Solar Reg Output

[Michael2]

I've got a semi flexible solar panel mounted flat on the roof rack of the Defender.

I open circuit it puts out about 19V

through the solar reg, it puts out about 0.2V above the battery level.

it always displays a 0.2 amp current, irrespective of the load on the battery, or the battery condition.

This I have verified with a multimeter.

Q. Do I have a bad solar panel?
Q. Do I have a bad solar reg?
Q. What amperage output should I expect to see?

Both batteries are new, I replaced 2 x 105 AH AGM batteries with two Optima batteries.

[d2dave]

A solar panel regulator should put out a voltage at least in the high 13 volt range. As for your question as to how much currant this is dependent on the size of you panel.

Do you know how many watts it is?

[knodes85]

Michael, I'm having the exact same issue. 100W Jaycar fully flexible panel with a Projector SC320D regulator.

I installed the system about a fortnight ago and was getting a solid 3 Amps in full sun. Took a look on the weekend and my numbers are now matching yours.

What regulator / panel brand are you using?

[d2dave]

100 watt panel should give a lot more than 3 amps if your battery is low. If you battery is well charged it will charge at what the battery wants, to a maximum of what your panel can supply.

I have 80 watt panels and in summer, with a low battery, I get around 4.8 amps. I did get a reading once in winter of 5.8 amps.

On a 100 watt panel with a low battery you should be getting around 6.2 amps.

[debruiser]

I have a 120W panel and have never seen more than about 4 or 5 amps. It can't maintain a charged battery with a mere 2amp continuous load. (100Ahr deep cycle battery)

[Tombie]

2ah load is 48a per 24 hrs.
Assuming 5a for 6 hours a day (and that's generous depending on location) you'll only put 30a in.

No way that can keep up!

[101RRS]

I found similar issues in a recent long term test I did. 120w panels in full sun, one 50l fridge as load and a MPPT controller - in 24 hours there was a few ah loss out of the system. During the day the panels put in more juice than was needed but not enough to cover night time load from the fridge - so over a week even with full sun the battery would slowly run down.

The MPPT charger seemed more interested in doing it thing in keeping the battery in good nick rather than getting as much power back into the batteries as quickly as possible - to me the software is all wrong as it is a solar charger and should take these matters into account.

I put the regulator on that came with the panels - not smart at all - just feeds power to the battery as it needs it and it certainly got more power back into the battery so its charge would last longer.

What I found worked best was at about 10 in the morning connecting the panels direct to the battery (no regulator) so a full 17v was going into the battery and also getting about 6 amps so getting nearly max watts into the battery. I was told that batteries can take this high voltage for shorter periods as long not left on permanently. I left the system like this for an hour or two and it really put the juice back into the system and then switched back to using a solar charger - this way in a 24 hour period the battery was fully charged by late afternoon and ready for the night time session.

I used Watts Meters on both input and output sides so had a good idea of what was going on.

The battery did not seem to suffer at all.

Garry

[d2dave]

I have a 120W panel and have never seen more than about 4 or 5 amps. It can't maintain a charged battery with a mere 2amp continuous load. (100Ahr deep cycle battery)

In this case you have a problem somewhere. Either a dud panel or regulator. My money would be on the reg.

I have one of these permanently mounted in my disco. I even have my alternator charge going through so I really know what is going on.

Plasmatronics PL Series Battery Charge Controller

I can assure you that the readings I stated for mine are correct.

The bloke I purchased my solar panels from is a solar expert. He told me to calculate currant, you divide watts by 16. And in my case 80 watt divided by 16 = 5, pretty close to what I quoted.

In your case with 120 watts, you should be getting around 7.5 amps into a discharged battery.

[debruiser]

1st up I was sold a controller that couldn't handle max output from the panel. So I blew 2 or 3 of them. I now have a bigger controller. Come to think of it I must get peak output of 10amps because it was a 10amp controller.... hmmmm

I'm a bit confused with this.... a 6-8amp charge should run a 2 amp load shouldn't it??

[d2dave]

I found similar issues in a recent long term test I did. 120w panels in full sun, one 50l fridge as load and a MPPT controller - in 24 hours there was a few ah loss out of the system. During the day the panels put in more juice than was needed but not enough to cover night time load from the fridge - so over a week even with full sun the battery would slowly run down.

The MPPT charger seemed more interested in doing it think in keeping the battery in good nick rather than getting as much power back into the batteries as quickly as possible - to me the software is all wrong as it is a solar charger and should take these matters into account.

I put the regulator that came with the panels - not smart at all - just feeds power to the battery as it needs it and it certainly got more power back into the battery so its charge would last longer.

What I found worked best was at about 10 in the morning connecting the panels direct to the battery (no regulator) so a full 17v was going into the battery and also getting about 6 amps so getting nearly max watts into the battery. I was told that batteries can take this high voltage for shorter periods as long not left on permanently. I left the system like this for an hour or two and it really put the juice back into the system and then switched back to using a solar charger - this way in a 24 hour period the battery was fully charged by late afternoon and ready for the night time session.

The battery did not seem to suffer at all.

Garry

Every year I holiday for two weeks in summer on the Murray. Temperatures on average range from 35 to 42 degrees.

Now my solar regulator tells me when it goes into float mode which means the battery is fully charged. My 80 watt panel, providing it is sunny which it usually is, easily runs the 40 litre Engle.

Here are some figures.

In January you can get around 12 hours of charging, so in a 24 hour period we have 12 charge and 12 discharge.

Now in the 12 hours that it is not charging the ambient temp drops so the fridge is not working as hard.

Now lets say in this 12 hours the fridge runs for nine, and I doubt it would even run this much except on an extremely hot night, a 40 litre Engle pulling 2.4 amps would consume 22 amps.

Now lets say in the next 12 hours as the temp rises the fridge runs for ten hours. It will use 24 amps. However in this 12 hours the sun is shinning.

Now I realize that full capacity can't be obtained from the solar panel for the full 12 hours.

Now this is an educated guess. For 8 hours, moving my panel to follow the sun, I get full charge, which equates to 39 amps.

Two hours at lesser currant of around 3 amps out put = 6 amps and the last two hours about 1 amp per hour =2 amps.

Total amps 47. Amps used 46. Now there are many variables here, a slightly cooler day and the fridge works less and the solar panel works better.

On most days my regulator goes into float mode between 5 and 6pm. At times when we get a few consecutive hot days around 40 degrees it might not go into float mode
which means the battery has not attained full charge, but it is close.

The above is with a 40 litre engle.

You state that yours is a 50 litre which looking at Engle's web site could not find a 50 litre, so I don't know what its power usage is.

If it is the same as a 40 litre you should **** it in with a 120 watt panel.