50kAIC class t fuse

[Carrquik77]

I’m building a Victron 24v lithium battery system using 6@202 ah bigbattery .com batteries.
I’m wanting to use the Lynx shunt for this install but not sure about the 6kAIC of a Blue Sea ANL fuse. I plan to use a 600a BS ANL fuse for the Lynx shunt. However, I’m also considering a 600a class t from Bussman. It is rated for AC/DC use with a 50KAC at 500vdc
Surely the buss man would work but is 3x the money of the ANL but is doesn’t fit in the Lynx.
Just looking for some insight
Thanks

 

[ricardocello]

Lynx Class-T Power In - Victron Energy

The Lynx Class-T Power In connects and fuses up to two strings of Lithium batteries. It features a positive and negative busbar, and connections for two...

www.victronenergy.com

But it only goes to 400A I think.

Also, the FWH series fuses you attached are not Class T (they are better, Class J, I believe).

Personally, I don't trust ANL for anything, even if they are from Blue Sea.

Also, 600A is a crazy amount of current to handle, I^R heating is going to be considerable, even if you oversize everything.
One little milliohm will generate 360W of heat!
How much current are you expecting nominally, and can you match the fuse to the wire size needed?

 

[740GLE]

ANL and Megafuse have had a proven track record at 24v with lead acid.

Now does that apply for 24v and LiFePo? I’d trust a Megafuse over an ANL for my 230ah 24v pack, and I feel a class t is overkill. Again at 24v, if I had 48v I’d have a different opinion.

 

[Carrquik77]

Lynx Class-T Power In - Victron Energy

The Lynx Class-T Power In connects and fuses up to two strings of Lithium batteries. It features a positive and negative busbar, and connections for two...

www.victronenergy.com

But it only goes to 400A I think.

Also, the FWH series fuses you attached are not Class T (they are better, Class J I believe).

Personally, I don't trust ANL for anything, even if they are from Blue Sea.

Also, 600A is a crazy amount of current to handle, I^R heating is going to be considerable, even if you oversize everything.
One little milliohm will generate 360W of heat!
How much current are you expecting nominally, and can you match the fuse to the wire size needed?

I’ll be using two 5kva Quattros. The batteries have a built in 300a anl fuses but I want a main load fuse between batteries and system like it’s supposed to be. I’ll use Megas for the Quattros. The power demand from the Quattros will be close to max most of the time (without overload) but also want to consider enough margin for overload and any solar incoming. With that I figure 300-400 amps could be the regular. The class t Lynx is nice but only enough space for two batteries so I’d have to triple down on the terminals, which is not ideal.

 

[ricardocello]

I’ll be using two 5kva Quattros.

OK, that's what I have, except mine are 48V, not 24V.

Running 8000W continuous at low battery voltage, say 24V, and assuming 90% efficiency, you are looking at 370A continuous.
You definitely want a Class T or the FWH Class J fuse you've shown above for the doomsday scenario.

I've got 4/0 cable and a 300A JLLN Class T fuse for 48V, so I get why you would want a 600A Class T or J fuse for 24V.
It's just horribly difficult to keep the heat down at those current levels.

 

[robbob2112]

If you are going to pull that much current it makes a lot more sense to switch to a 48v system. Current drops by half, as does the wire size and fuse size.

I would use the actual class T holders verse having to buy a lot of the Lynx.

At those current levels ANL and Mega will generate a lot more heat than a class T. For the class T the higher the rated amps the lower the resistance.

200amp has 0.39 mohm and the 300amp has 0.22 mohm. This is because there is more material in the fuse link.

 

[ricardocello]

Current drops by half

And dissipated heat is only 1/4 as much because of I^2R

 

[ricardocello]

Link to the OP Eaton/Bussmann Fuse

https://www.eaton.com/us/en-us/skuPage.FWH-600A.html

 

[LakeHouse]

I want a main load fuse between batteries and system like it’s supposed to be.

What is this fuse intended to protect that isn’t already protected by other fuses? Each battery needs a fuse or breaker, each connection from the bus bars to an inverter needs a fuse or breaker… What’s the scenario where this main fuse has a job to do?

Also, I second the call to go to 48V. 10kW is well into the realm of don’t go less than 48V.

 

[ricardocello]

What is this fuse intended to protect that isn’t already protected by other fuses?

Presumably the wire from where the batteries are combined to the inverters cannot take the output of qty 6 202Ah bigbattery.com batteries (1212A at 1C).
It needs to be fused. We have not seen the OP racking/busbar topology yet.

 

[740GLE]

If you are going to pull that much current it makes a lot more sense to switch to a 48v system. Current drops by half, as does the wire size and fuse size.

I would use the actual class T holders verse having to buy a lot of the Lynx.

At those current levels ANL and Mega will generate a lot more heat than a class T. For the class T the higher the rated amps the lower the resistance.

200amp has 0.39 mohm and the 300amp has 0.22 mohm. This is because there is more material in the fuse link.

I second this.

I hope you didn’t buy those Big batteries yet. They have less than ideal track record. If your planning to really tax them I fear you’re going to be disappointed.

My personal cut off for 24v is 5k, anything above this needs 48v, again just my preferences.

 

[LakeHouse]

Presumably the wire from where the batteries are combined to the inverters cannot take the output of qty 6 202Ah bigbattery.com batteries (1212A at 1C).
It needs to be fused. We have not seen the OP racking/busbar topology yet.

Totally agree that we don’t have an answer since we haven’t seen the configuration, but that’s why I’m asking the question.
Surely the batteries could provide enough current to damage the wiring or bus bars (and that’s why the batteries are fused), but only if there’s a short. I’m not sure what the scenario is where a load (or loads) could draw enough current to damage anything, and not blow an inverter fuse.
Maybe such a scenario exists, in which case I’d be interested in what it is. But if there isn’t such a scenario, the ‘main fuse’ may not be necessary at all.

 

[Carrquik77]

OK, that's what I have, except mine are 48V, not 24V.

Running 8000W continuous at low battery voltage, say 24V, and assuming 90% efficiency, you are looking at 370A continuous.
You definitely want a Class T or the FWH Class J fuse you've shown above for the doomsday scenario.

I've got 4/0 cable and a 300A JLLN Class T fuse for 48V, so I get why you would want a 600A Class T or J fuse for 24V.
It's just horribly difficult to keep the heat down at those current levels.

It’s a build I’m doing for someone and was looking for any potential advice for larger “class” fuses. I have a dual 3kva 24v and have zero fusing between batteries and system. However as i stated, the batteries have their own bms switch and anl fuse. My system runs at about 70-80% max capacity everyday with 4/0 wire and the heat has never been an issue. Thanks for replying

 

[Carrquik77]

If you are going to pull that much current it makes a lot more sense to switch to a 48v system. Current drops by half, as does the wire size and fuse size.

I would use the actual class T holders verse having to buy a lot of the Lynx.

At those current levels ANL and Mega will generate a lot more heat than a class T. For the class T the higher the rated amps the lower the resistance.

200amp has 0.39 mohm and the 300amp has 0.22 mohm. This is because there is more material in the fuse link.

Yes I agree with going 48v. However, I’m building a new rig out for the owners and we are reusing their current batteries in the new build. The batteries are only 4years old and have never really been relied on for more than 2 months out of those four years. They’re glampers so spent most of the time plugged in at parks.

 

[Carrquik77]

What is this fuse intended to protect that isn’t already protected by other fuses? Each battery needs a fuse or breaker, each connection from the bus bars to an inverter needs a fuse or breaker… What’s the scenario where this main fuse has a job to do?

Also, I second the call to go to 48V. 10kW is well into the realm of don’t go less than 48V.

Reusing barely used 24v batteries for a rig. Otherwise stepping up to 48v would be the plan. They already have one 24v Quattro and just need to buy one more for a S/P system.
Yes the batteries have a bms switch and their own anl fuse, but I guess im creating a redundancy for a dead short scenario? have the same batteries installed in my own rig with no disconnect or fuses in between the Lynx power in “in” and the lynx power in “out”. So even I am relying on the battery’s bms switch and 300a anl for safety.

 

[Carrquik77]

Presumably the wire from where the batteries are combined to the inverters cannot take the output of qty 6 202Ah bigbattery.com batteries (1212A at 1C).
It needs to be fused. We have not seen the OP racking/busbar topology yet.

You are correct. 4/0 couldn’t handle the 1212a load even at 24v. Or, even 600a load for very long.
The batteries have their own fuses. In my System (which is very similar to this one that I’m installing) they’re all wired directly to a Lynx power in. I have a second power in that distributes to equipment (typical build style for VE equipment)

 

[Carrquik77]

Totally agree that we don’t have an answer since we haven’t seen the configuration, but that’s why I’m asking the question.
Surely the batteries could provide enough current to damage the wiring or bus bars (and that’s why the batteries are fused), but only if there’s a short. I’m not sure what the scenario is where a load (or loads) could draw enough current to damage anything, and not blow an inverter fuse.
Maybe such a scenario exists, in which case I’d be interested in what it is. But if there isn’t such a scenario, the ‘main fuse’ may not be necessary at all.

“Maybe such a scenario exists, in which case I’d be interested in what it is. But if there isn’t such a scenario, the ‘main fuse’ may not be necessary at all.”

I’m leaning towards that.

 

[Carrquik77]

I second this.

I hope you didn’t buy those Big batteries yet. They have less than ideal track record. If your planning to really tax them I fear you’re going to be disappointed.

My personal cut off for 24v is 5k, anything above this needs 48v, again just my preferences.

Reusing current components for a new build in a newer rig. These batteries have barely been used. They will get capacity tested first. But yes BB’s had bms issues with many of their batteries in the early days (20-21).

 

[robbob2112]

OK,

You are using two 5k inverted at 24v. That means max draw if both are pegged is 416amps.

If you want to bring things together and run from one bus bar to the other with a shunt between you need 500amp wire like 105c 500 kcmil which presents problems with sourcing the wire and the lugs and being able to source and crimp is. It will be easier to find 750kcmil but that is even more expensive. Better to just use two shunts and battery monitors. Also with this kind of current you better figure in the cost of a contactor that can handle 1000amps to be able to shut it down and not fry it the first time it opens/closes with a load on it.


BUT, each Quatro only needs to use 208 amps at max - your problem becomes easier -

If using Windy Nation 105c welding wire - 2/0 would do the job. The 4/0 would run cooler but I suspect the 2/0 is overkill. If you use wire that isn't 105c they you have to go up a couple of sizes to be safe. Use the 2/0 cable capable of 325amps. Use class T fuse at 250amps. Just be careful as the holders come in two sizes - I linked the correct one for the larger size fuse.

Blue Sea Class-T Fuse ~ Current Connected

The Blue Sea Systems Class T Fuse offers a high interrupt capacity for larger battery banks. Perfect for systems need a stronger fuse. Specifications: 125V DC Maximum Voltage 110A - 400A Compatible with BlueSea Class T Fuse Weight: 0.3lbs

www.currentconnected.com

https://www.windynation.com/products/2-0-gauge-black-red-welding-cable-various-lengths-available
They can also make cables with the ends on to length

Either of these holders - The lever one is easier to change a fuse so I use that style. It also prevents any shorting from occuring from stuff shoved in a bay.

BlueSea Class-T Fuse Block ~ Current Connected

The BlueSea Class-T Fuse block allows the use of Class-T fuses for fast acting circuit protection. Specifications: 320A Maximum Amperage 160V DC Maximum Voltage 5/16" - 18 (M8) Terminal Stud Size Weight: 1.10lbs

www.currentconnected.com

Blue Sea Systems 5502100 Ignition Protected Class-T Fuse Block 225-400A

Get two extra class T fuses, they aren't commonly carried so having a spare stored right next to the inverter is a win-win

When you say the batteries have ANL built in what do you mean? ANL fuses tend to get hot and also have a low AIC. Doing a trailer for someone else I would be all about safety and preventing shorts in any way possible.

I would personally switch out the ANL fuses to class T as well. The internal resistance of an ANL rated 200amps is 0.88mΩ and the Mega is 0.57mΩ. The class T 200amp is 0.39mΩ. So much lower resistance much lower heat radiated or wasted energy. I would fuse at 200amps and use the 2/0 wire from the batteries to the bus bar - They max out at 175amps discharge each. Max current in is 29amps each.

The other problem with ANL fuses is the low AIC rating on them, to much energy floating around with this setup not to play it safe.

For protection devices like this I wouldn't worry about a 1 time cost, if the rest of the system is correct they won't ever need to be replaced.


Just to illustrate what I mean - this is incomplete




The contactor is controlled by a 12v to 24v switched voltage. It is normally open, so no power now battery connect. I would run it off the vehicle battery.

 

[740GLE]

If you are running dual 5k in split phase power, 120/240. How much of your load is 240v?

It might be hard to balance 120v loads between units to get up towards the top of the capacity.

 

[LakeHouse]

If you want to bring things together and run from one bus bar to the other with a shunt between you need 500amp wire

There is an alternative: bolt the shunt directly to both bus bars.
It’s exactly what the Victron Lynx Shunt (and power in, etc.) is intended to do. No big wires required, the whole thing is bolted bus bar connections.

 

[robbob2112]

There is an alternative: bolt the shunt directly to both bus bars.
It’s exactly what the Victron Lynx Shunt (and power in, etc.) is intended to do. No big wires required, the whole thing is bolted bus bar connections.

I can see that. I would do a contactor bolted to the bus bar, then a shunt, the a smaller bus bar, then the cables to the inverter.

They other possibility would be 6 contactors, one per battery all tied to the same stop button.

I still would keep all the class T fuses.

 

[robbob2112]

A more complete version with switch and contactor and shunt all bolted together

The other option would be to use a 500a or 600a breaker instead of a similar sized contactor - but in that case you have to reach into wherever it is installed to turn it on and off verse being able to just mount a switch anywhere and feed the contactor control 12v. Contactor would be a NO style so when you have no power to the control it is de-energized.

 

[ricardocello]

are you going to fuse the 12v contactor control line, or put a fuse at the 12v battery before the switch?

 

[robbob2112]

are you going to fuse the 12v contactor control line, or put a fuse at the 12v battery before the switch?

Forgot that, it only would need to be a 5 amp inline fuse since the contactor control is in the neighborhood of 300~600ma, depends on the contactor.

Note - the contactor can also run off the 24v battery bus bars, but I think it is better to have the control completly isolated in case something bad happens. It is possible to run a dc-dc charger to keep the 12v battery topped up and also still isolated. And the 12v can easily be a lfp battery or as small as a motorcycle battery, just needs to have enough power to keep the contactor energized when using the main battery.

And - note - the drawing is just a suggestion to the op of something that would work and be safely fused using the equipment he has.

A little back of the napkin figuring the bus bars involved should be 2" wide and 1/2 thick pure copper 110 annealed.

pre made punched and coated

https://monti-inc.com/services/copper-machining-fabrication/bus-bar/

or just bare 110 copper - $55 for 12"

I've used these before

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Attached the drawio file as well.