Is my solar setup faulty?

[Phil_G]

I know you're are being tongue in cheek here, and I mean no disrespect, but I have seen 6V and more dropped on long cable runs in 24V systems, where the cable size is more than enough to carry the current.

You're missing the point Jay - there is no panel current. The panel is not supplying any current and the voltage at the controller input is 12.6v
To see any voltage drop across the cable there would need to be significant current.
I maintain, this isnt voltage drop over an inadequate cable - to me its either a resistive joint, a duff panel or blown schottky.



If the system was professionally installed I would (at least initially) respectfully assume the cables were adequately specced.
Further, having completed a bulk charge in the morning, why would the cable suddenly become underspecced in the afternoon?
As you said, no disrespect, but clues in the story seem to have been missed...
Cheers
Phil

 

[T6Jay]

You're missing the point Jay - there is no panel current. The panel is not supplying any current and the voltage at the controller input is 12.6v
To see any voltage drop across the cable there would need to be significant current.
I maintain, this isnt voltage drop over an inadequate cable - to me its either a resistive joint, a duff panel or blown schottky. I'm an EE too

View attachment 87477

Yes, you are right. 0 amps is not a small cable issue.

I think talk of wet string not dropping 6V triggered me, as I know Volt Drop is a real problem in 12V (and 24V) systems, for this reason, I'm still interested to know what the cable sizes are. I've seen too many systems where 'engineers' have only considered the current capacity of a cable.

 

[Phil_G]

Good man, sorry I drove it home a bit...

 

[Grim Reaper]

The 'Charges in the morning' when it's cool, and 'Doesn't charge at midday' when it's hot shouts out faulty panel to me.

 

[monsteruk]

What size cables has the installer used? some cables have --AWG or --mm² written on them. If you can't see that, what's the diameter of the cables (if they used 2 or 3 core flex, what's the diameter of the flex?).
If you don't have a vernier, use an adjustable spanner and a ruler to measure it.
Also, what's the length of the cable?

Hi @T6Jay and @Phil_G

I have had a look at the cables going to / from the MPPT controller. Some pics below.

There are 4 cables connecting to the MPPT - 2 going to the battery and I assume the other two go to the panel?

• I can read this on one of the cables "TWINFLEX 2x6 mm2" (see pic) - all 4 cables look the same diameter as this one (so suspect would all say the same).
• I have used the "adjustable spanner" approach to check the diameter. I estimate the outside diameter of all 4 MPPT cables to be around 8mm
• Cables length from MPPT to battery - I would guess around 60cm (2ft) or so (I can see the cable, so this is relatively accurate)
• Cables length from panel to MPPT - hard to say, as it runs behind the cladding and I cant see where it goes. I would guess around 180cm (6ft)

Do the cables gauges and lengths used for my setup sound appropriate?

Also, see the last photo with a blue arrow - highlighting where the MPPT cable joins the positive battery terminal? The nut on the battery must be tight, as the connectors are rock solid on the post. However, the cable itself wobbles a lot into its own connector (if that makes sense) when I gently move it. I.e. if I hold the cable near the battery post and gently wiggle it, the cable flexes where it joins the connector - the connector itself on the battery post does not move, it is rock solid. The same IS NOT true on the negative post. The cable does not flex at all when I try and gently wiggle it. Not sure if that could be an issue? Thinking about it though, I guess a bad connection there would not account for the poor readings from the MPPT controller?!?!?

Thanks,

Roy

 

[Loz]

Cables are big enough.. but if that terminal is loose, then either crimp a new one on or I would just solder it up.

 

[T6Jay]

Hi @T6Jay

I have had a look at the cables going to / from the MPPT controller. Some pics below.

There are 4 cables connecting to the MPPT - 2 going to the battery and I assume the other two go to the panel?

• I can read this on one of the cables "TWINFLEX 2x6 mm2" (see pic) - all 4 cables look the same diameter as this one (so suspect would all say the same).
• I have used the "adjustable spanner" approach to check the diameter. I estimate the outside diameter of all 4 MPPT cables to be around 8mm
• Cables length from MPPT to battery - I would guess around 60cm (2ft) or so (I can see the cable, so this is relatively accurate)
• Cables length from panel to MPPT - hard to say, as it runs behind the cladding and I cant see where it goes. I would guess around 180cm (6ft)

Do the cables gauges and lengths used for my setup sound appropriate?

Also, see the last photo with a blue arrow - highlighting where the MPPT cable joins the positive battery terminal? The nut on the battery must be tight, as the connectors are rock solid on the post. However, the cable itself wobbles a lot into its own connector (if that makes sense) when I gently move it. I.e. if I hold the cable near the battery post and gently wiggle it, the cable flexes where it joins the connector - the connector itself on the battery post does not move, it is rock solid. The same IS NOT true on the negative post. The cable does not flex at all when I try and gently wiggle it. Not sure if that could be an issue?

Thanks,



View attachment 87541

As others have said, my concern about cable sizes was never going to be the sole cause of such poor charging. And now you know they are 6mmsq , and relatively short runs. That seems fine to me.

On the 'wobbly' connection; can you lift the red cover, and have a look at the yellow crimp, specifically at the battery end of the yellow bit. Usually you should be able to see the copper strands at least reaching the end of the tube, if not extend out a little past it. Also check for signs of any heat damage, melted plastic etc. Take a pic and post it. Compare it with the black connection.

If it was me I would pull the inline fuse out and give the red cable a good pull (at the battery crimp), and see if it's crimped properly, if it pulls out easily, then that could be the problem. However, I have to tools and crimps to remedy this, I don't know if you have? Maybe you should video this being done, in case you need to show the installer.

The other thing that may be worth checking is the connections on the inline fuse, and the fuse blades, I have seen dirty fuse blades and crappy fuse holders give problems before.

 

[Loz]

I was checking a similar problem with a solar setup installed by a car audio firm and when I checked, I saw an ominous bit of black tape, removed it and found this.

 

[monsteruk]

As others have said, my concern about cable sizes was never going to be the sole cause of such poor charging. And now you know they are 6mmsq , and relatively short runs. That seems fine to me.

On the 'wobbly' connection; can you lift the red cover, and have a look at the yellow crimp, specifically at the battery end of the yellow bit. Usually you should be able to see the copper strands at least reaching the end of the tube, if not extend out a little past it. Also check for signs of any heat damage, melted plastic etc. Take a pic and post it. Compare it with the black connection.

If it was me I would pull the inline fuse out and give the red cable a good pull (at the battery crimp), and see if it's crimped properly, if it pulls out easily, then that could be the problem. However, I have to tools and crimps to remedy this, I don't know if you have? Maybe you should video this being done, in case you need to show the installer.

The other thing that may be worth checking is the connections on the inline fuse, and the fuse blades, I have seen dirty fuse blades and crappy fuse holders give problems before.

OK, quick pick of under the battery cover. No evidence of any melting. Wobbling is as the red cable goes in to the yellow bit, as in blue arrow below.

Just off now to take camper to installer.... I will pass on all the info. Anything else I should mention to him>



Roy

 

[Grim Reaper]

Those crimp terminals are terrible, never seen one that worked well. I always take the plastic bits off them, solder and cover with heatshrink.

 

[Skyliner33]

Those crimp terminals are terrible, never seen one that worked well. I always take the plastic bits off them, solder and cover with heatshrink.

I’ve never had a problem with one.

 

[t0mb0]

I’ve never had a problem with one.

Me neither, our camper, like almost every other camper out there is full of them and I’ve never had an issue. Given it almost never crops up on the forum, I’d say it was pretty rare.

Having said that though, if that one in the solar setup feels loose, definitely replace it and see if it helps.

 

[oldiebut goodie]

Those crimp terminals are terrible, never seen one that worked well. I always take the plastic bits off them, solder and cover with heatshrink.

Yes those crimps are a pain, the number of heaters that pass through my hands with them on that have poor connections is amazing. It is common to find that a small tug pulls the cable out - work of the devil I tell ye along with Scotchlocks.

 

[T6Jay]

Those crimps are industry standard in industrial electrical control panels worldwide. If applied properly they are fine. Too many of them are put on with the wrong tool, pliers etc, or maybe just poor quality crimps.

The RHS one in the last photo looks terrible, although it's impossible to say from here if it's connection is good.

The LHS one looks like the crimp tool was applied better, but I can't see if the cable itself is inside the crimped barrel. the bend in the cable looks too sharp to me, almost as if it's not into the barrel at all?

 

[Phil_G]

Just another thought, your cable sizes are fine, however, solar panels are not supplied with that type of cable, therefore you have a joint somewhere between the red/black 6mm and the solar panel cables. It could be solar connectors (they're huge so usually get snipped) could be a solder joint, choc block, or crimps. However its connected, that junction could be bad, corroded, wet or not plugged in properly. My money is still on the panel itself.

 

[Grim Reaper]

Have you got a multimeter? Preferably one with a 10A capability.
Disconnect the panel wiring from the MPPT, test voltage on the end of the wires, 20V? Good. Change meter to A setting, move wires to 10A terminal on the meter and check again, in good sunlight you should get around 5.8A, if it's around 0A then your panel is faulty, or you have a very poor connection somewhere that is not allowing current to pass.

 

[monsteruk]

Have you got a multimeter? Preferably one with a 10A capability.
Disconnect the panel wiring from the MPPT, test voltage on the end of the wires, 20V? Good. Change meter to A setting, move wires to 10A terminal on the meter and check again, in good sunlight you should get around 5.8A, if it's around 0A then your panel is faulty, or you have a very poor connection somewhere that is not allowing current to pass.

Thanks @Grim Reaper. I have just dropped the camper back at the installer and left it with them. They are speaking to panel and MPPT supplier to decided the specific tests to do. I will pass your suggestions to them.

All the responses you guys have given have been invaluable to me. I was able to talk in (semi) intelligent terms to the installer, and they accept there is an issue - so hopefully will resolve it.

Just need some advice now on a good test now, so when it returns I can be sure they have actually resolved the issue! I guess your test above would be a good starting point.

Thanks,

Roy

 

[Phil_G]

Any news?

 

[AussieMick]

Yes as post above, what was the outcome , just curious.

 

[monsteruk]

Hi chaps.

With regard to the panel, the converter agreed there is an issue, and has booked it in for the start of next month to replace both the panel and MPPT controller. Hopefully that will resolve the issue.

I now have ANOTHER electrical issue I am afraid. Maybe related? I dont know!

I have continued to use the van (until lockdown) but have obviously had to use pitches with electric hook up. The last time we went away we had another bizarre electric issue.

So, we spent two nights on full electric hook up with no issues (leisure batter 100% as one would expect). We checked out, and drove toward home. We stopped at one location for 20 mins on way home and I know the eclectics were ok at that stop, as I got something from the fridge. Our total drive home was about 2 hours (and done in the light), so the split charger should be doing its thing and keeping it topped up.

When I arrived home, first job was to empty the fridge. But I found the fridge was off, and all the lights were flashing is a crazy manner (see videos linked below). There was no way to turn off the fridge, it was just stuck like it. Then when I checked the battery charge from the LED indicator panel inside the van, it showed 1 red light, and beeped (showing it was flat - again, see videos linked below).

I turned the electric back off inside the van, and tried multiple times, always same result... would show 1 red LED and beep.

Here are the videos I took of it when it went weird.

20201110_124354.mp4

drive.google.com

20201110_124318.mp4

drive.google.com

I then left it a while (whilst unpacking other things) and also flicked this switch on and off (which I am not sure is even related to running off leisure battery):



And as if by magic, next time I tried it, it was all ok again. Switch was off, and switch back on again, and all of a sudden, I was getting all LED indicators showing full battery charge. Nothing had happened, i had not charged it or anything, simply waited for 25 mins, and flipped that switch on and off! The victron bluetooth app also showed battery as full charge, so no idea what had happened!

Has anyone seen anything like this before, or have an idea what it could be? I told the converter about it (sent him videos) and he said he would like whilst changing the panel and the MPPT - but I dont think he knows what this fault is. Obviously, it is intermittent, and has not done it in last week or so.

Any ideas or info much appreciated

Thanks,

Roy