# Anyone running circuit breakers instead of fuses?



## Zak650 (Sep 20, 2008)

Hi, I'm looking for people that are running circuit breakers for fusing their car's battery pack and how it's worked out for them, if you are please respond with your thoughts and experiences.

Zak


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## TheSGC (Nov 15, 2007)

I have been using an Airpax 250 AMP breaker and it's worked out great. It trips at 313 AMPs, which has been fine for my system. These can be paralleled for better current, but I have only tripped mine once when I had my battery current to high. My old EV was limited to 300 AMPs from the batteries to be nice to the floodies, but I am going to get a second one for my new lithium EV.


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## ruckus (Apr 15, 2009)

Please thank you.

I have thought the same for some time. Must fuse BLOW?? Why not just trip a breaker to be re-set?? so simple. so easy. so reliable. 

I envision a breaker assembly like you have in your house. Why not?

Cheers


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## Coulomb (Apr 22, 2009)

ruckus said:


> I envision a breaker assembly like you have in your house. Why not?


Because interrupting DC is a lot harder than interrupting AC; with AC, the current passes through zero twice per cycle.

You can get breakers with DC ratings, and you can even find DC ratings for breakers that are intended for AC operation. However, the voltage ratings are often vastly different, and you often need a ganged breaker with several contacts in series to get enough voltage rating.

Don't assume ratings for a breaker; don't even assume that if you get a rating for one pole, that you can add the voltage ratings when you series them. You need ratings from the manufacturer or from a reputable testing laboratory.

The last thing you want is a false sense of security, where the breaker turns out not to be able to interrupt traction current, and will just arc over and contribute to the fire rather than prevent it when it's finally called on to perform its duty (open a high voltage, high current circuit usually with significant inductance). It might also be that you have to replace it after one opening under load, which means it's no better than a fuse, and may in fact cost more to provide assurance that it will open next time it's needed.

Don't cut corners with safety!


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## Zak650 (Sep 20, 2008)

I picked up 4 125 volt DC breakers, 200 amps each on ebay for a delivered cost of $40. Since my controls are limited to 116 volts I think they will work well, just need to decide how many to run in parallel. Twin Sevcon controllers fused at 350 amps each on the controls.


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## onegreenev (May 18, 2012)

I use both.


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## dladd (Jun 1, 2011)

I have both in my battery loop. The fuse is on the main battery cable in the trunk, and the breaker is on the cable between the two separate packs of battery cells in the trunk. I suppose only the fuse OR circuit breaker is really needed, but protection on every high voltage run seems prudent, and a manual disconnect (the breaker) sure is handy for maintenance or storage!

For a breaker, I have a single Airpax 250a breaker with the -53 long delay option (pretty standard part for an EV, I think). It is nominally rated at 250a, but according to the spec sheet it will sustain 200% (500a) for 20+ seconds and 400% (1000a) for 4+ seconds. That's plenty more than my battery pack will do, so it's fine. For those with larger stronger battery packs, you can run them in parallel. 

I know mine is only rated to 160v, but I'm sure you can buy them for higher voltages too.


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## Coulomb (Apr 22, 2009)

Zak650 said:


> I picked up 4 125 volt DC breakers, 200 amps each on ebay for a delivered cost of $40. Since my controls are limited to 116 volts I think they will work well, just need to decide how many to run in parallel.


Breakers that are connected in series or parallel have to be mechanically linked so that the break at the same instant. Otherwise, whichever one breaks last carries then breaks the full current, and there is no advantage to paralleling them.

Do you have a link to the Ebay page that still works? I've not seen a DC rated breaker that cheap.


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## subcooledheatpump (Mar 5, 2012)

http://www.ebay.com/itm/Cutler-Hammer-HFD-DC-Circuit-Breaker-70Amps-600VAC-3-PL-/200520859264?pt=BI_Circuit_Breakers_Transformers&hash=item2eaff97e80

Outside the USA need not apply.. but there are a good number of them out there. 

Of course this is just one example, only 70 Amps. Here in the states, you can get quite a bit of electrical goods from ebay pretty cheap

EDIT: Another example 

http://www.ebay.com/itm/Square-D-KH...uit_Breakers_Transformers&hash=item2ebb5a7ff8


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## Zak650 (Sep 20, 2008)

Coulomb said:


> Breakers that are connected in series or parallel have to be mechanically linked so that the break at the same instant. Otherwise, whichever one breaks last carries then breaks the full current, and there is no advantage to paralleling them.
> 
> Do you have a link to the Ebay page that still works? I've not seen a DC rated breaker that cheap.


It was one lot buy of the 4 breakers, opportunity knocked and luckily I was right there at the door, lucky me. Eaton Heinemann brand 

I can machine a link to join the breakers together so that they act in parallel.

Here's a link to similar lot of three 250 amp, it says not working but that may just be for seller's protection:
http://www.ebay.com/itm/Qty-3-Heine...uit_Breakers_Transformers&hash=item20c654ebd3

Here's a link to a new breaker 250 amp 125VDC $115
http://www.gogreensolar.com/product...anel-mount-circuit-breaker-obb-250-125vdc-pnl


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## Coulomb (Apr 22, 2009)

Zak650 said:


> Here's a link to a new breaker 250 amp 125VDC $115
> http://www.gogreensolar.com/product...anel-mount-circuit-breaker-obb-250-125vdc-pnl


Ok, these do seem to be DC rated. Though the one above seems dodgy to me; the breaker in the image is only 15 A. Only one dimension is given: 1.5" wide.


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## ddmcse (Oct 9, 2008)

I'm using some Hiney man breakers heinemann
GJ1P-Z120-2W
400 amp 160 vdc built in shunt that I do not use 
It has only popped once and that was seconds before the Logisystems controller made like the forth of July

http://ddmcse.com/amped/blogs/blog4.php/2010/05/08/2010-05-01-14-59-59-jpg


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## Zak650 (Sep 20, 2008)

ddmcse said:


> I'm using some Hiney man breakers heinemann
> GJ1P-Z120-2W
> 400 amp 160 vdc built in shunt that I do not use
> It has only popped once and that was seconds before the Logisystems controller made like the forth of July
> ...


Do you have an idea what kind of amps you were running when it popped?

What amps and volts did it normally see during your normal driving routine?


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## JRP3 (Mar 7, 2008)

dladd said:


> For a breaker, I have a single Airpax 250a breaker with the -53 long delay option (pretty standard part for an EV, I think). It is nominally rated at 250a, but according to the spec sheet it will sustain 200% (500a) for 20+ seconds and 400% (1000a) for 4+ seconds. That's plenty more than my battery pack will do, so it's fine. For those with larger stronger battery packs, you can run them in parallel.
> 
> I know mine is only rated to 160v, but I'm sure you can buy them for higher voltages too.


I've been running the same breaker in my 120V 550A max system, very handy for service disconnect. Mine has a note that the ratings are for vertical mounting, I think horizontal mounting increases the trip current some, which is how I have mine setup.


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## ruckus (Apr 15, 2009)

dladd said:


> a manual disconnect (the breaker) sure is handy for maintenance or storage!


Yeah, A breaker on the battery + and - would allow 'tinkering' on the motor/shunt/contactors/controller without manually unbolting the battery pack.

Of course it adds one more point of resistance...

I was actually thinking small 12v breakers would be nice instead of fuses. Anyone have good examples of those?


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## JRP3 (Mar 7, 2008)

Here are some that plug into conventional round fuse holders
http://www.delcity.net/store/Snap!in-Circuit-Breakers/p_167863.a_1.r_IF1003?gclid=CMXcp63Ut7ACFYeo4AodI1H_8A


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## ddmcse (Oct 9, 2008)

Zak650 said:


> Do you have an idea what kind of amps you were running when it popped?
> 
> What amps and volts did it normally see during your normal driving routine?


very minimal amps . was going approx 25mph
it was definitely caused by the Logisystems controller
normally I see 300-400 amps at the motor but on weekends I turn it up and can see 900amps at the motor
I have a 156v pack which can see up to 180-ish volts off the charging


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