DC connector melted while connected to bluetti. salvageable?

[lostinabox]

So one hot afternoon I went outside to check my bluetti AC30 and found the connector had melted onto the port. I assume that this was due to my lack of due diligence of keeping the connector clean. Is there a way to salvage this?

The setup was two 100 watt panels, both Weize, connected in parallel. I've charged the bluetti (max 150 watt input) and an older rockpals (max 52 watt input) many times. Also a couple of test runs on an Ecoflow Delta. I've never had an issue with the connectors getting hot.

 

[Bluedog225]

I don’t think it was a cleaning issue. But a loose connection. Either between the connector parts or between the wire and one of the connectors. Or not fully plugged in? There are a variety of ways it can be fixed. An oem replacement or a pigtail with a new connector type. Nice it wasn’t worse.

 

[Ekard]

"It worked until it broke".
VOC is 21.69 volts, with ISC of 5.71 amps, so 2 in parallel give you 21.69 VOC and 11.42 amps ISC. The ampacity of that connector is probably 10 amps max. You overloaded the port, plain and simple.
Can it be repaired? Yes, in several different ways. Get in touch with Bluetti tech support to find out.

 

[lostinabox]

Thanks for the replies.

A search on replacing the part almost exclusively produces links for laptop repairs. And it's difficult to find anything on the AC30 anymore.

Regardless, I'll be replacing all my mc4, etc, while trying to see if there's some obvious issue with my current setup. There's one point where the mc4 extension won't quite push all the way in just by a hair.

Here's some specs if it matters.


Edited, removed a couple of statements.

 

[Ekard]

"I guess i can contact bluetti but it seems like nothing less than a 1 star amazon review gets a response from companies like this"
Let's have a "come to Jesus (or your favorite rabbi)" talk. First, most of us have found Bluetti to be very responsive on the rare occasion we have needed support. Secondly, and most importantly, nobody but you is to blame for this situation. It's a 10 amp connector you insisted on shoving as much as 11.4 amps and 200 watts through. In my youth, I advanced the heck out of the ignition timing and slapped straight pipes on my Harley, and proceeded to drive it like a bat out of hell. Oddly, none of my motorcycle buddies had a lick of sympathy for me when I burned the crap out of my exhaust valves.

If you're lucky, the 8mm barrel connector (female end) is mounted to some circuit board and if you or a friend is handy with a soldering iron you can try to replace it (if you haven't damaged the circuit board as well). It probably looks a bit like this. Bluetti will probably want a bit to fix it for you or if you're really lucky and polite, and the part is not so expensive, they may just send you one for free.

 

[Vigo]

There's basically nothing that goes straight into Joe Blow hands that fails when you go 14% over its Joe Blow rating. "How many amps can this connector support?" "Who's asking? Joe Blow? 10 amps."

So i disagree it was 100% user error in terms of exceeding that spec. But most terminals, from male to female, rely on a 'spring tension' to create solid contact between the two terminals. The quality of that connection degrades over time as things are plugged and unplugged over and over. Things have a recommended cycle life, basically, and if you take an old connector and add a bit of dirt, pitting on the surfaces, or misalignment while the parts are being forced together by a terrifyingly huge human (proportionally, i mean), and that cycle life can go to zero very quickly.

I think the connector was likely 90% worn out and 10% overworked, and while the result is still 'broken' i personally don't put any real blame on the panels you had hooked to it or the way you use your paws on it. I think this is a fairly normal result for a highly used, older connector of this type. Plenty of old laptops were junked over this connector failing mechanically even when they were way under the current limit. You just happened to be using it close enough to its amp rating that you melted it, but you didn't need to melt it for it to eventually fail of old age. You just accelerated it slightly.

 

[lostinabox]

"I guess i can contact bluetti but it seems like nothing less than a 1 star amazon review gets a response from companies like this"
Let's have a "come to Jesus (or your favorite rabbi)" talk. First, most of us have found Bluetti to be very responsive on the rare occasion we have needed support. Secondly, and most importantly, nobody but you is to blame for this situation. It's a 10 amp connector you insisted on shoving as much as 11.4 amps and 200 watts through. In my youth, I advanced the heck out of the ignition timing and slapped straight pipes on my Harley, and proceeded to drive it like a bat out of hell. Oddly, none of my motorcycle buddies had a lick of sympathy for me when I burned the crap out of my exhaust valves.

If you're lucky, the 8mm barrel connector (female end) is mounted to some circuit board and if you or a friend is handy with a soldering iron you can try to replace it (if you haven't damaged the circuit board as well). It probably looks a bit like this. Bluetti will probably want a bit to fix it for you or if you're really lucky and polite, and the part is not so expensive, they may just send you one for free.View attachment 140895

Thanks for the lecture. I'm the type to obsessively research things, especially of an electrical nature, before doing anything. I first set this up a couple of years ago and it did not get heavy use by any means. So either i missed something back then, or i overlooked something later on when i got the bluetti.

If bluetti actually is responsive then i can give it a try. I've become too accustomed to being ignored by customer service, be it American or Chinese, so please excuse my pessimism on this.

 

[farmhand]

"I guess i can contact bluetti but it seems like nothing less than a 1 star amazon review gets a response from companies like this"
Let's have a "come to Jesus (or your favorite rabbi)" talk. First, most of us have found Bluetti to be very responsive on the rare occasion we have needed support. Secondly, and most importantly, nobody but you is to blame for this situation. It's a 10 amp connector you insisted on shoving as much as 11.4 amps and 200 watts through. In my youth, I advanced the heck out of the ignition timing and slapped straight pipes on my Harley, and proceeded to drive it like a bat out of hell. Oddly, none of my motorcycle buddies had a lick of sympathy for me when I burned the crap out of my exhaust valves.

If you're lucky, the 8mm barrel connector (female end) is mounted to some circuit board and if you or a friend is handy with a soldering iron you can try to replace it (if you haven't damaged the circuit board as well). It probably looks a bit like this. Bluetti will probably want a bit to fix it for you or if you're really lucky and polite, and the part is not so expensive, they may just send you one for free.View attachment 140895

^^^This, or a computer repair guy would have the skills if you have the part (I'd assume anyways).

 

[cs1234]

I agree with @Vigo .

It's got an MPPT controller. It wasn't pulling 200 watts through that connector, because it's not a 200 watt MPPT controller. It won't pull more amps through that connector than they (Bluetti) designed/allowed it to pull through it.

Those connectors are junk, and shouldn't be being used on anything pulling 150watts. They are easy to damage, and wear out rapidly. I've always hated them on the thousands of laptops I've repaired over the years, and I hate them on my Bluetti. Sticking right out the front like that, they are easy to accidentally bump on something and damage the connector or it's solder points on the board. Even just the weight of the cable dangling off the front is enough to slowly damage them. At the very least, it should have came bundled with a right angle adapter to face the cable down instead of straight out.

Sometimes manufacturers/designers make really dumb decisions, almost as though they never actually use products in real life or lack common sense.

 

[Alkaline]

I think you may have pushed too many amps thought it meaning the connector was not rated to handle the load. Sad but a similar thing happened to a Chinese RC car charger I bought, the plugs melted at just 12 amps even though it was rated for 30.

 

[D71]

Okay so what has the customer service response been from Bluetti? Did you contact them? That should always be first go to… the manufacturer… then look elsewhere. At least contact them for a baseline to resolve your issue.
most barrel type connectors are NOT rated real high for amps. Lot of them are rated ~ 5amp or so.

Why some ppl complain and want xt30 or larger connectors or solar mc4 with 10awg connectors rated 30amps. As pointed out your system is rated 10 amps if you exceed that then weakest link will reveal itself with smoke. Right? We as humans generally want more with less. It is a mental thing either obvious or not. Everyone wants to push things. SMOKE is the indicator of the absolute limits.

Make sure you get a rated plug if you attempt to replace burned up plugs. See below … not rated. Example to avoid.

 

[lostinabox]

I took another look at my setup and did some research again. Either I'd misunderstood something or miscalculated back then. I had notes but I don't know what happened to them. So this is what I think that I was looking at.

-The bluetti has a max input of 10 amps
-16awg is the minimum for a 100w panel
-One panel would be safe to use, though wouldn't reach the max charge rate of the battery

This may be where I screwed up.

My possible assumptions
-Two panels = just over 10 amps
-16 awg can handle 10 amps
-Wired in parallel, it works as the bluetti won't accept more than it's designed for

Reality
-Even though the wiring is rated for those amps, and the bluetti won't accept the full 200 watts, the 16awg can't handle more than 100 watts
-Need at least 14awg, ideally 12awg, for the end cable.

Is this right? Because as I'm going over this in my head, well, this is getting embarrassing.

 

[lostinabox]

Then one more question. My ecoflow has a max solar charge rate of 400 watts. It came with a 14awg cable. I feel as if I'm finding conflicting information. Is it solely amps that matter, or total wattage?

 

[zanydroid]

For wires and connectors amps and max voltage (insulation rating related) matter.

As a connector wears out the resistance will go up which means the current that’s safe to put through it goes down.

When you exceed the safe current (which is related to the quality of your connections and ambient temperature) you have an increased chance of thermal runaway. Resistance goes up with temperature, which causes temperature to go up, in a vicious cycle.

For components doing active work like batteries, transistors/transformers in power converters, light bulbs, motors — watts matter. But for fixed voltage things you can just as well look at amps.

 

[Vigo]

Is this right? Because as I'm going over this in my head, well, this is getting embarrassing.

Not totally right but also totally not embarrassing.

As a connector wears out the resistance will go up which means the current that’s safe to put through it goes down.

Zany has got it exactly right.

Watts matter in general but in terms of melting things we can be very specific and say that really only the HEAT matters in this case.

A perfect example was given:

a similar thing happened to a Chinese RC car charger I bought, the plugs melted at just 12 amps even though it was rated for 30.

So, not even the amps matter, not directly at least. In terms of melting stuff, just the heat matters.

When thinking of heat here we have to break it down more specifically to temperature. Just like Watts=Volts X Amps, total heat/thermal energy can be broken down into components, temperature being one of them. A small mass at a high temp has same energy as larger mass at lower temp, etc.

So connectors are rated for a certain amount of amps with the expectation that the connector itself will be a miniscule proportion of the total resistance of the circuit. This is important because voltage in the circuit drops in proportion to resistance. If something is half the resistance of the circuit, it drops half the volts. When voltage 'drops', where does it go? It is converted into some other form of energy such as light, heat, sound, movement, etc..

In the case of wiring and connections, they convert the energy to heat. It is easy to quantify that in terms of Watts of heat because Volts x Amps = Watts.

So let's say a connector has 1 ohm of resistance in a simple series circuit with a total of 10 ohms. That connector will drop 1/10th or 10% of the voltage of that circuit. Let's say it's a 10v circuit. 10v / 10ohm = 1amp. 10v X 1amp = 10 watt circuit. 1 amp flows through this connector. Connector drops 1v, so 1v X 1a = 1watt of heat energy dissipated by this connector.

Now, let's make this connector shitty and raise its resistance. Let's say its 5ohms now. Rest of circuit remains the same which means total circuit resistance is now up to 14ohms. Circuit probably even still 'works'. 10v / 14ohms = 0.7amps. So it's flowing LESS current through the connector now! But it might melt.. how? Well, now it is 35% of the resistance of the circuit instead of 10%, so it's dropping 35% of the volts. 3.5v X 0.7a = 2.45W. It is dissipating more than double the heat, even though it has LESS current going through it.

Even then, Watts are not degrees of temperature. How disperse is the heat that is being generated? If you concentrate all the heat generation in a tiny area, that tiny area will go to a very high temperature. If you spread the heat generation out over a wide area, the actual temp rise will be smaller. It also may or may not be able to dissipate the heat to the surrounding material fast enough to stay under the 'melting temp'. This is the same reason that a certain wire may have a different current rating if it's 'direct burial' in dirt vs in a conduit with other conductors, because it affects how well the wire can get rid of the heat it is generating. The direct burial is using 100% of its surface area as a heat exchanger to a cooler surface and unloading that heat into a truly massive number of lbs of earth. The conduit one has to put heat into air, or into other stupid hot wires it is touching, which means it effectively has a lower limit in its local conditions.

This is an example of how JUST an amp rating is sort of an oversimplification because you can't know how much heat is actually going to be converted in the connector unless you also know the voltage drop across the connector AND how well the connector can get rid of the heat. You can take a perfect 10a connector and make it safely flow 20a by keeping it cold, or you can take a 10a connector and put a bunch of minor mechanical damage on the contact points and it will melt while flowing 4 amps. Or you can put it under a heat lamp and have it melt at 7amps, etc etc. A 10a connector can easily be melted by less than 10amps, due to poor connection issues. When the connector is tiny and half of its contact points are basically impossible to observe because they're buried in the middle of it, you can't blame a person for not noticing it was going downhill before it melts. It's not like you walk into the room and go "WHY IS IT SO HOT IN HERE?!". It probably took less than 10w (focused into a tiny area on a tiny plug) to melt that thing. That sucks, but you don't suck for failing to prevent it. I didn't know all this back when and then, i do now, maybe now you do too, tomorrow it's somebody else. It's certainly nothing to be embarrassed by. Noone was born knowing it!

 

[zanydroid]

unless you also know the voltage drop across the connector

Isn't the voltage drop across the connector going to be "constant" for a given current? I put "constant" in quotes because the drop will vary depending on how the connector was engaged a particular time, and how worn out the connector is.

I would expect an MPPT to hit a similar I_mpp regardless of the voltage drop across the connector.

I think a couple other tips

• know what the amps rating of the connector is
• these kind of easy-connect/disconnect connectors have a really finite lifespan vs more permanent connector types
• the more current you drive through a connector and the more thermal cycles, the faster it will wear out

 

[Vigo]

Isn't the voltage drop across the connector going to be "constant" for a given current?

Ehh.. constant IF source voltage, temp of every single thing, resistance of the rest of the circuit, etc all don't change. Any changes to the electrical circuit cause voltage drops to 'redistribute' basically instantly.

So the voltage drop of anything in a circuit depends on what the rest of the circuit is. You can take a connector that is sitting there passing current, change nothing about that connector, but if you lower the resistance of some other part of the circuit, you will raise the voltage drop across the connector, thus increasing its temperature even though nothing physically changed at that connector. If the source voltage didn't go up, then any change that would increase current would basically require that something else went down in resistance. If something else went down in resistance and your connector didn't, then proportionally your connector is now a larger resistance and will drop more volts and gain more heat.

But in general stuff won't melt from brief 'transient' conditions. You can send 'spikes' down a line all day if the duty cycle is short enough (1% of time way over current rating, 99% of time cooling off). Usually when something melts it just accumulated heat faster than it could get rid of it, but it happened over a longish time period of minutes if not hours, as a result of something that was happening near continuously. When something is so far over the current rating that it would 'instantly' fail, it's more like explosion damage than melting damage because the actual metal contacts passing the current heat up so much faster than the plastic housing that they 'phase change' into liquids and gases and thus their volume goes way up creating local pressurization pushing/blowing outward. The way fuses blow is basically like this.. Plastic fuses rarely melt their housing when they blow, but if they were sealed up to be airtight they might crack from the expansion of the trapped air. But if you take a 10a fuse and block 90% of its terminal contact area to make everything flow through only part of it, you may melt the housing without blowing the fuse.