Shout out to excellent Midnite tech support

[OffGridInTheCity]

I'm just past 4 years of off-grid solar production and I had a serious issue and the fantastic Midnite support I got that helped me resolve the issue.

I use one of my Midnite Classic 150s AUX1 relay to turn on/off my inverters based on battery voltage. It started cycling every few minutes turning the inverters on/off - which cause all my ATSs to switch back and forth. It's not good for my system.

I went to the control room and all 3 Classics where blaring GND FAULT. So I like a good DIY'er I stuck my head in the sand and rebooted. Howerver, the one would not boot up - it just started to and then cycled over and over. I pulled out a spare and the same thing. I'm going to myself - did I just destroy 2 Midnite Classics?

Fired off a general tech support request and within 60minutes got back this:
---------------------------- email from Midnite ---------------------
From: Ryan [mailto:ryan@midnitesolar.com]
Sent: Wednesday, October 12, 2022 2:13 PM
To: Information; xxxx
Subject: Re: General Information - MidNite

Xxx,
You have a bad electrical connection some where between the battery and that classic. it is high resistance so when the classic tries to start it drops the voltage and resets
--------------------------------------------------------------------------

So I scratched my head and wondered how the 15ft wire from the Battery buss to the Midnite could possibly cause this. Bypassed the breaker and redid the lugs - no go. I took both Midnite Classics to my office and hooked them to a 48v battery - and they both booted properly!

Then I remembered the original electrician put in a junction box and wa-la. He did butt-joints on 4AWG that carry up to 80a and one of them burned thru. Here's a pic of the junction box from Feb 2020....


And here's the butt-join that burned up last week (Oct 2022)


Midnite tech support was 100% correct - bad connection between the battery and the Classic!

Connection is fixed and the Midnite Classic 150 is back onlineas good as ever. Also a good example of fire prevention gained by using metal junction boxes!

In these days of seemingly poor support, I just wanted to do a shout out to Ryan / Midnite Support!

 

[Supervstech]

Sucks an electrician would use butt joints with 4Ga... but good that he put it in a box!

 

[Supervstech]

Looks like the wire itself fried... something is wrong for sure.

 

[OffGridInTheCity]

I have the 3 x Midnite Classic temperature probes in various boxes and one was in the junction box. But after a couple of years I stopped paying attention as they never got above 55C.

I've since added logic to turn the temps red on my dashboard if they go >= 60C. If I'd payed attention I would have been alerted up to 5 days (Oct 7) prior to the failure Oct 12... Oct 11 it reached 81.4C = 178.5F hi - and the probe was 6" away... so it got HOT in that box.

 

[x98myers7]

wait... did he butt joint and shrink-wrap ONLY on loose connectors? mechanical butt joint is good and correct in this case. I've never seen anything like those before as a "loose" install. they should be secured to a plastic bracket.

for 4AWG for anyone referencing this in the future... use DC rated "power distribution blocks" or "terminal blocks".

I don't think DINKLE makes UL listed DC terminal blocks that will work for 4awg/80amp. but they do for 6awg/60amp.

 

[Steve_S]

This also serves as warning about "Licensed Electricians", especially those who are clueless about real DC Systems.
Hopefully your setup is such that you can eliminate butt joints and run a clean wire from point to point. Even if it involves some minor work, likely a prudent move to "clean up" such messes. It could have gone really badly if the one classic hadn't acted up when it did.

 

[x98myers7]

great points Steve. I'd also recommend everyone get in the habit of opening up every DC junction box to confirm there's no damaged/overheated/moisture evidence every 6 months. might have been able to see this coming long before ground fault occurred.

I wonder.... is the junction box in an attic?

 

[OffGridInTheCity]

great points Steve. I'd also recommend everyone get in the habit of opening up every DC junction box to confirm there's no damaged/overheated/moisture evidence every 6 months. might have been able to see this coming long before ground fault occurred.

I wonder.... is the junction box in an attic?

The junction box shown above is under the house - tucked up in the insulation under the floor. Based on my experience, I agree 100% with comments to 1) check and 2) get rid of butt-joint connections. I'm in year 4 of operations - and a learning point for me is that it's not just a mater of checking when you 1st wire things - but perhaps a yearly check? or every other year? Definitely a multi-year health check.

I do have the temp probe in the box and updated my software to do 'in my face' alerts if it goes >60C - so I won't just glaze over the numbers. And because of this event - I'm now 100% in favor of *metal boxes* for connections rather than exposed connections. It not only protects against shock but in my case - might have protected against fire under the floor.

 

[x98myers7]

100% could not agree more. i ALWAYS use a grounded metal box unless outdoors/marine/water-tight.

 

[PreppenWolf]

That butt joint connector looks like it was mild steel? The screws appear corroded/rusted in the pic supplied. If I was using a butt joint there I would have used a copper connector, hydraulically crimped it and shrink wrapped it.

 

[OffGridInTheCity]

That butt joint connector looks like it was mild steel? The screws appear corroded/rusted in the pic supplied. If I was using a butt joint there I would have used a copper connector, hydraulically crimped it and shrink wrapped it.

Yea.. I repaired it by crimping on copper lugs / bolting them together + wrapped heavily electrical tape

 

[Supervstech]

Yea.. I repaired it by crimping on copper lugs / bolting them together + wrapped heavily electrical tape
View attachment 123394

Ooooh… crimped AND soldered… brave.

 

[PreppenWolf]

C'mon. Just wire nut it. Live on the edge!


**Do not do this. If you don't know why this is a joke, please hire an electrician for every project you have.

 

[OffGridInTheCity]

Ooooh… crimped AND soldered… brave.

You bet! No way will this have a 'loose connection' any more

 

[x98myers7]

Yea.. I repaired it by crimping on copper lugs / bolting them together + wrapped heavily electrical tape
View attachment 123394

eh....... well... so.... honestly, i'm just not a fan of not having the terminal connections firmly secured to something. floating connections is ALWAYS going to present a potential for problems, IMO.

I would highly recommend something like this, instead. UL listed for 180amps.

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