Another power controller question

Submitted: Saturday, May 01, 2010 at 16:08
ThreadID: 78137 Views:8160 Replies:6 FollowUps:14
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We have a 120w solar panel charging 2 x 100ah batteries. We are going to fit another 120w solar panel so we can run our Engel fridge. Will our charge controller Powertech MP3129 handle this or should we upgrade to a larger charge controller.

Thanks
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Reply By: Member - John and Val - Saturday, May 01, 2010 at 16:40

Saturday, May 01, 2010 at 16:40
Ron,

I believe that the MP3129 is rated at 20 amps. 240 W of panels won't deliver much over 15 amps, so the controller should handle the two panels ok with a reasonable safety margin.

Cheers

John
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Reply By: Maîneÿ . . .- Saturday, May 01, 2010 at 19:57

Saturday, May 01, 2010 at 19:57
I would be asking why a 120 watt (~7 Amp) solar panel won't run an Engel fridge

Do you presently have the second 120 watt panel ?

Maîneÿ . . .
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Follow Up By: oldtrack123 - Saturday, May 01, 2010 at 22:05

Saturday, May 01, 2010 at 22:05
Hi
Your Engel fridge will draw a min of about 64amp hrs per 24hrs[day] running as a fridge & much more if you run it a freezer[80<100amphrs per day]
Your single panel will put out around 50amps hrs per day
YES you do need another panel
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Follow Up By: Maîneÿ . . .- Saturday, May 01, 2010 at 22:19

Saturday, May 01, 2010 at 22:19
oldtrack123,

I don't have an Engel fridge ??

however my 70Lt Reefer Premier Fridge/Freezer draws ~10 Amps, so my ~200 watt solar system is very capable of 12 Amps output, therefore maintaining my battery system well above 12v at all times, but you already know that - don't you :-)

Maîneÿ . . .
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Follow Up By: Dennis Ellery - Saturday, May 01, 2010 at 23:40

Saturday, May 01, 2010 at 23:40
Oldtrack there is something wrong with your Engel
My Engle uses less than half the figures you're quoting
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Follow Up By: oldtrack123 - Sunday, May 02, 2010 at 09:54

Sunday, May 02, 2010 at 09:54
Hi Dennis

No , nothing wrong with my fridge
It's amphr draw is similar to most compressor fridges
Actually total amphrs per day is dependent on many factors,ambient temp , thermo setting , opening frequency, amount of warm loading, etc etc.
Rather than go thru all this again perhaps you may be interested in reading THIS thread:
http://www.exploroz.com/Forum/Topic/77704/Solar_Question.aspx

Mind you ,you will have to sort the "wheat from the chaff" [rubbish ] ,particularly that posted by one poster.
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Follow Up By: Bonz (Vic) - Sunday, May 02, 2010 at 12:13

Sunday, May 02, 2010 at 12:13
The amp-hour figs for a 24hr day seem reasonable, I would say even more so in warmer climes
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Reply By: ronrox - Saturday, May 01, 2010 at 21:56

Saturday, May 01, 2010 at 21:56
No we dont have the second pannel yet..... the pannel we have will run the fridge but it draws a lot from the batteries when its on freeze most of the time

ronrox
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Follow Up By: Maîneÿ . . .- Saturday, May 01, 2010 at 22:20

Saturday, May 01, 2010 at 22:20
ronrox,
What model Engel fridge do you have ??

Maîneÿ . . .
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Follow Up By: oldtrack123 - Sunday, May 02, 2010 at 10:01

Sunday, May 02, 2010 at 10:01
Hi Ronox
I should have added that your reg will cope with an extra 120w panel
Perhaps you too may be interested in reading this thread:
It gives a general consensus of opions on what TYPICAL Engel will DRAW[amp hrs per 24hrs] UNDER VARIOUS CONDITIONS

http://www.exploroz.com/Forum/Topic/77704/Solar_Question.aspx

Again you will need to sort the "wheat from the chaff" [rubbish] posted by one particular poster
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Follow Up By: Maîneÿ . . .- Sunday, May 02, 2010 at 11:49

Sunday, May 02, 2010 at 11:49
oldtrack,
Obviously you refere to your post, as it's you who believes you can ascertain the Wattage of a solar panel using the charging voltage of an auxiliary battery and the Amps produced by the solar panel.

As you clearly don't understand solar power, relevant to charging a battery when running a fridge

Maîneÿ . . .
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Follow Up By: Bonz (Vic) - Sunday, May 02, 2010 at 12:05

Sunday, May 02, 2010 at 12:05
bleep guys please dont get into this crap again, just stick with the question in the post
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Follow Up By: Bonz (Vic) - Sunday, May 02, 2010 at 12:11

Sunday, May 02, 2010 at 12:11
Sorry ronrox, not talking about you by the way
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Follow Up By: Maîneÿ . . .- Sunday, May 02, 2010 at 13:55

Sunday, May 02, 2010 at 13:55
Bonze, why not be a bit more specific, I was sticking with the specific post question, I only asked what model fridge ronrox was using as a freezer?

Now the thread oldtrack referrs to is also 'locked'

Maîneÿ . . .
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Follow Up By: Bonz (Vic) - Sunday, May 02, 2010 at 13:59

Sunday, May 02, 2010 at 13:59
Bonze?

The original question is:
Will our charge controller Powertech MP3129 handle this or should we upgrade to a larger charge controller.

Not an arguement about wattage of a solar panel. Thats been done to death mate. Leave it at that.

And I just looked at the other thread. 81 followups to one reply. Sheesh THAT's what I mean about crap.
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Follow Up By: Maîneÿ . . .- Sunday, May 02, 2010 at 14:53

Sunday, May 02, 2010 at 14:53
Bonz,
Woops, sorry about the misspelling, it was an honest mistake I can assure you

However, ronrox is stating he believes he requires two solar panels, I've questioned why he thinks he needs the second panel, as he only has one panel at present, that is where the "argument about wattage of a solar panel" is relevant to the thread - in my own opinion.

Maîneÿ . . .
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Follow Up By: Bonz (Vic) - Sunday, May 02, 2010 at 14:56

Sunday, May 02, 2010 at 14:56
And you've questioned it, so lets not have the argument again, it turns people off even starting to read a thread on solar.

Mistake forgived
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Reply By: kimberleybloke - Sunday, May 02, 2010 at 12:42

Sunday, May 02, 2010 at 12:42
Hey Ronrox,we have a similar setup to what you want.Go with 2x 120w panels,
set them up in the morning pointing somewhere north,go and spend the day doing what you want to do,come back and find your batteries fully charged.No having to hang around camp all day moving panells to follow the sun.Our engle is a 60 litre and it was used as a freezer all the time for six months,never missed a beat,never had battery problems.This is our experience from a practical point of view.(This was across northern Australia,)Not familiar with your controller but if as others have said it can handle 20amps then it will handle another panel.
AnswerID: 415092

Reply By: Maîneÿ . . .- Sunday, May 02, 2010 at 12:46

Sunday, May 02, 2010 at 12:46
ronrox,
to use only 'numbers' to ascertain the fridge and solar panel equations you have to know what those numbers truly represent.

Stated *simplistically* the fridge (not freezer) will be running part time, on a duty cycle of about 50%, (mine is only 33% - 20 mins per hour, for comparison purposes only) so if your fridge is on every second half hour and at the same time your solar panel is on 100% of the time (not 50%) then in the time the sun is shining the battery remains fully charged.

Using a fridge as a Freezer, the duty cycle will be slightly longer, but once frozen it will be easy to maintain frozen, because the freezer is not opened as often as a fridge and maintains temp.

Only in the evening when the sun is not shining, supplying the power to maintain the battery, will the fridge or freezer be taking power that is not being replaced.
However in this time the duty cycle is also shorter, because the ambient temp is also lower.

Hope this assists you

Maîneÿ . . .
AnswerID: 415093

Reply By: Lex M (Brisbane) - Sunday, May 02, 2010 at 15:24

Sunday, May 02, 2010 at 15:24
"Will our charge controller Powertech MP3129 handle this"

Yes

"should we upgrade to a larger charge controller"

No.
AnswerID: 415108

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