Short power life

[bpdchief]

I have 200 watts solar on roof, 210 AH battery storage. PWM  charges up to 14.4 v after about 2-3 hrs of morning sun, the monitor drops to 12.9v when fridge cycles. I have an Edgestar FP430 12v fridge running off solar and in the evening have an LED light on while cooking. 

When sun goes down the batteries settle to 12.6v. After about 2 hrs of fridge cycling the battery monitor is showing 12.3v and drops to 11.9v when fridge comes on again. Doesn't seem that I'll get 12aH  out of my battery bank at that rate.

Any thoughts on what's wrong besides I need an MPPT Controller??? :huh:

 

[29chico]

These days with lithium becoming more common I need much more battery info before attempting to help.  Make and part number for the solar charge controller please.  Is there a remote temp sensor on the battery so the charge controller can compensate it’s voltage output for variations in temp?

 

[GypsyDogs]

my first thought is ..
Why does your fridge cycle so much????

Mine comes on for about 1-2 minutes about every hour..

 

[Weight]

Are you using the power lug on the controller for the fridge. Or direct wired to the battery. What size (awg) and length are your cables. You are not charging your battery.

 

[Seminole Wind]

while yes a bit more info would help, not sure what the proliferation of lithium has to do with it.

assuming the op has either a pair of golfcart batteries or a pair of large RV/Marine batteries ( the 2 most common ways to have 210 amphours of storage) it would appear from the info that has been provided the op may be facing a couple of issues.

you may be facing not having enough storage and or not getting them fully charged.

as for enough storage, i tried to look up that fridge to find the specs but the company website is listing the specs for a much larger 115 volt ac fridge on the page for your fridge. good job edgestar... but i think a conservative estimate of 30-40 amp hours per 24 hours as refrigeration (not freezer) is reasonable for our troubleshooting. with 210 ah's of storage you should get close to 3 days of run time before dropping below the "dreaded" 50% state of charge (SOC) but if your batteries are not getting fully charged you may be giving up a large part of your storage. like starting a road trip with 3/4 tank of gas... also if the batteries have been chronically under charged they may be suffering from sulfation. this could seriously reduce the capacity of the batteries and that compounded with not starting out full can be a real bummer

let us now explore how discharged your batteries actually are. first ACCURATELY determining state of charge by reading the voltage is difficult in real world situations. most, if not all the SOC charts based on voltage are using the resting voltage. this means no loads and no charging going on. AND they expect that the batteries have been resting for around a day. now i dont know about you, but i dont want to disconnect my batteries for a day to see their state of charge. the problem is when you apply a load, as you have seen, the volts drop. that drop or sag, at least most of it is temporary. when the load is removed, the volts will recover and continue to rise for some time.

as a general rule of thumb that i find useful. with a target of keeping my batteries above the 50% and running a light/moderate load like your fridge with a moderate battery back like you mention i get concerned if the running volts get down around 11 or 11.5. i also get concerned if the short resting voltage in the morning is at or under 12 volts. so based on the data you provided, it is hard to say if there is a problem yet. while it does sound like there might be a problem. if you could let us know what the volt reading is first thing in the morning before the sun starts to charge through the solar panels. that would help considerably

now as for if your batteries are starting from a real full charge. you mention getting to 14.4 volts after a few hours. i suspect that 14.4 is a bit low for the set point, but you would need to check with the manufacturer to get the proper voltages to set your controller to be safe. also just getting up to the set point, in your case 14.4 volts is only "half the battle" that is only somewhere around 80% full. it will take several more hours with the batteries being held at that voltage to get the last 20% (or so) of charge into the batteries.

based on the info you provided and assuming basic flooded lead acid batteries i suspect you are not get a true full charge and having run in that partial state of charge cycling the batteries are probably sulfated thus reducing their capacity.

without further contradicting info i would do what you can to see that the batteries are reaching a true full charge as often as possible. i would also see about doing an equalization cycle on then to combat the built up sulfation and hopefully regain some of your lost capacity.

if you can provide more details and info/data as per your actual batteries and charge controlers and "resting" voltage in the morning and anything else you can think of to give us a better picture of your system. then we can go more in depth as to what is going on and what can be done to improve your situation.

 

[Trebor English]

What is the battery condition? When new it was rated at 210 amp hours. How old is it? What has been it's recharging history? When it gets charged to 14.4 volts does the charging get stopped or is the 14.4 volts held for several hours? Do you have anything that reports charge current? What is the hydrometer reading?

It seems to be behaving like a sulfated or worn out battery. It is like normal except it charges quickly then discharges quickly. It is like the 210 amp hour battery is only 21 amp hours.

According to the interwebs the Edgestar FP430 uses 5.4 amps. 200 watts of solar should be able to provide that with no drain of the battery. The drop to 12.9 volts could be due to some high resistance, small wire, or bad connection causing the battery to provide some of the 5.4 amps while the sun is shining.

 

[bpdchief]

Wow....
27 Series RV/Marine Deep Cycle flooded batteries are about a year old. Morning voltage prior to sunrise is 11.9 - 12.2v. PWM controller is set to float at 13.7v max at 14.4v which it stays at as long as sun shines. Fridge is wired to batteries through fuse block with 10 gauge stranded wire using 2 prong Johnson plug at fridge connector...and I am finding that it is getting warm. I'm using the same connector to connect solar panels through back of van to the charge controller and with panels pushing 19v it too gets warm to touch.I

Alternatively, I have a battery disconnect switch wired to charge batteries on cloudy days through 2 gauge wired back to batteries.

Today is overcast... Battery monitor showed 12.2v this morning, sun came out batteries slowly went up to 13.8 then 14.4. Fridge seems to cycle about every 20-25 minutes for about 3-4 minutes (which seems excessive to me). With clouds, batteries drop to 12.2 then climbs back to 12.6-12.8v. I know I'm getting solar through the clouds, but am admittedly ignorant as to how the system is operating.

 

[bpdchief]

I don't have a hydrometer as yet, but, it is on shopping list. Checked timing on fridge - it ran for approx. 7 minutes then about 1hour 20 minutes it came on again. At night I have heard it come on for about 2 minutes... do it again about 5 - 10 minutes later.
Should the connector be getting warm? Maybe I need to shine up the connector probes with emery cloth !?

As I am in town, I'll go back where I bought the batteries and have them checked.

The charge controller is a Chinese model... $13 - 15 purchased on eBay with intent of upgrading as money allowed. I need to find a meter/charge controller that shows amps coming from panels and one showing amperage being drawn.

 

[Trebor English]

With flooded batteries you can use a hydrometer.  That tells you the actual state of charge.  The voltage while charging and discharging is not a good indication of state of charge.  A $10 hydrometer can be used to diagnose your battery issue.  You need to measure the specific gravity of all cells at the max charge point in the afternoon and the minimum charge point in the morning before solar charging starts.  

The specific gravity tells you how much sulfur is in the sulfuric acid.  Missing sulfur is in the lead plates as lead sulfate.  More charging can get it back to the acid unless it has been in the plates too long.  

If you have one cell with low specific gravity you may get better performance disconnecting the battery with a bad cell.  

If both batteries are bad replacement is necessary.  If the refrigerator is loading the system too much you need another solar panel or a smaller refrigerator.  Until you measure the battery specific gravity you can make guesses and randomly change parts.  That can be expensive.  

As to the MPPT controller, you can do that and get 10% to 20% more energy.  A third 100 watt panel will give 50% more energy.  Compare the prices of panels and MPPT controllers.  That will lead you to the right choice after you figure out how much you need..

 

[Weight]

Your wires, cables, and connections, including plugs, should stay ambient temperature, cool to touch. You must fix that problem first. New larger wires, new connections. Hot stuff like that keep batteries from charging and also can cause fires.

 

[bpdchief]

10 gauge throughout system... should I go with 8 gauge? I read many places to use 10 ga and figured since panel leads were 10 ga that would sufice. I'm looking into replacing my current van so now would be the time to change it all out. Don't understand why the plugs are getting warm, they weren't two months ago. To the uninformed ( nicer than ignorant ) solar seems like it should be "plug and play" - connect battery to charge controller, connect panel to charge controller, the battery to fuse block and you've got power.... but, so many variables to contend with. Now I need to find a controller that compensates for temperature -

At 5.4 amps the fridge shouldn't be overloading the system - should it? Fridge cycle times seems to vary throughout the day.

 

[B and C]

Connections getting hot is an indication of a poor connection. 10 Ga wire for the solar system is sufficient, that is what mine has. 10 Ga should be plenty for the fridge too. You do need a programmable controller and some more solar. I run my panels in series and have two sets (one portable that I put out) that I can parallel when conditions aren't good enough for one set. A battery monitor is what I use (Trimetric) but I have AGM batteries. Checking the specific gravity is something I never want to do (I AM lazy).

 

[jonyjoe303]

I use to have one of the edgestars fp430, at 40 degrees the fridge will use about 25 amps in 24 hours. I measured it with a dc wattmeter, even when I thought the fridge was cycling too much, it always use about the same amps. So your system is more then adequate to keep up with. 

I think the battery is done for, it looks like it got discharged down low to many times and not fully charge backed up. If the battery ever goes below 11 volts, it usually wont last long. It will behave like your battery, charges quickly to 14.4 volts but then quickly discharges once you start putting loads on it. 

When I bought a lead acid battery the person at the battery store told me that with solar I would be trickle charging my battery most of the day, he recommended I charge it at high amps every once in a while so it would last longer. One thing I would definitely check, is the voltage difference between the battery terminals and your controller. If you have voltage drop, your controller can read 14.4 volts but your battery terminals might read 13.9 volts. I encounter that so many times I always compensate by raising the bulk setting to 15 volts to get the battery terminals to 14.4 volts. If you had voltage drop, your battery was never getting a full charge and that will lead to an early demise for the battery capacity.

With solar always keep your float voltage high, if you can get it to 14.4 volts do it. Some controllers shift to float too early after reaching 14.4 volts. The sun goes down before solar can fully charge a lead acid. 14.4 volts all day long won't harm a lead acid, it will actually make it last longer.

If you decide to get an mppt controller, I recommend the ecoworthy 20 amp mppt. (cost 100 dollars), mine has been running non stop 24/7 for almost 6 years. The reason I recommend is because you can adjust the bulk/float voltage on the unit itself to compensate for voltage drop. And it has a built in lcd screen.

 

[Ticklebellly]

First thoughts are that 200 Watts of solar are about half what is needed for a 210 Ah battery.   14.4 says to me that charging is still in bulk phase.   No indication that SOC has gone to float?   Voltage is a less than good way of checking SOC.   All the other listed voltage levels at times lead me to believe the batteries are not getting to full charge.

 

[Matlock]

^^ This.
It does sound like your not getting the bank to float.
Just a thought, when's the last time you added distilled water to the cells?

 

[Seminole Wind]

First thoughts are that 200 Watts of solar are about half what is needed for a 210 Ah battery.   14.4 says to me that charging is still in bulk phase.   No indication that SOC has gone to float?   Voltage is a less than good way of checking SOC.   All the other listed voltage levels at times lead me to believe the batteries are not getting to full charge.

the size of the battery bank (within reason) does not dictate "how much solar" you need. the size of the battery storage determines how long or how much you can run loads before having to recharge. what is far more critical to solar array size is daily consumption. you DO NEED to put more into the battery to get to full charge than what was removed by your use/loads.

a good rule of thumb for how much you can get out of your solar panels is to take 1/3 of the watt rating and that # is the amp hours you can ecpect under decent solar conditions. so as a few here have mentioned the fridge in question should use 20-30 amp hours per day. with 200 watts of solar you can reasonably expect around 66 amp hours a day, assuming decent conditions (of course low sun angle in winter, cloudy conditions, low quality panels and controllers would be cause for adjustment). barring other negative factors this being more than 2 times the daily load should suffice to recharge the batteries. the difference between a 100/200 or even 300 amp hour battery bank would far more affect how long you could run before needing to recharge. with the bigger battery bank you could park in the shade or survive cloudy weather a few days longer.

while having more solar can and is very beneficial to being able to "catch up" after an extended period with less than decent solar conditions it is not mandatory to have such a surplus of panels so long as you have sufficient input to replace what was used with a buffer or 50-100%

if 200 watts of solar is not consistantly bringing batteries back to full charge after a daily draw of 20-30 amp hours. you need to determine first that there is not some other "load" that you were not aware of. and/or determine why you are not getting good production from your panels. poor instal, cheep worn out/damaged panels or controller, climate/clouds, shading and such. also the possibility that the batteries are worn out/sulfated and not holding/accepting the charge.

for example, in this case a 100 amp hour battery bank is large enough to run that fridge for more than a day, close to 2 days without going below the dreaded 50% but the solution is not to reduce the battery bank from 200 amp hours to 100 amp hours, that would make a negligible affect to the problem

 

[ckelly78z]

I'll leave the battery/solar/controller/wiring to the experts.

I will add that it sounds like your fridge is cycling quite a bit, and could possibly benefit from some rigid foam insulation around the outside of your unit to hold the temperature inside at a steady rate for a longer period of time. If you could reduce the run time/duration by half, your batteries would hold a charge for a longer time period as well...win/win !

 

[Trebor English]

Now I need to find a controller that compensates for temperature -

I manually change my charge controller.  I use a multimeter at the battery and adjust.  I set it to 14.8 volts in the winter and 14.4 in the summer.

 

[Trebor English]

  10 Ga wire for the solar system is sufficient, that is what mine has.  10 Ga should be plenty for the fridge too.  

The length of the wire matters.  Doubling the length doubles the resistance.  AWG 10 might be enough.  

There are many internet based calculators like this:
https://www.calculator.net/voltage-drop-calculator.html 

I once bought some AWG 8 wire on the internet.  What I got was AWG 8 size wire that's copper clad aluminum.  The resistance is like AWG 10 copper.  Details.

 

[wayne49]

Until the hot connections are corrected, nothing else should be considered.

A live victim is bleeding out. Do you worry about anything other than stopping the blood loss?

@bpdchief, fix the connections, then report back.