Solar setup issue

Submitted: Sunday, Apr 01, 2018 at 09:57
ThreadID: 136495 Views:1670 Replies:8 FollowUps:13
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Hi. I am trying to diagnose whether i have a problem with my solar setup. I have a 100ah battery installed in the back of my ute. It has a redarc system attached which works as both isolator and regulator. I use a 140W solar page to charge the battery. While travelling full time i used this system successfully to run an 80L fridge in the back of ute, led lights and 12V plugs in caravan to charge phones laptops etc. Voltage in the morning would generally be down to 12.6, 12.5 depending on what we had used the night before. I recently got the battery replaced as old one was only charging to 12.4V. However I seem to be getting way less power with the new battery. I am only running the fridge now and have been plugging it in to 240V during the day while I charge battery via solar panel. The battery is showing 13.3V and redarc is on 'float' within 2 hours of plugging in solar panel in morning. When I unplug solar the voltage drops back to the fully charged volts of 12.9V. I unplug fridge from 240V at about 9 or 10pm and plug it into battery supply for overnight running. However by morning the volts are down to 12.2 or lower. Why would it be using so much power? The fridge supposedly uses 1-1.5 amps/h on the setting I have it on.
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Reply By: Frank P (NSW) - Sunday, Apr 01, 2018 at 10:02

Sunday, Apr 01, 2018 at 10:02
Is the new battery the same capacity as the old - ie same amp-hours?
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Follow Up By: Dee78 - Sunday, Apr 01, 2018 at 10:17

Sunday, Apr 01, 2018 at 10:17
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Follow Up By: Frank P (NSW) - Sunday, Apr 01, 2018 at 10:23

Sunday, Apr 01, 2018 at 10:23
95 Amp hours. What amp-hours was the old battery?

If the new battery is significantly smaller than the old, that could account for at least some of what you're seeing.
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Follow Up By: Dee78 - Sunday, Apr 01, 2018 at 10:31

Sunday, Apr 01, 2018 at 10:31
I'm pretty sure the old one was a 100ah battery.
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Follow Up By: Frank P (NSW) - Sunday, Apr 01, 2018 at 13:38

Sunday, Apr 01, 2018 at 13:38
5 amp hours shouldn't make that much difference.

Was the old battery the same type as this new one - flooded wet cell? Or was it AGM or gel? Reason I ask is that if it's different you may have to change the configuration of your Redarc.

Also, try a reset of the Redarc: First disconnect the solar input to the Redarc. Then disconnect the Redarc from the battery. After about 10 seconds reconnect the Redarc to the battery and then the solar to the Redarc.

And if anyone else wants to jump in here, please feel free.
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Follow Up By: Dee78 - Tuesday, Apr 03, 2018 at 21:13

Tuesday, Apr 03, 2018 at 21:13
I'll follow these up. I think this battery is a different type to last one. Thanks Frank. ??
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Reply By: Member - Racey - Sunday, Apr 01, 2018 at 17:09

Sunday, Apr 01, 2018 at 17:09
Hi Dee, the 95 amp/hr battery has 5% less capacity than the original and that is enough to bring the overnight voltage voltage down approx 12 volts. However, you say you are using less connected load, then I would suspect the battery is not getting fully charged and suspect the Recarc unit. Where is the Redarc located in relation to the pane and the battery; at or near the battery is best.

Do you have a manual for the Redarc? If so , check the charging characteristics , I.E., Bulk Charge Voltage and Float voltage.

Cheers
Jon
AnswerID: 617970

Follow Up By: Dee78 - Tuesday, Apr 03, 2018 at 21:16

Tuesday, Apr 03, 2018 at 21:16
Thanks Jon. I do have the manual and have read it but there's not a lot in there I understand is the problem. The redarc is right next to the battery box. I think I may just take it to an expert.
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Reply By: HKB Electronics - Sunday, Apr 01, 2018 at 17:47

Sunday, Apr 01, 2018 at 17:47
Please elaborate on the battery was only charging to 12.4V, how long was the battery left standing before your checking the voltage?

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Reply By: oz doc - Sunday, Apr 01, 2018 at 22:45

Sunday, Apr 01, 2018 at 22:45
HI Dee- may I suggest you do a little sleuthing. You need to establish a couple of things- how much the fridge is drawing, how much the solar is putting out via the redarc, and is your voltage reading of the batter actually accurate .This will define your problem . Doc
AnswerID: 617983

Reply By: Member - McLaren3030 - Monday, Apr 02, 2018 at 15:23

Monday, Apr 02, 2018 at 15:23
Hi Dee, I think your 100ah battery is a little small to run an 80 Ltr. Fridge, you would be better with at least 120 ah. There are a number of guides on line that can help you determine the correct size & type of battery for you fridge. Have you chosen the correct type of battery.

You don't mention what brand your fridge is, or how old. These two factors have a lot to do with how efficiently your battery will run your fridge. Is it an adsorption or compressor fridge. Compressor fridges are much more efficient. Check the seals on the fridge door/lid. Ensure you have enough ventilation space around the fridge.

Macca.
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Follow Up By: Dee78 - Tuesday, Apr 03, 2018 at 21:21

Tuesday, Apr 03, 2018 at 21:21
Thanks Macca. Will do some more reading into battery requirements. Fridge is an everkool glacier. 2 years old. Seals are good. Maybe fridge needs a service?
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Reply By: swampy - Monday, Apr 02, 2018 at 19:20

Monday, Apr 02, 2018 at 19:20
hi
Standing voltage will be a little less with the current Century WET flooded than an AGM type
For a 80ltr 1 amp per hr consumption would be considered low =24 amps in a 24hr period . In hot weather at cold temp setting 75ah /24hr period would not be unheard of .

FYI 40lt Engle etc use around 40ah in24hrs when worked hard low temp setting and hot weather. Also well proven that 65lt fridges use 50-70ah when worked hard

200watt solar and 120ah batt min. would be an improvement .
Ideally 300-400watt and 200ah batt min

AnswerID: 618008

Follow Up By: Dee78 - Tuesday, Apr 03, 2018 at 21:24

Tuesday, Apr 03, 2018 at 21:24
Thanks Swampy. Yes think an upgrade of whole system might be required. Really want to be off grid and be able to free camp so got to make this work and work well.
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Reply By: RMD - Tuesday, Apr 03, 2018 at 09:53

Tuesday, Apr 03, 2018 at 09:53
If the fridge is plugged in during the day, why can't you have it plugged in during the night too?

Have you tested the "actual" run time of the fridge and how much power it uses while running, ie, the actual AH it really does use. Those results are often far in excess of the stated theoretical achieved by the factory. That will mean the battery you have is insufficcient in storage ability, ie more batter needed.
The best idea is to have a system which can charge the battery AND run the fridge, ie be charging the battery while the fridge is not running and also enough to catch up the overnight loss.
80L fridge and small battery and not quite enough solar to do it

If the system can't keep the battery amount charged then there is a deficiency.

You mentioned while travelling it works, that is possibly because the vehicle is doing the major/bulk amount of the charging and the solar is only topping up the system when stopped.

To only use 1 ah to 1.5 ah your fridge must be very efficient indeed. Especially being an 80 litre on. A 40 litre Engel can't even approach that low usage. I would suspect your fridge is using at leat double what you think it is, Maybe more.
I use a 40litre Engel and 32L Waeco as a freezer, freezers use much more I know but the power requirement is vastly larger than your stated requirements for the 80 litre.
AnswerID: 618014

Follow Up By: Frank P (NSW) - Tuesday, Apr 03, 2018 at 11:29

Tuesday, Apr 03, 2018 at 11:29
"To only use 1 ah to 1.5 ah your fridge must be very efficient indeed. Especially being an 80 litre on. A 40 litre Engel can't even approach that low usage. I would suspect your fridge is using at leat double what you think it is, Maybe more."

I agree. If the manufacturer's blurb says it uses an average of 1 to 1.5 amps then a reasonable assumption is that those figures represent 50% duty cycle in mild conditions over 24 hours. IE, in mild test conditions the fridge actually runs for 12 hours a day. Taking the worst case, 12 hours run time at 1.5 amps gives a consumption of 36 amp-hours - which the manufacturer averages out over 24 hours. But it also means that WHILE RUNNING, the fridge is drawing 3 amps, not 1.5.

In warm and hot conditions the fridge will be running considerably more than the manufacturer's favourable advertised average, and pulling 3 amps, not 1.5. It's then easy to see where the power might be going.

There are too many assumptions here for this to be definitive. We really do need some hard figures to be of real help.
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Follow Up By: Dee78 - Tuesday, Apr 03, 2018 at 21:35

Tuesday, Apr 03, 2018 at 21:35
Thanks for your input and tips RMD and Frank. Only don't have the fridge plugged in to 240v during the night because power lead is running from inside caravan to back of ute, and caravan door won't shut on power lead.
Will do some investigating into ACTUAL amp draw of fridge and go from there.
Cheers ??
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Follow Up By: Member - McLaren3030 - Wednesday, Apr 04, 2018 at 12:14

Wednesday, Apr 04, 2018 at 12:14
Dee78,

"Only don't have the fridge plugged in to 240v during the night because power lead is running from inside caravan to back of ute, and caravan door won't shut on power lead. "

Doesn't your caravan have an external 240v power outlet? Most do.

Macca.
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Follow Up By: Frank P (NSW) - Wednesday, Apr 04, 2018 at 13:51

Wednesday, Apr 04, 2018 at 13:51
OOPS!

In my follow-up 889840 above, my logic was right but the words were wrong.

The first paragraph after the quote would be better if it said .....

I agree. If the manufacturer's blurb says it uses an average current of 1 to 1.5 amps then a reasonable assumption is that those figures represent 50% duty cycle in mild conditions over 24 hours. IE, in mild test conditions the fridge actually runs for 12 hours a day. Taking the worst case, an average current draw of 1.5 amps over 24 hours means a consumption of 36 amp-hours per day. Using the assumed 50% duty cycle, the fridge runs for only 12 hours. Therefore the current drawn WHILE RUNNING is 36/12 = 3 amps, not 1.5.

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Follow Up By: Dee78 - Wednesday, Apr 04, 2018 at 16:08

Wednesday, Apr 04, 2018 at 16:08
My van is an 80's model Millard so no mod cons like exterior plugs. :D
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Reply By: swampy - Wednesday, Apr 04, 2018 at 02:18

Wednesday, Apr 04, 2018 at 02:18
HI
Dee78
A watt meter can tell u the consumption Ebay 10-20$
Expect results as everybody has stated to be higher than makers mention by far , in aver. to hot conditions .

There are many online comparisons that back this up .

A 40ltr test is on Camper trailer.org
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