voltage rapidly drops when battery reaches certain voltage. Plz help

[jalal]

Five month ago I installed a small solar system for light use which includes: two 100W solar panels, cheap 20A PWM controller, 300W inverter (for modem and phone charging only), and 100Ah Gel battery (or maybe AGM ....i am not sure).
I only use the system at night mainly for lighting (12V lights connected to the controller output) and modem use.
mostly, the battery voltage doesn't go less than 12V which i always check. however three days ago the lighting went off and the inverter's alarm started, when i check the voltage it was 10.5V . when i cut off the load (one 9W lamp and modem) the voltage bounce back to 12-12.2V . when i turn on the light the battery rapidly drops. i tried to check the other day but same problem. the battery is normal until it reaches 12V and starts to drop
what's the problem? the battery almost gets full charge everyday (14.4 boost and 13.8 float)
can u help me
thanks

[Logan5]

Sounds like your battery has failed. I would use a carbon pile load tester to verify. My question is why use an inverter at all? Your Modem is likely 5v, 9v or 12v, 12v can be run direct from the battery and a cheap step down can be used for 5v or 9v if needed. Your 9watt LED light is already 12v. Inverters are inefficient and noisy and in your case unnecessary.

[jflorey2]

three days ago the lighting went off and the inverter's alarm started, when i check the voltage it was 10.5V . when i cut off the load (one 9W lamp and modem) the voltage bounce back to 12-12.2V . when i turn on the light the battery rapidly drops. i tried to check the other day but same problem. the battery is normal until it reaches 12V and starts to drop
what's the problem? the battery almost gets full charge everyday (14.4 boost and 13.8 float)

The battery is dead. It probably got discharged at some point and was left there; gel cells don't recover from that.

[jalal]

Thanks Logan and Jflorey for your responses.
i want to ask, is there anyway i can recover it?
by the way about 2 weeks ago i noticed that the positive connection was loose, could this be the reason behind what happened to the battery?

[Logan5]

Thanks Logan and Jflorey for your responses.
i want to ask, is there anyway i can recover it?
by the way about 2 weeks ago i noticed that the positive connection was loose, could this be the reason behind what happened to the battery?

No recovery, Yes a loose cable likely helped destroy battery,

[PNjunction]

jalal - one had better know the difference between gel and agm. They have different charging requirements *despite* what most (but not all) manufacturer spec sheets get wrong. Many just give up and let the consumer buy gels more often when they overcharge them to agm specifications.

If that battery was a gel, then the absorb voltage should be no more than 14.1v *temperature compensated* - nothing near 14.4, which is the common absorb for generic agm.

Your battery, if agm, could also have been severely undercharged and sulfated. But from this distance, it sounds to me like the classic case of gel-kill.

[jflorey2]

Thanks Logan and Jflorey for your responses.
i want to ask, is there anyway i can recover it?

Nope. Gel cells and AGM batteries cannot be "fixed."

[Sunking]

i want to ask, is there anyway i can recover it?

No possible way. A Gel battery as you have painfully learned should not be used for daily cycle purposes.

Think of a Gel Battery as a Christmas Jello Mold no one eats and gets stuck in the back of the refrigerator. When you over charge or let them stay discharged, the gel dries out and develops cracks and voids which are permanent irreversible damage. Just like that Jello Mold you just found in the back of the refrigerator and forgot about until Easter Holiday. There is no hope of reviving it.

Take your losses and learn from it. You learned the hard way by loosing money. No better teacher other than fear.

[jalal]

Thanks guys for your valuable info.
Dear Sunking, what type of battery do u recommend for my daily cycle use? Flooded vs AGM?

[Mike R]

Similar question!

I am knew at solar energy and just purchased the following equipment:

6 Master Solar batteries
Deep Cycle - RA 12-200 D
12V 200AH/20 HR

Outback Charge Control 80 AMPs 150 VDC
AIF-M80 - 150

Pure Sine Wave Inverter charger 6kw.24VDC, 115/230 VAC,DIP5,BTS
(Including) Remote LCD Panel

6 Solar Panels 295 Watts Mono Crystalline

I am not sure if the system is working properly because on a good day I can get 10 hours of sun, no appliances or lights on (with the exception of the refrigerator) and the batteries do not get completely charge. Also I notice that when the sun sets and the system switches to batteries, I only get about 3 hours of usage (with one inverter 17,000 btus air condition), but the person who installed the equipment had said that I should get from 6-7 hours of batteries usage. Is this normal?

I also noticed that the equipment fans are on about 90% of the time. Is this also normal?

Mike R

[Sunking]

Thanks guys for your valuable info.
Dear Sunking, what type of battery do u recommend for my daily cycle use? Flooded vs AGM?

That is easy, FLA cost 1/4 of AGM. AGM has a place in Solar, a very niche place you have to pay up for. Where would you use an AGM:

• Polar Ice Caps where temps drop below -40
• Aircraft where batteries experience 0 G's or Inverted upside down and spills cannot be tolerated.
• Where high charge and discharge rates are encountered.
• Extreme mobile applications.

Does any of that apply to you

AGM batteries cost twice as much and last half as long as FLA. That means they cost 400% mo money. Smart money buys FLA. Only Democrats, Socialist, and Communist buy AGM.

• As for Gel batteries, they have two niche applications? Egress Lighting. When you are in a store and see those emergency lights with a battery box use Gel Cells. They are Float charged and never cycled or leak or need any attention. Just replace them every 4 years. Does not maatter if they have ever been used or not.
• Alarm Panels. Just like Egress lighting, the batteries are never used, Float Charged, and get changed out every 4 years. Only used for an emergency.

FWIW AGM was invented by Concorde Battery to support Military and Aerospace aircraft.

[Sunking]

Similar question!

I am knew at solar energy and just purchased the following equipment:

6 Master Solar batteries
Deep Cycle - RA 12-200 D
12V 200AH/20 HR

Outback Charge Control 80 AMPs 150 VDC
AIF-M80 - 150

Pure Sine Wave Inverter charger 6kw.24VDC, 115/230 VAC,DIP5,BTS
(Including) Remote LCD Panel

6 Solar Panels 295 Watts Mono Crystalline

I am not sure if the system is working properly because on a good day I can get 10 hours of sun, no appliances or lights on (with the exception of the refrigerator) and the batteries do not get completely charge. Also I notice that when the sun sets and the system switches to batteries, I only get about 3 hours of usage (with one inverter 17,000 btus air condition), but the person who installed the equipment had said that I should get from 6-7 hours of batteries usage. Is this normal?

I also noticed that the equipment fans are on about 90% of the time. Is this also normal?

Mike R

You system is grossly undersized. If your battery was sized properly along with the panels, you should be able to run 5 days without Sun. Your system is not even remotely close to what is require. You are off by a factor of 20. Your batteries will be destroyed in a very short time. Bet you do not even have a genny which is required. You have not even made a down payment on a system yet capable of doing what you want.

In the biz you got your body shook, and money took. You believed what a salesman told you. That was the bait. Now time to rob you blind and sell you whaat it will really takes to run that window shaker. To run that Window Shaker 6 hours a day (10 Kwh) requires a 3000 pound, $7000 battery and a 4000 watt solar panel. You are no where close to reality. Should have done your homework. Now all you have is pain and lost money.

[Mike R]

Undersized! How many panels go with how many batteries?

[Mike90250]

Undersized! How many panels go with how many batteries?

Enough to supply 10% of battery capacity charge rate, 600A battery needs 60A to properly charge (spec is 8-15% for flooded cells)


but first, get the battery size right.