# OK I have questions that I am sure you folks can answer



## steff bugielski (Nov 10, 2003)

First I would like to say I am not new to this even though it may sound that way. DH understands it better than I but refuses to use a computer.
We have had solar electric for about 4 years now. Started small and have gradually gotten to where we can run almost everything on solar most of the time. We are using a new charge controller, diversion charge controller.
Here are the facts...
We have a 12 volt system,
panels average 48 Amps
we have 8 batteries, only 6 hooked up, other set had a dry cell, floor scrubbers
NAPA AUTO PARTS
Specific gravity is 1210
The charge controller shuts off at 14.1 but the batteries are not charging.
All batteries have been checked for dry cells.
Voltage at rest is 12.6 in batteries.

It is a beautiful sunny day and I can not get any power in my batteries.


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## Jim-mi (May 15, 2002)

On used (used up) batteries the voltage can/will rise very quickly.
Hence the controller shutting off. . . .even tho the bats are not charged up.


Be very very careful with this;
Try a jumper bypass of the controller . . . .and feed what ever voltage your PV modules can achieve direct to the bats
Yes that is 15-16-17 volts . . . . . . . . .
Watch the water levels from "boiling batteries" . . . . BE CAREFUL......

If after 2-3-4 days doing this your bats do not hold "more" charge then your going to half to admit that the bats are shot.................


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## steff bugielski (Nov 10, 2003)

The voltage is 12.6 but the specific gravity is low. They are bubbling. When I run them all night they only loose 1/2 volt. But the SG does not rise.
These are not old batteries maybe 1 year at most.
Can you explain SG in laymans terms for me.
How do I know what the SG should be.


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## steff bugielski (Nov 10, 2003)

These batteries were given to me, I was told they were new, looked brand new. If a few were a few months older than the others how big a problem is that? Exactly what can go wrong with adding two new batteries to a 6 month old bank of four batteries?
Are those batteries destroyed, useless?
Is there any fixing it?


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## farminghandyman (Mar 4, 2005)

If the batteries were not properly keep charged when in storage they may not be much good, (see the quote below)

Trojan Battery Company

after charging a battery they will get a "surface charge" which looks like it fully charged but is not the amount of power in a surface charge is minimal, 

I would take a load tester and test them that way, first it drains off the surface charge, or let it set for about 12 hrs, (even a cheap load tester) and See where the SP is and see if it is charging to 100% or 1.265 SG.

BatteryStuff Articles | Guide to Understanding Flooded, AGM, and Gel Batteries
lots of info on the link and some posted below, on battery life,







> 8. Battery life and performance - Average battery life has become shorter as energy requirements have increased. Two phrases I hear most often are "my battery won't take a charge, and my battery won't hold a charge". Only 30% of batteries sold today reach the 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery's lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous. Let me list some for you.
> 
> 
> 
> ...



you stated,


> Specific gravity is 1210


 guessing that was meant to say, 1.210, according to the chart that that battery is only holding about 50% to 60% charge 

TABLE 1. State of charge as related to specific gravity and 
open circuit voltage 

Percentage of Charge Specific Gravity Corrected to 
80o F Open-Circuit Voltage 12V 

Percent-SG----voltage
100 1.277 - 12.73 
90 1.258 - 12.62 
80 1.238 - 12.50 
70 1.217 - 12.37 
60 1.195 - 12.24 
50 1.172 - 12.10 
40 1.148 - 11.96 
30 1.124 -11.81 
20 1.098 - 11.66 
10 1.073 - 11.51


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## steff bugielski (Nov 10, 2003)

I am so missing something here.
How can the voltage be 12.4 at rest and only 50% charged?


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## Jim-mi (May 15, 2002)

It is a thing called 'surface charge'.

Leave the volt meter on . . now switch on a load . . .and watch the voltage really drop.


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## steff bugielski (Nov 10, 2003)

The charge controller is a voltage meter and it is on all the time with voltage read out with a load or not. 

What should the voltage of a 12 v battery be?


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## Jim-mi (May 15, 2002)

The volt meter I am talking about is a 'tool' everyone should have. . . .A DMM (digital multi meter) . . . . .And I don't mean the $5 super elcheapo pieces of 'dollar store' junk.

Not knowing the charge controller that you have I can't comment on it.

That is an very subjective question you ask about battery voltage.


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## wy_white_wolf (Oct 14, 2004)

Deep Cycle Battery FAQ

Lots of reading there and they do have a voltage chart for voltage at % of charge. Specific gravity readings are more accurate for measuring state of charge as they require no rest period between charge/discharge and taking the reading.

WWW


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## wy_white_wolf (Oct 14, 2004)

steff bugielski said:


> The voltage is 12.6 but the specific gravity is low. They are bubbling. When I run them all night they only loose 1/2 volt. But the SG does not rise.
> These are not old batteries maybe 1 year at most.
> Can you explain SG in laymans terms for me.
> How do I know what the SG should be.


Losing 1/2 volt a night tells me your using about 40 to 50% of the battery daily. It is recommended to run on the top 20% for battery life. Discharging like that on a daily basis could easily destroy a set a batteries in a year. 

The voltage being in the range of 90% charged (hopefully that was taken after the batteries rested for at least 2 hours) and a SG reading that tells me they are only 50% charged confirms to me that the batteries have lost capacity from over discharging on a regular basis.

Do as Jim-mi suggested to try and equalize the batteries and see if you can get some capacity back. It would even be wise to hook up a generator and give them a good charge from it first.

WWW


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## ralph perrello (Mar 8, 2013)

Lead/acid deep cycle batteries must be brought up to 14.8 volts and held there for at least 2 hours to charge properly @ 80 deg F. If this happens then equalizing is not necessary. With a battery temperature sensor the voltage will vary with the battery temperature. A battery bank that has not been fully charged will drop voltage fast when used a little bit. This is a dead give away that the batteries are not fully charging.

Been there and done that until I renovated the system the experts put in.

Rule of thumb: one battery per 100 watts of panel.


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