Solar Panel Discharging Battery When Dark

VicS said:
Is it just the regulator drawing a small current from the battery or is there in fact a reverse current through the solar panel ?
Click to expand...

Originally, I had one diode to stop backfeed to the panels, then out of the diode to the two regs, one for each domestic bank. I've cured the problem by using a split charge diode in the feed from the panels so that's stopped backfeed through the regs as well as to the panels.
 
So, I popped down to the boat this morning, armed with a multimeter and my findings are thus...

Panel output in daylight is about 16V.
Panel output in lovely direct sunlight is 18.5V.
The battery is 110AH not, as previously stated 110mAH
When I put the panel in a locker, the light in the regulator goes red (not charging). The voltage across the battery over the 5 hours I was there dropped by 0.8V.(nothing else was connected to the battery)
I took the reg to pieces, found a rather black looking diode and it smelt hot!

Conclusion -Replace regulator with something a little meatier.
Cause - Possibly an underrated Reg or just just bad luck.

Thanks for all your input though.
 
A quick update. I ordered a new regulator on FleeBay, this one is 20AMP. Fitted and tested last night, works a treat. So in conclusion,the old 10AMP had either been over loaded or cooked itself! Thanks for your help chaps. P
 
Thanks for posting the outcome. A lot of these threads present fascinating problems but we often don't get to read the outcome. It's like a good novel with the last page missing
(PS I am probably as guilty of this as anyone)
 
Pkewish said:
A quick update. I ordered a new regulator on FleeBay, this one is 20AMP. Fitted and tested last night, works a treat. So in conclusion,the old 10AMP had either been over loaded or cooked itself! Thanks for your help chaps. P
Click to expand...
It is the own 10. I have one also. Because the inverter/regulator is powered by battery power it drains when mo sun
 
Pkewish said:
I have a 110mah leisure battery which charges up OK from the mains charger and holds it's charge for months when not connected, or provides a good supply of power for Nav aids and VHF etc for a few days whilst on board. I also have a 120watt solar panel connected via a regulator. If I put a multimeter over the solar panel connection in daylight, it's putting out over 13V. Great! When it's connected up via the regulator in daylight, all seems to charge up OK. However, if I leave it over night (dark), the battery if flat by morning. The regulator is a 12v PWM 10A, all fitted via a fuse.

Is it possible that the panel could be pulling the charge back out of the battery?
Could the Reg be faulty?

Your ideas would be appreciated.
Click to expand...
I admit, I lived under the impression (backed by a lot of expert opinions) a diode is needed (if there is no regulator) untill a few days ago. I installed a new 500W monocrystaline system and while waiting for the regulator, I connected it directly. I checked the back current at night: it was measly 0.1A (about 1W) in this huge 500W system! The power loss on a diode is definitely many times greater as you can tell from the need of a massive heatsink preventing overheating. So, the conclusion: definitely NO diode.
 
I am of the opinion that a solar panel connected directly to a battery will not discharge though the panel at night to any significant degree. OP should check witha digital multimeter on milliamps scale with panels covered for any loss. Possibly if there is loss it is in the regulator or perhaps via panels. OP should check all possibilities for the batteries going flat including bad battery. ol'will
 
William_H said:
I am of the opinion that a solar panel connected directly to a battery will not discharge though the panel at night to any significant degree. OP should check witha digital multimeter on milliamps scale with panels covered for any loss. Possibly if there is loss it is in the regulator or perhaps via panels. OP should check all possibilities for the batteries going flat including bad battery. ol'will
Click to expand...
Hi William
I think maybe the OP sorted his problem by now and if not killed his batteries as the thread is 7years old , :)
 
Tbird37887 said:
It is the own 10. I have one also. Because the inverter/regulator is powered by battery power it drains when mo sun
Click to expand...
It should be little trouble for designers of the regulator to have the power turned on or off according to the incoming potential from the panels, thus having the regulator working only when it's needed.
 
HissyFit said:
It should be little trouble for designers of the regulator to have the power turned on or off according to the incoming potential from the panels, thus having the regulator working only when it's needed.
Click to expand...
The regulator will always be drawing a small residual current as it has to remain active, albeit on "standby". However, the residual current drain is of mA order so nominal.

I can't be bothered to read the thread because it is so old, but if the regulator in this case was draining the battery at night, it was either a tiny or a defective battery or the regulator was faulty. Either way, it's all history now. ;)

Richard
 
RichardS said:
The regulator will always be drawing a small residual current as it has to remain active, albeit on "standby". However, the residual current drain is of mA order so nominal.

I can't be bothered to read the thread because it is so old, but if the regulator in this case was draining the battery at night, it was either a tiny or a defective battery or the regulator was faulty. Either way, it's all history now. ;)

Richard
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I was actually replying to the guy who revived the thread. Just as a matter of logic: why does a solar charge controller/regulator have to remain on standby when it's dark? It's not as if it will ever have to leap into action at midnight. Some may feel reassured by a display reading zero volts for zero amps, but what is the point?
 
HissyFit said:
I was actually replying to the guy who revived the thread. Just as a matter of logic: why does a solar charge controller/regulator have to remain on standby when it's dark? It's not as if it will ever have to leap into action at midnight. Some may feel reassured by a display reading zero volts for zero amps, but what is the point?
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I do understand that you were replying to post #26.

The regulator remains powered by the battery as it needs to start reacting/processing as soon as the panel begins to output. It therefore remains in a standby state drawing very little current. It might well be possible to design an alternative where the regulator is completely shut down and therefore has no 24 hour monitoring and draws zero current but I would hazard that the complications arising from that design and the lack of monitoring compared to the tiny overnight current draw would make such a design unattractive to purchasers.

Richard
 
Or perhaps because the regulator needs to know whether the battery system is 12 or 24v before doing anything useful when the sun comes up. Hence why they need to be connected to the battery first and then the solar panels.

Pete
 
Pete7 said:
Or perhaps because the regulator needs to know whether the battery system is 12 or 24v before doing anything useful when the sun comes up. Hence why they need to be connected to the battery first and then the solar panels.

Pete
Click to expand...
Although that's a slightly different issue. My Victron can auto-detect, which it could do as soon as it switches itself on in the morning in HissyFit's scenario. I've actually turned off autodetect and set mine to permanent 12V so, as it happens, mine doesn't need to do it anyway.

Richard
 
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