Breaker from controller to batteries getting too hot!

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  • BB.BB. Super Moderators, Administrators Posts: 29,229 admin
    Re: Breaker from controller to batteries getting too hot!

    Oh boy--Another one of those questions that generates a lot of posts here. :p

    Basically, from an Engineering/Design point of view--A good quality crimp connection is much better and safer. The crimps are gas tight and will not fail / pull apart if there is an "over heating" event. Also, solder tends to wick up stranded wire and cause a fulcrum point where bending forces are concentrated and can cause wire to fail if not well supported. I have also had some issue with corrosion cause by flux as it is impossible to fully clean the stranded wire after soldering.

    On the other side, many folks here (including me :blush:) have made up solder connection for years and they have held together pretty well (taped and supported). And some folks tend to prefer soldered over crimped connections (I think) and some have even soldered crimp connections (not something I would recommend).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Breaker from controller to batteries getting too hot!

    Somewhere on the forum is the thread where john p tested exactly this issue. Turned out a good crimp and solder was best, as I recall.

    The wires should never get hot enough in use to melt the solder. If they do, there's something else drastically wrong.
  • BB.BB. Super Moderators, Administrators Posts: 29,229 admin
    Re: Breaker from controller to batteries getting too hot!

    Here are a couple threads on crimping vs soldering:

    MC connector crimping

    welding cable
    mike90045 wrote: »
    Attached, pic of CRIMPED, overheated cables.

    Now imagine, if you had a soldered connection, the solder melting, and dripping on the battery case. I'm a convert to hydraulic crimp connections.

    attachment.php?attachmentid=956&stc=1&d=1266980900

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ThomThom Solar Expert Posts: 187 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    even my batteries look better then that. !


    Thom
    Off grid since 1984. 430w of panel, 300w suresine , 4 gc batteries 12v system, Rogue mpt3024 charge controller , air breeze windmill, Mikita 2400w generator
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    In reality that photo of the melted cables only shows [everyone is here to learn. -BB] the user is. Why were fuses/circuit breakers or similar not fitted.
    OK being crimped compared to just soldered saved damage to the battery case but how badly were the battery/ies discharged ?

    It is NEVER sensible to solder only terminals onto cables.
    Measured tests prove that a crimped and solder filled lug gives the lowest reistance connection. Crimped only no mattter how good will eventually end up with a higher resistance connection..The reason the exposed wire will suffer from oxidation.it may take months but it will happen.
  • 65DegN65DegN Solar Expert Posts: 106 ✭✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    I fully agree with a crimped and soldered connection. IMO, you can't get a better connection than a mechanical connection combined with a molecularly bonded connection.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Breaker from controller to batteries getting too hot!
    65DegN wrote: »
    I fully agree with a crimped and soldered connection.
    OK, but what about Bill's concern about the fulcrum point:
    BB. wrote: »
    Also, solder tends to wick up stranded wire and cause a fulcrum point where bending forces are concentrated and can cause wire to fail if not well supported.
    Does crimping first somehow mitigate the fulcrum point issue?
    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Breaker from controller to batteries getting too hot!
    vtmaps wrote: »
    OK, but what about Bill's concern about the fulcrum point:

    Does crimping first somehow mitigate the fulcrum point issue?
    --vtMaps

    No, it doesn't.

    But you have to bend the wire in order for this to become a problem. Most installs are connected for years without the wire being moved at all, much less enough to create damage. The mechanical action required for it to be an issue can also cause problems with a crimped-only connection.

    I've done crimped and crimped & solder but never solder only as one of the first rules I learned (back when a soldering iron was a soldering iron) is that you need a sound mechanical connection first. Without that you're toast, no matter what you do afterward.

    Ah, those halcyon days of joining component leads on terminal strips! PC boards? What are they? :p
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    In this forum the majority of solar installs are in residences or small commercial buildings... ok?

    Now if we accept the above statement. Why is it every time someone talks about lugs on cables battery interconnects the first thing that gets mentioned is VIBRATION. WHY??? Where do these people live that the places the batteries are installed suffer from constant vibration.?? If they really live in such constant earthquake places surely there must be more serious things to be worried about with the building and the panels on the roof vibrating than the batteries sitting on the ground????? Reality check time.

    BB in an above post had a link to "welding cables" That is an ok article. And it says what I have always advocated Crimp with the best crimping tool you can get your hands on . NEVER HAMMER lugs on to wires, the metal tends to spring apart a small but dangerous amount.Then heat up the lug preferably with a small gas blow torch ,hold the lug hole downwards and feed solder into the space between it and the cable until its full and any resin rises to the top and runs out .
    After that use good thick glue inside shrink tube about 3"long so it goes over the lug nearly up to the hole and then the remainder along the cable. this will seal the joint as well as its possible against battery fumes/acid. You now have a joint that has very good protection against cable kinking or breakage at the joint.

    To repeat again NEVER SOLDER ONLY a lug to cable.

    If you really want to be keen all battery connections should be removed once a year . The terminals cleaned. use a not metalic scouring pad or a brass one NEVER a steel scouring pad or steel wire brush brass brush is ok. Then do the same cleaning of the battery interconnects and the lugs on the cables to and from the batteries.
    Another simple way to clean the lugs and interconnects and nuts etc is soak them in Coca Cola about an hour. Dont drink it after you finished unless you feel you have a copper/brass deficiency.

    There are also some that claim if the cable overheats then the solder will melt. That will only happen if the battery setup has been done very badly. fix it first.
    (1) You should have a fuse/breaker or similar as close as possible on ALL cables to and from the batteries.
    (2) If your cables are opperating continuously above 50deg C then the cable/s are to small.
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    Have a look at the photo showing all the melted cables and the insulation. HOW did that happen? Look carefully its not a case of one cable overheating and melting the others. Look at the top cable it only just touches the others as it goes across them..
    Are they all paralled cables to one device???
    A classic example of how not to do it.
    Fuses /circuit breakers etc are the batteries best friend .keep them close together.. They will thank you for it .so will your insurance company because it doesnt have to pay out on a burnt down building..
  • BB.BB. Super Moderators, Administrators Posts: 29,229 admin
    Re: Breaker from controller to batteries getting too hot!

    To me, it looks like a poor connection at the battery post/bus point that overheated everything attached to the post/bus. It only heated the end and not the length of wire (the opposite of what I would expect if there was over current going through a cable).

    Looked very similar to power connections in computers/test equipment where the connector pins failed and overheated.

    -Bill

    (and one cable got hot enough to start a small fire in the insulation which cooked some of the other wiring).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    Bill you may be right but if you look at the very top one just under the nut it looks like its a ok connection.and its wire really is no wherenear the other wires, And there is a lot of overheating in the wires below that top wire.
    But even if its not a great connection there must be a lot more current being drawn than what I would say is acceptable for that size cable??
  • CDN_VTCDN_VT Solar Expert Posts: 492 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    On some of the fancy Euro Vehicles that are 90 Node + (computers/processors) on the vehicle, I have run into this exact problem. Commutation codes , or unattainable parameters. Fancy words for a power fur-bar ""Somewhere "".

    I have found crimps of cables causing voltage drops so severe that the tail chasing stops after a long running of powers.
    After finding the main problem with voltage drop checks, repair is cable replacement if the cable shows bad signs of heat past the very short working length.
    Most cables are included in the main harness purchase of $$$$$$ and then there's the TIME to replace.
    For just a poor crimping of a main power or earth/grounding terminal , the repair cost would be outrageous.
    Vehicles are new still under Warranty ,within 6 years,not old POS .

    Repair is New terminal , cable length plus a splice terminal.
    We / I use the terminal facing up as a bowl and heat with Mini ductor melting solder in the cup/hole then install the cable , crimp and reheat the terminal only. Solder will travel towards heat & gravity works . so keeping the cable higher than the solder pot , the wicking is minimized.

    Almost the same on the splice connection terminal with crimp & solder , heat shrink after to seal . Cordless Mini ductor is used to melt solder & warm the heat shrink.
    Terminals are 20.00 + each so don't make a goof. the splice with the squeeze nuts cost more but it just sitting for the rest of its life , crip & solder type kit is just fine.
    BB is correct on the wicking that could cause fulcrum fatigue from improper soldering.
    After all soldering, crimping , cleanup is done on the cable strands , Silicone Dielectric sealant / grease is heat shrink in to stop the air from further corrosion.

    YMMV

    I also have some of those breakers that YostFMX posted up.
    I'll give them a good voltage drop test this week just to see.

    VT
  • BB.BB. Super Moderators, Administrators Posts: 29,229 admin
    Re: Breaker from controller to batteries getting too hot!

    In general, if there was too much current flowing through the cable--The jacket along the entire length (or in a conduit/going through rubber bulkhead grommet/etc.) would be melting and the ends (especially if connected to a big piece of lead at the battery post) would be relatively OK (battery lug=heat sink).

    In this case, from what I can see, none of the cables show overheating more than a few inches beyond the battery post.

    Again, my guess, is that the connection at the post got hot (corroded ring lug to post, or corroded wire to crimp) went high resistance and you have I2R heating... It is also possible that the ring lug itself was not heavy enough to carry the current.

    Notice the heavy cable for battery interconnect behind--It shows corrosion--So there is electrolyte mist in the area (again, guessing) and not kept clean enough and neutralized.

    -Bill "just guessing" B.

    There are some other possible issues--Sometimes people use parallel cables (say all 4 of the above are paralleled to same destination). Not usual for a home PV system--But very common in computers. The issue is that with paralleled connections is that they "LOW RESISTANCE" cable/connection is the first to fail.

    Notice that we are again talking about I2R heating--If the resistance of one wire/path/connection is 1/2 the others, then you will get 2x or more current flow on one of the parallel wires. And 2-4x the heat because of the squaring of the current flow.

    Typically, that one connection fails, then the next lowest resistance path now gets increased current flow, then heating, then failure--So I would see a series of damage along paralleled connector power pins.

    Another reason why I recommend against parallel battery banks--It is difficult to get consistent current sharing over time. (another reason is battery strings may be different temperatures, which will affect load current/charging current flow too).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    "Again, my guess, is that the connection at the post got hot (corroded ring lug to post, or corroded wire to crimp) went high resistance and you have I2R heating.."

    you know that rung a bell as sometimes the excess rosin in the solder when not properly heated could lay in such a way to eat away the wire and the connector. this flux, when allowed to stay on, has been known to have caused problems wherever solder is utilized. under heating often causes the flux to not be raised to the surface where it can be cleaned off. if you can't get a good solder joint along all surfaces to be joined then i would not recommend using the solder. pretinning often helps to achieve this and is often a good indicator if it will work well or not for if it doesn't tin well it will not solder up well too.
  • CDN_VTCDN_VT Solar Expert Posts: 492 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    I had a chance to play with a 40 & an 80 amp unit breaker like the OP picture is.
    The 40 amp unit got warm and blew , so i needed to go to the 80 amp unit for my testing setup.
    I was using an Iota 90 amp battery supply @ 14.2 volt keeping a vehicle in "limbo" (key on not running ,fan blowing max , headlights on & max beams , everything working) , Load was 60-74 amps . I noticed that the brass stud's are just below the plastic frame , maybe keeping the Aluminum lug from having a good seat. After 3 hours of 60-70 amps , the breaker was warm , but not hot. 100 F was the thermal gun temp in imperial. there brass studs & BS plated gold nuts that are steel that's plated.

    Myself , I'd do copper lugs to go from wire/cable to the stud adapter , trash the nut & use better. Its metric with 11 mm to look like 7/16" .. Wish they would Get over it & just do metric , but USA is "noneleftbehind".. MAke sure the plastic body is not holding the surfaces apart.

    Good luck !
    VT
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    cdn_vt,
    maybe i overlooked it, but i did not see about aluminum connections and if this is the case then there may be differing metals causing galvanic reactions and eating away at the wires and connectors. you can use copper, brass, and stainless lugs for connections to copper wire and if the copper or brass is pretinned with solder then that too is fine.
  • CDN_VTCDN_VT Solar Expert Posts: 492 ✭✭✭
    Re: Breaker from controller to batteries getting too hot!

    Aluminum always need Nolox paste , but for such small cables , tinned copper is cheap (for this repair), But @ huge Gauge , Aluminum & nolox paste is what we did as sparky's .
    From huge amps then as a kid to pico speed & micros now ;)

    VT
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