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Old 31-05-2015, 07:46   #1
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Electrical question

I am looking for basic list of steps to take to find what is causing what I calculate as excessive battery drain and possibly the least expensive solution. Thanks in advance for any helpful input from the members.

Given:

3 Group 27 12v batteries, 1, 3 and 4 years old respectively, in parallel, about 255Ah altogether give or take, may be more or less as I have yet to master Xantrex's complex steps to reset the Ah meter function.
4 solar panels of 110W each just installed on the hard top roof with 30A controller and decent size wiring (forget the size now but probably 6 or even 4 if not larger.
Older Adler-Barbour fridge, large capacity, about 11-12cf with manufacturer stated draw of about 4.5-5A on average. Fridge is somewhat poorly insulated but for the purpose of my question a thick blanket or two is put on top of the lid and it helps significantly but overall there is barely 3" insulation in the box itself.

Symptoms:
During the sunny day Xantrex meter is showing at least 12.60-12.90 or higher with a draw of 5A with fridge on and all other electrics off. On a cloudy or rainy day voltage drops to 12.30-12.50 at best. Overnight with the fridge running and all other electrics off the voltage drops to below 12v by morning, about 11.85-11.95v or even lower.

My attempts to rectify the situation such as sandpaper cleaning all battery connections, etc. helped but have not solved the issue.

My question is - what is step by step way to figure out what is causing this? My own hunches are - fridge's poor insulation, batterries' age/size, controller being a tad undersized (I am looking for affordable 40A or larger piece), fault at some cable as only some cables are new, others are old/older.

I am not an engineer or electrical wizard but don't mind getting my hands dirty and will reasonably fix most basic problems with proper guidance. Some issues are not at this point are up for consideration due to budget constraints such as replacing the fridge compressor and/or the box as well as any major rewiring job. All others, incl. new or add'l batteries, larger controller, etc may be affordable. If no affordable solution is found I will probably go back to ice hauling as I don't live on the boat and spend no more than about 3 days in a row on it.

Thanks in advance for any input or comments.
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Old 31-05-2015, 09:00   #2
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Re: Electrical question

Sounds to me like those batteries have lost considerable capacity over time. A few observations based on your comments:

  • 12.9 is too low a charging voltage; assuming they're flooded batteries, charging voltage should be 14.4-14.8, then floating at 13.2-13.4
  • if the controller voltage is set too low, the batteries may not be getting a full charge
  • discharge below 12VDC is WAY too low
  • mixing battery types and AGES in a parallel bank is not a good idea; one bad battery can compromise the others
  • a 30A controller should be able to handle those 440 watts of solar panels
OK, what to do?

  • be sure the batteries are FULLY charged, either with a shorepower charger or on the panels; disconnect the frig and other loads for a day or two if you can
  • test the capacity of each battery; most efficient way is with a sophisticated tester like the Midtronics series....try to borrow one if you can
  • measure the SG of each battery individually; you'll likely find significant differences not only between batteries but between individual cells in each battery
  • remove any bad battery from the bank
  • equalize the remaining "good batteries", using a controlled charge of 15.5-16.5vdc for several hours; you'll likely need to do this at dockside with a battery charger capable of doing an equalization cycle
  • finally, see what results you get with the frig and other normal loads; don't let the voltage drop below about 12.2VDC before recharging
  • if you still have problems OR if you just want to eliminate all the foregoing tests, just replace the battery bank with all new batteries and treat them right
FWIW,

Bill

Quote:
Originally Posted by Island Time O25 View Post
I am looking for basic list of steps to take to find what is causing what I calculate as excessive battery drain and possibly the least expensive solution. Thanks in advance for any helpful input from the members.

Given:

3 Group 27 12v batteries, 1, 3 and 4 years old respectively, in parallel, about 255Ah altogether give or take, may be more or less as I have yet to master Xantrex's complex steps to reset the Ah meter function.
4 solar panels of 110W each just installed on the hard top roof with 30A controller and decent size wiring (forget the size now but probably 6 or even 4 if not larger.
Older Adler-Barbour fridge, large capacity, about 11-12cf with manufacturer stated draw of about 4.5-5A on average. Fridge is somewhat poorly insulated but for the purpose of my question a thick blanket or two is put on top of the lid and it helps significantly but overall there is barely 3" insulation in the box itself.

Symptoms:
During the sunny day Xantrex meter is showing at least 12.60-12.90 or higher with a draw of 5A with fridge on and all other electrics off. On a cloudy or rainy day voltage drops to 12.30-12.50 at best. Overnight with the fridge running and all other electrics off the voltage drops to below 12v by morning, about 11.85-11.95v or even lower.

My attempts to rectify the situation such as sandpaper cleaning all battery connections, etc. helped but have not solved the issue.

My question is - what is step by step way to figure out what is causing this? My own hunches are - fridge's poor insulation, batterries' age/size, controller being a tad undersized (I am looking for affordable 40A or larger piece), fault at some cable as only some cables are new, others are old/older.

I am not an engineer or electrical wizard but don't mind getting my hands dirty and will reasonably fix most basic problems with proper guidance. Some issues are not at this point are up for consideration due to budget constraints such as replacing the fridge compressor and/or the box as well as any major rewiring job. All others, incl. new or add'l batteries, larger controller, etc may be affordable. If no affordable solution is found I will probably go back to ice hauling as I don't live on the boat and spend no more than about 3 days in a row on it.

Thanks in advance for any input or comments.
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Old 31-05-2015, 09:22   #3
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Re: Electrical question

It sounds very typical to me. Your fridge is huge, and your battery bank is not. I had similar experience with a less than 2 cu ft refrigerator box and more battery capacity. .. and there were no faults.

However, one thing to check, especially with batteries of different age:
-Charge the system completely, then disconnect all batteries from each other. -Measure the voltage of each battery the next morning or a few hours anyway.
-If one battery is very low and the other two are not, there's your culprit. Possibly a shorted battery,.
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Old 31-05-2015, 09:47   #4
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Re: Electrical question

Yes, I agree that 255AH total capacity is pretty low to run an inefficient refrigeration system.

From what the OP said, I'd bet the problem results from:

1. some lost capacity in the battery bank (maybe a bad battery as Cheechako said); and

2. overall bank too small; and

3. batteries never reach really full charge.

Bill
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Old 31-05-2015, 10:18   #5
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Re: Electrical question

First of all, I wouldn't worry about resetting the amp-hour monitoring on your battery monitor. They don't work very well and can give misleading "data". Continue to monitor the amps and volts like you have been doing.

But from what you are saying, the previous posters are probably spot on. But even if you replace your batteries and/or get a larger battery bank, it does not sound like you are completely replacing the juice to the batteries that your refrigeration is sucking out.

A more efficient reefer system - insulation, compressor, etc. would definitely help of course. If you can get more amps out of a better solar charger that would help too. But if you are thinking of going back to hauling ice to the boat you might first consider just removing items from the boat for the times you are not on it and shut down the reefer. You did not describe your usage other than "three days at a time" so this may or may not work.

But in the end you will have to get enough charge in to the batteries from solar to get them to a float charge for enough time to fully recharge them. AGMs would recharge faster during the day so they would be more efficient in capturing the solar power you do get but the tradeoff is cost.

But you can't continue to run your batteries in deficit mode. It will kill even new batteries much faster (far fewer cycles). You are never fully charging them with your setup.
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Old 31-05-2015, 10:36   #6
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Re: Electrical question

Try turning your fridge thermostat down a bit. The compressor will cycle less frequently then. This will the allow some battery recovery. Previous quotes are valid for low capacity batteries. Especially you should try to equalize the batteries as suggested.

Quote:
Originally Posted by Island Time O25 View Post
I am looking for basic list of steps to take to find what is causing what I calculate as excessive battery drain and possibly the least expensive solution. Thanks in advance for any helpful input from the members.

Given:

3 Group 27 12v batteries, 1, 3 and 4 years old respectively, in parallel, about 255Ah altogether give or take, may be more or less as I have yet to master Xantrex's complex steps to reset the Ah meter function.
4 solar panels of 110W each just installed on the hard top roof with 30A controller and decent size wiring (forget the size now but probably 6 or even 4 if not larger.
Older Adler-Barbour fridge, large capacity, about 11-12cf with manufacturer stated draw of about 4.5-5A on average. Fridge is somewhat poorly insulated but for the purpose of my question a thick blanket or two is put on top of the lid and it helps significantly but overall there is barely 3" insulation in the box itself.

Symptoms:
During the sunny day Xantrex meter is showing at least 12.60-12.90 or higher with a draw of 5A with fridge on and all other electrics off. On a cloudy or rainy day voltage drops to 12.30-12.50 at best. Overnight with the fridge running and all other electrics off the voltage drops to below 12v by morning, about 11.85-11.95v or even lower.

My attempts to rectify the situation such as sandpaper cleaning all battery connections, etc. helped but have not solved the issue.

My question is - what is step by step way to figure out what is causing this? My own hunches are - fridge's poor insulation, batterries' age/size, controller being a tad undersized (I am looking for affordable 40A or larger piece), fault at some cable as only some cables are new, others are old/older.

I am not an engineer or electrical wizard but don't mind getting my hands dirty and will reasonably fix most basic problems with proper guidance. Some issues are not at this point are up for consideration due to budget constraints such as replacing the fridge compressor and/or the box as well as any major rewiring job. All others, incl. new or add'l batteries, larger controller, etc may be affordable. If no affordable solution is found I will probably go back to ice hauling as I don't live on the boat and spend no more than about 3 days in a row on it.

Thanks in advance for any input or comments.
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Old 31-05-2015, 11:13   #7
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Re: Electrical question

Thanks for all the replies. At least now I get a clearer picture. As I suspected (and was told by my marine-pro friend who helped me install the solar panels) I need a bigger battery bank (I'll probably be looking at getting 6v Trojans if I get a deal on a bunch of them). Also will check to see if the solar controller can be set at a higher voltage for recharging as well as will check each battery individually. I did play with the fridge thermostat and there is a considerable difference when it's on max vs. medium or least cold. As well as some improvement battery wise if the top of the fridge is covered with heavy blanket for add'l insulation.

For me at this point having a fridge, especially this huge, is not that important as I am used to being fridgeless on my previous boat for 5 years. My main reason for installing solars was so that I can run a laptop, etc. all day without worrying about draining the batteries or running the engine too much. But of course with the current situation this may also be problematic until I find the chief culprit for the draw down. I personally suspect that it is both the batteries and the solar charger's settings that are the problem as the panels themselves put out good juice as does the alternator.

Again thanks to all for your insightful replies and I will update when I find out more.
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Old 31-05-2015, 11:19   #8
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Re: Electrical question

Another thought is to reduce your fridge size. I had one boat with a large compartment but it had 2 doors. I made one half (actually less than half) into the fridge with an insulated divider and use the other half for dry storage.
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Old 31-05-2015, 11:40   #9
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Re: Electrical question

"Overnight with the fridge running and all other electrics off the voltage drops to below 12v by morning, about 11.85-11.95v or even lower. "
So, let's say the Xantrex is right and your fridge is taking 5A when it runs. Being forced to make some guesses, please pencil in the correct real numbers here.
With a 50% duty cycle that would be 2.5Ah, and let's say "overnight" meaning when the solar panels aren't putting out full power, from 2PM until 8AM, that's 18 hours when the batteries alone have to supply the fridge, which is going to pull 45 amps out of the batteries. Even a cheaper G27 might start out at 80AH+, so if you disconnect the oldest one, you should still have 150AH+ capacity and only be drawing that down by 1/3, which might take you to 12.2~12.3V certainly not down to under 12.
So there's something wrong with the picture.
As the choir has said, you'll need to "divide and conquer". Test each battery, or at least the two older ones. Disconnect them, charge them all the way, let them rest and load test them. (That may mean disconnecting & cycling one on each of 3 days, so you don't ever have to shut down entirely.) First step, make sure there isn't one bad battery pulling them all down.
Battery connections & cables are all solid? With a handheld voltmeter, there are no cabling losses to be found?
And if the batteries are good, you may just need to check the fridge. If it is pulling 5A all the time and cycling excessively, that could mean it has lost enough gas to need servicing or replacement. It could be that simple, too. If it is 20 years old...good repairmen are incredibly expensive and hard to find. New fridges with thicker insulation added only seem expensive in comparison.
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Old 31-05-2015, 12:26   #10
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Re: Electrical question

Make sure your solar cells are receiving full sun. Any shade whatsoever on a panel, even a small corner of it, will substantially reduce any current coming from the panel.
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Old 31-05-2015, 12:43   #11
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Re: Electrical question

Btrayfors post has a lot of good information for you start accessing what's going on. What are you seeing as your max voltage during the peak charging time?
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Old 31-05-2015, 18:55   #12
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Re: Electrical question

Quote:
Originally Posted by Cheechako View Post
Another thought is to reduce your fridge size. I had one boat with a large compartment but it had 2 doors. I made one half (actually less than half) into the fridge with an insulated divider and use the other half for dry storage.
Yes I was also thinking along those line. My fridge had originally 2nd access under the cockpit hatch but that bin was sealed shut. I can install a well insulated divider and use the space under the cockpit as beer and wine storage. But it would be a winter/spring project anyway.

2nd alternative would be putting add'l 3-4" thick insulation along the inner fridge walls and lid. I actually prefer this route to dividing the fridge space.
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Old 31-05-2015, 19:04   #13
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Re: Electrical question

Quote:
Originally Posted by hellosailor View Post
"Overnight with the fridge running and all other electrics off the voltage drops to below 12v by morning, about 11.85-11.95v or even lower. "
So, let's say the Xantrex is right and your fridge is taking 5A when it runs. Being forced to make some guesses, please pencil in the correct real numbers here.
With a 50% duty cycle that would be 2.5Ah, and let's say "overnight" meaning when the solar panels aren't putting out full power, from 2PM until 8AM, that's 18 hours when the batteries alone have to supply the fridge, which is going to pull 45 amps out of the batteries. Even a cheaper G27 might start out at 80AH+, so if you disconnect the oldest one, you should still have 150AH+ capacity and only be drawing that down by 1/3, which might take you to 12.2~12.3V certainly not down to under 12.
So there's something wrong with the picture.
As the choir has said, you'll need to "divide and conquer". Test each battery, or at least the two older ones. Disconnect them, charge them all the way, let them rest and load test them. (That may mean disconnecting & cycling one on each of 3 days, so you don't ever have to shut down entirely.) First step, make sure there isn't one bad battery pulling them all down.
Battery connections & cables are all solid? With a handheld voltmeter, there are no cabling losses to be found?
And if the batteries are good, you may just need to check the fridge. If it is pulling 5A all the time and cycling excessively, that could mean it has lost enough gas to need servicing or replacement. It could be that simple, too. If it is 20 years old...good repairmen are incredibly expensive and hard to find. New fridges with thicker insulation added only seem expensive in comparison.
The fridge may be original - about 30-35 years old. (( The manual says it should draw 4.5-5A AFTER 50% cycling is figured in (may be my Xantrex is not giving me a true number). I did talk to several mechanics one of them HVAC pro with 40 years of experience. All said unless it's a freon issue it's cheaper to replace than to keep tinkering with it. Personally I think that even if I replace the fridge guts I'd have to insulate the box and the lid. So I'll start any project with that and see if it helps so that I can postpone the replacement of the rest.

I was also told that there is an official replacement for R12 which allows one to keep old compressors running instead of switching completely to R134 system. That also may be the chepest short term solution.
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Old 31-05-2015, 19:12   #14
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Re: Electrical question

Quote:
Originally Posted by Mycroft View Post
Make sure your solar cells are receiving full sun. Any shade whatsoever on a panel, even a small corner of it, will substantially reduce any current coming from the panel.
The panels are on top of the hard top which has replaced soft bimini. They are about a foot aft of the boom and the only shade they get is from a single backstay. But even that shade is usually over or across one or two panels at most so at least two others are always unshaded completely. The panels were bought brand new 1.5 years ago and installed 3 weeks ago. All wiring from the panels to controller and from controller out is about 2-3 sizes larger than the specs suggest.
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