How to unregulate solar panel

[MidLifeCrisis Out of control poster! Find all posts View Profile Close MidLifeCrisis]

The guys from Redarc called me and gave a detailed explanation. Unfortunately I am somewhat illiterate when it comes to matters concerning the electrical triangle and related matters. Suffice to my position remains unchanged.

The unit needs 17.2 volts to turn on (you know that). I don't know why and I'm too electrically stupid to understand why, but smart enough to know that this will have some logical reason. I also understand it will work down to 9V. I'm sorry Dane, it doesn't help your issue in the original post but rather than rely on the comments here try ringing them both. If I had a panel that did not work I would try someone else's panel and
1. If that worked, ring my panel supplier; or
2. If it didn't, ring redarc (or projecta etc)

The only certain thing is Redarc haters will blame Redarc and Projecta haters will blame Projecta.

Regards MLC - useless as a vibrator without batteries. (But the pleasant thought is there)

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Point is:

Test other panels... Does BCDC work?
Test other BCDC... Does panel trigger other BCDC

Bit of fault finding.

[Fred63 Advanced Member Find all posts View Profile Close Fred63]

i have a 1225 and it works fine with my panel now.

When i unplugged the regulator and plugged the cable straight in and connected it.
I did not work.
What i failed to notice was the male female configuration of the plugs reverses the polarity on the cable when plugged directly to the panel.
Swapped the cable over to correct the polarity and worked no problems my panel output voltages are similar to what you have quoted.
Only a thought check the polarity.

[danestead Junior Member Find all posts View Profile Close danestead]

Hi All,

I've double and triple checked the polarity and all seems fine.

I also did another test in midday sun today. 22 volts open circuit, 17.8 volts loaded at the panel (peaked at 18.0 volts for a little bit, this might be the MPPT finding the most efficient voltage/amperage combo), 16.5 volts loaded when measured going into the redarc solar relay. There is obviously some voltage drop there but it should still be working according to the redarc 1225 manual. It states that it needs 17.5 volts or greater 'open circuit' to activate. I have 22 volts. It needs greater than 8 volts loaded to continue working. I have 16.5 volts.

Not sure where to go from here. I might ring redarc again.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

If it is 17.8 volts loaded then it would appear the regulator is drawing current, what
is the battery voltage?

What lights are lit if any?

Can you measure the current being drawn?

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Voltage drop suggests current is going in. As Leigh said what lights are showing?

[danestead Junior Member Find all posts View Profile Close danestead]

I've spoken to Lex at Redarc again. He tells me that I have been reading the open circuit voltage wrong. I was testing the voltage across the wires of the panel when it wasn't plugged in. Lex says I need it plugged in and to measure it then. There are no lights illuminated on the BCDC 1225 other than the AGM light flashing. He said this is the open circuit voltage as the BCDC is not charging. So according to Lex, I am only getting 16.5 volts open circuit (which is what i previously thought was the loaded voltage).

I changed the leads to some heavier gauge wire (probably 3 or 4 times the mm2) and hooked it up to determine if that lead was the problem. I'm now getting 14 volts open circuit (open circuit according to Lex). The voltage drop was 0.2 volts from the panel to the car.

Lex said the best way to test for dodgy wiring on the solar panel is to do a short circuit current test. My panel is rated at 6.86 amps @ 17.5 volts. The fuse in my multimeter is busted so I can't test that but I'm hoping my mate has one I can use to test with later this afternoon.

Thoughts?

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

With regards to solar panels Lex's terminology is not right, the open circuit voltage is the
voltage the panel is generating without anything connected to the terminals so Lex is using the wrong terminology.

He is referring to minimum input voltage at the 1225 needs to higher than 17.5V
volts with the Redarc connected to the solar panel.

For the panel to be dropping to 16.5V in bright sunshine you should need to be drawing around 6.86A, if the charger is not running there should be very little load on the paneland you should seeing more or less the open circuit voltage at the charger, certainly higher than 16.5V.

I would get yourself a good meter and start doing some short circuit current tests on the
panel and the wiring. Don't do a short circuit test across the battery and make sure
the meter can handle more than the panel can put out ie 10 amps.

Can you post up some photos showing all your wiring?

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

Don't do a short circuit test across the battery

Pretty sure that's why the fuse in his multimeter's blown..

[danestead Junior Member Find all posts View Profile Close danestead]

Pretty sure that's why the fuse in his multimeter's blown..

Haha yeah it didn't blow on the car battery but a few years ago I remember testing something and an almighty bang went off and its just not been the same since!

[danestead Junior Member Find all posts View Profile Close danestead]

I haven't had a chance to test the short circuit current yet but I may buy a new multimeter tomorrow to do just that but I am also interested to see what the battery voltage is when I have the solar plugged in. As someone suggested, the voltage drop might be indicating there is a big draw on it, so I'd be interested to see if the battery voltage jumps up when the panel is plugged in or not. This may indicate an issue with the lighting on the Redarc controller (although it works fine on alternator charging).

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

Haha yeah it didn't blow on the car battery but a few years ago I remember testing something and an almighty bang went off and its just not been the same since!

I have a handful of fuses for my Fluke and I'm in the trade...

[danestead Junior Member Find all posts View Profile Close danestead]

I put a mates 50w panel on my car yesterday and got a max input voltage of 15.5v. I also tested the battery voltage and it's definitely not getting charged by solar as yet. That same panel was putting out 2.7 amps (basically it's max) when plugged into his Kimberley camper. I'm starting to think there's something wrong with my bcdc. That mate is wiring up his bcdc 1240 this week so will see if his panel works on his car. If his panel works on his car it pretty much indicates there is an issue with my wiring or redarc. I'll also go buy a new fuse for my multimeter and do a short circuit current test although I'm not expecting any issues with that.

[danestead Junior Member Find all posts View Profile Close danestead]

Ok, some measurements.

My projecta 120w panel is getting a short circuit current of 7.45 amps in midday sun. Unconnected today it read 21.5 volts. When connected to the redarc it settled on 16.5 volts and didn't activate the charging as it is less than 17.5 volts. I measured the aux battery and it was at 13 volts (Id just driven home so the voltage would have still been settling down). What I'm trying to say basically is that the aux battery is definitely not receiving any sort of solar charging.

I tested the cranking battery and it was reading 16 volts! I then disconnected the solar panel and the crank battery immediately dropped to the 12 volt sort of range. Why is the crank battery being charged when my solar panel is hooked up and why is it receiving 16 volts? I double checked the relay wiring and it seems to be hooked up correctly as per the Redarc 1225 manual. Sounds like unregulated voltage is going from the solar panel direct to the crank battery. I'm going to pull the relay off and double check everything later this arvo.

Edit:

I've now pulled the relay off and checked the terminal numbers against the relay kit wiring diagram and all terminal numbers, wire colours and where the actual wires go to (to rule out the wrong wire colours) and they all appear correct. I thought that the centre terminal which is the solar positive in terminal must be touching the red wiring which goes direct to the crank battery. That doesn't appear to be the case. I've tried ringing redarc but they are not open today.

[adrian5800 Advanced Member Find all posts View Profile Close adrian5800]

Are you sure it's a changeover relay you have there? Do you have 2 terminals marked 87 or one 87 and one 87a? The solar panel should be connected to 87a (centre terminal on a changeover relay or normally closed) and the red input to the BCDC is connected to 30, start battery goes to pin 87 - normally open.
So the solar panel is connected to the BCDC until the ignition is on then the changeover relay disconnects the solar and connects to the start battery with the engine running. I'm sure your panel and BCDC are working fine just the relay connections need looking at.
The minimum voltage req by the BCDC should be the Voc (volts open circuit) rating of the panel not the under load figure.