of thimb is - If it is under warranty try the claim first, if denied then take your item back and try to repair it is still yours.
Most of the electronics these days are either not or not easily repairable to the end user even an avid electronics diyer. So opening it doesn’t usually yield anything but a mild curiosity cure for most and usually an exercise in futility.
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Especially when devices are flooded with resin like Victron MPPTs. 
With an color X-ray camera 
I had my 300A ip65 smartshunt go on its second connection, LFP battery at nearly 54V. I had it replaced under warranty but there does seem to be an issue with connecting Smartshunts to well charged LFP batteries where the inrush causes a V spike. I added a resistor and capacitor to the harness and the replacement has survived the last 3 months.
If it is this issue its been ongoing since 2023.
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Yep… but the digital world has all the signals in reference with DC negative.
And what happens in the situation when the negative is interrupted before the positive and the positive remains connected and all BIG currents are not returning anymore through the big negative cable, but instead through all the (usually data) cables that also have negative DC inside on some products… All data cables will fry, not to mention low power PCB GND paths…
This is why it’s better to have (opto)isolated data interfaces, but unfortunately not all devices have this.
And Cerbo and Ekrano are one of them…
And if you look closely, the Victron CAN cable that connects to the battery also has the negative DC inside the cable…
And Cerbo also connects to the inverter on the negative DC…
So do the math…
And for this reasons many recommend to have the negative permanent connected. Hence a vicious circle…
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I totally agree with you.. sadly still the reason for another fried Smartshunt.
Looking at the LM5163 datasheet and also at the topic @kommando quoted, it seems that a capacitor (or low pass filter) is in order, as the internals of the shunt doesn’t seem to have an adequate one for the usual configuration where, indeed, the input is through a long wire, Victron supplied one.
Any recommendation for a capacitor or filter?
I would (for my 48V system) put a low esr 47uF/63V electrolytic capacitor between Vbatt+ and Battery minus.
Thank you!