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How low can the battery get?????

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Rchel

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My 12v 50 amp deep cycle battery it’s normally ( my system is just 1 week old) at 13.9 v but when I turn the inverter on with my load 50 watts load) right away gets to 12.1v, is this normal?
It’s just started to get really cold , I have this battery in a battery box insulated but it’s outside
I know if this continues my battery won’t last long?
Do I have a bad battery?
Thank you
 
Is this a 50ah AGM deep cycle battery?
50w/12v=4.16a
So with a 50ah lead acid battery its actual capacity is half that or 25ah.
I would say you are close to normal as that is a small battery & might last 6 hours at that draw. If you hang in there the voltage might recover a bit as the chemistry heats up before it continues its sag to 11.5.
 
Yes it’s AGM
I GUESS I’m trying not to kill the battery
I’m new at this
How high do the voltage gets?whats the ideal?
The other day it said 14v
 
The higher voltages you are seeing are likely from the charger. Once allowed to rest the battery will likely settle @ 2.6-2.8VDC. That is the actual battery voltage. The charger needs to push more voltage in order to jam more energy into the battery near the end of the charge.
 
A deep cycle is more suited to lower amperage discharge over sustained periods. Auto stating batteries are more suited to high amperage discharge events of short duration.
 
You say your battery is outside. I assume your inverter is inside? How long and what gauge is the wire? Too small wire gauge or too long a run and the voltage at the inverter will drop considerably. Where are you checking the voltage? At the inverter? Put a meter on the battery and see what it says.

Also, why is it at 13.9v? It must be being charged with a voltage that high. Is it solar charging? Has this battery ever been fully charged with a mains charger?
 
SolarRat said:
You say your battery is outside. I assume your inverter is inside? How long and what gauge is the wire? Too small wire gauge or too long a run and the voltage at the inverter will drop considerably. Where are you checking the voltage? At the inverter? Put a meter on the battery and see what it says.

Also, why is it at 13.9v? It must be being charged with a voltage that high. Is it solar charging? Has this battery ever been fully charged with a mains charger?
Click to expand...
The inverter it’s outside too behind the coop in a insulated box, cover with a tiny window on bottom for ventilation
The cable from battery - charge controller it’s 6 gauge, about 3 feet long, the cable from battery - inverter ( I’m using the cable that was with the inverter ) it’s 10 gauge, short
It’s 13.9 when charging, this value is in the screen of the charge controller, I will measure with voltage meter later.
The battery has never been fully charge other than with the PV
I must be doing something wrong
?
 
Test the voltage both at the battery and at the inverter input when under load. Maybe the CC is reading incorrectly. Is the inverter shutting down or acting like it's got low voltage? Make sure all connections are good!!!

The main problem with lead acid batteries (including AGM and gel), is that they bulk charge easily up to 80%, but that last ~20% (absorption) usually takes longer than there are sun hours left in the day, so that stage never completes and the battery never reaches full charge. A huge PV array helps here, as does days off between discharge cycles. So does a bigger battery where 80% SOC is plenty. A 50ah battery at 80% is skating on thin ice....and that's IF it's at 80%. How big is your array and how many amps is your CC? What is the battery's resting voltage with no load or charge?
 
Rchel said:
How high do the voltage gets?whats the ideal?
The other day it said 14v
Click to expand...

On FLA batts the absorption stage can be as high as 14.5v and over 15 if in a equalization stage. Your's is an AGM so 14.3v is more like it for both bulk and absorption, and NO equalization stage (will kill AGM batts). Float (stage 3), if it ever gets that far on solar, should be about 13.3ish volts.
 
SolarRat said:
Test the voltage both at the battery and at the inverter input when under load. Maybe the CC is reading incorrectly. Is the inverter shutting down or acting like it's got low voltage? Make sure all connections are good!!!

The main problem with lead acid batteries (including AGM and gel), is that they bulk charge easily up to 80%, but that last ~20% (absorption) usually takes longer than there are sun hours left in the day, so that stage never completes and the battery never reaches full charge. A huge PV array helps here, as does days off between discharge cycles. So does a bigger battery where 80% SOC is plenty. A 50ah battery at 80% is skating on thin ice....and that's IF it's at 80%. How big is your array and how many amps is your CC? What is the battery's resting voltage with no load or charge?
Click to expand...
I only have a 100 watt panel
I need to buy another one, the CC it’s up to 60 amp, resting voltage when read in CCis from 12.9-13-14
 
That’s my CC AND inverter
 

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Right away getting from 13.9v surface charge to 12.1v using a 50 watt load on that battery means your battery is crap. Sorry. Now need the history of that battery to understand why it's crap. How long was it stored, how often discharged to empty how many times was it thrown against a wall in frustration (none? Is that just something I do?).. It's your battery. Well I think so anyways.
 
Kcp said:
Right away getting from 13.9v surface charge to 12.1v using a 50 watt load on that battery means your battery is crap. Sorry. Now need the history of that battery to understand why it's crap. How long was it stored, how often discharged to empty how many times was it thrown against a wall in frustration (none? Is that just something I do?).. It's your battery. Well I think so anyways.
Click to expand...
 
Okay I recommend watching Wills video on how to size a solar system- it uses the watt hour method:

So your 12v 50ah battery is 600wh/2=300wh usable before 50% drain.

Your 12v 50watt load is 50wh per hour. As SCClockDr calcuated 50watts @ 12v=4.16amps, call it 4.2a. It will use those amps if it runs continuously.

So your 50wh load should run 6 hours on that battery before it hits 12.1-12.2v. None of this takes your inverter watt hours into account so figure, 3-4 hours in reality.

(PLEASE anyone check my math and assumptions, I am horrible at math and assume too much)

In contrast I have 2 6v batteries in series that equal 1350wh at 50%. My 45watt load running 24/7 for months (a small 12v compressor fridge) has never taken the batteries below 12.6v. When both controllers were working the batteries were still 12.9v at 3am.

Hence why I'm looking at the battery being the problem, from 13.9v it should have at least hovered at 12.5 for a but then 12.3 for a time before hitting 12.1.

And look at Solar Rats post about charging voltage, 13.3v in your picture is too low for even the float stage. Hope this helps.
 
Kcp said:
Right away getting from 13.9v surface charge to 12.1v using a 50 watt load on that battery means your battery is crap.
Click to expand...

The 13.9v is just from the solar charger...doesn't have much power behind it. Either nothing is wrong (12.2v under load isn't too abnormal), or the battery isn't charged.

We don't have nearly enough correct information to determine anything.
 
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So when charging the battery should read more than 13.9v?? I’m more confuse now
How many volts should it read when charging? Normally with or without the load
Thank you
 
Kcp said:
Okay I recommend watching Wills video on how to size a solar system- it uses the watt hour method:

So your 12v 50ah battery is 600wh/2=300wh usable before 50% drain.

Your 12v 50watt load is 50wh per hour. As SCClockDr calcuated 50watts @ 12v=4.16amps, call it 4.2a. It will use those amps if it runs continuously.

So your 50wh load should run 6 hours on that battery before it hits 12.1-12.2v. None of this takes your inverter watt hours into account so figure, 3-4 hours in reality.

(PLEASE anyone check my math and assumptions, I am horrible at math and assume too much)

In contrast I have 2 6v batteries in series that equal 1350wh at 50%. My 45watt load running 24/7 for months (a small 12v compressor fridge) has never taken the batteries below 12.6v. When both controllers were working the batteries were still 12.9v at 3am.

Hence why I'm looking at the battery being the problem, from 13.9v it should have at least hovered at 12.5 for a but then 12.3 for a time before hitting 12.1.

And look at Solar Rats post about charging voltage, 13.3v in your picture is too low for even the float stage. Hope this helps.
Click to expand...
So this means that my battery it is crap!!
It’s new
Only 2 months old
I had it in the box before connecting everything together,
Should I return it?
The load was not even long in three and thus batter drops really fast the voltage?
 
Rchel said:
So this means that my battery it is crap!!
It’s new
Only 2 months old
I had it in the box before connecting everything together,
Should I return it?
The load was not even long in three and thus batter drops really fast the voltage?
Click to expand...
I would. Provided that can be accomplished without additional penalty.
 
You really need the charge specs for your specific battery but:

First you could try and charge the battery at 14.7 volts if your charger will let you, let that happen 2 days with no load on the battery. Bulk and absorb charge states should be around 14.7 volts then float 13.6ish once the battery is fully charged.

With no load if you set the bulk charge to say 14.7 and know full well the panel is clear in the sun, angled towards the sun even and that battery will not reach 14.7 but is hanging out in the 12s and low 13v range let it go that way to see if over time it can reach 14.7v. If it slowly creeps to 14.7 the battery is sulfated, if it hit 14.7 no problem battery is probably fine and charging voltage just had to be upped. If it never reaches 14.7 bad battery. Even the creeping situation ain't good but a day or two at 15.3v might save it (thats a standard equalize voltage and the only AGM I know that can't be equalized are Full River AGMs).

For prospective: Just had the same problem happen here. Got a new charge controller a month ago, hooked it up, said it was only putting in .5amps. Battery monitor said other controller was shoving in 17amps so shrugged and forgot about it. Yesterday morning batterys read 12.2 volts- the lowest I ever saw them since buying them last Dec. Turned out the new controller was broke and the other controller was failing. Another controller swapped in set to 15.3 volts for 240 minutes, the batteries struggled to reach 15.3 but finally did- damage was slight but with no loads held 12.9v at 4am.

If you have an AC battery charger with an AMP guage everything gets easier. This is a trick the owner of LifeLine batteries told me. Get your battery to 12.1v and make sure it stays there, want to be sure the battery needs a good charge. Hook up the charger and turn it on. Over the next 15 minutes watch the amp guage, a smart charger will ramp the amps DOWN when the charger thinks the battery is full. So you should have full amps to the battery at the start, if not badly sulfated or flat out bad batttery. If full amps draw down fast, sulfated battery. If full amps for entire 15 minutes, battery seems fine. Trick here is adjust the target time for battery size. This LifeLine test is for their AGM 12v and 6v 100+ah and has to be for 30 minutes for their batteries (warranty test purposes) but I've seen batteries fail time and again under 15 minutes. Evn one GRP24 that simple would not charge beyond 12.2v- flat out wouldn't even passed this test but it stayed at 12.2- never figured that one out..

I know, there's a lot here.. I started throwing money at solar in 2012 and in 2012 NONE of this would have made sense to me..you'll get there a piece of knowledge at a time.
 
Kcp said:
...
With no load if you set the bulk charge to say 14.7 and know full well the panel is clear in the sun, angled towards the sun even and that battery will not reach 14.7 but is hanging out in the 12s and low 13v range let it go that way to see if over time it can reach 14.7v. If it slowly creeps to 14.7 the battery is sulfated, if it hit 14.7 no problem battery is probably fine and charging voltage just had to be upped. If it never reaches 14.7 bad battery. Even the creeping situation ain't good but a day or two at 15.3v might save it (thats a standard equalize voltage and the only AGM I know that can't be equalized are Full River AGMs)...
Click to expand...

That is a good way to destroy a brand new AGM. You can equalize FLA's because the water is replaceable. With AGM's, gels and SLA's, there is no way to replace the electrolyte that gasses off during equalization...so you end up with a doorstop.
 
Kcp said:
You really need the charge specs for your specific battery but:

First you could try and charge the battery at 14.7 volts if your charger will let you, let that happen 2 days with no load on the battery. Bulk and absorb charge states should be around 14.7 volts then float 13.6ish once the battery is fully charged.

With no load if you set the bulk charge to say 14.7 and know full well the panel is clear in the sun, angled towards the sun even and that battery will not reach 14.7 but is hanging out in the 12s and low 13v range let it go that way to see if over time it can reach 14.7v. If it slowly creeps to 14.7 the battery is sulfated, if it hit 14.7 no problem battery is probably fine and charging voltage just had to be upped. If it never reaches 14.7 bad battery. Even the creeping situation ain't good but a day or two at 15.3v might save it (thats a standard equalize voltage and the only AGM I know that can't be equalized are Full River AGMs).

For prospective: Just had the same problem happen here. Got a new charge controller a month ago, hooked it up, said it was only putting in .5amps. Battery monitor said other controller was shoving in 17amps so shrugged and forgot about it. Yesterday morning batterys read 12.2 volts- the lowest I ever saw them since buying them last Dec. Turned out the new controller was broke and the other controller was failing. Another controller swapped in set to 15.3 volts for 240 minutes, the batteries struggled to reach 15.3 but finally did- damage was slight but with no loads held 12.9v at 4am.

If you have an AC battery charger with an AMP guage everything gets easier. This is a trick the owner of LifeLine batteries told me. Get your battery to 12.1v and make sure it stays there, want to be sure the battery needs a good charge. Hook up the charger and turn it on. Over the next 15 minutes watch the amp guage, a smart charger will ramp the amps DOWN when the charger thinks the battery is full. So you should have full amps to the battery at the start, if not badly sulfated or flat out bad batttery. If full amps draw down fast, sulfated battery. If full amps for entire 15 minutes, battery seems fine. Trick here is adjust the target time for battery size. This LifeLine test is for their AGM 12v and 6v 100+ah and has to be for 30 minutes for their batteries (warranty test purposes) but I've seen batteries fail time and again under 15 minutes. Evn one GRP24 that simple would not charge beyond 12.2v- flat out wouldn't even passed this test but it stayed at 12.2- never figured that one out..

I know, there's a lot here.. I started throwing money at solar in 2012 and in 2012 NONE of this would have made sense to me..you'll get there a piece of knowledge at a time.
Click to expand...
Wow great information
Thank you I’ll try that
Very helpful
 
SolarRat said:
That is a good way to destroy a brand new AGM. You can equalize FLA's because the water is replaceable. With AGM's, gels and SLA's, there is no way to replace the electrolyte that gasses off during equalization...so you end up with a doorstop.
Click to expand...
Why this would kill the battery?
 
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