Battery cutoff switch on negative or positive cable?

[timselectric]

I don't plan to open the switch with current flowing. Even Sol-Ark warns not to open the built in battery breaker with current flowing.

We never plan to do that. But in an emergency, it would be bad if the only option caught on fire.

 

[timselectric]

These switches will only ever get turned on or off when there is virtually no current flowing.

Hopefully

 

[Steve_S]

FIRST & MOST IMPORTANT RULE !

NEVER EVER TEMPT Murphy's Laws !

 

[pvgirl]

It's even harder to find one that's UL listed. I searched all over Amazon recently looking for a DC breaker switch, and couldn't find one that was 100A+, 60V+, and UL Listed. I seriously considered one that was around $140, which seemed way too high. It looked high quality, but I couldn't find anywhere that it was UL Listed.

I like the one that you linked in that thread.

Not cheap or compact but there is the MidNite Solar MNDC125 also available in 175 and 250 amps

 

[a619]

Blue Sea has similar switches some of which can support 80V (72 Volt system). WARNING, there are cheap knockoffs out there, be aware of that and don't furtle with switches, breakers or fuses, that is NOT where to pinch pennies.

Battery Switches - Blue Sea Systems

Engineering high quality marine electrical components for safety, reliability and performance

www.bluesea.com

Below is one my generic diagrams to help you out.
View attachment 173533

My system also includes a larger class-T fuse between the battery busbar and disconnect switch. I'm not completely sure if that adds any value since I already have individual 125A fuses for each battery. I have read conflicting opinions on that, but wanted to err on the side of caution.

 

[Oldphile]

We never plan to do that. But in an emergency, it would be bad if the only option caught on fire.

It's not the only option. Each battery has an ON/OFF switch.

 

[timselectric]

It's not the only option. Each battery has an ON/OFF switch.

As long as you are the only person who will have access to it. And you never actually use it as it's intended. You might get lucky and never have a bad day. All that I can do is make recommendations.
It's your risk, so it's your choice.

 

[SeaGal]

Like others, I'd shy away from a cheap switch. When do you expect to use it and why?

Why only one pole? What about using a proper fused battery disconnector like this - designed for the job (up to 400V) and won't break the bank... (about 50 euro) - available with different size fuses from 40A up to 160A?

Jean Muller Fuse-switch-disconnector KETO size 00 body (battery isolator) - Segen UK

Add robust and secure battery disconnection with the Keto range from Jean Müller. They are well known for their attention to detail in ensuring maximum user safety. Keto size 00 Maximum DC current = 160A DC voltage rating: 250V Overall width: 106mm System size: 195mm Terminals: M8 lugs with...

www.segen.co.uk

 

[Partimewages]

Unfortunately I do not, it was posted in here about 6-8 months ago or so. There have been a couple of posts over the years showing the results of cheap knock offs.

The GOTCHA that catches people with their pants down is the common assumption that when someone says 48 Volt, that this is the voltage limit they need to support but in reality is HAS to be 60 Volts. Even with Lead Acid when running Equalization you are above 48V, and LFP for example can see 58V without effort, let alone other chemisries....

So I went to Blue Sea but every switch available that I found is 32 or 48 volt rated. I didn't find anything for 72-80 volt rated. Maybe I looking in the wrong place. I've got a ton of NEC behind me but the DC and solar is not in that. Please point me in the right direction.

 

[Rexracer]

I never really paid this much attention since I was only using a 12.8v 100 ah battery. I bought a Blue Sea 6006 which is rated 48v dc max, 300a continuous, 500a intermittent ( 5 minutes), and 900a cranking (30 sec.). CE marked, ISO 8846, UL Listed, UL 1107, meets UL 1500 and SAE J1171, IP66 Water rating. I have to wonder what kind of additional testing it would need to get a 60+ vdc rating as-is.

 

[Rexracer]

Don't know if this will be read fast enough , but the black version of the Blue Sea Systems 6006 switch that I used is 79% off on Amazon RIGHT NOW. that's $ 8.79 I think it was. I just bought 2. The red one is $27 and typically they're about $35. If anyone is looking for a 48vdc, 300 amp on/off switch, this is great for a high quality switch. Don't know how long, or how many there are.

 

[AmpD]

The OP switch states it should be installed on the negative line. “It is advisable to have the switch disconnect the negative side instead of the positive side as voltage can still run through the switch even if its off and still have the ability to short out when installed in the positive side.” That said it shows it installed on the positive line in one of the three installation diagrams. It also talks about its amperage ratings only at 12v though it states it can go up to 48v max.

Bep marinco has switches available up to 120v dc “upon request”. I bought a 770 off ‘zon. Picture showed 120v rating. Product received said max 48v. The 6006 is also a 48v max.

I ended up going victron. Not that I plan on disconnecting under load but the claim that it can provided some reassurance. It is rated at 60v 275a continuous. Used like new sale costed me $25 per switch. Just had open packing nothing even looked like it had been used. No marks or discoloration ect.

Frugality is good. Peace of mind is better imo.

 

[JoeHam]

Don't know if this will be read fast enough , but the black version of the Blue Sea Systems 6006 switch that I used is 79% off on Amazon RIGHT NOW. that's $ 8.79 I think it was. I just bought 2. The red one is $27 and typically they're about $35. If anyone is looking for a 48vdc, 300 amp on/off switch, this is great for a high quality switch. Don't know how long, or how many there are.

Read this entire thread, a 48V rated switch is not adequate for a 48V NOMINAL system that will get up to 57V.

I wouldn’t want someone to read fast enough and try to quickly order potentially the wrong thing to save a few bucks.

 

[Oldphile]

I searched and searched and could not find a switch rated higher than 48VDC.

 

[SparkyJJO]

That's why I went with a DiHool double pole MCCB - not to be confused with MCB. This thing is very large and heavy rated to cut 20kA at 500V DC, and still be functional, or 25kA max (though by self destruction).

 

[AmpD]

I searched and searched and could not find a switch rated higher than 48VDC.

Click on the victron hyperlink in my post above if you’re still looking.

 

[Rexracer]

Read this entire thread, a 48V rated switch is not adequate for a 48V NOMINAL system that will get up to 57V.

I wouldn’t want someone to read fast enough and try to quickly order potentially the wrong thing to save a few bucks.

Exactly, which is why I specified that I'm only at 12.8 vdc. I wouldn't use any of these 48vdc switches past a 24vdc system. I didn't look at the Victron. I plan on using this one in my single lifepo4 ammo can to shut off the Anderson sb175 coming off the side supplying power. May use the second as a master for my Victron tr-smart 12/12-30 charger, which will be mounted in my Jeep.

 

[Zwy]

I searched and searched and could not find a switch rated higher than 48VDC.

I have one of these on my shop battery bank

Thread 'An actual 600A 48V+ disconnect switch'

Dec 18, 2023

This has come up numerous times where almost all of the DC rated switches you see for sale aren't actually rated for over 48V DC. I believe I actually found one that comes in 400A, 500A, and 600A versions! https://evolveelectrics.com/collections/contactors/products/rincon-power-hvbd-600a-disconnect

From spec sheet it sounds like you can actually use it to disconnect under load even at full rating as long as you are below 100V DC which we always would be for a 48V nominal system.

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• Forum: DIY Solar General Discussion

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