fuses should be sized for the wire, not for the system. this is a common misconception
read up a bit from google on this and you should know how to.
How do you size a fuse for your system?
I have a 100.8 volt system and want to protect Cells. The Cells can safely do 250amp after that is pushing it so I don't want to past that.
i am guessing that i can just pick any 250 amp fuse but there are a few different options and voltage ranges at the 250 amp like slow blow, fast blow, 250a @ 1000v, 250a @ 80volts , etc.
just want to know if if i am picking the right one.
Thanks guys
i am guessing that i can just pick any 250 amp fuse but there are a few different options and voltage ranges at the 250 amp like slow blow, fast blow, 250a @ 1000v, 250a @ 80volts , etc.
just want to know if if i am picking the right one.
Thanks guys
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read up a bit from google on this and you should know how to.
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Ok, well i've over sized my wires that is for sure. I am using 2/0 for my 100.8v. so if i am thinking correctly, the fuse should be the "weakest link" in the wire so that the wire dosen't act as a fuse. and if i want to protect at 250 then i need a fuse that is at 250 amps
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47 Posts
also in sizing a fuse does the voltage matter?
I assume that if one is to select a 32v fuse at 250 amp rating
and if you use that same that 32v- 250a fuse on a 100v and 250 amp it just makes it so that the fuse blows faster.
right?
I assume that if one is to select a 32v fuse at 250 amp rating
and if you use that same that 32v- 250a fuse on a 100v and 250 amp it just makes it so that the fuse blows faster.
right?
Yes, the voltage rating of the fuse must be at least as high as the voltage of the application, like any other electrical equipment.
Wrong.
The current (and time) is what blows the fuse, regardless of the voltage. Remember that there is nearly zero voltage across the fuse, since it has little resistance. Whether both ends of the fuse are 32 volts above ground or both ends of the fuse are 100 volts above ground makes no difference to whether or not the heating due to current flow melts the fuse... only the amount of current and how long it flows.
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6,613 Posts
Hi Mathis
Fuses are time and current devices -
If you have a 250 amp fuse it is expected that it will last forever at 250 amps - it would be nice if it would immediately blow at 260 amps
Unfortunately it does not work that way - if you go past the "forever" current the fuse will heat up and eventually blow - but if you are only 10% high it may take an hour or longer to blow
I'm using the fuse built into a Chevy Volt service isolator as my main fuse - in the Chevy the most it sees is about 300 amps
In my Device the battery current peaks at 1200 amps - but because that is only for a second or so the fuse does not blow
So when do you use 250 amps? - is that just a peak current for a couple of seconds?
Or is that a continual current as you drive up a hill?
If 250 amps is your peak current and you normally use 150 amps then something like a 180 amp fuse may well be ideal
Google - fuse current time graph
And have a read of the articles
Fuses are time and current devices -
If you have a 250 amp fuse it is expected that it will last forever at 250 amps - it would be nice if it would immediately blow at 260 amps
Unfortunately it does not work that way - if you go past the "forever" current the fuse will heat up and eventually blow - but if you are only 10% high it may take an hour or longer to blow
I'm using the fuse built into a Chevy Volt service isolator as my main fuse - in the Chevy the most it sees is about 300 amps
In my Device the battery current peaks at 1200 amps - but because that is only for a second or so the fuse does not blow
So when do you use 250 amps? - is that just a peak current for a couple of seconds?
Or is that a continual current as you drive up a hill?
If 250 amps is your peak current and you normally use 150 amps then something like a 180 amp fuse may well be ideal
Google - fuse current time graph
And have a read of the articles
Joined
·
6,613 Posts
Hi Mathis
Fuses are time and current devices -
If you have a 250 amp fuse it is expected that it will last forever at 250 amps - it would be nice if it would immediately blow at 260 amps
Unfortunately it does not work that way - if you go past the "forever" current the fuse will heat up and eventually blow - but if you are only 10% high it may take an hour or longer to blow
I'm using the fuse built into a Chevy Volt service isolator as my main fuse - in the Chevy the most it sees is about 300 amps
In my Device the battery current peaks at 1200 amps - but because that is only for a second or so the fuse does not blow
So when do you use 250 amps? - is that just a peak current for a couple of seconds?
Or is that a continual current as you drive up a hill?
If 250 amps is your peak current and you normally use 150 amps then something like a 180 amp fuse may well be ideal
Google - fuse current time graph
And have a read of the articles
Fuses are time and current devices -
If you have a 250 amp fuse it is expected that it will last forever at 250 amps - it would be nice if it would immediately blow at 260 amps
Unfortunately it does not work that way - if you go past the "forever" current the fuse will heat up and eventually blow - but if you are only 10% high it may take an hour or longer to blow
I'm using the fuse built into a Chevy Volt service isolator as my main fuse - in the Chevy the most it sees is about 300 amps
In my Device the battery current peaks at 1200 amps - but because that is only for a second or so the fuse does not blow
So when do you use 250 amps? - is that just a peak current for a couple of seconds?
Or is that a continual current as you drive up a hill?
If 250 amps is your peak current and you normally use 150 amps then something like a 180 amp fuse may well be ideal
Google - fuse current time graph
And have a read of the articles
Joined
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47 Posts
Thanks guys,
so my motor, the DLC-28 or ME1302, continuous will do 15kw. so, correct me if i am wrong...
@100.8 volt that is about 148 amps lets say 150 amps to maintain that power, right
This same motor will do 38kw peak, so doing the same math that is 380 amps rounding up.
since i don't plan to push it beyond 250 amps
i need a fuse that is like this:
125v and 175 amps
http://www.cooperindustries.com/con.../product-datasheets-a/Bus_Ele_DS_1037_ALS.pdf
something like this?
so my motor, the DLC-28 or ME1302, continuous will do 15kw. so, correct me if i am wrong...
@100.8 volt that is about 148 amps lets say 150 amps to maintain that power, right
This same motor will do 38kw peak, so doing the same math that is 380 amps rounding up.
since i don't plan to push it beyond 250 amps
i need a fuse that is like this:
125v and 175 amps
http://www.cooperindustries.com/con.../product-datasheets-a/Bus_Ele_DS_1037_ALS.pdf
something like this?
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1,960 Posts
Don't try to use a fuse to limit the current--use a current measurement circuit to monitor the level and pull back the current command if it exceeds your set point. This is a basic negative feedback control system.
Why would you want to end up on the side of the road with a blown fuse and not able to get back home?
Fuses are intended to protect the wiring, not used to limit the performance.
Why would you want to end up on the side of the road with a blown fuse and not able to get back home?
Fuses are intended to protect the wiring, not used to limit the performance.
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47 Posts
Well if this helps to clear thing up
I am using Nissan leaf Cells 82Amphr Cell.
I've been told that the nissan pack is fused at 250amp, so I just wanted to size accordingly to my system size. my controller can handle up to 600 amps but i actually blew up my last one ( thank God for warranty) and the fuse i had did not do its job in protecting it... so I trying no to make the same mistake.
i will make sure the BMS and Controller talk to each other to protect the pack.
I appreciate every one explaining this to me.
my idea of fuses was completely wrong.
I am using Nissan leaf Cells 82Amphr Cell.
I've been told that the nissan pack is fused at 250amp, so I just wanted to size accordingly to my system size. my controller can handle up to 600 amps but i actually blew up my last one ( thank God for warranty) and the fuse i had did not do its job in protecting it... so I trying no to make the same mistake.
i will make sure the BMS and Controller talk to each other to protect the pack.
I appreciate every one explaining this to me.
my idea of fuses was completely wrong.
Joined
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6,613 Posts
Hi Mathis
I am using the Volt main fuse in my system - similar to the Leaf in power levels
My controller is set to 1200 amps - and I do use full power at the track
So far the fuse has not blown - although I did blow my armature windings at the last event
I am using the Volt main fuse in my system - similar to the Leaf in power levels
My controller is set to 1200 amps - and I do use full power at the track
So far the fuse has not blown - although I did blow my armature windings at the last event
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5,347 Posts
Neither. You fuse for the wiring. The inverter needs to guard its own butt.
my wiring is 180amp welding cable. my proposed fuse is 225 amp. I am looking at 225 Amp A2D225R type fuses rated for 250 v. My battery is 144v. The inverter is not high powered. 120 amps max input.
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5,347 Posts
"180 Amp welding cable" means nothing. Most consumer welders have a low duty cycle.
What GAUGE wire is it?
What GAUGE wire is it?
35mm2 > I think in the USA they call that gauge 2
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5,347 Posts
Dude...that's kinda puny (that's what she said, as well?) and is as I thought:
www.wireandcabletips.com
Depending on the insulation max temp (it's continuously stamped on the cable), you only have about 115 amps you can put through it continuously vs a welding duty cycle.
What is wire ampacity and how do you find ampacity rating?
When selecting a cable, one must know its wire ampacity rating. This rating has been determined by the NEC (National Electrical Code)..
www.wireandcabletips.com
Depending on the insulation max temp (it's continuously stamped on the cable), you only have about 115 amps you can put through it continuously vs a welding duty cycle.
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