Looking for DC switch

[SunEagle]

I did not see a Blue Sea DC switch rated for 50 amps. The switch earlier where I started this thread, I e-mailed Blue Sea about a rotary AC switch and they contacted the manufacturer schneider who said that switch should be OK to 45 amps DC. To me its either Yes its good, or no its not. No in between. They do have their battery switches 250 amps+, but that is a bit bigger and pricier than I want.

I found someone who is using two of these switches in post #12 on another board to run Air Conditioning with a 13.5K BTU unit off 12 volts. Claims 1500 watts continuous. I would think this gets to about 120 amps for 11.5 hours for a battery capacity test.

This will be for a 600 watt hour battery that will see 15 amps continuous with a max of 40 amps before the fuse blows. Its part of a tiny homemade "Bluetti" type solar generator. I certainly have no intention of using this at the 120 amps that other guy used it at.

I believe NASCAR use some type of master kill switch in their cars. I don't know what they are rated or how many contacts are on them but maybe you can look into automotive equipment.as a source.

[chrisski]

I would look for a switch made by Blue Seas.. They have been around for years, and are solid. A critical switch from some no-name company makes me queasy

I did not see a Blue Sea DC switch rated for 50 amps. The switch earlier where I started this thread, I e-mailed Blue Sea about a rotary AC switch and they contacted the manufacturer schneider who said that switch should be OK to 45 amps DC. To me its either Yes its good, or no its not. No in between. They do have their battery switches 250 amps+, but that is a bit bigger and pricier than I want.

I found someone who is using two of these switches in post #12 on another board to run Air Conditioning with a 13.5K BTU unit off 12 volts. Claims 1500 watts continuous. I would think this gets to about 120 amps for 11.5 hours for a battery capacity test.

This will be for a 600 watt hour battery that will see 15 amps continuous with a max of 40 amps before the fuse blows. Its part of a tiny homemade "Bluetti" type solar generator. I certainly have no intention of using this at the 120 amps that other guy used it at.

[chrisski]

Find a dead inverter with an internal DC disconnect switch and cannibalize the switch. They are usually nice, very expensive looking high voltage DC switches. Solar is now over 10 years old since the industry expansion occurred in 2008 and lots of those early inverters are now out of warranty and failing. I've got a few of them if your interested...

Not really sure where to go for this. I have not had a lot of luck at my local auto salvage yard for parts. Mine were either picked clean, or we don't keep that car around here and scrap them as soon as we get it. Not sure where the inverter recycle center is.

[solarix]

Find a dead inverter with an internal DC disconnect switch and cannibalize the switch. They are usually nice, very expensive looking high voltage DC switches. Solar is now over 10 years old since the industry expansion occurred in 2008 and lots of those early inverters are now out of warranty and failing. I've got a few of them if your interested...

[Mike90250]

On a different project I am working on, I want a DC small DC switch for a 25 ah battery bank. I expect no more than 30 amps to flow from this (battery is rated for much more than that), and I have a 40 amp ANL fuse.

I think I will get this DC switch. It’s a 48 volt DC on off rotary switch rated to 275 amps continuous. Only 2” X 2” X2” I did not find anything close to the size or 50 amp rating for a good battery cutoff switch.

Not sure how I feel about going to the full 275 amp rating, but I think the smaller amp rating will be fine.

I would look for a switch made by Blue Seas.. They have been around for years, and are solid. A critical switch from some no-name company makes me queasy

[chrisski]

On a different project I am working on, I want a DC small DC switch for a 25 ah battery bank. I expect no more than 30 amps to flow from this (battery is rated for much more than that), and I have a 40 amp ANL fuse.

I think I will get this DC switch. It’s a 48 volt DC on off rotary switch rated to 275 amps continuous. Only 2” X 2” X2” I did not find anything close to the size or 50 amp rating for a good battery cutoff switch.

F8782B76-AFF1-49D0-BF72-BE46F2DD9521.jpeg
Not sure how I feel about going to the full 275 amp rating, but I think the smaller amp rating will be fine.

[chrisski]

Look at these. They are rated for this usage

https://www.industrialcontroldirect.com/dc-disconnects-316/enclosed-dc-disconnects-317/?zenid=hh6kps6c7m8dbq6btoijd09a56

Andy

Thanks. Pretty expensive.

I am going to try out the panels in parallel and not worry about putting them in series to start. Turns out this project is bit harder than I thought. Just building, wiring and crimping the combiner / circuit breaker boxes for these panels is taking 3 days.

[PVAndy]

Where do I find a 3 DC Switches?

I’m looking for a DC switch for no more than 30 amps and max of 45 Volts DC just like this
91333DF4-DACE-4CBE-983D-31A3D06FDE4B.png
This switch is made by Blue Sea https://www.bluesea.com/products/909...20_240V_AC_65A, but unfortunately its rated for AC Power, 65 Amps 120 / 240 volts.

I want to take a single input and send it to a choice of a 30 amp breaker or a 15 amp breaker. THe positions will be 15 AMps, 30 amps, off. This will all be whether my suitcase panels I attach to my RV are 4 in series for the lower Amp breaker, or in parallel for the night amp breaker.

I think the terminology of the switch is 3P4T (3 Position 4 THrow), but that’s not producing any DC results, if it shows the switch I want, rated for AC only.

Look at these. They are rated for this usage

https://www.industrialcontroldirect.com/dc-disconnects-316/enclosed-dc-disconnects-317/?zenid=hh6kps6c7m8dbq6btoijd09a56

Andy

[Mike90250]

If you are going to design something, consider DC solid state switches/relay. They too, require a snubber circuit for each switch to prevent it from voltage spikes, but once you design one, and get a kit of parts, probably cheaper by the dozen !
Beware - many knockoffs of major brands exist, only buy from reputable mfgs

https://www.digikey.com/en/products/filter/solid-state-relays/183?s=N4IgTCBcDaICIGEAEBlFAlEBdAvkA

[bob-n]

The Krause and Naimer switch sounds like a good solution.

As a side: I have a DC light in my shed. I switch DC from a battery to the light with a simple mechanical switch. To protect the contacts and make the switch last longer, I put an RC snubber across the switch. RC snubbers or RCD snubbers SHOULD be adequate to make any AC switch safe switching DC. The capacitor needs to be large to handle the surge current and also large enough value to absorb one-time current surges from stored energy in the wire, without excessive voltage excursions. The resistor can be relatively small because you don't switch often, and even then, power resistors are really cheap. For my 2A/12V light, the snubber was tiny and cheap, and the voltage spike never goes over 20V.

I'm not suggesting this as the best solution to your problem. It's more an academic solution. To learn more, here is one of many possible references:

https://www.daycounter.com/Calculators/Snubbers/Snubber-Design-Calculator.phtml

[littleharbor]

While not a traditional switch, per se, Midnite Solar and Outback DC circuit breakers are rated for higher voltage (150 and 300 Vdc,) and switching while current is flowing.

[chrisski]

Best find out if it will work at the DC voltage & amps it will be running at. 32v is often the limit for many marine and automotive gear.

I still won’t install it without asking Krause and Naimer myself. I had asked about 45 Volts and 30 amps to Blue Sea, but if they are not making it, I’m going to want to hear the DC specs from the company itself directly.

This probably would not have worried me had I not seen three 100 watt panels in series arc.

[Mike90250]

....”Thank you for the question. We have been told by Krause and Naimer the maker of the Rotary switch that is will work for DC also.....

Best find out if it will work at the DC voltage & amps it will be running at. 32v is often the limit for many marine and automotive gear.

[chrisski]

Well, the arcing in DC switches may explain I why its not available. Blue Sea makes a battery switch I could get two for and do what I want, but they are big. Since arcing is a problem and my three panels in series already arc when I do an amp check, than I really do not want any switch I can find unless its rated for it.

Relays may work, but will take some thought on my part and will take some thought on my part so whatever chain of relays I have are open with no power.

EDIT:
Just got his EMail from Blue Sea and the switch will work for DC:

”Thank you for the question. We have been told by Krause and Naimer the maker of the Rotary switch that is will work for DC also.
Please ask if you have any additional questions.
Best Regards,

Blue Sea Systems Tech Support”

[bob-n]

Will you have to switch with power applied and current flowing? No? If you can be certain that you never close or open with current flowing, then an AC switch will do the job. The main difference is that DC switches can handle the arc that forms when relay contacts open.

If you need to switch with power flowing, consider using relays. You may need more than one, and build a small box to house them. There are many high-current relays available for the automobile industry that are rated 50VDC and 30A.

Here's the Schneider Electric relay catalog:

https://download.schneider-electric.com/files?p_enDocType=Catalog&p_File_Name=8501CT1003R09_20.pdf&p_Doc_Ref=8501CT1003

Omron, TE Connectivity and others also make quality DC relays.