A Tale of Two KIDS

[Westbranch]

My lake neighbour now has 2 KIDS @ 12V into 2 12V batteries, parallel, but different make and size.. and only one bank is charging...

Background...

Well Kid #1 was a snap as the 4 series connected  140W PV's have been up and functional for 2 years....  A  borrowed MX-60 was used temporarily...
We hooked it up this summer, lots of production, and then the solar sickness set in !  ......  You know Wow, look at all the things I can do with all this power.....  Well KID #2 was on its way , in the mail.....  2 x 230W panels and 2 more (different) batteries  too!  ::
Then his well pump died and next he has 250 feet of recovered  #8-3 wire.  So now the existing system can stay intact and another pole can have the 2 x 230W PV's on it... ( A boundary disagreement ensued  with another lake neighbour       )

Well there was incoming Volts from the 2 series connected PV's  but not  quite as many as expected and only 0.1A to 0.3A...?

His first thought was that in the setup he had 'bricked' his newest KID..     .. so  I suggested that we swap the 'good array' onto the new KID, Voila, there is full power ( for a cloudy day and setting sun)
OK lets check the Amps with my clamp-on-ampmeter,  at the bottom of the pole for the PV's.  It is the same as at the KID...hmmm

Sun now gone for the day so tomorrow....  Question now is what should we check?  There is connectivity through the whole wiring.  The PV's have MC4 connections, and different wire down the pole.   

There are some regular tube crimped connectors that go from the Solar sun resistant # 10 AWG wire that we will re-crimp with my hydraulic crimper but other  than that?? The wire did not appear to have any corrosion where the connectors are.

A bad PV panel?? if so how to test it?

[ClassicCrazy]

You can test a panel by disconnected the panel so you have just the positive and negative leads from the panel  and then short them together and put your DC clamp meter on it . You should see current . Next do the other panel and that should have close to the same current.

I have had wire that has had corrosion in the middle of  the  run - you could barely tell it was there but it didn't conduct any longer and once I found it at a knick in the insulation  it broke right apart . 

Larry

[Westbranch]

We are hoping for good sun tomorrow. Will test the panels separately.
Thanks for the tip.

[TomW]

Then his well pump died and next he has 250 feet of recovered  #8-3 wire.

Just curious on this recovered cable?

Is it on the system with issues?

Cable can be easily damaged by cracking or nicking when being removed, especially if buried.

It doesn't take much to let moisture in and kill the conductivity of said cable.

Just a heads up on including used cable in a system and then having issues.

Been there, done that.

As WB mentioned, it is trivial to test individual modules by simply shorting the leads and measuring current in decent light.  Voltage is not a good indicator of health without current flowing it will be pretty close to max.

Just a few ideas.

Tom

[Westbranch]

Then his well pump died and next he has 250 feet of recovered  #8-3 wire.

Just curious on this recovered cable?

Is it on the system with issues?

Yes.

Cable can be easily damaged by cracking or nicking when being removed, especially if buried.

It doesn't take much to let moisture in and kill the conductivity of said cable.

Just a heads up on including used cable in a system and then having issues.

Been there, done that.

As WB Larry mentioned, it is trivial to test individual modules by simply shorting the leads and measuring current in decent light.  Voltage is not a good indicator of health without current flowing it will be pretty close to max.

Just a few ideas.

Tom

Just saw the sun hit the panels 5 min ago and before we got there some light high clouds rolled in. no output  ...

more later.

[ClassicCrazy]

Then his well pump died and next he has 250 feet of recovered  #8-3 wire.

Just curious on this recovered cable?

Is it on the system with issues?

Cable can be easily damaged by cracking or nicking when being removed, especially if buried.

It doesn't take much to let moisture in and kill the conductivity of said cable.

Just a heads up on including used cable in a system and then having issues.


Tom

All the same I have been using recycled indoor rated wires and have had them laying on the ground not in conduit  and buried in grass and snow etc for years and have had no problems. The more modern wiring insulation is really tough stuff !  Problem I had was with older wire - it knicked and rotted away much more easily.

It is on my list to put all that in conduit one of these days though - and use fresh new wire too .

Larry

[TomW]

Point being, eliminate the obvious points of failure first.

Even "new" does not mean "good" these days with little to no quality control many places.

I hope I am wrong but I would bet a dollar to a donut (old saying from when donuts were a dime) that you find an issue with either that used cable or connections to it.   

Repurposing is all well and good except when there are issues in the same system that could reasonably be attributed to the repurposed parts.

Voltage drop and current limiting fit in with a buggered cable. I always start with the easy stuff and work my way from there bugging out failures.

If the short circuit tests on panels are good you might need to address the cable issue as you work towards the battery / controller  to be sure it is as good as you hope.

Just saying.

Tom

[Westbranch]

Point being, eliminate the obvious points of failure first.
.....
I hope I am wrong but I would bet a dollar to a donut (old saying from when donuts were a dime) that you find an issue with either that used cable or connections to it.   

Right Tom, that was my suspicionfrom the get go...  Oh, up here with the weak dollar we bet '' dollarS to doughnutS ''     

Well it turned out to be an almost obvious thing...
Sun Up and full power should be coming from the PV  we hope,
so we started at the KID ... still the same... volts but no amps...

Up to the array, yup,  Amps showing on the clamp meter, Volts showing but a bit low, Ah ha, there are some small shadow lines, OK that fits... Then, (drum roll) friend asks me why his V meter was showing   (-) , "shouldn't it be  (+) or blank.... (me)'' YES!  Are those panels hooked up backwards?''

so from the ground we traced the + wires and - wires,  hmmm looks OK but wait that wire has a + on it and it is going to the Neg wire (Black)... 

Back to the KID and, thanks to MN for having reverse protection built into the KID, we re-wired the circuits wiring and  BINGO, its charging.
10 minutes later it enters Absorb!

We will keep an eye on the total W and make sure it is up to expectations...

thanks for the tips, they did help..

[ClassicCrazy]

Always nice to find and easy problem
I mark all the positive wires with a piece of red electrical tape - makes it a little easier to avoid that kind of mix up.

Glad you are charging again.

[Westbranch]

Yes, that error came from looking at the Neg marking on the 'pigtail MC4' connector instead of the marking on the wire coming from the Panels Junction box... and thus,  connecting the PV output in REVERSE...

It is an easy, simple mistake that can kill a less than well made CC, but NOT the KID!      

The batteries on KID #2 went into Absorb    after about 15 minutes. So there was little parasitic load while the PV was in reverse polarity.....

Will have to check tonight  if they made it to Float...

Sometimes when your logic tells you what may be wrong, the belief, in your mind, that it is not that solution, is hard to shake off ....  My $$$ was on a bad connection

[ClassicCrazy]

well - it was a bad connection !

[Westbranch]

Good one!.... errrr no Bad One