# HV Disconnect Switch



## F16bmathis (Jun 6, 2008)

I'm helping some guys build a 144V 500 amp EV (Chevy S10) and they want a HV Disconnect Switch. 

I'm pretty sure I bought the one at cloudelectric, http://www.cloudelectric.com/product_p/sw-20259.htm but it says its a 5000 amp at 12V, or 2500 amp at 24V, or.....

Is this the proper switch to disconnect main power?


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## EVfun (Mar 14, 2010)

I'm not seeing any rating that would indicate it can interrupt high DC voltages, so I suspect it isn't suitable as a HV disconnect.


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## EV-propulsion.com (Jun 1, 2009)

These are available,








limited by the anderson connector rating. Rating can be found here: http://www.andersonpower.com/products/multipole-sb.html


and these that are rated at 145 v DC and 600 amps, which also hold a fuse.








Both are relatively large compared to the little switch that you mentioned, which in my opinion is NOT anywhere near rated for high voltage DC. The problem with using a switch rated for low voltage in a high voltage system is if switched under load, the voltage can arc between the contacts and continue the current flow (plasma ball style) possibly making a bad situation worse.
Mike
www.EV-propulsion.com


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## brainzel (Jun 15, 2009)

Take a look at these battery switches from BepMarine:









There are several switches with different ratings available.


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## F16bmathis (Jun 6, 2008)

EVfun said:


> I'm not seeing any rating that would indicate it can interrupt high DC voltages, so I suspect it isn't suitable as a HV disconnect.


I know! I had bought this disconnect as part of a kit that was made years ago. I don't remember who designed the kit, and I've been using the switch for years, even had a Zilla and a Curtis go up in smoke, and both times that disconnect switch was then turned off. The Zilla died and that was that, when the Curtis blew, I started going for a ride till I turned off my key and pulled that disconnect switch.

I guess I could try putting a few hundred amps through it and disconnect it to see if it does actually work...

Do most people not use a HV disconnect? Or maybe this is meant for disconnecting while working on the vehicle. I've got over 15,000 miles on this switch!


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## dtbaker (Jan 5, 2008)

F16bmathis said:


> I'm helping some guys build a 144V 500 amp EV (Chevy S10) and they want a HV Disconnect Switch.
> 
> I'm pretty sure I bought the one at cloudelectric, http://www.cloudelectric.com/product_p/sw-20259.htm but it says its a 5000 amp at 12V, or 2500 amp at 24V, or.....
> 
> Is this the proper switch to disconnect main power?


this is really NOT appropriate, and may not work if you pulled it under load due to arcing.

Do you have a main circuit breaker (you should!). A big fat GE or Airpax rated to interrupt 500amps at 250vDC ? you can rig a choke cable pull from the cabin..... or use a big fat anderson at the very least.


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## mizlplix (May 1, 2011)

The one you reference to is a battery disconnect. Not an emergency interrupt. It will arc under a high amperage/high voltage disconnect. Even an Anderson will arc under a *loaded* disconnect, they open way too slow.

Anything that will not snap open, will arc under load (and even some of those do too). 

For an emergency disconnect, there are two schools of thought:

Buy a large, correctly rated switch or breaker (expensive).

Buy one with the right amp rating, but lower voltage rating (like the one mentioned) and make a way to remotely disconnect it. If it is used under a *full load*, The switch will be sacrificial in that instance. Just have it in a spot where a possible large smoking hole will not be a problem...LOL 

Both will save the car. 

I have two of the BEP Marine types, rated at 650 amps continuous. One before my contactor with a 10" dielectric handle, one between battery packs, for maintenance safety.


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## Gozer (Jul 3, 2008)

I am currently putting in the anderson disconnect and wondered if disconnecting the positive run in the connector would be adequate. I would leave the negative run from the battery teminal to the controller.


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## Guest (Sep 1, 2011)

F16bmathis said:


> I'm helping some guys build a 144V 500 amp EV (Chevy S10) and they want a HV Disconnect Switch.
> 
> I'm pretty sure I bought the one at cloudelectric, http://www.cloudelectric.com/product_p/sw-20259.htm but it says its a 5000 amp at 12V, or 2500 amp at 24V, or.....
> 
> Is this the proper switch to disconnect main power?


These are basically just a battery shut off and not meant for HV disconnect under loads. They are great for disabling the main pack when you leave the car for any time. It will shut off power to every thing. But not a load shut off. 

Pete


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## mizlplix (May 1, 2011)

If you have ever flipped a circuit breaker on-off-on-off, and noticed it makes a snapping sound? It is because it connects/disconnects very quickly to minimize arcing. 

Anything interrupting a closed, operating, loaded circuit will arc. The faster it gets done and the farther the contacts are apart, the less the arcing will be.

A 100 Amp switch rated for 600 volts will have the contacts farther apart than a 100 Amp switch rated for 60 volts. Even though they both will carry the same 100 Amps.

No matter what the rating, anything opening slowly under load will arc.


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## greif (Jun 26, 2010)

so if you have a 48v 500 amp controller you should have at least a 48v 500 amp dc breaker?


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## green caveman (Oct 2, 2009)

If we're talking emergency disconnects then there's a thread on this. jackbauer suggested the kilovac ev200 You get to break 2000A, 320V. You can only do this once (but, obviously you can make/break many cycles at lower power). 

There's also a suggestion from Dan Baker to use an inertial fuel shutoff switch so that you'll drop power if you crash.
http://relays.tycoelectronics.com/datasheets/ev200.pdf


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## mizlplix (May 1, 2011)

In theory, yes. Everything electrical needs to be up to the system rating.

(in theory)......my emergency disconnect is rated at 600 amps continuously . It is rated at 48vdc and I am running 120vdc. It has a dielectric handle for that once in an emergency full power disconnect. Because it is going to make a mess....It is in a place where it will cause minimal harm and easy to put out the fire. (but remember, you are stopping from having a greater problem.)

My old jet electrica had for a disconnect, a vise grip looking deal with copper contacts and a choke cable for remote operation. Not good either and it was a factory affair. You could even make one of those easily.

In my opinion, all emergency disconnects need to be manual, not electric. 

And I might take some heat from the forum members, but an Anderson plug is just that.....a plug. Not a good disconnect. They will get damaged if opened under load, even with that fancy unplugging contraption.

It is like unplugging your welder when a rod is stuck. Not a wise thing to do.

Whatever you use must meet the amperage rating of your motor. It needs to be accessible and marked. A red handle is nice too.


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## cruisin (Jun 3, 2009)

mizlplix said:


> If you have ever flipped a circuit breaker on-off-on-off, and noticed it makes a snapping sound? It is because it connects/disconnects very quickly to minimize arcing.
> 
> Anything interrupting a closed, operating, loaded circuit will arc. The faster it gets done and the farther the contacts are apart, the less the arcing will be.
> 
> ...


Here is what you need available in classifieds


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## m38mike (Dec 27, 2008)

In my EV I installed an industrial breaker rated at 160vdc and 600amps. It cost me about $300 for the breaker and another $20 or so for the housing and hardware to mount it. Here's how I mounted it.



















The cables enter from either end of the 2" pull box and bolt directly to the breaker. I cut a slot in the cover for the breaker lever to stick out. For operation in a remote location, a hole could be drilled in the lever, and a cable attached that could pull the breaker to disconnect power. 

I use this as my master shutoff when I'm not using the EV. My charger bypasses this switch so I can still charge the pack with this breaker off.


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## dtbaker (Jan 5, 2008)

green caveman said:


> If we're talking emergency disconnects then there's a thread on this. jackbauer suggested the kilovac ev200 You get to break 2000A, 320V. You can only do this once (but, obviously you can make/break many cycles at lower power).


Kilovac is good as a main contactor, but you STILL should have a manual pull circuit breaker.



green caveman said:


> There's also a suggestion from Dan Baker to use an inertial fuel shutoff switch so that you'll drop power if you crash.


inertia switch is good idea in case of accident, but you STILL should have a manual pull circuit breaker because it only cuts the 12v power to your main contactor which could potentially be welded shut.


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## mcbrems (Oct 28, 2011)

Well, I ended up buying the Albright ED250B, with magnetic blowouts:

http://www.cloudelectric.com/product-p/sw-ed250b.htm

It's a great buy - Don't know what Cloud Electric has up their sleeve.
The switch is very beefy, and will easily accept 1/0 or 2/0 cable with
5/16" lugs. It also _snaps_ quite well when operated. The switch is ON
when pulled out, and disconnected when pushed.

I was planning to mount in my center console, at the bottom, just in
front of the shifter boot. It will be breaking the cable that joins the front 
and rear packs as it travels up the tunnel. It won't require a large hole
in the console panel to mount.

So far so good. I was pleased that the switch was hefty, but didn't expect
the button to be so large. It's like a sizable clown nose - 3 to 4 inches
in diameter. It screws onto the switch shaft with an 8mm thread (Albright
is British).

I hope you've been entertained thus far. The question is whether anybody
knows of a source for 8mm thread clown noses that are maybe half
this size. Maybe something that will look more James Bond-ish on my
console.

Cheers,
McB


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## Ziggythewiz (May 16, 2010)

You might want to rethink the location for that, especially if you want to make the shroom smaller. Mine is on the dash to the left of the steering wheel so an emergency responder can easily see and get to it.


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## Ivansgarage (Sep 3, 2011)

This is what i used for a em. disconnect 53 bucks. Got a pull cable going up to the dash. I took this all apart to check
it out, it is very heavy duty contacts and well made.

http://www.newagemarine.com/bep720.html













Ivansgarage Electric Sonoma
http://ivanbennett.com/


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## swoozle (Nov 13, 2011)

Ivansgarage said:


> This is what i used for a em. disconnect 53 bucks. Got a pull cable going up to the dash. I took this all apart to check
> it out, it is very heavy duty contacts and well made.
> 
> http://www.newagemarine.com/bep720.html


I've got the same one for use as a maintenance disconnect, but can you really rely on it to disconnect under load? It didn't look like there was anything special in there to keep it from arcing and welding shut.


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## lowcrawler (Jun 27, 2011)

Agreed. I use the BEP for a maintenance disconnect... but I'm not sure I'd trust it in a full-on condition.


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## PStechPaul (May 1, 2012)

I asked in another thread, but has anyone tried adding a freewheeling or flyback diode to the DC load to reduce arcing when the switch, breaker, or connector is opened? It should be fairly easy to set up an experiment by running a small DC motor and observing the arc with and without such a diode. I found a suitable fast-acting rectifier module for less than $50.
http://www.electro-tech-online.com/...ews/85310-when-flyback-diode-necessary-2.html
http://en.wikipedia.org/wiki/Brushed_DC_Electric_Motor
http://en.wikipedia.org/wiki/Flyback_diode


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## PorscheFan5 (Mar 24, 2015)

All,

I would like to post a few questions to this thread. I realize that it has been a while since the last post, however new products have/can be available.

Background: I am working on my 2004 Boxster conversion and am currently looking at the Emergency disconnect...My system is 144V DC, 1000A controller. Expect the operating current to be around 300-500A DC.


Have procured a Ez-Safe Disconnect from Recharge car - DPST with Anderson 350 connectors. This one is solid however have difficulty in finding the mounting location to easily get to it from the cockpit. Also this is a dual pole so can be used for maintenance disconnect (at no load) and can be mounted near my main contactor in the rear trunk...Has anyone used this? Where did you install it?
Now to the emergency disconnect. Has anyone looked the Gigavac HBD41 master disconnect switch? EV-Propulsion carries it and has a continuous current (400A) overload current 1 minute (2000A) and nominal voltage (1000vDC) ratings that I could use. Refer - http://www.ev-propulsion.com/disconnects.html .

I could potentially mount this in series with my batteries so switching this will open the circuit and no power would be supplied to the controller. Also this could be mounted inside the cockpit with the contacts on the outside (bottom of the car) where the battery wires are passing so as to be able to easily reach and break the circuit.

Would like to get thoughts from the knowledgeable people on this board. Thanks!


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## mcbrems (Oct 28, 2011)

I use the Albright 400 amp snapper as a dual purpose maintenance and emergency disconnect, and it's mounted in the driver's console between my front and rear pack modules:

http://curtisinstruments.com/?fuseaction=cDatasheets.dspListDS&CatID=7

400 A - ED 402

Using it as a maintenance disconnect will not cause arcing, since the main contactor will be disengaged. It has worked flawlessly, and thankfully I have never had cause to use it on the freeway!

McB


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## dtbaker (Jan 5, 2008)

PorscheFan5 said:


> Have procured a Ez-Safe Disconnect from Recharge car - DPST with Anderson 350 connectors.





my impression of anderson connectors is that they are not a great thing to use in the main Battery loop for a couple reasons.... one is fairly high resistance. Second is that with a relatively 'slow' disconnect, they should NOT be counted on to disconnect under load because of possible arcing.

You may be better served with big circuit breaker(s), and put them under the hood out of the passenger cabin. It is not hard to rig a pull cable thru the firewall in a 'standard location' by your left knee and labeled so that you and ER personel might see it if you are unconcious.

one specific circuit breaker that people have used successfully is the Heinman GJ1-B3-DU0250-01C . This is what is in my Miata (160v/1000amp controller) and it has never blown under load even though it's nominal rating is 250amps.... I think it's because I rarely pull 250amps for any length of time as I am up to speed in less than 10 seconds. If you wanted to beef it up, you could use a pair like the dragster guys do.

The gigavac disconnect I believe is rated for 24vDC make/break at 400amps.... I don't know what it would do at pack voltage; I would look into those specs a little closer.


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## PorscheFan5 (Mar 24, 2015)

Dan,

See the specs of Gigavac switch attached. Let me know what you think...

On a separate note, I was planning to use the red Anderson connectors to connect 2/0 cables between battery boxes (will have total 5 battery boxes)...reading your comment about the resistance makes me think...


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## dtbaker (Jan 5, 2008)

PorscheFan5 said:


> Dan,
> 
> See the specs of Gigavac switch attached. Let me know what you think...


I saw that. what caught my eye was the fine print in the make/break at 400amps was done at 24vDC..... telling me that perhaps the internals are not designed for anti-arcing at higher voltages.



PorscheFan5 said:


> On a separate note, I was planning to use the red Anderson connectors to connect 2/0 cables between battery boxes (will have total 5 battery boxes)...reading your comment about the resistance makes me think...


The Anderson resistance issue is hearsay... I have not measured that personally compared to a regular lug. But, why would you want to introduce the cost and two additional connections per connector anyway? Simpler to run your cable to the cell terminal without an Anderson in the middle.


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## PorscheFan5 (Mar 24, 2015)

McB,

Thanks for your response. Could you post a pic of the placement of the Gigavac switch in your EV? Since my battery cables are running under the car in the middle kinda hollow cylindrical area along the center-line, I was thinking of mounting the switch somewhere near the right foot say under the stick or the somewhere there...somewhere near 8 'clock 4-6 inches outside the attached pic...what do you think?

Also your earlier post indicated you were going to use the ED 250B and seems like ended up using the ED402...any specific reason? Also did you find the smaller diameter button you were looking for?


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## PorscheFan5 (Mar 24, 2015)

Dan,

I plan to use the Anderson connector specifically for the front battery box (BB) that is fitted where the gas tank used to be just aft of the frunk. In the other 4 BBs I will most likely connect directly with lugs...primarily owing to usability when and if I have to pull the front BB out...hope that makes sense...


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## dtbaker (Jan 5, 2008)

PorscheFan5 said:


> McB,
> 
> Thanks for your response. Could you post a pic of the placement of the Gigavac switch in your EV?



in my Miata, the circuit breaker is mounted on the rear 'rail' of the battery box.
http://envirokarma.org/ev2_mx5e/gallery/130125_new_dcdc.htm

in the Swift, I have it on the left side of the central 'component board'....
http://envirokarma.org/ev/gallery/110313_component_box.htm

in both cases operated using a choke cable pull with pull knob mounted under dash by left knee where it can be reached by driver and/or EMTs outside vehicle.


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## dtbaker (Jan 5, 2008)

mcbrems said:


> I use the Albright 400 amp snapper as a dual purpose maintenance and emergency disconnect, and it's mounted in the driver's console between my front and rear pack modules:
> 
> http://curtisinstruments.com/?fuseaction=cDatasheets.dspListDS&CatID=7
> 
> ...


the problem is that you don't have a MANUAL way to cut power under load in case main contacter welds itself together when it closes (which COULD happen if it closed under load or heavy inrush current). redundancy is a good thing when it comes to power off.


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## miscrms (Sep 25, 2013)

My local electronics recycler has one of these Jurassic Park type disconnects on the shelf. I really want it to use as an emergency disconnect. Breaks 100,000A at 480V.  Unfortunately they weigh 140lbs and cost about $1.5-2k used.  The mechanical "pump" handle featured in the movie is used to cock a large spring that breaks the contacts when opened.










Heck, I'd probably use it to start the car every day


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## mcbrems (Oct 28, 2011)

PorscheFan5 said:


> McB,
> 
> Thanks for your response. Could you post a pic of the placement of the Gigavac switch in your EV? Since my battery cables are running under the car in the middle kinda hollow cylindrical area along the center-line, I was thinking of mounting the switch somewhere near the right foot say under the stick or the somewhere there...somewhere near 8 'clock 4-6 inches outside the attached pic...what do you think?


I think you are speaking of the center tunnel. My battery cables definitely use that avenue to tie together the front and rear packs. This made it very easy to install the emergency disconnect in the center dash console. I think it's important to place the disconnect plunger in plain view, so First Responders will see it.

Here's a link to the install:
https://914electric.wordpress.com/2012/07/08/comfort-and-control/

Cheers,
McB


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## mcbrems (Oct 28, 2011)

That is what this switch is designed to do. The contact bar inside is under spring pressure, so it snaps open quickly to avoid arcing. I appreciate redundancy. I have Shawmut fuses for any possible runaway.


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## PorscheFan5 (Mar 24, 2015)

Hey Guys,

I just found out that Albright have a model ED 252B. This is quite a bit beefier than the 250 and I can use the two poles in parallel hence can also double up on 'breaking current' capacity. The B stands for magnetic blowouts that help reduce arcing (not available on the 402). I think this is ideal for my application... At $109 plus shipping it is a real good option.

Now I have to find the best location for it...As mentioned I will install it somewhere near my center console as my battery wires are passing though the hollow opening under the car in the center line. I could easily put it inside the glove box at the back of the center console, however need it to be easily visible to first responders so may have to find another place...suggestions...? I have abandoned the idea of putting the red EZ Safe disconnect behind the passenger seat as shown in the pic...

McB,

I have used up the center console space on the dash for my Andromeda display...:-( so cannot put the switch there...The display install did turn out pretty good though... I discarded the CD storage (who needs that...) and the cubby under it and was able to fit the Andromeda display!


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## PStechPaul (May 1, 2012)

That switch is only rated to break 1500 amps at 96 VDC. Many EV battery packs have much higher voltage, and peak current may be as high as 20kA or more. A fast-acting fuse can safely break such current and voltage. An EV battery pack should have such a fuse in the middle of the pack. The safest emergency disconnect might be a solid short applied across the battery (+) and (-) connections. The fuse and the shorting switch will be damaged or destroyed, but their combined cost is probably less than the disconnect switch or contactor.


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## TooQik (May 4, 2013)

These might be worth making some inquiries about:

http://www.reblingplastics.com/powerconnectors/high_current_dc-battery_disconnector.html

No idea what sort of price they go for though.


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## PStechPaul (May 1, 2012)

Those do not seem to be rated for high voltage battery pack disconnect under load. The version for HV has an interlock that disconnects the high voltage load separately before opening the battery connector.

A pretty cool ******* circuit breaker might be constructed using a fuse and a blank shotgun shell or perhaps a blasting cap to blow open the conductive strip. There is a patent for a similar device:

http://www.google.com/patents/US3848100


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## PorscheFan5 (Mar 24, 2015)

Interesting information Paul.

I have just ordered the Curtis/Albright ED252B-1 which has a 150V rating as against the 96V rating for the 250 (and even the 402). The magnetic blowouts will help with the arcing too. I will wire the two poles in parallel so will double on the current capacity too. Will get it next Wed. Need to finalize the placement when it comes. Will keep you guys posted on how it turns out...

Cheers for now.


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