Not sure if battery is charging fast enough

[scheek]

Ok. I am trying to recharge my 12 volt/ 125 AH marine battery to full charge. I actually discharged it to 11.2 volts so I could get an idea of recharge time.

I have a cheapie greenenergiesllc charge controller 12v/15amp. I have (3) 60 watt panels in parallel. Sunny days now the panels are showing 17-18 volts output.

Wire size from panels to controller is #14 gauge. Wire size to battery is about #14 wire clip.

So far after 3.5 afternoons volts reading on battery is only up to 11.7.

I've got to be doing something wrong. Give me an idea.

[Sunking]

I actually discharged it to 11.2 volts so I could get an idea of recharge time.

Sounds like you did some damage to your batteries to start with. At 11.2 volts (rested) was way past 100% discharged at 11.9 volts. FWIW 11.9 rested is 0% charge, and you should never go below 50% (12.2 volts) rested voltage. You went well beyond that point of no return.

With a 180 watt solar panel system and 125 AH 12 volt battery this time of year after 3 days is more than enough time to fully charge them back up. Assuming your panels and CC are operating correctly, your batteries are now boat anchors.

[scheek]

Do you think I should put my ac charger and see if it will go back up and hold. If it does, I suppose my controller could be bad.

[scheek]

If that doesn't work I'll carry it back to Walmart. This is the only time I've used it. I bought it a year ago. My test was that I ran an ac light with my (1500watt) inverter hooked up until it auto cut off. The light was pulling .5 amps. I turned it on about 1:00PM and when I went to bed it was still running. The next morning I read the battery voltage and it was 11.2. I think the inverter shuts off at 11.5. It was buzzing. Not sure how the battery got to 11.2V.

So in laymen terms a battery is 0% charge at 11.9? Fully charged at 12.6?
(.7 volts is the differential).

[Sunking]

Do you think I should put my ac charger and see if it will go back up and hold. If it does, I suppose my controller could be bad.

I certainly would.

[Sunking]

So in laymen terms a battery is 0% charge at 11.9? Fully charged at 12.6?
(.7 volts is the differential).

Yes but you must understand we are talking about AT REST VOLTAGES or State of Charge Voltages, not operating voltages.What i mean is the battery is disconnected and left to rest for several hours with no load or charge. So if you measure 11.2 after resting a while, it was below 0%. However if the battery was new, and you completely discharged it, it should be OK. just lost capacity which you cannot ever get back. The worse thing you can do is put a battery up in storage for prolonged period of times whithout being fully charged and topped off every week or so. When a battery sits discharge sulfate crystals form on the plates and destroy the battery.

[scheek]

I put the battery charger on it for 1.5 hours at 20amps before bed. This morning it read 11.89. So this probably all it's going to do. I think I'll go see Walmart.

[scheek]

So, a new battery full charge is about 12.6. To mantain that battery I need to use it every month and recharge.

Too, the other batteries (3) I have are all in the 12.2-12.5 range at rest. I guess it's best to keep a load on them in some way to keep them working and then repeatively recharge. Of course, if I put a light load on them, I surely don't won't to discharge too much and get the same problem I've just created.

[Sunking]

I put the battery charger on it for 1.5 hours at 20amps before bed. This morning it read 11.89. So this probably all it's going to do. I think I'll go see Walmart.

Scheek what is the AH rating of the battery in question? 125 AH?

20 amps x 1.5 hours x .80 = 24 Amp hours. If your battery was completely discharged you only charged it up 20% Bu ti do think your battery is toast it should be reading 12 or more volts at rest.

[Sunking]

So, a new battery full charge is about 12.6. To mantain that battery I need to use it every month and recharge.

No Sir you do not understand batteries yet. You need to do some homework to learn the basics of lead acid batteries. Otherwise you are going to be spending a whole lot of money learning the hard way replacing batteries frequently.

The best way to store a battery is to keep them on a float charger at all times. This keeps the batteries fully charged. There is no need to cycle them, just keep them charged up. If you cannot keep them on a float charger. then about once a month they need charged up to top them off.

Lead acid batteries have what is called Self Discharge. That means when they just sit there with nothing connected to them, they discharge themselves. Let them set long enough and they will completely discharge themselves and self destruct.

80% of all lead acid battery failures fail prematurely due to the plates becoming sulfated. Lead sulfate crystals begin to form when the capacity drops below 100%. The process accelerates as the capacity goes lower. Once the battery reaches the 50% capacity mark, the sulfate crystals harden on the plates and cannot be removed, the damage is pernament. Above 50% and they can be removed with a good EQUALIZE CHARGE. An Equalize Charge is controlled over charge condition.

• To maximize battery life, keep the batteries fully charged at all times.
• Design your system as such you never discharge the batteries more than 10 to 20% in a 24 hour period. This will give you 5 days (10%), 2.5 (20%) days for cloud cover before you have to shut down and wait for the sun to recharge the batteries, or start your generator to recharge.
• Never ever discharge your batteries more than 50%.
• Use a quality 3 or 4 stage battery charger and/or charge controller.

Lastly keep this in mind. Batteries have a limited number of charge/discharge cycles. The deeper you discharge them, the fewer cycles you will have. For example a popular L-16 renewable energy battery on the market has 5000 cycles at 10% Depth of Discharge, but only 500 cycles at 50% DOD.

[scheek]

Ok. thanks for info. I took the battery back to Walmart and they said it was dead but charged it up. It now has 12.6 volts. So you were right. I had not charged it enough.

So I have finished my battery bank stand that I made. I need to upload pictures so others can see this neat way to build a battery bank.

I do appreciate your help.

[scheek]

Just to make sure. My voltage with all three batteries is about 12.5. So 10% usage will let me drop it to 11.25 volts before recharging if my panels are not doing the job well?

[Mike90250]

Just to make sure. My voltage with all three batteries is about 12.5. So 10% usage will let me drop it to 11.25 volts before recharging if my panels are not doing the job well?

NO ! 11.25V is nearly dead. 12.5V, your battery bank is still not fully charged.

Look at the Deep Cycle Battery FAQ.

The Voltages section has a chart to follow (scroll down a bit to the chart)

[Sunking]

Just to make sure. My voltage with all three batteries is about 12.5. So 10% usage will let me drop it to 11.25 volts before recharging if my panels are not doing the job well?

No sir 11.25 volts is dead. If you keep deep discharging the batteries you will destroy them in quick order.