Victron energy multiplus-2, DO NOT MAKE THIS MISTAKE. 

Glad you seem to have gotten it fixed, however, you've opened yourself up to the *potential* of creating a new problem. The crimp sleeves you used are not designed or intended for that purpose. What you used is designed for, intended for, and UL listed for combining several bare ground wires. They are not intended to be used as a ferrule. The crimping tool that it seems like you used for the crimp sleeves provides a substandard crimp that is almost certainly not uniform around the circumference of the conductor, and therefore may result in a high resistance connection. The result of that you've already experienced once before...HEAT. I would strongly suggest you purchase the proper ferrules and the proper crimping tool for those ferrules and redo what you have. It will make a MUCH more durable connection, far superior to what you have. Otherwise, you may have a technician tell you that once again, it's your fault, because you used the wrong components and the wrong tool. Search for "#6 AWG Ferrule" (or the appropriate size for your conductors). You find the right parts, as well as the proper tool.

Sorry to see the struggle. I will say that the ferrules you used are probably going to cause the same issue. The ferrules to use actual crimp the wires in perfect squares to fit nicely in the inverters terminals. Just my two🤙🏼

FYI: Ferrules are for fine stranded cable, the cable you are using for AC OUT does not require a ferrule and will likely be detrimental to connectivity.

Others have already suggested that you use the proper ferrule or risk a repeat problem, so I'll elaborate on wire selection. Even people in the electrical field often don't know the potential problems with solid vs, stranded, vs fine stranded wire. Some connectors are designed for only solid wire. Some are designed for solid or stranded but NOT finely stranded wire. Some can be used for finely stranded or stranded but NOT solid. If the terminal is not rated for solid you do not want to use a ferrule because you are essentially making a stranded wire into a solid one. Most connectors will accept solid and stranded but not finely stranded and that's where most of the issues arise. Stranded would be wire with 7 or 19 strands, 30+ would be finely stranded. Finely stranded is common like in SO cable or welding cable. The BIGGEST issue is simply finding out what type of wire a particular terminal is designed for. Sometimes that info is even hard to find in the terminal manufacturers data sheets. In your original failure, looking at the damaged cable it looks like the connector pinched the insulation and not the conductor and the only reason it worked at all is because it was barely making contact. Without knowing anything specific on the connector ratings, I would recommend to replace the fine strand wires with 19 strand and not use any ferrules because you don't have the correct ferrules or crimper. Wire strip length IS a common problem with electrical terminals whether too short or too long. Using a screwdriver or pick in your case to hold the spring open while inserting the wire is good practice. These types of spring cage terminals are becoming more popular because you are assured of having the correct wire clamping force (and fewer meltdowns), whereas a screw type terminal relies on the user using a torque screwdriver to the proper torque. The problem with these spring cage terminals is that you can strip the wire too short, insert it, and not be able to see that it is pinching the insulation and making a poor connection. Sometimes you'll get lucky and it won't make any connection at all and you'll then find and correct the problem. Other times you end up in the situation you found yourself in...

I ordered a victron on Amazon. When I saw the connection on the unit, I sent it back and got a different inverter with studs

I just installed this unit on my 5th wheel. Tested everything but defiantly going to do a longer test pulling more amps and checking for heat at those connections. I was a little worried about my connections so I looked in the manual and it said wires should be stripped .7 inch. Thanks for your video, it does'nt take much to burn one of these rigs down!

Thanks for the info. I have just purchased the same one along with new solar and more Lithium batteries. Getting ready to install and I’m sure glad I came across your video.

Awesome video my friend! That's what good friends do..put it out there that a mistake was made and don't do what I did.. Great for the company to step up and help out. RU-vidrs..the good ones like yourself are their voice on these matters..alot of people watch you and helps them (the company) out in the long run..free PR!! Great job as usual my friend! Keep on keepin' on!!

One thing to watch for on those push in type connectors: If the exposed wire is too short, you could shove some of the wire covering into the connector. This would partially pry the connector apart and reduce the amount of current it can handle. I personally dislike this type of connectors. They use these reduced force connectors in cars to make it easier to install wiring but I've had several in a dodge and chevy melt when the blower was cranked up and stayed there. Just too much current. I've also had a fire melt an electric clothes dryer power cable because the wiring in the fuse box was a poor connection. It was old so fibration could have loosened the connection, the copper wires oxidized or the screws were never torqued to begin with. Just venting, hope this is helpful.

Ahhh.....the easy life a of motorcycle vendor lol. Really cool that the company stepped up and warrantee the system. That says a lot about their business ethics. Good stuff man!

I just ordered this same unit from them today. The guy was very helpful. Told them I saw it on your video.

Trim your cable cover 8” back, exposing the 4 wires. Expose 3/4” of wire. Shape the exposed 8” of wire in an “S” shape. Insert the end of the wire into the proper hole on the Inverter. Insert a pick (eyeglass screwdriver, etc) to release the pressure lock. Force the wire into the hole 1”. Remove the pick. Repeat for the other 3 wires

Two small things, if you have wires without a solid core (which is common in Europe for cabling) always use ferrals if you don't have special connectors like eg. Wago clamps. As for crimping I preferr the hexagonal crimpers, create cooler connections here. And the most important one, if you have connections that are loaded to or near max, use an IR cam to make a quick check... They are cheap compared to the equipment that burned up and you can also check if cabling is ok (it's perfectly fine if it's just a usb ir cam that you attach to your phone) Btw... If you'd use the victron quattro you can have your backup generator automatically used.

Your a top bloke for sharing this Adam ! I will certainly be adding a "service loop" into the wiring prior to termination for stress relief.

I agree with you on the use of friction type connectors. What's even more is that a ferrule might tend to prevent more strands from contacting the spring loaded friction connector. And if that is true you may burn another unit. I agree with you on the use of lugs rather than those connection points that you cannot see. I'd much rather have a Sigineer, or Aims.

Screw terminals have shown to fail in the automotive and rail industry through vibration. Spring loaded contacts are the norm and stop the cable from working loose and are used widely in these industries. This is a good modification to the original screws.

Adam, you’re assumption is absolutely correct and I would bet you did everything correctly. Those spring connections are horse shit and should be screw thread lugs. The burning is caused by a loose connection and as the temperature goes up with amperage and loose spring connection, the cheap spring metal loses even more of it’s spring strength and the problem spirals out of control. Heat up a safety pin and watch it lose it’s spring strength. Keep in mind that the metals needed to make strong spring connections are nothing like the metals needed to make the best electrical connections. They say not enough extra bare wire hanging past the shark bite…I say bullshit, it was a weak shark bite connection.

Nice of you to share the info to make sure no one else runs into the same issue.

Thanks for caring about helping others of us who may do the same thing.

Definitely a New PCB on the Old Unit is required, That's totally amazing that they covered that on the warranty 👍 Victron is the unit I like but I go for a Quattro 15,000W 230V unit 48V with Victron MPPT 250V/100A terminal type Victron or BYD Batteries

New subscriber here. I have always thought Victron was made better than the rest. I am glad the distributor and manufacture supported you. I am with you on the ferrule usage. I plan on using those on solar charge controllers as well. All the best! Thanks for your video.

I usually strip the outer insulation of the cable way more. Let's say 4". Use the excess length to make a 360 degree curl towards you to allow each wire to move independent from each other. It will make mounting easier and there is less risk of mechanical stress since each wire can move independent form the others.

Thanks for explaining this issue you had, just about to hook one of these up in my campervan.

Thanks for sharing Adam, I have the same inverter, but I used a full #6 wire for the ground

It’s because your ground is the most important art of the system, I don’t know how many systems I’ve gone to fix for others, where they installed it, the ground was bad and toasted everything else. Ground #1 priority!

Very good video! thanks for sharing. I'm about to install one for a friend and since I have the original I had no idea they changed lug input on the AC side.

Push it in as far as it can go.

when you are testing your system, try using a thermal tester (infrared) to see if the connector and cables for getting too hot.

Thanks for sharing your precious experience! Cheers from Ukraine!

Glad I ran across this video, since I’m getting a victron system good to know. So what possibly caused it that the wire was not stripped far enough back and kept it from fully making contact on the bare wire, meaning that spring loaded device to hold the wire was probably on the very end of the insulated wire and barely touching the end of the bare wire.

Few years ago I had contact with a technician from Phoenix (who I believe is the manufacturer of that type of PCB connector mounted on the Multiplus-II). I had a project working with Phoenix SPT spring loaded connectors and they where NOT recommending using ferrules when using spring-cage connections on heavy loads. My project was concerning high DC loads in 12V systems, but If you can check the P/N number on the damaged mutliplus and look into the datasheet from Phoenix you would get all recommendations i believe.

Mate, with the amount of power you’re consuming, consider moving from using 12v to 48v or at least 24v. Using higher voltage means lower currents and hence less heat on connectors. Also you won’t have to use such heavy gauge wires. It may be expensive to do but in the long run, it will pay dividends

awesome glad you got it installed Adam dont need those problems at the rallies.

I really dislike these types of connectors. The screw down seem much less prone to error

Great video Adam thanks for sharing stay safe 👍

I learned a valuable lesson! Thank you for posting !

The manual for the multiplus II clearly states input and output connections are to have ferrule pin crimps applied to the ends of the cable with a length of 0.7 inches. But they're not stating that what you should really be using is finally stranded wire like the SOOW cable you have for one of your connections. You don't force those cables into the spring connections you should release the spring tension with a small flathead screwdriver first, then insert the wire with ferrule crimps on it into each termination and release the spring. This has got to be done correctly or people are going to start having fires. I think people have gotten lucky. Keep in mind that this is a European design and in Europe wiring is not done the same way as here in the United States. Everything is 240 volts or higher and therefore wire size is typically smaller for delivering the same amount of wattage.

i am on my second victron first was victron multy plus 12 2000 80 on more than one occasion i have triped 30 amp shore power using pass through never a problem with the lugs screws at all two years of service. Live aboard vessel i am so glade i seen this before i got any futher on installing a multy plus II 24 3000 70 Its still in the box

Glad you got it fixed. I’m pretty sure the installation manual mentions using ferrules.

Had to watch this because I completed my install with the same inverter just recently. I’m happy to report that I noted all the issues you encountered here but fortunately, my instincts forced me to make the corrections before applying power. I replaced my 6/3 THHN wire bundles with 6/4 SGX like I see you using. So much easier to work with. When trying to apply ferrules, I noted that 1) they were too short and 2) after crimping I could see gaps between the conductor and the ferrule. I didn’t like that so my solution was to tin the leads with silver solder and then using a small screw driver to pry open the port (you showed the same with your pick tool) to insert the conductor. I did all of this while the Victron Inverter was on the shop bench and I could verify connectivity and they passed the “pull test”. It made the install a bit tricky with both wire bundles coiled up and hanging down, but with planning and careful execution, I got it in. I’ve tested my install several times here at home and on a couple of shake down cruises and haven’t had an issue. I’ve loaded the inverter up almost to the point of overload and tested the 4/0 cables and the 6/4 SGX cables with my IR temp gun and they were fine. Fingers crossed they remain stable. Thank you for this production and I’m happy to see that your solutions were similar to my install. I can rest easy knowing that I didn’t do something that could be a problem later. Cheers!!

Do not use ferals with that inverter, the cause of the first failure was because the wire was not stripped enough, This is a good connection that will stay tight forever, unlike a screw terminal.

As an industrial electrican iv used these same terminals one other point is to make sure the jacket of the wires is cut back so the insulated wire is exactly straight in to these terminals cocking them reduces the surface area that the spring can contact wire / furrel, less surface area will produce more heat for given amperage. the spring terminals in these are great verses screw terminals with viberation spring will give constant pressure screw will loosen with the vibration going down the road or if machinery viberates.

Oh wow I was going to get a Victron. but after seeing they use spring terminals for these heavy wires. I will switch to the Schneider | Conext XW PRO 6.8KW. I really do not like spring terminal connections. Also thinking unless your using a ferule that is long enough for the entire wire length it may have an even harder time making a good connection probably better off with the bare wire making contact without any uneven surface. Or you can try to find longer ones online. definitely appreciate the heads up on this issue.

Ref commentry from 20:28 onwards. Quite sure that AC-Out is bigger than AC-In because of Power Assist capability of the MultiPlus II. What this means is that max current coming from grid/generator (AC-In) will be added to by the inverter itself (from batteries) in order to provide an even larger current on the AC-Out. Hope this makes sense.

I wish they just used proper screw terminals indeed, just feels more secure.

that 7 strand 6/3 solid romex definitely doesn't need a ferrule, it will just eventually get loose and fall off without soldering. But the fine stranded marine wire did need the ferrule.

Suggest you rewire ASAP to prevent more problems. Look into marine wiring standards : domestic solid wire cable is a very bad idea in vibration prone environments - it will stress fracture. You should be using flexible cable, such as Arctic grade and ferrule sleeves that go the full depth of the socket.

I 100% agree with you those plastic wire connections should be lugs. There should be a heavy tinned crimped lugs on the end of each wire and those thread on to a lug that is the safest and most secure conection

Thanks

Its nice that they warrantied it for you. Oh yah... it was fairly obvious from where the damage began (at the terminal block), but it is doubly clear from that picture of the wires that you didn't have enough lead-out stripped. If you look at that red one, the insulation shorted through from the pressure of the terminal almost twice the wire-length from what you stripped. And yet there was still good insulation further up towards the stripped part of the wire. That means there was pressure on the insulation behind that point from the terminal block when there shouldn't have been any contact at all with the insulation. What almost certainly happened is that the friction terminal rode-up on the insulation when you pushed the wire in and lost pressure on the 'good' part that you had stripped, resulting in arcing. So you definitely did not strip enough wire. This is making me nervous, actually.... tonight after the solar shuts down I am going to re-check all the connections into my solar inverter which use a similar mechanism. To make sure that I stripped enough insulation(!). -Matt

It's possible to replace those connectors, probably made in Germany 🇩🇪 or Netherlands 🇳🇱, you will probably need a proper desolder station & you will need to get all the carbon deposits off the PCB's or you can have tracking problems, I've repaired worse than that in my past, If your doing the repair yourself please be aware you don't damage the PCB, I agree the connections on those units would be best with nut & bolt connectors 👍 I was working in the Aerospace Defence industry were very aware of things that can be improved as a Electronics Manufacturing Hardware Test Engineer... your 100% right ✅ improvements can be made on those units.

Great tip! 8:19, I'm also OCD, I would get an insulation cutter to neaten things up. The 12V system will get hot, those cables are handling a lot of current.

Just a general comment on ferrules similar to what others have mentioned. Getting the correct ferrules with the proper crimping tool goes a long way, but above that get UL listed parts as well. The correct 6awg ferrule from Panduit for example are less than $1 each. Many other companies to choose from as well that offer UL listed components. Again, also highly recommend the proper crimp tool, for all your crimps! Stay safe out there everyone 🤙

I agree, you need marine grade wire and the proper ferrules with a proper ferrule crimper.

Thank you very much !

I am switching from a multiplus i to a multiplus ii inverter. Im not sure why they used this style connector on the multiplus ii instead of the connector on the multiplus i. I will take greater care in connecting the wires to make sure we do not have a problem. Thanks for sharing your experience here. Larry

Adam you made this harder than you needed too my experience as a electronic technician to solves this problem i would just apply a good even coat of solder to the expose copper and than insert them leads into there location and no need for sleeves

I am an engineer that designs power electronics. Some years ago, I designed a product with similar terminal blocks. It was a mistake. When terminated perfectly, they work but it is really easy to not be perfect. It is also nearly impossible to know if the wire has been terminated properly, especially by end users. For similar voltage/current connections - I now use dual screw blocks, lugs, and even custom machined blocks to be more reliable. I also use Victron gear and love them. They should re-consider using these terminal blocks in my opinion, the rest of the design is really robust.

I had the exact same thing happen to mine. I had the Mutiplus II 2X120. I did get the unit replaced under warrantee. My comment to Arizona Wind and Solar was that spring clamps for a 50 amp outlet is a bad idea. It was the same common white wire outlet that burned out. I raised the draw off the generator to 42 amps and it burned up. I'm not an electrical engineer and this is strictly a guess, I'm thinking that when this is powered by the generator, the sine wave is synchronized. The would mean the common white wire could have as much as 84 amps on it. Unlike a split phase where the return voltage is self canceling, therefor reducing the voltage on the common wire to near zero.

Advice from experience get the correct diameter ferrules and length doubling them up not the best and pre bend the wire before ferrule crimping other wise you risk the wire stands pulling loose

@amsoil Adam. The needed stripping length should absolutely be specified in the manual of the inverter, AND it’s always written/specified on the green (phoenix Contact) terminal itself (mostly in one of the sides.) The use of ferrules, especially with those quite ridged cables you use, are not a must. Only with high flex cable it’s recommended, ensuring you get all thin copper wires in, but also then you can do without. So: using the right stripping lengt of the wire is a must! IF you Thea want to use ferrules, they should be exactly the diameter of the used wire, and the should have the same length as you adviced stripping length. On top of that you should then use a calibrated stripping tool to crimp them properly, because otherwise you creating a high resistance point between the wire and the ferrule again.. beware of that!

The same or similar terminals are used in industrial automation wiring from Phoenix Contact, Wago, Weidmuller, and Weind (all German I think), w/ Phoenix known for green. You can use crimped ferrules (I do), mainly to avoid a stray strand sticking out, but most electricians insert the bare stranded end. I use ferrules w/ a plastic collar (Digi-key catalog). Even with a ferrule, I never just push the wire in, rather hold the spring open via thin screwdriver in the release slot, as you did on this 2nd pass. I recall the spring-cage type are usually only for ~10 A max and ~16 awg wire. For power wiring, the terminals usually have a screw clamp. Seems a bad choice for Victron to use spring-type for such high currents. I would worry as the system ages and the wires corrode.

Good Idea for this video. I know you will be using this if this happens again 😊.

If the grapping connector part of the Victron inverters are flat and the ferrule is round, it only makes contact on 2 places. When it still was the multistrand cable, it would be squeezed over the whole length on top and bottom. This would be a better connection in my opinion.

Those connectors are great, I do not use ferrules, max contact is with the multi strand wire, do not use low strand count “hard wire”. Use a small electricians screwdriver to open the contacts and Bobs yer uncle. (I see your point re ring terminals)

Geeze man, I hope it all works out for you from here forward. You seem to have had a run of bad luck, hopefully you’re still smiling. Thanks for making this YT. 👍

Ha Adam. sorry for your equip meltdown. For the feral's, they make feral crimpers that do a lot better job crimping the ferals than some pliers or whatever you used. the crimped ferals should reform the wire and feral into a long square shape. properly crimped ferals look way different than your new wire ends in the video. amazon has these crimpers and various lengths of ferals. good luck on the replacements. I had to learn this lesson also. I also recheck all electrical connections tightness every 6 months or so. I always check new install connections after putting a new piece of gear into service. There should be torque specs for all the connections.

Yikes, that ranks high on the pucker factor meter! Glad you caught it quick and I agree, that's an odd connection terminal for your ac out. My multiplus and quattro units use stud and ring terminals for ac and dc. I guess victron went with that clamp style on the multiplus 2's to save space (?) I've had great experiences with NAWS as well. James and Logan are fantastic. Thanks for sharing!

12:20 Well, i can understand your concerns, and for high power fixed installations, it's still standard to use screw bolts in most of the cases... But additionally it usually entails you to fasten those bolts to a very specific torque for optimal connectivity and safety.. Those 'Cage-Clamp' connectors on the other hand, are - if handled correctly - usually a way better solution for smaller loads, even up to your 50amp boxes. They always provide a defined amount of pressure, usually even provide a small edge to break oxydation on conductors and they're way easier to handle, especially if you change things from time to time. Maybe look out for some WAGO vs Wirenut comparison clips on youtube. Even on the heating and melting side, wagos and other cage-clamp connectors usually come out as first in terms of security and easy handling. ;) Juste some 2 cents from someone others ocd. ;)

Thanks for the heads up!

I don't think there is anything wrong with saying "This unit requires all wires to be of 4 Gauge with Ferrules of ". But to not have a sticker covering the terminal block that says that, and to let people learn it the hard way is pretty garbage. They should be doing more to inform the user of the requirement.

Many thanks for the good advise however, besides this particular problem which you have clarified for us all, I always tend to put a round loop on any wire that connects to a circuit board both for flexibility and against any potential stretching that might occur by a pulled external cable.

I wouldn’t use ferrules unless manufacturer called for them. I have tinned the wire/cable ends that go into the connector on that unit. The result is a very low resistance connection

I have installed similar multiple here in South Africa they had screw terminals there, I don't those push in are a great idea

The springs are made wit a rounded end to accomodate just pushing in without depressing the spring. If the wire isnt stripped long enough, the pressure of the spring pushing the wire back out, along with vibration, will cause the connection to fail. We found this out the hard way with connections on conveyor for the cables powering the rollers and we would lose power.

Thank you for the video!. I was just about to purchase one of these Victron units. However, I'm not convinced you were at fault here. I'm not impressed with those spring-loaded connectors. I'll most likely look for a unit that uses lugs.

Thanks Informative

THANK YOU, THANK YOU, THANK YOU. Have two Quattros on order and I would have been in the same dang boat. (a $7,000 boat wo the pull of a channel ... ouch!)

Thank you

If your generator is dual wound then you will need to jumper the AC input into the ATS. The Victron MPII 2 x 120 will only pass through AC input L1 when the incoming power is single phase. If your generator is putting out single phase power (Dual wound) then you are only pulling from L1 of the generator. This can bog down or overload the generator. Open up your ATS and check the voltage between L1 and L2 on the gen input with it running. If they are 0V - 10V then you can bond them safely with a piece of 6G wire. This will resolve your generator issues. As for the ferrules, I would forgo them altogether. The thick copper ones you are using aren't intended for that purpose but the thin metal ones will pull right out. I tested this myself and found that no ferrule is the best option with both fine and thick stranded wire. I'm sorry if this was already discussed in the comments. I didn't have the time to read over 200 comments but I thought I would share my input.

I bought a Victron Multiplus II from Battleborn Batteries in March of this year. Installed it in my rig in April. Started camping in May at a frequency of 5 days camping and 3 days home, so been giving the rig a fair amount of use. 50/50 dry camping and hookups. We are currently camping and are going through a heat wave as is most of the country. The AC has been running a lot. Yesterday, I went to the store while my wife stayed with the rig. When I got back, she told me that everything turned off in the rig, then came right back on again. I took a look at the Victron app and saw that we were inverting. Checked the shore power and it was fine. Opened up my multiplus and found the neutral lead of the input terminal had fried. No other lead was affected. My question is, has your second unit been okay with what you did to try to prevent the problem again? I do not think that you or I had done anything wrong. I had about 5/8” of bare wire in that terminal. I think it’s simply a very poor design. It needs screw down terminals, period. Sorry for the long message.

Thanks for sharing this. I am contemplating buying one of these and was not happy about the type of push connector they use. I'm on 230v ac so half the current and cable size you work with, so hopefully less potential for such issues. If they must use push connectors, I wish they used a lever type, like Wago lever connectors, rather than having to use a spike in a hole. Glad you had a decent dealer to help you out.

Thanks for the very important tip.

Quick-release terminals are a bad tone for such expensive equipment. I hope they are smart enough to abandon them and put the bolts.

thanks for info

You might want to get an infrared camera to check all your terminations... loose connections and not torquing your lugs will cause this

This is not bad damage. I had to fix mine from rain once and from a mistake with a grid tie inverter connected to ac out. I had to replace transistors and some capacitors and it was about 100$ to fix it. If the logic board is fine its fixable.

the second message might be from andy aystralian guy off grid garage ... he mentioned at least 2 times on his videos about disliking the style of those green terminals!!!! nice choice man... costy but worth trusty i guess!!!

You see the top hole you need to stick a thin screw driver in it before inserting the wire all the way in

They also had a bad bunch of these units go out initially. They’ve been good to get them replaced as they fail but have not done a recall - Victron seldom does recalls.

i lost my previous comment ... but for what you do and what i hear... youll need 2 x Qaudro 5/10.000 48v depending on the budget and i would place some 48v 100amp batterys rackmount Litime/sok or something... there about 1400$ a piece...5kw ..4x 20kw ...but that means youll need to change your mppts also maybe depending on what you already have ( look up on victron mppt calculator and play with your panel info / strings and s / p and youll know if you can keep them or just by one more normaly you can keep them because 48v is better you can put more on the mppts than if you run a 12v system...so ja ... advantages ..) ... buttt the load you can put on those is higher pass true ...smaller calbles for the batterys ...but 48v batterys you can expand them more easy you just add as you go..in p.. - - sell what you have now and upgrade haha hard life ..i know ... and or ....install a bridge so you can switch from wall only as a fail safe so that the high voltage is isolated from the solar side also an option ... and if you do change mppts you may keep one to run external folable panels ...so dont just trow parts away sometimes you can still use them haha

Adam... use 600 volt Anchor Marine wire...not what you are using. West Marine!

When copper is oxidised as shown, any weak acid will take it of chemically in seconds. I use oxalic acid but hydrochloric acid, diluted will work too. This oxidisation can reach way up into the cable. Also, I agree that Victron is top notch but they have as so many other brands fallen in love with certain suppliers of cable terminals. They offer a simple solution to go from PCB to cable but is in my experience sub-standard.

Thanks for this information and video

Bro you are a saint Your OCD attention to detail is a salutary warning to all DIYers. Any kind of joint in high current needs careful attention. Those Cheap Charlie grip terminals are a disgrace. Victron should hang its head in shame. I suspect Victron knew about their shabby design which is why they sent you a replacement under gaurantee PDQ. Bolted terminals are the answer as you said. I would rip out those grip terms and replace with bolted ring terms. They are visible, you can inspect them. You dont know what goes on inside the grip terms. The Boaty Boys are very particular about connections as they are in marine salty air. Clean and sand the term surfaces and bolt up quickly, then cover in Si grease to keep out moisture. Maybe one of those Flir type clone IR cameras ca $200 you plug into your Iphone might help to survey for hot spots when running on full load. Seems a necessary tool for peace of mind (after all you blew $1700 of kit.)

I enjoyed this video. It was very helpful. Do you still have the damaged unit? I know it’s been awhile, just thought I would ask

Thanks for the video.

Use ferule....I always use ferrules, it keeps all wires together and prevent a bad contact that would eventually generate fire..

Good vid, nice try, glad to see they honoured the warranty for ya, you have had a shite load of troubles I’m sorry to hear so I am not going to rattle on about the ferrule situation, there is plenty of good guidance in above comments. I will add however to ur comment about why they dont have robust exposed terminals on the input/output terminals as they do on the battery terminals, ‘Code’ would not allow such exposure of high voltage conductors/terminals, 120v/240v can kill, 48v is considered reasonably safe/low voltage in regard to shock hazard. It is a good title for discussion though, as I am sure many people have made similar mistakes, but probly mostly have been lucky and get away with it for now. Thanks for ur time here, and nice looking Rig! Cheers

I watched a video where after installing his Victron Multiplus II, the guy stress tested it with 5700W (700W above rated power), for a good while, and filmed the unit and all the wiring in his system with a thermal camera to see if anything got alarmingly hot. I'm thinking this might be a good thing to do after learning of your experience. Even if I have an electrician do the install for me, there's no harm in checking his work that way... better safe than sorry.