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Michael2
1st December 2014, 04:09 PM
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
1st December 2014, 10:59 PM
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
5th December 2014, 07:43 PM
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
6th December 2014, 11:08 AM
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
6th December 2014, 11:17 AM
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
6th December 2014, 11:34 AM
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
6th December 2014, 11:53 AM
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
6th December 2014, 11:53 AM
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 (http://www.plasmatronics.com.au/common/pl204060.html)

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
6th December 2014, 12:05 PM
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
6th December 2014, 12:36 PM
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.

d2dave
6th December 2014, 12:39 PM
I'm a bit confused with this.... a 6-8amp charge should run a 2 amp load shouldn't it??

Absolutely. If you charge is 6 amps and the load is 2, the balance goes into your battery, in this case 4 amps.

Tombie
6th December 2014, 07:53 PM
Absolutely. If you charge is 6 amps and the load is 2, the balance goes into your battery, in this case 4 amps.


Correct.. Now don't forget..

24 hours in a day.
2amps per hour x 24 = 48amps a day

And don't forget the sun sets but the fridge keeps running!

Now - without moving the panels to track the sun you will get around 6 hours of close to full output (let's assume 5ah to keep the maths simple)

6 x 5 = 30ah made that day.

30 (in) - 48 (out) = -18ah per 24hrs.

With a 100ah to 50% SOC that's just over 2.5 days before it runs out...

d2dave
6th December 2014, 09:44 PM
Correct.. Now don't forget..

24 hours in a day.
2amps per hour x 24 = 48amps a day

And don't forget the sun sets but the fridge keeps running!

Now - without moving the panels to track the sun you will get around 6 hours of close to full output (let's assume 5ah to keep the maths simple)

6 x 5 = 30ah made that day.

30 (in) - 48 (out) = -18ah per 24hrs.

With a 100ah to 50% SOC that's just over 2.5 days before it runs out...

Yes you probably would struggle without tracking the sun, but I do. Every year for about the last 8 years for a two week holiday, I had no problems running my 40 litre Engle on an N70z battery, providing the sun is shinning.

As for your maths of 2amps per hour x 24 = 48amps a day, this is correct, but a fridge does not run for 24 in 24.

Tombie
6th December 2014, 09:46 PM
Agree Dave.. Too many factors though...

Temp set at, fridge volume occupied, frequency of opening, ambient temp...

Panel position and angle, geographical location etc.

Tombie
6th December 2014, 09:55 PM
Engel fridge in normal use I always went 1ah as a guide in warm weather.

Here is someone's test using a shunt and their results confirm it - you can easily bring one down quickly...
http://www.campertrailers.org/fridge_power_consumption.htm

d2dave
6th December 2014, 10:58 PM
Engel fridge in normal use I always went 1ah as a guide in warm weather.

Here is someone's test using a shunt and their results confirm it - you can easily bring one down quickly...
engel fridge power consumption (http://www.campertrailers.org/fridge_power_consumption.htm)

So working on 1 amp we only need to generate 24 amps per day which my 80 watt panel does easy.

However and I know this varies greatly depending on ambient temp, that on days with average temps around 36 degrees it uses a lot more than 1 amp per hour. Also how often it is opened and I do drink a lot of beer when on holidays.
Come to think of it I also do this when not on holidays.:beer:

My solar regulator has a 20 amp load terminal. I have my fridge connected to this. Now the reg at any time can tell me battery voltage, min and max voltage in previous 24 hours, current draw, total amps in and total amps out for the past 24 hours with a 30 day memory.

Now as my memory isn't what it used to be I can't remember the numbers from last holiday in Feb, but I do remember seeing many 24 hour consumptions in the 30's. I will record next February's findings and post them up.

The reg has other features such as state of charge of battery in %. This is calculated by inputting battery size and it then moniters current in and current out. It also tells me the open circuit voltage of the solar panels, usually 20 to 21 volts. It also tells me what time it goes into float mode if the battery obtains full charge.

Also by using a current shunt I have my alternator input also recorded which in the event I run the engine this is factored in to total amps input for state of charge.

debruiser
7th December 2014, 06:46 AM
So working on 1 amp we only need to generate 24 amps per day which my 80 watt panel does easy.

However and I know this varies greatly depending on ambient temp, that on days with average temps around 36 degrees it uses a lot more than 1 amp per hour. Also how often it is opened and I do drink a lot of beer when on holidays.
Come to think of it I also do this when not on holidays.:beer:

My solar regulator has a 20 amp load terminal. I have my fridge connected to this. Now the reg at any time can tell me battery voltage, min and max voltage in previous 24 hours, current draw, total amps in and total amps out for the past 24 hours with a 30 day memory.

Now as my memory isn't what it used to be I can't remember the numbers from last holiday in Feb, but I do remember seeing many 24 hour consumptions in the 30's. I will record next February's findings and post them up.

The reg has other features such as state of charge of battery in %. This is calculated by inputting battery size and it then moniters current in and current out. It also tells me the open circuit voltage of the solar panels, usually 20 to 21 volts. It also tells me what time it goes into float mode if the battery obtains full charge.

Also by using a current shunt I have my alternator input also recorded which in the event I run the engine this is factored in to total amps input for state of charge.

Wow, you must have shelled out for that unit. I got a cheap and cheerful one.... it has a led on the front Red=charging, green=floating. Done. lol. Thanks for the maths on this stuff guys I have never bothered to research all that stuff, I trusted that the solar panel dude I bought my system from knew what size gear to get.

So I was thinking that if these solar charge regulators are very bias to save the battery, can do a workaround? So what I was thinking was before Garry said he bi-passed the controller a couple hours a day to get a good charge going. Now I wouldn't think throwing away the regulator is a good idea, so I was thinking that I would use the "charge wire" as a signal to switch a relay that bi-passes the regulator. I would then get the pull charge capacity of the panel charging up my battery nice a quick :)

Writing that down makes me think, maybe I am going to shoot myself in the foot here. If the charge regulator sees the high voltage going in then it might drop out the charge, then see a low voltage.... O no....

d2dave
7th December 2014, 10:03 AM
Wow, you must have shelled out for that unit.


It was $280 back when I got it. They are now $335. Good thing is they are made in Australia, Melb.

When I fist got it I did not have time to install it so I used it portable for my first holiday. I just had wires with alligator clips and would just open the bonnet and rest it in the engine bay.

Nearing the end of my holiday when removing it, one of the wires that should not touch the battery did and fried it.:( Good thing was that being made here it is repairable.:) Cost me $90 though which is better that it being a write off, which often happens when made in China.

Unlike my 25 amp Ctek charger. My new dog got hold of it and chewed off the positive clamp which also included the temp sensor. Can't be fixed, no one in Au services them. And these are not cheap.:(:mad:

spudboy
7th December 2014, 10:17 AM
I have a related question, if I may.

We have a standard 12v truck battery powered by a huge array of solar cells (ex-rooftop solar - overkill but 'free') through a 30A MPPT charger.

It is powering an Engel 39L fridge that is 25 years old.

In the morning, the voltage shown on the battery can be as low as 11.8 or 11.9v, but generally 12.0 or 12.1. After an hour of sunlight, the voltage goes to 14.1 for an hour or two, then back to 13.4/13.5 for the rest of the day.

Is this damaging the battery to go down this low every day? I know that fully charged is 12.7v, but not sure what the lower limit on a lead-acid battery is when this is happening on a daily basis.

Is 11.anything volts doing damage?

Thanks - David

debruiser
7th December 2014, 11:04 AM
I have a related question, if I may.

We have a standard 12v truck battery powered by a huge array of solar cells (ex-rooftop solar - overkill but 'free') through a 30A MPPT charger.

It is powering an Engel 39L fridge that is 25 years old.

In the morning, the voltage shown on the battery can be as low as 11.8 or 11.9v, but generally 12.0 or 12.1. After an hour of sunlight, the voltage goes to 14.1 for an hour or two, then back to 13.4/13.5 for the rest of the day.

Is this damaging the battery to go down this low every day? I know that fully charged is 12.7v, but not sure what the lower limit on a lead-acid battery is when this is happening on a daily basis.

Is 11.anything volts doing damage?

Thanks - David

Was about to say "don't all fridges have low voltage cuttoff" but then I reread as I typed and I see your fridge is old... maybe google your model fridge to see if it has the low voltage cuttoff.

debruiser
7th December 2014, 11:06 AM
It was $280 back when I got it. They are now $335. Good thing is they are made in Australia, Melb.

When I fist got it I did not have time to install it so I used it portable for my first holiday. I just had wires with alligator clips and would just open the bonnet and rest it in the engine bay.

Nearing the end of my holiday when removing it, one of the wires that should not touch the battery did and fried it.:( Good thing was that being made here it is repairable.:) Cost me $90 though which is better that it being a write off, which often happens when made in China.

Unlike my 25 amp Ctek charger. My new dog got hold of it and chewed off the positive clamp which also included the temp sensor. Can't be fixed, no one in Au services them. And these are not cheap.:(:mad:

Wowzer, thats steep. I got the cheap and cheerful $100 Chinese rubbish model. Unfortunately I have to draw a line in the sand on the budget of these things... :(

I hate the lack of user serviceability on modern stuff; well the lack of serviceability in general really. It's a crock, and extremely wasteful.

Robmacca
7th December 2014, 11:10 AM
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

Just curious here, but would there be any electronics that would be exposed to the higher volts even though the ignition is off?? (Not sure what type of car u are doing this to)

101RRS
7th December 2014, 11:35 AM
No car involved - just a camper battery and stuff that runs off it, mainly the fridge that has a range of below 12v to just over 24v.

d2dave
7th December 2014, 11:41 AM
I have a related question, if I may.

We have a standard 12v truck battery powered by a huge array of solar cells (ex-rooftop solar - overkill but 'free') through a 30A MPPT charger.

It is powering an Engel 39L fridge that is 25 years old.

In the morning, the voltage shown on the battery can be as low as 11.8 or 11.9v, but generally 12.0 or 12.1. After an hour of sunlight, the voltage goes to 14.1 for an hour or two, then back to 13.4/13.5 for the rest of the day.

Is this damaging the battery to go down this low every day? I know that fully charged is 12.7v, but not sure what the lower limit on a lead-acid battery is when this is happening on a daily basis.

Is 11.anything volts doing damage?

Thanks - David

The short answer to your question is yes and no. The best way to answer this is; What you are doing should not kill the battery as such, but it will shorten its life. Even with deep cycle batteries, the more you discharge it regularly the shorter its life.

When I am camping with my solar panels I try to keep the voltage above 12.

Your old Engle will be pulling 4.5 amps, unlike the new ones which use 2.5.

PhilipA
8th December 2014, 11:50 AM
Was about to say "don't all fridges have low voltage cuttoff" but then I reread as I typed and I see your fridge is old... maybe google your model fridge to see if it has the low voltage cuttoff.

All Engels certainly up to 2000 or so don't have low voltage cutouts and I think even the latest don't.
I just buy a Projecta ( lasted about 14 years) or ABR ( recently new but looks the same product) low voltage cutout and place it in the fridge wiring.
The battery going from 14.1 to 13.7 is the controller going from charge to float.
My 120watt cheapo panels , run in series, with 20 metre 12 gauge marine cable, into a GSL 12 amp MPPT controller next to the batteries gives 6.25 amps into batteries reading 12.7 at connection but soon go into float. I like to keep them as high as possible and connect the panels on the first morning.
Regards Philip A

debruiser
8th December 2014, 12:24 PM
I would have thought low voltage cuttoff was a standard thing on all fridges. We had a waeco YEARS ago that had it....

PhilipA
8th December 2014, 02:20 PM
We had a waeco YEARS ago that had it....

Yes AFAIR that is the thing that makes em fail to start without notice if your wiring is the slightest dodgy.
And when you finally set up camp there are these flashing lights that tell you all your stuff is warm, just when you wanted a cold beer.LOL
Regards Philip A