Page 1 of 2 12 LastLast
Results 1 to 20 of 24

Thread: 100A Battery Switch Isolator To Hot to Touch as The 150A Meter.

  1. #1
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default 100A Battery Switch Isolator To Hot to Touch as The 150A Meter.

    I've got a 24v batteries setup in the man shed and I have two solar controllers as I have two solar banks. One on the house roof (North Facing), and the other on the shed itself (East and West facing).

    The House solar controller is 60Amps and the Shed controller is 40Amps.

    There is a 100A switch that separates the solar supply to the Controller that gets REALLY hot. Far to hot to touch. So I 'bridged' it with a thick cable and at it's peak it's ok to touch, so the bridging certainly works. The other 100A switch is after the controller and before the battery bank - this 100A switch gets REALLY SUPER hot as well, but I haven't bridged it as then I have no way to quickly disconnect the solar supply to the battery bank.

    I know that these 'switches' have really thin copper contacts inside and it annoys me that one is supposed (and driven into ones head), that THICK THICK cable should be used - The THICKER the better!! Then to have this thick cable narrowed to virtually nothing (inside the switch), is surely stupid!

    So would buying a 200A switch be suitable? The ones I have found look the same as the 100A I am using. Is a 'switch' the same as an 'Isolator'?


    And then, as I wanted to see the total Amps going into the battery bank (60A+40A), I bought a 150A digital shunt meter - and this has two thin plates for the current to go through. So all the THICK copper cable goes into these two thin plates, before it gets into the batteries, and they get super hot as well.

    So what's the loss of current/Amperage that the battery's aren't getting as to the loss (resistance/heat), as A) From the panels to the controller, then B) From the Controller to the Batteries, then C) Bottlenecked at the Shunt Meter, before it gets into the batteries?

    Am I cabling things up stupidly?







Look Here ->
  • #2
    Junior Member
    Join Date
    Jul 2010
    Posts
    72
    Thanks
    567
    Thanked 46 Times in 32 Posts
    Rep Power
    185
    Reputation
    840

    Default

    Is your total current load 100A?
    From your second picture, you seem to be using a 50mm2 lug onto a smaller cable diameter (hard to tell, but maybe 35mm2 cable?) the crimp does not look right, if you get too high resistance on any of those it will heat up all the connectors attached to the lug (copper is a very good heat conductor).
    If your current load is 100A max, try to use something with a higher rating as a switch, probably something on 3 or 4 times the max current.
    Your shunt should not be the source of the heat, but if the lug next to it is not crimped correctly it will be cooking it.
    It may be easier to put separated switches for each source, as they will need to carry less current each.

    Good Luck

  • The Following User Says Thank You to ammlione For This Useful Post:

    GT250 (30-09-17)

  • #3
    Member
    Join Date
    Jan 2008
    Posts
    391
    Thanks
    27
    Thanked 98 Times in 72 Posts
    Rep Power
    242
    Reputation
    1584

    Default

    100A is a f'load of current...

    Couple of things to consider is the ACTUAL rating of the said switch (and shunts) - most of the time there is time rating for which the switch is rated. So even a 200A switch might only be rated at 50A 100% of the time and then a sliding scale up to the peak short burst of 200A (it's duty cycle). The other consideration is the connection to the switch - most of the time it is the actual bond on the terminal that creates most of heat, any form of corrosion, oil film, dust etc will reduce it's capacity and result in heat.

    As far as I knew, the difference between and switch and an isolator is the fact the isolator removes (or disables) the power source and and includes a secondary safety function to ensure the power can not be activated - such as a removable key, other form of interlock, or an electronic interlock.

    As for the losses, too many variables to answer. Normally, I would expect to be able to touch all the parts of the system without it being a comfortable temperature, so maybe check (and find better specs) and over rate all you connections, switches, shunt etc.

  • The Following User Says Thank You to Gitch For This Useful Post:

    GT250 (30-09-17)

  • #4
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,433
    Thanks
    934
    Thanked 1,661 Times in 724 Posts
    Rep Power
    836
    Reputation
    32307

    Default

    I think that the first thing I'd be doing would be to disconnect all of the cables shown in your pictures and giving them a darn good cleanup.

    At the sort of currents you're talking about, everything should be shiny clean....just the slightest amount of resistance in any connection will generate significant heat.

    Clean everything up......lugs, washers, and terminals, until your'e back to the base finish, then reconnect with a thin film of petroleum jelly or silicon grease.

    Hard to tell from the photo, but is that washer in the top left of photo 1 a plain steel washer? It seems to be rusted?

    If it is, I'd ditch it altogether. Dissimilar metals are not your friend in a system like this.

    As mentioned above, some of the lug-to-cable connections look a bit suss as well.

    To be honest, the whole system as shown looks like it could do with a complete workover and retermination.

    Don't forget, at the currents you're talking about there will always be some heat generated, particularity at connection points.....it doesn't take much resistance to generate a few watts at 100 amps, and it doesn't take many watts to feel fairly hot to the touch.

    But by the sound of it, your system might be a bit beyond that point.

  • The Following 3 Users Say Thank You to Thala Dan For This Useful Post:

    GT250 (30-09-17),gulliver (01-10-17),lsemmens (30-09-17)

  • #5
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,433
    Thanks
    934
    Thanked 1,661 Times in 724 Posts
    Rep Power
    836
    Reputation
    32307

    Default

    To give you a comparitive idea, here is a 70A shunt from a very old General Electric mainframe computer (ex-Snowy Mountains Authority):



    The metal strips are 12mm wide, by 0.3mm thick.

    From your photos, I'd say that your shunt should be well and truly up to the job.

  • The Following User Says Thank You to Thala Dan For This Useful Post:

    GT250 (30-09-17)

  • #6
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Thank you to everyone's replies. I do appreciate them.

    The lugs were brand new and the 'little finger thick' cable was all bought new. I have crimped the lugs and then soldered them in.
    The dirt that can be seen is conductive grease - messy stuff

    Glitch: Yeah, 100A @ 24V is a lot (I hope so), but I'm charging 6*banks 155ahr batts, but I think I will only get 100A+ peak at a few hours of the day. I have seen 124A read on the 150A shunt when I plugged it all up one time in the middle of the day - and then the controllers settled down...



    Thala Dan: The 'rust' nut is actually a lug. But you're right I think I have neglected to keep them clean. However, I have undone nuts/connections that have had corrosion ont he outside, but when undone it's shiny inside.
    You're correct though and a good reminder to me. I'll undo them tomorrow after dusk and check them. Sometimes one gets focused too much on the big things and maybe it's the little things that are cuasing the problems.
    I'll report back and let you know what I find.

    Your 70A shunt looks great, but I still find it hard to understand that those thin strips of metal are meant to allow a full 70A-100A of current @ 24V through them.

    So if 80A is input - what A comes out?

    Gitch: I understand that the switches are designed for 'bursts'. That's why I'm finding it hard to source something that allows that 100A through all the time for hours at least.

    I was thinking, what are those 'switches' called that you see in the horror movies that have a handle and pull down and have two sides? I don't know the terminology of them...

    All I want to do is have the ability to isolate the solar input to the controllers and from the controllers to the batteries.

  • #7
    Premium Member
    SS Dave's Avatar
    Join Date
    Feb 2010
    Location
    North Canberra
    Age
    63
    Posts
    2,117
    Thanks
    5,296
    Thanked 7,917 Times in 1,280 Posts
    Rep Power
    3335
    Reputation
    154682

    Default

    Hi GT250


    You are probably thinking of a Knife Switch


    Death smiles at everyone. Grumpy old men smile back.

  • The Following User Says Thank You to SS Dave For This Useful Post:

    GT250 (01-10-17)

  • #8
    LSemmens
    lsemmens's Avatar
    Join Date
    Dec 2011
    Location
    Rural South OZ
    Posts
    10,585
    Thanks
    11,867
    Thanked 7,061 Times in 3,338 Posts
    Rep Power
    3153
    Reputation
    132592

    Default

    Your link throws a 404 error, SSDave, try
    I'm out of my mind, but feel free to leave a message...

  • The Following User Says Thank You to lsemmens For This Useful Post:

    GT250 (01-10-17)

  • #9
    Member
    Join Date
    Jan 2008
    Posts
    391
    Thanks
    27
    Thanked 98 Times in 72 Posts
    Rep Power
    242
    Reputation
    1584

    Default

    Quote Originally Posted by GT250 View Post
    Thank you to everyone's replies. I do appreciate them.

    The lugs were brand new and the 'little finger thick' cable was all bought new. I have crimped the lugs and then soldered them in.
    The dirt that can be seen is conductive grease - messy stuff
    Not sure what other opinions are, but I was alway taught never to use solder on high current connections. Few reasons, firstly a soldered joint is considered rigid and the heating and cooling (resulting in expansion and contraction) will cause a fractured joint; secondly depending on the quality of solder and technique of the joint the heat can cause the solder to melt resulting a failed connector and at 100A shit can go bad with a stray cable or melted solder landing where it shouldn't!

    Glitch: Yeah, 100A @ 24V is a lot (I hope so), but I'm charging 6*banks 155ahr batts, but I think I will only get 100A+ peak at a few hours of the day. I have seen 124A read on the 150A shunt when I plugged it all up one time in the middle of the day - and then the controllers settled down...

    Thala Dan: The 'rust' nut is actually a lug. But you're right I think I have neglected to keep them clean. However, I have undone nuts/connections that have had corrosion ont he outside, but when undone it's shiny inside.
    You're correct though and a good reminder to me. I'll undo them tomorrow after dusk and check them. Sometimes one gets focused too much on the big things and maybe it's the little things that are cuasing the problems.
    I'll report back and let you know what I find.

    Your 70A shunt looks great, but I still find it hard to understand that those thin strips of metal are meant to allow a full 70A-100A of current @ 24V through them.

    So if 80A is input - what A comes out?
    Remember a shunt is basically a massive resistor with a really low (and known) resistance and you are measuring the voltage across the shunt to determine the current flow - hence the look of shitty thin bits of metal.

    Commonly, full scale is measured at 100mV so using good old Ohms Law of P=VI; P = 0.1 x 100 = 10 Watts, a fairly decent little heater!

    The other issue with using shunts at and above there maximum is the heat they create will actually cause the small metal strips to have a change in resistance - a double fold negative as it leads to inaccuracies, and creates more heat causing further deterioration...

    Other methods to measure the current is to use a Hall Effect sensor, these are non invasive / indirect (meaning there is no direct electrical connection like a shunt) but require a bit more in detection circuitry.

    Gitch: I understand that the switches are designed for 'bursts'. That's why I'm finding it hard to source something that allows that 100A through all the time for hours at least.

    I was thinking, what are those 'switches' called that you see in the horror movies that have a handle and pull down and have two sides? I don't know the terminology of them...

    All I want to do is have the ability to isolate the solar input to the controllers and from the controllers to the batteries.
    As for the switch, this one is rated at 250A Continuous and 2500A Intermittently (also goes to show the difference between real ratings..)

  • The Following 2 Users Say Thank You to Gitch For This Useful Post:

    GT250 (01-10-17),tristen (01-10-17)

  • #10
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Quote Originally Posted by SS Dave View Post
    Hi GT250


    You are probably thinking of a Knife Switch


    That's what I was thinking of! Well done...

    Just did a bit of scouting feeBay and not sure about this one;

    don't mind paying more of course, but the others don't seem to be better. I'm just looking at the amount of metal that would carry the current. It would be 60A @ 24v and I only want to 'disconnect' the POS feed.

    Glitch: You're quite correct about the 'hall effect' reading. I should have looked into that. Had a look and there's one for $165 gulp!
    There's this;

    But the diameter is too small - 19mm. Would need about 25mm I think.
    I wouldn't mind getting rid of the shunt meter...

  • #11
    Senior Member
    fromaron's Avatar
    Join Date
    Jan 2008
    Posts
    2,133
    Thanks
    268
    Thanked 732 Times in 387 Posts
    Rep Power
    543
    Reputation
    13794

    Default

    Just a question - do you have both cable and terminals made of the same material? Meaning they are not subjected to chemical attack?

    If you can get hold of infrared camera you could take a snapshot and see the hot areas which gives much better idea of the problem. It could be connection stud or the crimped terminal etc.

  • The Following 2 Users Say Thank You to fromaron For This Useful Post:

    GT250 (01-10-17),tristen (01-10-17)

  • #12
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Quote Originally Posted by fromaron View Post
    Just a question - do you have both cable and terminals made of the same material? Meaning they are not subjected to chemical attack?

    If you can get hold of infrared camera you could take a snapshot and see the hot areas which gives much better idea of the problem. It could be connection stud or the crimped terminal etc.

    fromaron, the cable and terminals are all copper, bought brand new and all soldered up. None of the terminals get warm besides the ones connected to the switches and the shunt.

    I'll need to do some research on those knife switches.

    I'd appreciate anyone's advise if they think that the 'blade' of metal will be more in substance than the copper element inside my existing switches...

  • #13
    Premium Member
    hoe's Avatar
    Join Date
    Jan 2008
    Age
    60
    Posts
    6,367
    Thanks
    266
    Thanked 4,596 Times in 1,948 Posts
    Rep Power
    1820
    Reputation
    70528

    Default



    Last edited by hoe; 01-10-17 at 07:43 PM.

  • The Following User Says Thank You to hoe For This Useful Post:

    GT250 (02-10-17)

  • #14
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Well everyone,

    I've ordered a few Knife Switches and a Hall effect 100A meter.

    The Knife Switches certainly have more metal than the current 'twist' switch.

    Plus the hall effect Amp meter means I can do without the shunt meter - so straight through..

    I'll let everyone know how it goes when they arrive.

    Many thanks once again for every ones help.
    GT250.

  • #15
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    UPDATE:

    Well the 100A Hall Effect Meter arrived a few days ago. But it doesn't seem that accurate - even though the cable is pretty thick. The Meter is supplied with a short 15cm cable and a 2mtr.
    I used the 2mtr as I wanted the display away from the battery's.

    Anyway, when the regulators were collecting about 96A (and I then checked it with a Fluke Meter at the same spot that the Hall Effect wizbang thing was - the readings being about 2A out), the display was only showing 77.6A!

    Now, I'm aware that most meters have a 'sweet' spot of accuracy around the middle. Hence, no point measuring 10v on a analogue 1000v meter and 975v. But 400v-600v will be pretty dead on though (Am I wrong in this theory people?).

    So I waited another day when I was home and checked it as the sun progressed across the sky. Up to about 60A it's sort of ok. Pretty damn good at around the 40A areas.

    I contacted the Feebay seller and his reply was a bit weird. "I have no ideal. We do know this meter available in +/- 50 amp range. Sorry about this". I've asked him to clear up the +/-50A as I'm hoping he's not saying that this is the accuracy level

    The Hall 'Ring' where the cable connects is marked at the 100A marking. There's 50 - 100 - 200 - 400.
    The seller suggested using the shorter cable. When I did this change over and time taken, faffing around etc, going to the shorter cable made it a bit more accurate, maybe 5-8A. Would the shorter cable really make that much difference?
    It's still out by 10A-15A and will not go any higher than 78A, that I've seen.

    So I have ordered a 200A model from another seller (as he can't get the 200A), and awaiting that...

    As for the knife switches, I have installed a few. I found a double 'pole' one in Germany of all things! So wondering if I should join the two and have the current dissipated over two connections...

    I've yet to test the heat as I haven't been home to when the full 60A current comes in to the first solar regulator for a long period. Remember, that the incoming and outgoing 100A turnable switches would be too hot to touch.
    The 40A regulator has a push button 70A Jaycar fuse/switch and that can get very warm.


    I'll update when I get the 200A Hall wizbang thing as to it's accuracy and how warm/hot the knife switch gets across the 'bridge'.

    So before the pics: I have seen 137A going into the batteries from the 150A Shunt Meter I had. This happened after a few days of cloud, the morning was cloudy and then it cleared up at about 11:00Am and the panels went 'holy crap'... I've seen many 115's, 120's, 108's etc.

    Now: Is anyone interested in a 150A Shunt meter, nice and cheap. Large Red Digital Display. Let me know ok.

    100A Hall thing...



    The Meter Display



    The Knife Switch.


    The Double Knife Switch - With old 100A Switch that to hot to touch.

  • #16
    Junior Member
    Join Date
    Apr 2009
    Location
    Tauranga
    Posts
    145
    Thanks
    51
    Thanked 13 Times in 13 Posts
    Rep Power
    188
    Reputation
    120

    Default

    Your hall effect meter is way to go but looks like a toy (was ebay after all), those knife switches look good! Know anyone who builds switchboards as they will have access to real gear that's up to the job

  • The Following User Says Thank You to NZ Alarm Tech For This Useful Post:

    GT250 (27-10-17)

  • #17
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Today was the first day I was present as 60A was coming through the new knife switches. The temp in the middle of the switch was lukewarm. No where near hot. So very pleased with that.

    Just shows that the other (I think they are 120A), switches that got to hot to touch were crap. But how does one know when buying them? It's trial and error I guess. That's why I hope my fails and success's help other people out.

    I sent a 'item not as described' (Bad accuracy), to the eBay seller. Got an automated reply with return postage label - and have to use UPS to send it back to the USA... So basically not worth it.
    I'm still waiting for the 200A version to arrive.

    As for a 'toy'. How can a buy a proper one? Where? Plenty of hall effect 'rings' out there with 3pin connections but how do I get a Amp meter to talk to It?
    I'll happily buy a 'good' one if I got the correct Amperage.

  • #18
    Premium Member
    Skepticist's Avatar
    Join Date
    Apr 2009
    Posts
    1,139
    Thanks
    714
    Thanked 670 Times in 525 Posts
    Rep Power
    475
    Reputation
    12780

    Default

    Does the LCD meter for that current sensor have a calibration adjustment?
    Should be a small potentiometer on the PCB for that. Also the hall sensor itself is probably not very linear so if you make it accurate at high current, the reading at other currents will likely be worse.

  • The Following User Says Thank You to Skepticist For This Useful Post:

    GT250 (05-11-17)

  • #19
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Quote Originally Posted by Skepticist View Post
    Does the LCD meter for that current sensor have a calibration adjustment?
    Should be a small potentiometer on the PCB for that. Also the hall sensor itself is probably not very linear so if you make it accurate at high current, the reading at other currents will likely be worse.
    No S,
    I had a look for one, it's all solid state.

    As I said 'somewhere', I understand the readings will differ within the specified range. This one seems to be accurate at around 40-50A.

    There is a note that says that the meter is paired to the Hall Ring.

    I'll wait until I get the 200A version in.
    Cheers,
    GT250

  • #20
    Premium Member

    Join Date
    Jan 2010
    Posts
    1,077
    Thanks
    632
    Thanked 306 Times in 180 Posts
    Rep Power
    300
    Reputation
    4620

    Default

    Update:

    The 200A Meter arrived yesterday. So I decided to put the 100A and 200A side by side and see the results...

    I didn't get into the 100's today. As I've said before I've seen 120+ go through the 150A shunt meter. BTW the PL60 never goes over 60, but the 40A MPPT has regularly gone over 40A into the 60's on it's plugin display. These 60+60 have shown to be true by the 150A shunt and the Fluke meter.


    Remember that the 100A never went over 78A when the Fluke was reading 20A more and the Shunt meter was about 3-4 off that.

    200A on the left. No decimal point option on the 200A!
    Fluke in the Middle.
    100A on the right.
    Both on the short data cable. The 200 arrived without a long data cable. Tomorrow I'll put the 200A on the longer data cable (Have to wait and see if the longer length makes a difference), and move it away from the battery vents.
    I'll put the 100A on the PL60 input as the PL60 doesn't permanently show the Amps on the display - you have press the button to light it up. The 40Amp MPPT controllers plugin shows it. So it'll be nice to see what the PL60 is always showing and the 40AMPPT, and (hopefully), see the total in the 200A hall effect display.

    All good fun people

    50A


    75A


    90A



    So the highest I have seen the 200A unit so far is 87A

  • Page 1 of 2 12 LastLast

    Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •