This is very useful indeed. It will be even more useful to reference the brands and even models @SolarMike tested as that might have to do with resistance. For example, some unheard of brands also make “Class T” fuses and “DC circuit breakers”.
Damn it, I ordered EF3 yesterday.
I’ll test them with a micro-ohm meter next time I’m in the shop and compare their resistance to comparable MEGA, MIDI, MRBF, CNN, ANN, and Class T fuses of similar amperages, depending on what we have in stock. I have four 250A EF3 fuses that were carried back from German for me. I’ll post my results. MEGA fuses seem to also have high resistance and are usually the component with the highest temperature when we use a thermal camera to measure systems when we load test them prior to delivery. It will be interesting to see if the EF3 fuses are better or worse. I only have four EF3 fuses so my sample size will be small.
There is one USA distributor for Adler products but they don’t stock any EF3. They have to be ordered and have a lead time of 12 weeks by sea, and 5 weeks by air. Worldproducts.com is the distributor that Adler pointed me to. dredemer@worldproducts.com is the guy I have corresponded with.
Once I measure the fuses I’ll replace some MEGA fuses in a system with EF3 fuses and see how they do under continuous load for a while. We have a 24V 5000VA MultiPlus in an RV we are commissioning next week. I’ll send them off with a MEGA fuse, too, in case they have any issues.
Thanks for sharing the information.
P.S. I meant to say that I plan to ask my Victron rep if it’s something they would carry if they work well. I just haven’t had time to really test them but I’ll find some time over the holiday break.
Makes sense, when you look at a class t power in it has a massive amount of vent slots for cooling versus a relatively sealed regular power in or distributor.
Potentially could mount some cooling fans on the front cover of the distributor (like this ai generated image but with holes cut in cover for the air flow, maybe one blowing in and one blowing out. Would also help cool the bus bars themselves if you are getting up there in current.
I have measured the Voltage drop of a Victron 125Amps ceramic megafuse in a Victron fuseholder with an accurate dc meter @87 amps current: 91.40 milivolt, 8 Watt powerloss.
Total loss at the battery is 180milivolt, nearly 16 Watts; fuse + dc breaker + bms and terminals, voltage loss between each cell is average 3 milivolts, 0.26 watts.
But I don’t care🤪
I took some time to measure common fuses we sell and use in our shop. The measurements are below, along with some notes. It appears we are out of stock on the ceramic 200A 80V MEGA fuses by Victron. I only had one so I measured using the one and then four 225A fuses. My power loss calculations for the EF3 fuses don’t jive with the datasheets posted by @Brucey and @Vladyslav_Kh and the datasheet I have from Adler. I calculated about half the power dissipation that the datasheet shows. I used P=I^2 * R formula at 200A. Let me know if I did something wrong.
In our shop we use Class T fuses with large 24V battery banks and all 48V batteries. I wanted to explore standardizing on EF3 fuses for 12V-48V systems. They can’t be (readily) mounted directly at the battery terminals like MRBF fuses can, but if the battery cables from the terminals to DC buss (i.e. Lynx) are kept short and of sufficient ampacity, then the EF3 fuses in the Lynx might be acceptable.
For 48V systems we mostly use Pytes batteries, which have some form of OCPD right at the battery so Class-T or EF3 fuses in the Lynx is a good option for us. With Victron 48V batteries we will continue to use Class-T fuses very close to the terminals.
Does anyone have an opinion on using Victron’s individual MEGA fuse holder with an EF3 fuse very close to the battery terminals? It would save quite a bit of space given the size of Class-T fuse holders from Blue Sea Systems. The clear cover does not fit when using an EF3 in a Victron MEGA fuse holder, but we can 3D print replacement covers if we wanted to.
Please share any comments or questions. Thanks!
Seems like a solid replacement for an 80V ceramic megafuse on a distributor or power in. Biggest issue in the US prob be availability of spares.
The problem of the Adler EF3 fuses is not only the higher resistance, but it barely fits in the Victron Lynx Distributor. And because of that. The lack of enough ventilation. I mean. We are talking about something like your fingernail between the plastic cover and the fuse. So guess what. Somehow it wil get so hot that it leaves a mark on the inside, and after a while you might see it on the outside of the cover as well.
That’s a very good table. Can you add your interpretation of it? From what I can deduce, everything tallies with conventional wisdom. Class T and EF3 are the best for batteries. Mega from Victron would be good but for the rather low AIC. As you concluded, Midis are bad.
Out of curiosity, you don’t use DC breakers in your shop? A similar comparison for breakers would be very helpful.
You are right that there is less space between the EF3 fuse and cover of a Lynx Dist. I measured it using rubber washers before I could feel it impede the lid and I get 3.5mm to 4mm of clearance between the fuse and lid. I have three 5kVA Multi-II running my shop. I’m going to replace the three 200A MEGA fuses with three EF3 200A and run the chargers at full capacity for a couple of hours and see how it goes. The batteries are low so I can run each charger at close to 4kW (12kW total) for several hours. The three fuses will be in the same LD with a Lynx PIN on either side. Batteries and MPPTs are connected to the PIN’s on each side. If my measurements are accurate, that will give us about 40W of heat in a single LD. I’ll let it go for a few days if the lid doesn’t melt or show signs of damage.
One thing to note is that we design our systems to have no more than 400A flowing on any section of the Lynx buss bars because despite how Victron markets them, they CANNOT sustain 1000A continuous without melting plastic. We calculate 500A max continuous current without active ventilation is about all they can handle. Here’s a video that describes this: https://youtu.be/xCZEvgtnihk?si=cLRszrfyHLuDAI2Y
I’ll report back.
Generic MIDIs are bad, not quality MIDIs. That’s likely true across all types of fuses. I intentionally didn’t offer my commentary because I was hoping it might spur some conversation 
But yes, the table confirms the conventional wisdom. Chiefsolar brings up an interesting point that I haven’t yet tested. Will the EF3 fuses cause too much heat in a Lynx Distributor? I’m about to find out.
Here we go:
Here are the results after two hours of running each fuse at 4kW constant load:
Ambient temperature in the shop was 66°/19°. Between hour one and hour two the temperatures increased slightly, but no where near the temperature when ABS plastic begins to soften. See below from Google AI. Even in a 105°/41° compartment, I seriously doubt the fuses will get hot enough to soften ABS plastic.
I could run this test for one or two more hours and the temperatures would rise a little more but I’m going to call the test positive for using the size of EF3 fuses I am using in a Lynx Distributor. It’s a Saturday afternoon and time to call it a day
Because high-quality DC breakers above 20 or 30 amps are very expensive and take a lot of space. But mostly it’s a cost item. Instead, we use proper DC disconnects along with quality fuses. Only our commercial customers would stomach the cost of 200A or higher molded case DC circuit breakers - polarized or not. We will use good quality (i.e. CHINT, made by CPS) two-pole DC breakers for small PV arrays on mobile situations. Otherwise, we use IMO multi-pole PV disconnects and PV fuses and on the battery side it is fuses and high-current disconnects rated for DC use.
We don’t use any of the thermal DC breakers that so many installers use. They are banned from the shop and if we’re asked to fix an installation we will remove them. The main reason is I don’t trust them, but I also don’t want customers getting in the habit of tripping a breaker and resetting it all the time. There is a reason the breaker trips and I want the hassle of replacing a fuse to make them seek assistance and hopefully the person they ask for help knows to find the root cause of the issue and doesn’t just say “well, let’s use a bigger breaker or fuse”. 
If a 200A fuse blows I sure as hell want to know why! haha
Good call, I think using fuses and disconnects rather than breakers is the way to go as it’s more pocket-friendly. But I have been finding it difficult to find high-current, good-quality disconnects. I saw your excellent post on the subject and will do more research in that direction. For now, I use a DC breaker of questionable quality as a disconnect but make sure there is a high quality fuse before it.
What were his sustained currents, temperature of the fuses, and ambient temperature? Were his fuses properly torqued? How much current was passing through the buss bars at that point? What device(s) were connected to the fuses? It would be helpful to have some details. Those pictures don’t alarm me but it would be nice to avoid.
My test was in a cool environment and I was only pulling about 80A through a 200A fuse. I should be using 150A fuses but 200A EF3 is all I have. The 200A fuse will have a lower resistance than the 150A fuse, too.
I think for my next test I will double up inverters on one of the fuses. That should put me close to 160A continuous flowing through a 200A fuse. If I go in with my Tesla at low SoC and full batteries in the shop, I can probably run 6-8 hours (full discharge then recharge) continuous 160A through the fuse and see what happens.
Does the Lynx Power-In (M10) non T-Class have exactly the same spacing as the LD?
I’m thinking to use that for a project with EF3’s. I need 3 bus bar connections and like to avoid buying 2 T-Class Power Ins and save some $.