Solar regulator confusion

Submitted: Tuesday, Oct 15, 2013 at 16:20
ThreadID: 104730 Views:1826 Replies:5 FollowUps:8
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G'day guys I have a 50watt solar panel connected to my boat yet my boat battery (12months old) keeps drawing down below 12.5v. I have out a clamp meter across all positives coming from the battery and found no load on it when not in use (I an thinking the panel is sucking the battery). I just tested my solar panel at the actual panel before regulator. Got a healthy 21-22v. Yet after the regulator I am getting 10,11,12v (not connected to anything). I know if there is no battery connected this could be quite normal but I tested another panel (110w) and it was getting 21-22v after its regulator with no battery connected. Does it sound like the first regulator is not working anymore? It's a landstar regulator http://www.kencove.com/fence/Assets/documentation/MSC10LVDP_2012.pdf
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Reply By: Brian 01 - Tuesday, Oct 15, 2013 at 17:44

Tuesday, Oct 15, 2013 at 17:44
From the evidence supplied it is not possible to determine whether the regulator is faulty or not.
Many regulators require the battery to be connected in order to decide their charging parameters, and will give erroneous results if that rule is not adhered to.
Most modern regulators incorporate a blocking diode as do many panels, make sure your system has at least one to prevent backfeed at night.
As you have access to a voltmeter, why not connect the battery during daytime and see what voltage you have then.
Two things should happen when you have the battery connected:
1. The panel volts should drop to that of the terminal voltage of the battery.
2. The battery voltage should begin to climb fairly rapidly, this will only be surface charge, but it will indicate that the controller and panel are working.
If you then disconnect the panel and check with your voltmeter across the solar input terminals of the controller you should have a very low (millivolts) or no reading on the meter. If you are getting more than that then you probably need to install a blocking diode in the line, there may already be one at the panel but an extra one won't make a lot of difference to the charge regime.
You might also check charge current with the meter as well just to ensure that the panel is actually outputting a reasonable current.
Is it possible that the battery is at fault?
AnswerID: 519744

Follow Up By: Chris85 - Tuesday, Oct 15, 2013 at 18:16

Tuesday, Oct 15, 2013 at 18:16
Thanks mate. The battery is newish but its possible it could be the issue. No reading on the clamp meter. No increase in battery voltage when connected. I will draw down another good battery, then put panel on it all day and see if voltage has risen by the time I get home from work. Sounds like that should confirm it?
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Reply By: Member - Bruce C (NSW) - Tuesday, Oct 15, 2013 at 17:57

Tuesday, Oct 15, 2013 at 17:57
Hi Chris,

Sounds like the regulator is at fault and the panel is not far behind.

Can you do an amps reading with your meter on the panel first to see what sort of amps it is producing then an amps test on the regulator output.

I assume the battery is about an N70 size (truck battery size) and if that is the case then a 50 watt panel will never do the battery justice.

I have read that a flooded cell battery will lose 4% of its charge per week whereas AGMs only lose about 4% per month.

This means that a flooded cell battery will need to be charged sufficiently on a regular basis or continually as you are doing, but, in my opinion that 50 watt panel is not big enough. I would be using something in the order of 150 watts for the above battery and certainly nothing under 100 watts for a small car battery.

If you need to get a new regulator then you could do worse than one of These cheap LED display units.

I am not sure where your budget takes you so I have suggested a cheap one but if you can afford better try a Fangpusun regulator as I have a couple and find them excellent despite them being a PWM.

Here is a link to a Fangpusun
20 amp regulator. I like them because they have a clear indication of SOC, Panel output,
Reg output etc and show the SOC in a tank gauge like indicator.

I have used several different types of regulators and I find them one of the best as there circuit board is virtually a Stecca type board.
For the uninitiated Stecca is a well respected brand of Solar regulator.

Cheers, Bruce.
At home and at ease on a track that I know not and
restless and lost on a track that I know. HL.

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Follow Up By: Brian 01 - Tuesday, Oct 15, 2013 at 18:29

Tuesday, Oct 15, 2013 at 18:29
I have an unregulated 20 watt panel connected to three N70 sized batteries in my boat, and it keeps them in tip top condition.
Obviously not there for charging, but good for float.
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Follow Up By: Chris85 - Tuesday, Oct 15, 2013 at 19:52

Tuesday, Oct 15, 2013 at 19:52
I appreciate your advice. The 50watt panel is essentially for float as I charge the battery to full on a mains 7 stage projecta charger then connect panel. I must add this panel has done this to two batteries same problem. I'll place the panel on a discharged (say 12.1v) 33ah deep cycle tomorrow and see how it is when I get home, if it hasn't increased the battery voltage then it's a fair call to say the regulator has died. Any further advice is appreciated.
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Reply By: Chris85 - Tuesday, Oct 15, 2013 at 18:18

Tuesday, Oct 15, 2013 at 18:18
The panel is there to keep a fully charged battery topped up on the off season (fishing) so battery is never flat when I connect solar panel.
AnswerID: 519749

Reply By: Chris85 - Tuesday, Oct 15, 2013 at 18:19

Tuesday, Oct 15, 2013 at 18:19
It's a marine battery
AnswerID: 519750

Reply By: Ross M - Tuesday, Oct 15, 2013 at 20:18

Tuesday, Oct 15, 2013 at 20:18
Chris85
If you have had the panels charging and disconnected the battery terminal, then the regulator will have been open circuit.
Possibly this has damaged the regulator and it uses some current instead of blocking.

I may be wrong but a couple of my regulators say "Do not disconnect while solar is active" othewise it fries the reg. You have been testing the reg open circuit output while solar is active, not good.

Try a new regulator.
AnswerID: 519756

Follow Up By: Chris85 - Tuesday, Oct 15, 2013 at 20:28

Tuesday, Oct 15, 2013 at 20:28
Surely I can remove the alligator clips from the battery during the day? Never had a problem with any other panel doing that, why would an open circuit be an issue as most panels can be permanently mounted without having anything connected (ie: taken the boat/ caravan away on holiday). I don't mean to be making statements just trying to gather info and learn more and more about solar.
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Follow Up By: Member - LeighW - Tuesday, Oct 15, 2013 at 21:40

Tuesday, Oct 15, 2013 at 21:40
Some regulators work by shunting the current, though I think they are mainly used for wind generators. Removing the battery can cause them to overheat.

Leigh

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Follow Up By: Chris85 - Tuesday, Oct 15, 2013 at 21:48

Tuesday, Oct 15, 2013 at 21:48
So how could you ever disconnect a solar panel? Wait till dark?
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Follow Up By: Member - LeighW - Tuesday, Oct 15, 2013 at 22:03

Tuesday, Oct 15, 2013 at 22:03
Sorry but of confusion there, you shouldn't disconnect the regulator from the battery without first disconnecting the solar panels from the regulator or shading them etc.

Leigh

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Follow Up By: Chris85 - Wednesday, Oct 16, 2013 at 06:20

Wednesday, Oct 16, 2013 at 06:20
Cheers mate, I might replace this regulator and with the new one set it up where it's easier to disconnect it from the panel
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