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maa avatar image
maa asked

Battery switch 275 A VICTRON

Hello,

Observations and astonishments

I've been trying to understand the temperature rises on the DC cable (multi <-> batt) for a while now. So I tried with 50mm² and 95mm² just in case I was a little stingy on the section and caused an "incompetence" warm-up ;)

But different cables and identical results: The VICTRON 275 A battery switch causes a throttling which causes the cable to overheat, supporting thermal photos:


1. Photo with VICTRON Switch (48V/100A)

img000009.jpeg

2. Photo without Switch, terminals directly connected (48V/100A)

img000002.jpeg

Can anyone tell me what's going on? Dead switch? Normal?


PS: the little wire on the terminal is just a temperature probe

switch
img000009.jpeg (64.7 KiB)
img000002.jpeg (64.9 KiB)
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6 Answers
wolfgang-s-aus-b avatar image
wolfgang-s-aus-b answered ·

Hallo

Do you unterstand what happends now? Or do you still need some explanation?

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maa avatar image
maa answered ·

ohhh yes, I removed the 275A VICTRON Battery switch, no desire to burn

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wolfgang-s-aus-b avatar image
wolfgang-s-aus-b answered ·

This is also a solution :D
It is because of the contact resistance. The 275A Switch has a contact resistance. This causes a power loss, heating the switch.
But 100A and 67°C is ok for me .... I'd say I have the same ...

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Craig Chamberlain avatar image
Craig Chamberlain answered ·

I also use the Victron 275A switch with my Multiplus-II 5kva and even with 100A+ running through it, it doesn’t heat significantly.

HOWEVER, as I have commented in other threads on this forum, these switches can be very easily damaged either by turning the switch off while under load or, more commonly, turning the switch on with the Multiplus internal capacitors discharged and thus causing a current surge and associated arc which damages the internal contacts. I went into more detail on the correct power up/down sequence in this thread if you’re interested: https://community.victronenergy.com/questions/313922/what-is-the-correct-order-to-power-up-a-mp2.html

Another thing that’s important is to ensure that the bottom nut is tightened up before the crimp lug is fitted along with the spring washer and top nut. This bottom nut ensures that the internal contacts are correctly positioned in relation to the switch wiper. I don’t think there is a torque spec for the bottom nut but the top nut is 12.5NM (IIRC) so I’d suggest something like 6-8NM for the bottom nut. It’s important to check it every time because the bottom nut tends to loosen slightly when the top nut is removed.

I’ve gone through three of these switches and my latest one has never been switched so has pristine contacts. If you want to check yours, you can remove the 4 screws on the back of the switch and take a look. It’s not a complex assembly so just take care how it comes apart and don’t over tighten those screws. I posted a photo of the inside of one of my switches on the forum but I can’t remember which thread it was on.

HTH

Edit: This is the thread - look for posts by me on December 8th 2023 and you’ll find the photos of my switch (old and new). I tried to upload the pictures to this thread but I’m getting an error from the website so can’t.

https://community.victronenergy.com/questions/247351/what-happened-to-this-cable.html

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maa avatar image maa commented ·

you write this "Another thing that’s important is to ensure that the bottom nut is tightened up before the crimp lug is fitted along with the spring washer and top nut." and i agree with you 100%. that's what i checked first but unfortunately in my case it was always too hot. so as they say where i live "caution is the mother of all virtues"...

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Craig Chamberlain avatar image Craig Chamberlain maa commented ·
Yeah, I suppose the point I'm making is that everything has to be done just right with these switches to avoid poor performance and overheating. But ultimately, if the switch internal contacts are already damaged and contact surface area has been lost due to arcing, then it's already too late. It might be possible to restore the contacts using fine emery cloth or whatever, but it wasn't worth the time for me. That said, I don't intend to buy any more of these switches so unless Victron release a more robust solution then I'll be looking at third party alternatives if I need to replace it.
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maa avatar image maa Craig Chamberlain commented ·

Same for me

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ejrossouw avatar image ejrossouw maa commented ·

This is not unique to the Victron as you can see from this BlueSea switch failure. From the meltdowns I have personally observed, my findings are various as already highlighted above by others. Interestingly these failures appear to occur in predominantly in domestic installations, which are often subjected to prolonged periods of continuous high currents and associated heat e.g.when charging/discharging large battery banks.Depending on your specific use case, Jean-Muller or similar may be a more appropriate choice for large domestic systems.

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Craig Chamberlain avatar image Craig Chamberlain ejrossouw commented ·
Yeah I agree this isn't unique to Victron and the link to the BlueSea failure supports that conclusion. And it's a good point you make about this maybe being more specific to domestic ESS installs rather than marine or RV type installs.

However, I feel that this switch is by far the weakest component in what I would otherwise describe as excellent, robust Victron products in my own installation.

That said, my installation has evolved from rudimentary beginnings with an inverter, a couple of batteries and generic bus bars and mega fuse holders, to four batteries, two charge controllers, Lynx Distributors etc. So perhaps in my own situation, it's more the case that the DC isolator switch hasn't evolved along with the rest of my system. Definitely something I want to improve on but my pristine switch is performing fine for now so "if it ain't broke..." :)

It would be nice if Victron had a first party or white labelled third party solution for a beefier switch

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maa avatar image
maa answered ·

I didn't know the term "jean-muller" in France they call them "knife disconnectors" and indeed there is nothing better. These are the ones I put and no overheating since :)

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kyros32 avatar image
kyros32 answered ·

I want to comment on this. We have stopped using this switch after too many dangerous situations - the switch was totally destroyed many times.


The switch is poorly designed and its rating is WAY too high. All our problems with complete destruction were with currents BELOW 200 A. All the current is transferred on a few mm2-sized contact.


If something has 275 A rating for continuous duty cycle, then it MUST be ensured that heat is dissipated so that there is no risk of thermal destruction - given the internal resistance.


We have had multiple switches fail with only one start-up (during commissioning) - so the idea that this can be caused by the wrong start-up sequence is FLAWED.


Also, in none of the cases were terminals too loose or too tight - terminal failure was never the case.


I have reported this many times via our distributor, but it has never been reflected nor properly explained by Victron.

Problems with this switch are:

- poor construction

- overrated amperage

- resulting in overall bad quality

Period.


My advice (with all due respect towards good Victron products) -> don't use this if you want to be safe and have a good night's sleep. Knife disconnectors/fuses by Jean Muller for example are a good solution. If you can't use them, don't use the switch at all.

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