Help needed, please! Can’t find fault in PV wiring!

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Help needed, please! Can’t find fault in PV wiring!

Postby Wangapeka » Sat May 03, 2014 9:43 am

Hello,
I’m setting up a simple 12V system in a house bus for a friend, but for some reason the controller did not work (charge) in this setup. There must be a fault somewhere in the wiring but I can’t find it (tested everything I could think of)

I’m trying to explain what happened and hope not to be too confusing, please bear with me.
The panels are 12V/120W, 4 wired in series for 48V,VOC = 22.35 V, ISC = 6.97 A
Controller is Tracer 4210RN, 40A, (MPPT) rated at max. Input voltage 100 V (520W at 12V)
Battery is 12V (6x 2V), 400Ah (panels and controller are NEW, battery was in standby mode for couple years)
When I connected everything I measured ~ 88V at the PV terminals at the controller, so far so good. But when I measured at the Battery terminal of the controller I only got battery voltage at 12.5V and it stayed at this voltage even with this relatively high charge. I would have expected the batt voltage to slowly start rising, after a few minutes at least. I should add, the battery was at rest for a few days before connecting and measured 12.5V. The batt. LED light showed solid green as it should but no light at all on the PV LED. Even if the charge V doesn’t rise as quickly as I expected (because of battery size), this PV LED should be on! (There was no load on the battery.)
First I suspected the controller being faulty but I tried also with an older 30A (PWM) controller which I knew was working o.k. as I used it in a similar setup at home (in a redundant system) There, the controller always shows at least 13V on a 390Ah (charged) battery.
Because this PWM controller is only rated for up to 44V max. I connected only one panel at first, got the corresponding voltage at PV input (around 20V) but still the same 12.5V at Batt. terminal. Because of this small charge it probably takes a long time for the voltage to rise, but the controller got quite warm, too. Out of curiosity I took the risk and tried with 2 panels in series (which would have been just under 44V,but the controller started to smoke then! I Later on I found the 10A inline fuse at the panels had blown as well! I just can’t find any wiring fault (bad connection, reverse polarity etc.) (Meanwhile I know that the controller is working fine)A friend who has an electronic engineering background also had no explanation.

This is a very frustrating experience for me, especially since I installed my own much more complex system successfully. :oops:
My hope is now that, perhaps someone on this forum has an idea what could be wrong? Any help is much appreciated!!
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby jules » Sat May 03, 2014 10:28 am

Batteries dead?
Primary system: .8KW Trina panels; Plasmatronics PL40; 1,000Ah VRLA 12X2V battery bank; 1.7KW Selectronic inverter. Off grid for 30 years.

Spares; 5 x 12V, 1,000 Ah batteries plus a couple of regulators
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby Gordon-Loomberah » Sat May 03, 2014 1:18 pm

Wangapeka wrote:When I connected everything I measured ~ 88V at the PV terminals at the controller, so far so good. But when I measured at the Battery terminal of the controller I only got battery voltage at 12.5V and it stayed at this voltage even with this relatively high charge.


Which relatively high charge? You dont mention what current was going into the batteries, a vital piece of information!

If your PWM controller was only designed to charge 12V batteries, then it isn't surprising that the 2 panels you connected in series caused the magic smoke to escape! 22.35V *2 = 44.7V, and could have been higher in cold weather or due to cloud edge effect. Connecting in parallel may have been a safer move.
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby Wangapeka » Sat May 03, 2014 1:54 pm

jules: how can they be dead with 12.5V?

Gordon, from 4 panels in series I get ca. 8 A to the Tracer, then 40A from Tracer into battery, right?
I remember measuring over 60A at some point going into battery but didn't quite trust that (Chinese clamp meter).
Your remark about the PWM controller brought into my attention now that I was mistaken to think it was capable of handling 24V from panels! (I only got less than 44V before)
Of course you're right, I should have connected in parallel!
It still leaves me puzzled about it not working with the tracer - but I can see a "little light" now! Thanks a lot!!
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby davidg » Sat May 03, 2014 2:05 pm

Wangapeka wrote:My hope is now that, perhaps someone on this forum has an idea what could be wrong? Any help is much appreciated!!

Do you have the monitor unit for the tracer ?? If not then you are only are seeing a fraction of whats going on, get a monitor unit for the tracer.
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby Gordon-Loomberah » Sat May 03, 2014 2:11 pm

Wangapeka wrote:Gordon, from 4 panels in series I get ca. 8 A to the Tracer, then 40A from Tracer into battery, right?


Yes, you theoretically *can* get 40A output from the Tracer, if you get the theoretical 480W from the panels, and have no losses, but that is unlikely unless it is very cold and the panels are face on to a bright sun reasonably high in the sky.
If somewhat less than that is going in, then the voltage will only rise slowly in a battery with a low state of charge. Connect it up, use some patience (easier to find if you look somewhere other than at the battery! :) ), and see what it is doing in an hour.
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby Wangapeka » Sat May 03, 2014 2:17 pm

davidg, there is already an quite elaborate meter in place on the load side (installed by auto-electrician some years ago for megabucks, therefor my friend don't want extra meter). Unfortunately it's awkwardly positioned, my mate has still some work to do to make better access, then I'll have a closer look at it. Thanks for your input!
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby davidg » Sat May 03, 2014 2:24 pm

Wangapeka wrote:davidg, there is already an quite elaborate meter in place on the load side (installed by auto-electrician some years ago for megabucks, therefor my friend don't want extra meter).

However without the tracer one (monitor) you don't actually know what the controller is doing and you cannot program the unit without it as that's also what it is used for, you will continue going around in circles without it, it is used to set things like max voltage what type of batteries, temp compensation, etc. You really do need it, or your just wasting everyone's time.

I was very pleased when I bought one of these (Tracer MPPT charger controller ) for my 4WD that I also bought the monitor unit as well, as without it. I would not have been able to setup it (controller) up and know what it was actually doing without the LCD monitor setup/controller.

Once the controller is setup you don't need really it apart from maybe accurate monitoring after that, but to set it up you really do need it.
Last edited by davidg on Sat May 03, 2014 2:58 pm, edited 1 time in total.
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An OTT Genset for a house.
PVOutput Stats

Sparkys light up your life :)
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby Wangapeka » Sat May 03, 2014 2:31 pm

"If somewhat less than that is going in, then the voltage will only rise slowly in a battery with a low state of charge. Connect it up, use some patience (easier to find if you look somewhere other than at the battery! :) ), and see what it is doing in an hour."

Yes Gordon, I accept that, BUT: If it's charging o.k. why isn't the charging LED on the Tracer not coming on?
As it is a over 2 hours return trip to the installation site, I'm trying to gather as much useful information as possible before I have another go at it! The response so far is really great!! I'm really immensely grateful!!
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Re: Help needed, please! Can’t find fault in PV wiring!

Postby Wangapeka » Sun May 04, 2014 6:24 am

Once the controller is setup you don't need really it apart from maybe accurate monitoring after that, but to set it up you really do need it.


davidg, I didn't think it was needed for set up, the supplier of the controller did offer it but he didn't say it was needed. Battery type can be selected on the controller itself. My understanding is once the battery type is selected it operates on preset parameters. This should be sufficient for initial setup - and at least get the thing working. The problem, which I expect to be a wiring fault as the charging LED is not coming on, seems to have nothing to do with potentially wrong parameter settings?!
Of course, longer term it would be good to have it for monitoring purpose, but I wanted to see first what the existing meter does. I would find it hard to convince my mate at this stage to get one.
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