Solar or Battery Problem?

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Tomcor

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I have a 100w flex panel which usually shows 3.9A and 45 to 50W on my solar controller which is a Samlex pwm in full sun which I usally get plenty of each day. At night my controller shows battery voltage of 12.0 to 11.9. I only use about 20ah a day according my resettable ah meter, and I am using an 110ah walmart marine battery. I thought might be the battery so I exchanged it for a new one. It still goes down to 11.9v which I know is to low. During the day the battery will charge up at 12.7v.

I am only using a Dometic CF25 and some led lights. It didn't use to go to that low of a voltage at night.anyone have any ideas? It is wired correctly.
 

Tomcor

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Tomcor said:
I have a 100w flex panel which usually shows 3.9A and 45 to 50W on my solar controller which is a Samlex pwm in full sun which I usally get plenty of each day. At night my controller shows battery voltage of 12.0 to 11.9. I only use about 20ah a day according my resettable ah meter, and I am using an 110ah walmart marine battery. I thought might be the battery so I exchanged it for a new one. It still goes down to 11.9v which I know is to low. During the day the battery will charge up at 12.7v.

I am only using a Dometic CF25 and some led lights. It didn't use to go to that low of a voltage at night.anyone have any ideas? It is wired correctly.
 

jimindenver

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Your panel isn't producing enough to cover your needs. You need to get the voltage higher than that to do the charging you need.
 

SternWake

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You are a battery murderer. And this is why the cheapest learner battery is often recommended.  but do note that the failure of the previous battery was not Wal Marts or Johnson control's fault.  Your treatment of the battery would have destroyed the best lead acid deep cycle battery available.


The 12v lead acid battery really wants / needs to get to and be held at 14.4 to 14.8v each recharge cycle for a period of time, as often as possible, or its available capacity will walk down quickly.  Like a fuel tank which keeps shrinking in volume.

Never mind that you are not getting to 100% charged/refilling the tank, and that you are working with less than the battery's full original  capacity/ Tank size,...... Without the full charge applied every so many discharge/recharge cycles the battery's capacity shrinks  That 35 gallon tank is now a 20 gallon tank, never to become 35 gallons again.

  Each cycle without a full charge the battery will be able to store less, even if  later it is fully charged.

When the battery capacity shrinks and you do not use less electricity to stay above 12.19v ~50%, you are cycling the battery even deeper, making it lose capacity even faster.

Wally world also likes to rate their batteries not in the standard 20 hour rate, but at the 100 hour rate

Meaning a battery which can produce 5 amps for 20 hours  before voltage falls to 10.5v, is rated a 100 Amp hour battery
A battery which can produce 1 amp for 120 hours is rated by wal mart as a 120 amp hour battery, but put a 5 amp load on this battery and it likely could only last 20 hours, or less, before voltage fell to 10.5V(100% discharged)


Marketing wins again.  Release Curses here.  &)(*&^)(^&*&())(**  Shake fist at sky, and go write some hate mail to wally world.

 What are the dimensions of your battery?  10 inches wide, or 12 inches, or 13?

10 inches wide would be a group 24 at about 85AH
12 inches wide would be a group 27 at about 100AH
13 inches wide would be a group 29/31 and be about 115 to 125 AH depending on the region of the country it was purchased.

It is unlikely the batteries made for Wally world  by Johnson Controls Exide or whomever the current contract is with, would actually perform as rated anyway.  Lots of wally world batteries are now made In Saudi Arabia. Our 911 friends.

Your current battery, if you hope to restore it to its maximum remaining capacity, needs to spend many hours at 14.4 to 14.8 volts. And to be restored to this maximum remaining capacity (not the When new capacity, that is gone forever)  you would need to perform an Equalization charge, which consists of bringing the battery to as high as 16.2 volts after that extended time at 14.8.

Usually takes special equipment to achieve 16.2v at battery terminals.  Few off the shelf chargers will do this. Magical pulse desulfating chargers have been proven to be no more effective than a regular charger holding a higher voltage.  More marketing CRAP. 

One can try and achieve 16 volts this by either reprogramming their programmable solar controller by setting absorption voltage to 16.2v, Or by hooking solar panel directly to battery terminals after the battery has been otherwise fully charged.

In general it will require 5 amps per 100Ah of capacity to bring 'fully' charged battery from 14.8 to 16 volts.  Even getting it to 15.5v would likely get the specific gravity at least closer to 1.275+


So your 100 watt panel is a the very edge of this capability, on a good sunny day when it was fully charged when you attempt to get it to the 16.2 volts, or as high as possible upto that maximum.

Make sure the cooling unit vents on your fridge are not obscured.  100 watts should be more than  enough to cover the loads you have listed, UNless you leave the fridge door open pile it with warm items, and it is 100F ambient.
 

ccbreder

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3.9 amps is not much. Samlex are pretty good products. Do you have the 8 amp or a larger one? Are the wires of the right gauge? Is your solar panel shaded by racks or antennas or whatever?
 

Tomcor

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I am using a Samlex 30a controller. I just retested the panel with wires disconnected from controller I read 19.8V in full sun. If I reattach the wires to the controller I read 12.7 at the terminals of the controller. Used a clamp on amp meter I read 5.01A with everything connected.
My controller shows battery V, amps and watts. The display did show 12.7V now it shows 12.2 because the 12v cooler is plugged in. It has been plugged for 3 days now.
 

SternWake

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That battery at that level of depletion, would require about 45 amp minimum to instantly be brought from 12.2 to 14.8v.

5 amps will take about 7 to 8 hours before it gets to 14.8.

5 amps max is never going to recharge that battery while you still have the fridge running.

Soon you will get to replace it again.

the only thing wrong with your system is you do not have enough solar to achieve 14.8v by solar noonish each day. Either increase solar wattage or use additional recharging sources, or reduce the loads on the battery significantly.
 

Tomcor

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I will head to Flagstaff tomorrow to get some wire and fuses for hooking up my continus duty solenoid I already have. Could I get by with 8 gauge wire? I really don't run an inverter although I do have 400w for charging very low amperage items.
 

SternWake

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You can get by with 8awg, certainly, but thicker would be able to utilize the alternator better in shorter drives.

The distance from alternator to house battery really dictates what size wire 'should' be used.

If you samlex charge controller has programmable absorption voltage, and duration, put it to 14.8v and 4 hours.

Unless you stop cycling this battery, there is no reason for the controller to drop to float voltage.

The sulfated battery needs to be held at high voltage for longer each recharge, compared to when it was new and unsulfated
 

Tomcor

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The controller was set at 14.4v. Changed it to 14.8. I will get the battery charged off of AC tomorrow. Then will be running an alternator charge circuit soon.
 

SternWake

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When AC powered charger first flashes full charge green light, Apply load to battery just long enought to reduce voltage to below 12.6v, then restart automatic charger at next lowest amp setting, if available.

Automatic chargers generally declare 'full' at 92 to 95% charged, and to get this abused sulfated battery performing as well as possible a true 100% recharge is required.

Loading the battery and restarting the charger will better allow the battery to approach 100%.
It should also allow the battery to be somewhat easier to fully recharge( taking less time at 14.8v) in the future.

These 12v marine batteries are quite difficult to actually top charge. My last one, a USbattery group31 battery required 14.9v many hours each day, and a 16v EQ charge for an hour every 14 cycles to last for 500 total cycles before I removed it from my Van. This was determined with a Hydrometer and much testing/experimenting with the interest and proper tools to do so.

So seek to hold a high voltage for longer and the battery should be happier. Only in very hot temperatures should you really worry about too high a voltage on this particular battery. The wally world batteries seem to not use much water either, but 14.8v will increase the water consumption.

If your charge controller only holds absoption voltage for an hour or two, that is likely not enough time. As long as your fridge is in use and you cycle the battery daily, you could set float voltage to 14.8v too without worry. Only when you stop cycling the battery do you need to return float voltage to more regular 13.2v levels.
Premature application of float voltage by automatic charging sources is a battery killer.
A hydrometer will reveal this time and again.

Best of luck with it
 

TooManyDogs

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I was basically only "playing" with my setup of the 100W Renogy suitcase solar panel paired with an hybrid marine battery (105aH) earlier this summer. (I'm not on the road yet.)

I drove around with a 45qt Whynter 12 volt refrigerator delivering cold energy drinks and frozen bottles of water for a couple of days for a race. It took several days to recharge the battery using solar, and I still don't think the panel charged it up anywhere close to 100%. I ended up buying a charger to top off the battery. (Yes, SW, I know it's probably still not 100% topped off.)
 

jimindenver

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That's the problem with portables. A mounted panel would have covered a good deal of the load and the alternator should have helped too.

I've always seen 1 to 1 as a rule for watts to Ah's of battery. I think that is too weak and 2 to 1 is a better formula. My 235 watt panel has the ability to get my 95 Ah marine battery moving, The 250 Ah 8-D wasn't all that impressed. It snapped to with the 490w we used the next year though. It's not enoung just to have a panel up there, you have to have enough to push the battery around.
 

SternWake

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Part of the issue is that it is not as if the fridge is turned off and the battery allowed to accept the full available current of the Limited solar panel wattage

And it is the hottest part of the day when the fridge runs the most and consumes most of the solar's current in its sweet spot for power generation. So 5 aqmpa generation at noon, well say a conservative 25% duty cycle on the fridge, 15 minutes per hour total the fridge will be sucking up most of that solar current with little or none getting into the battery.

The result is the solar panel never gets the battery to 14.8v and/or does not hold it there for the required time. The battery sulfates, loses capacity, and becomes harder to fully recharge to the maximum of its remaining capacity each recharge cycle where it does not get to the 100% range.

If it does get it to 14.8v, when the fridge compressor kicks back on, the solar cannot maintain 14.8v and the absorption stage is continuously interrupted for long enough that when the sun starts going down, the battery is still far from fully charged.

Some strategies can help.

If driving in the morning and one's house battery is hooked to alternator, crank fridge ALL the way up. Recharge all portable devices when engine is running. If one has another fan, Aim it at the intake vent on the fridge's cooling unit. If one's vehicle has AC, crank it to the maximum. Turn fridge back down, or perhaps off when engine is turned off.

Increase fridge insulation, turn fridge way down or off after breakfast.

or

Turn fridge off and keep door closed until the battery is only in the latter half of the absorption stage and amps accepted by it at absorption voltage are much lower, then turn it back on.

Decrease vehicle's internal temperature by reflectix or insulation in windows on sunny side, and/or more ventilation. exchanging inside air for outside air. 10 degrees more F over 75 can double compressor duty cycle. A fridge sitting in a locked 95 degree vehicle will consume huge amounts of electricity, not only because of the temperature difference, but because the condenser will have that much harder of time venting the heat removed from the box to the atmosphere.

Generally keeping the fridge full will reduce duty cycle if door is opened often.

Make sure the vents on the fridge's cooling unit are not obstructed at all, meaning several inches space around them. The importance of this cannot be overstated. A fridge does not force things cold, it removes heat from them. This heat must be transferred to atmosphere as efficiently as possible, so if these vents are obstructed, the fridge compressor will have to run much longer to perform the same task. The compressor itself also generates heat and even after it cycles off, without good ventilation this heat will soak into the condenser, making it harder for the fan to do its job the next time the fridge cycles on. Also this is a heat source right next to the part one is trying to keep cold. Manufacturers did not really insulate this area as well as possible so ensuring it is no hotter than it needs to be makes a BIG difference in overall power consumption.

In this regard, DIY tinkerers might be able to slip some reflectix between compressor/condenser and fridge box. to reflect compressor condenser heat away from cold box.
The computer Fans also provided with these fridges are also not very efficient, and if designed to pull air through the condenser, instead of Push it through condenser( that thing that looks like a radiator), become even less effective. A 120MM fan like a Noctua NF-f12 consumes very little current(0.05 amps) and is very quiet when pushing air through a resistance, and has a very high static pressure rating for its CFM. When I replaced the 0.12amp 72cfm puller fan provided with my fridge, with the Noctua NF-f12 pushing, there was an instant improvement in duty cycle, and the quieter fan's amp draw was decreased by 60% at the same time. Win win.

One could add a second fan over grille on exterior of chest fridge to help improve airflow, again the Noctua NF-f12's 0.05 amp draw is so little that overloading the fan circuit is highly unlikely. It will more than make up for the slight increase in in amp draw Fridges with Danfoss compressors can handle powering 0.5 amps of fans which switch on and off with compressor.

The cooling units on these fridges basically act like vehicle air filters, trapping dust and lint and limiting airflow. Keeping out the lint and dust or blowing/brushing it out makes a huge difference when condenser and fan blades are occluded. The dust is not only a cause of poor fridge performance, they can cause its failure, or cause it to occur much earlier than it otherwise would.

Only refill the fridge with warm items in the coolest part of the early morning, make sure any warm items placed within are not baking hot when interred within.

If one does find their solar controller in Absorption stage and the fridge compressor does not draw voltage down below 14.8 volts, then turn up the fridge colder, until later afternoon when the sun cannot hold it at absorption voltage. Afterwards the fridge will not run or consume as much battery power. This can really significantly reduce duty cycle for the next several hours and take a big dent out of overnight Ah consumption from battery.

Even though LEDS do not draw much electricity, if one dims them to ~85% brightess, they can consume way less than half the amount of current as they do at full 100% brightness.

https://www.amazon.com/LEDwholesale...qid=1475467019&sr=8-2&keywords=pwm+led+dimmer

They are worth it just for the ambiance factor.

Strategies can also be developed to retrieve food and return food items to the fridge box as quickly as possible. Many people love to leave the door open while they pour milk or something, and this is unnecessary and insures more battery consumption. Break oneself from stick and brick habits.

Some people might leave something cold on the counter for 15 minutes after they dispensed the item within, and only then return it. More heat the unit must then remove. Return cold items back into fridge ASAP with as few door openings as possible.

The easiest solution, is simply more solar, if possible.

When the battery is most depleted, is when battery charging is most efficient, which is why I recommend a well wired alternator, and driving in the morning when battery is most depleted, if one has to drive. If later morning, then the solar will have replenished some of the battery and it will not accept as many amps from the alternator as it otherwise would.
I do not recommend idling, unmoving to recharge unless one knows their alternator is not approaching 220F. This can happen quickly on some vehicle platforms when recharging depleted batteries which ask for everything the alternator can make.

I have found even moving slowly( 15 to 25mph) at low engine rpms spikes my alternator temperature when it is producing more than half its rated output. Highway speeds, no issues maxed out.

No sense in destroying an expensive alternator trying to extend the life of the battery.

The goal is really to get the depleted house battery to absorption voltage as early in the day as possible to allow the battery to spend as much time as it needs each day to get to 100% charged. Once absorption voltage is achieved, the amount of amps required to maintain it keep dropping, and these extra amps can then be used to charge portable device batteries, or charge the fridge, by making it colder when there is the solar surplus.


When a battery goes several days being worked hard and not quite fully recharged, or perhaps not even close, it gets punch drunk, and becomes much harder to sober it up. When punch drunk, The absorption stage of holding 14.8v, will need to be held for much much longer for it to recover and actually reach full charge. Often longer than the day is long.
If at this point of punch drunkedness ,it still is not recharged to its maximum possible remaining capacity, and cycling begins again, that possible capacity regained from the true full recharge, is gone, forever, and it will become harder and harder to recharge the battery to whatever diminished capacity it now has remaining.
It is like a balloon whose skin gets crusty and less elastic and more full of pinholes unless it is regularly stretched out to its maximum size.

With this diminished capacity, and without using less electricity from it overnight, it is being cycled deeper each time, which reduces capacity even faster, and the problem compounds until "my battery no longer accepts a charge" WTF? Argggggghhhhh!

The battery is still taking a charge, but it simply has no room left to store it, and small loads and the voltage tanks and things stop working.

This is the big issue with lead acid batteries, and why the 100% recharge is so important. Does the 100% recharge need to happen each and every recharge, of course not, but it is better if it does. Much better. One can get several hundred worry free cycles if it does. if it does not one is lucky to get 150 cycles before "WTF!!!!!! ArrrrrggggggggggGhhhhhhhhhhhh!!!!!!"

And if one knows they have gone several days without the true full recharge, efforts to achieve it should be pursued, or one should expect to kiss some capacity good bye, forever. the longer one goes the harder it is to not only recharge the battery but the more likely it is that the capacity is unrecoverable.

Being able to plug in overnight not only allows a true full charge to occur, it gives the battery a rest.

Equalization charges of 16v applied only after a regular extended absorption charge, can restore some capacity that might appear to be gone forever, but these are fairly labor intensive and results are NOT guaranteed. 16 volts should not be allowed to reach 12v devices, and 16 volts is not so easy to achieve without proper equipment.

One does not have to obsess to get maximum lifespan from a lead acid battery, but neither should they expect it to just recharge to its maximum capacity at any point after it has been worked hard and chronically undercharged.

So, in Summary, Seek and Hold 14.8 volts should be a goal daily. How long to hold depends on what time of day the solar gets it there. If at 2PM the fridge compressor kicking on pulls it below 14.4v, consider turning off fridge for a little while.
 

Tomcor

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Thanks SW that's a whole lot of info!

I do have insulation around the cooler, and it has airflow for the vents. Will get the battery AC charged first. The deal is that just started full timing 3 weeks ago and need the cooler for cold drinks. I realize that if I unpluged the cooler it would help replenish the Voltage. I did absorb all the info in your posting, very great explanation.

Keep you updated.
 

SternWake

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https://www.amazon.com/Dometic-CF-025DC-Portable-Freezer-Refrigerator/dp/B005X9E6IK

tomcor, what thickness of wiring are you using between solar controller and solar panel?

Is the panel mounted on the roof or a portable?

I kind of expected 100 watts to be able to keep up better with your stated loads if the panel was on the roof. That Dometic is pretty small, and I'd expect more than 3.9 amps from a 100 watt panel at noon in Arizona this time of year.

I am getting about 11 amps at 32 north from 198 watts flat on my roof around noon.
 

Tomcor

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I am using the stock 10g wire. Flex panel mounted with industrial Velcro. On fiberglass roof.
I did buy the panel used off eBay. The seller said he used it on a sailboat in FL. There was some slight corrosion inside the wire from salt air. The panel does measure 19v output. Panel is in great condition except for the slight corrosion. I am thinking there maybe some corrosion in the panel wire junction box. The cable run to the controller is less then 3 feet.
 

SternWake

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Most 12v nominal panels in full sunlight will have an open circuit voltage (OCV) of 20 to 21 volts and perhaps higher, but you should find the specs for your panel to make sure.  The flexible panels are said to lose their efficiency much faster than framed panels.

Corroded copper cabling is not good.  The 12 awg copper which came on a schumacher charger purchased in 2007 always heated up way more than expected passing 25 amps.  When I cut it in the middle I found the copper black.  More recently I replaced the wire  to circuit board with 10AWG and found that it barely got warm, and the charger was able to deliver 2.5 more amps!

The condition of electrical connections makes a huge difference.  Any visible corrosion indicates huge levels of resistance causing oxidation.

How long is the 10 awg from panel to samlex controller?

You might be able to gain 10 to 20% more efficiency with better copper and connections.

https://www.amazon.com/CAIG-DeOxit-Cleaning-Solution-Spray/dp/B0002BBV4G

This stuff is magic electrical juice.  No other electronics contact spray cleaner comes remotely close.
 

ccbreder

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Just me, but my experience farmers and sailors squeeze every drop of use before they part with something.
 
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