Have I destroyed my batteries?

[andy_acacia]

Good morning.
For the last week I've been holed up in bed with plague-like symptoms. I've finally emerged and have gone to my off grid office. It is powered by 1220w solar array and 2 x 12v 200ah AGM batteries providing a 24v system.
I left the power "on" for the last week. Nothing drawing power except for a 10w 4g routerbut this morning I discover the batteries are under voltage and I'm wondering if I've done irreparable damage?
This is my first concern and I hope someone can help. See attached pics.
My second concern is how can the batteries be so "dead" after such little use. I know the weather is poor in the UK but this is ridiculous! Charge controller shows power going in to the batteries. Batteries are less than 2 years old.

 

[Mattb4]

Hitting a low voltage on AGM batteries is likely not harmful if they do not set at that voltage for a long time. As to why your PV system did not keep them charged? If you have more load than solar input over time the batteries become discharged. A lot of PV user find this out in the Winter periods since the days are short even if the sun is out.

One thing in regards to AGM. It is not unusual to find them going bad ( severely reduced capacity) in 2 years.

 

[andy_acacia]

Hitting a low voltage on AGM batteries is likely not harmful if they do not set at that voltage for a long time. As to why your PV system did not keep them charged? If you have more load than solar input over time the batteries become discharged. A lot of PV user find this out in the Winter periods since the days are short even if the sun is out.

One thing in regards to AGM. It is not unusual to find them going bad ( severely reduced capacity) in 2 years.

Thanks Matt.
I'll leave the batteries charging with no load. If they get back up to normal voltage do I assume the batteries are OK?
Severly reduced battery capacity after 2 years is ridiculous! Each battery cost me £400.

 

[Steve_S]

Sadly the quality of FLA & AGM has decreased drastically in the past 5 years, and for the damned dumbest reasons of all, the plates are getting as thin as they can get to make a product... Just compare the weight between the identical make/model from 5 years ago to today... Even the big Solar Co Batteries are suffering this (Trojan, Rolls Surette etc) although they are better than the "imports".

AGM like FLA is pretty tough and can take quite a bit of abuse....
Because you've drained them down really low, an Equalization Charge should be done and it is highly unlikely that your small solar can do that properly. You would require a proper Inverter/Charger that can charge the batteries from an AC source (genset or grid). The most common reason that FLA/AGM fail is due to lack of proper charging & managing. AGM is much easier as you don't mess with the acid within as they are sealed but they still need Equalization. Now there is a GOTCHA - Not all AGM are created equal and some will not tolerate a heavy Equalize (usually the cheap discount one from a big box) but a quality brand should be fine. One alternative to recovery can be to use a Car Battery Charger that can handle AGM (most do but not all) and do a full recharge with equalize of each battery... PITA but....

PLEASE PROVIDE THE FOLLOWING for better responses...
Make & Model / Version of Solar Controller, Inverter System, Battery.
Web Links to said products if available.
A Photo of the setup can also be helpful.

 

[Mattb4]

Thanks Matt.
I'll leave the batteries charging with no load. If they get back up to normal voltage do I assume the batteries are OK?
Severly reduced battery capacity after 2 years is ridiculous! Each battery cost me £400.

Several things can result in the reduced capacity. Battery initial quality, depth of discharge, amount of cycles, storage conditions and perhaps the biggest one quality of charger. Your Epever SCC may not be properly charging the AGM. SCC that have USB connectors built in are suspect in my opinion.

You see a lot of fake MPPT SCC that include USB plugs.

 

[Steve_S]

Does EPEver have an Equalize Capability ?
If mem serves, they also have 2 or 3 different AGM profiles as well... subtly different but enough to be quirky.

 

[mikefitz]

Batteries are less than 2 years old.

It's not unusual with the AGM batteries readily available in the UK to experience short service life. Steve_S suggestion on decreased quality is correct.
However its not confirmed your batteries are damaged or have reached the end of useful life. It's possible that the batteries have become inbalanced with the mid point over time, resulting in one battery being under charged. Any series battery bank really needs mid point balance circuits.
The default settings on Epever controllers do not have a long enough absorbtion duration and its probable the batteries are regularly under charged, this being a common issue with AGM that leads to a gradual walk-down in capacity. ( There are also other issues with Epever solar chargers that result in less than ideal yield and charging).
I suggest charging each separately with an AC powered charger to 14.8 with a long 4 hour absorbtion, followed by a 24 hour 13.8 volt float. Carrying out a capacity test would be useful. ( A 'one off' full discharge, immediately followed by a full charge should not impact on service life.)

 

[Blakes]

you are probably fine.

I have an old array of 12v Optima Blue Tops that gets discharged down to 12.0v every single day for the past ~7 years.

 

[andy_acacia]

Sadly the quality of FLA & AGM has decreased drastically in the past 5 years, and for the damned dumbest reasons of all, the plates are getting as thin as they can get to make a product... Just compare the weight between the identical make/model from 5 years ago to today... Even the big Solar Co Batteries are suffering this (Trojan, Rolls Surette etc) although they are better than the "imports".

AGM like FLA is pretty tough and can take quite a bit of abuse....
Because you've drained them down really low, an Equalization Charge should be done and it is highly unlikely that your small solar can do that properly. You would require a proper Inverter/Charger that can charge the batteries from an AC source (genset or grid). The most common reason that FLA/AGM fail is due to lack of proper charging & managing. AGM is much easier as you don't mess with the acid within as they are sealed but they still need Equalization. Now there is a GOTCHA - Not all AGM are created equal and some will not tolerate a heavy Equalize (usually the cheap discount one from a big box) but a quality brand should be fine. One alternative to recovery can be to use a Car Battery Charger that can handle AGM (most do but not all) and do a full recharge with equalize of each battery... PITA but....

PLEASE PROVIDE THE FOLLOWING for better responses...
Make & Model / Version of Solar Controller, Inverter System, Battery.
Web Links to said products if available.
A Photo of the setup can also be helpful.

Thank you Steve.

Unbranded AGM batteries supplied by SunshineSolar.co.uk
The MPPT is Epever 4210 40amp.
Pics attached in original post.
The Inverter is a 24v 1000w again supplied by SunshineSolar.co.uk
It all came as a complete 24v off grid kit.
The only addition is a Victron 500amp SmartShunt.

Have had all power draw, except MPPT and SmartShunt, disconnected for 24hrs.
In spite of the power added from Solar panels yesterday (see original pic) and today the battery is now more depleted than yesterday??

I think the MPPT is knackered and has possibly done irreparable damage to the batteries too?

 

[andy_acacia]

It's not unusual with the AGM batteries readily available in the UK to experience short service life. Steve_S suggestion on decreased quality is correct.
However its not confirmed your batteries are damaged or have reached the end of useful life. It's possible that the batteries have become inbalanced with the mid point over time, resulting in one battery being under charged. Any series battery bank really needs mid point balance circuits.
The default settings on Epever controllers do not have a long enough absorbtion duration and its probable the batteries are regularly under charged, this being a common issue with AGM that leads to a gradual walk-down in capacity. ( There are also other issues with Epever solar chargers that result in less than ideal yield and charging).
I suggest charging each separately with an AC powered charger to 14.8 with a long 4 hour absorbtion, followed by a 24 hour 13.8 volt float. Carrying out a capacity test would be useful. ( A 'one off' full discharge, immediately followed by a full charge should not impact on service life.)

Thank you Mike for some useful steps to take. Much appreciated!

I have a 12v car trickle charger but I assume this won't be powerful enough (max 70ah) and suspect is not what you're implying here.
Would you mind advising a specific AC charger with the functionality mentioned? I can then do some legwork and find local/avaliable/affordable equivalent.

UPDATE:
I have done a bit of Googling and reckon I've worked out what you're recommending. Victron does an AC smart charger which has an "equalise" function and also auto adjusts voltage as it moves through the charging stages.
I'll let you know how I get on. Thank you for the advice ?

 

[andy_acacia]

you are probably fine.

I have an old array of 12v Optima Blue Tops that gets discharged down to 12.0v every single day for the past ~7 years.

I hope so! Now need to work out how to recharge the batteries without the MPPT and see if they are definitely OK.

Mike has suggested an AC charger so I'll give this a go as soon as I've sourced something appropriate.

 

[Steve_S]

Thank you Steve.

Unbranded AGM batteries supplied by SunshineSolar.co.uk
The MPPT is Epever 4210 40amp.
Pics attached in original post.
The Inverter is a 24v 1000w again supplied by SunshineSolar.co.uk
It all came as a complete 24v off grid kit.
The only addition is a Victron 500amp SmartShunt.

Have had all power draw, except MPPT and SmartShunt, disconnected for 24hrs.
In spite of the power added from Solar panels yesterday (see original pic) and today the battery is now more depleted than yesterday??

I think the MPPT is knackered and has possibly done irreparable damage to the batteries too?

Before "Declaring" the batteries toast, I would certainly try reviving with an Equalize Run and testing first.
Sadly, it is possible the EPEver pooched itself, they do that sometimes... Value Gear...

Just reviewed SunshineSolar.co.uk and looked at their AGM's Choice is Victron or No Name Brand... I'm sorry but NN Brand != confidence of any kind.

 

[andy_acacia]

Before "Declaring" the batteries toast, I would certainly try reviving with an Equalize Run and testing first.
Sadly, it is possible the EPEver pooched itself, they do that sometimes... Value Gear...

Just reviewed SunshineSolar.co.uk and looked at their AGM's Choice is Victron or No Name Brand... I'm sorry but NN Brand != confidence of any kind.

OK... I've bought a Victron AC charger. It has an equalise function and suggests it can revive a "dead" battery.
I'll start with the equalise and go from there.
Thank you for spending the time to pass on your knowledge. Much appreciated ?

 

[Steve_S]

OK... I've bought a Victron AC charger. It has an equalise function and suggests it can revive a "dead" battery.
I'll start with the equalise and go from there.
Thank you for spending the time to pass on your knowledge. Much appreciated ?

Always happy to hep when we can... That's why we are here (some of us anyways) LOL, everyone else is a "student" and even the teachers continue to learn as well... never ending school ! LOL

 

[mikefitz]

It has an equalise function

Charge up fully first using normal charge and float voltages. My view is that a high volt equalise charge on an AGM has a risk and perhaps only be considered as a last resort. The battery manufacturer may be able to advise on subjecting a AGM to an equilisation charge. Most chargers with an AGM default charge profile do not have the equilisation option active.

It's still possible forthe batteries became out of balance with each other over time. Mid point balancers prevent this occurring,

9. Midpoint voltage monitoring

www.victronenergy.com

Battery Balancer - Victron Energy

Equalize the state of charge of two series connected 12V batteries using the Battery Balancer. Find a Victron Energy dealer near you.

www.victronenergy.com

 

[andy_acacia]

I wanted to thank all those who took the time to answer my questions.
Mike, Steve, Blakes and Matt, batteries recharged up using Victron ac charger. Batteries appear to be OK with no side effects following a full cycle recharge.
Now to work out why the batteries drained so dramatically. This leads to another question but I'll raise that separately.
Thanks again ?