Hi all...  Hope that someone here has some advice for me.

The background to my issue is that i should have enough battery power to last 4hrs, but am losing power off at around 1h55 (5 min short of the typical load shedding time).

I have 4 x vision 200ah 12v batteries, which should last almost 5 hours with 1kw draw.  (4 x 200ah x 12v = 9600kwh. 9600kwn x 50% = 4800kwh usable = 4.8h at 1kw draw).

My Inverter is an imeon 3.6, which i have been very happy with. I know that these are not well liked in general, and definitely not well supported in SA, but it has served me well for the last 6 years with these batteries.

I took voltage readings while the batteries were being used and i noticed that the 1 battery was showing a much lower voltage than the others (+-10v vs +-12v for the others). This made me suspect that there is an issue with this one battery.  After the power tripped i ran a number of tests on the battery and took voltage readings along the way, which i have attached. Some after charge, some after rest, some after testing machines.

The issue is that all of the subsequent tests suggest that the batteries are all fine. What am i missing, or is there another test that i should do?

Perhaps my bettery settings on the imeon are wrong?  I unfortunately don't have the admin password and am battling to get it. I have also set the DOD to 70%, but from the voltage readings it seems that i am not getting anywhere near 70% use.

A final resort might be upgrading batteries, in which case i will go lithium, but that is an expensive upgrade.

 

Any and all help will be greatly appreciated.

 

werner

 

I think 6 years is a very good outcome for lead acid.

Even lithium says you should expect 60% capacity after 10 years.

36 minutes ago, Buyeye said:

I think 6 years is a very good outcome for lead acid.

Even lithium says you should expect 60% capacity after 10 years.

Agreed. Load shedding is making mincemeat of lead-acid batteries because we lean on them so much more. I think this is a good outcome, but also that it is time to bite the bullet and get some new batteries.

Seems like you already know the answer. If under load a battery drops 2V then this points to a bad cell in that battery. You could try equalising the battery. I know AGM is not recommended to equalise but if the options are to throw them out or equalise, you have nothing to lose.

I have equalised my gate motor battery a few times now with a fair amount of success. I would have retired it about 2 years ago but it is still in operation. I have equalised it 3x in the last 2 years

I take the battery, make sure there is enough water and charge it for 2 hours on 15.5V.... this causes lots of hydrogen venting (so make sure the area has ventilation otherwise you could cause an explosion) but allows the sulphated battery to shed some of the deposits. The capacity of my battery is not great (and struggles during loadshedding) but it still opens the gate without issues  

@iiznh I have a similar problem, but mine is 6 x OmniPower 120ah Hybrid AGM/GEL batteries. This is only after about 2 years! Crap batteries I discovered. Planning to move over to 2 x Pylontechs 2.84KW.

I'm a bit cautious of doing an equalization on them. GEL batteries don't like that high voltages. It can explode.... so "liewers bang Jan as dooie Jan" ......  

 

All batteries (Hydrogen - Sulfur base) use a sulphuric acid electrolyte and vent Hydrogen when overcharged. AGM included. This is normal

The amount of hydrogen released is rather small and only becomes an issue in a closed room with no ventilation

The Hydrogen builds up to a point where a spark will ignite it... if you take precautions this is not an issue. Switch a fan on and open the window.

 

 

Some manufacturers even recommend up to 16.3V for 6-8 hours (you might need to repeat the process a couple of times also). Google is your friend.

 

Edited March 18, 20224 yr by iiznh
included youtube vid

thanks for all the comments and help thus far.

 

I guess that 6 years is good going for these batteries.  Looking at the Equalizing process i am missing some key pieces of equipment, not least of which is the Battery Charger that can be properly managed.  Perhaps it is time for the upgrade, just need some cash first, so i'll keep them going for a little longer.

 

Some advice please? 

As my imeon is a little old it does not have a CANbus port, which it seems is needed for a lot of the newer lithium batteries.  I can get an upgrade Module at the eye watering cost of R8k.

Should i rather bite the bullet and upgrade the Inverter as well?

Lots of people seem to have the GoodWe Units.

- Are these good?

- are they Hybrid units that are able to draw and prioritise power from solar/batteries/grid and to consumables/batteries/grid as per Imeon? - think so

- My only other worry is that the Imeon was able to output up to 6kw + when grid was up.  Every now and then i exceed 5kw and get closer to 6 (even 7) kw for short periods (oven, kettle and microwave on at the same time).  Can the Goodwe's reach this level of power output or are they capped at 5kw?

 

thanks again for the help to date.

 

werner

 

 

 

@iiznh Yep, have watch a couple of videos from this same guy. Still cautious though. There are always risks involved as you won't know how the batteries will react under that extreme conditions. Specially from batteries that is not well known all over.  Still trying to find out who and where these OmniPower batteries are manufactured.

I had the same problem with my Trojan T105-RE's. One cell on one battery seemed to have sulphated to a point that it shorted under load, bringing down the voltage of that battery, which in turn screws the bank voltage. Spent hours on special chargers, tricks and tips to desulphate the battery but with no success. It seems the only way to properly desulphate and recondition a battery is to open it up and properly clean the plates, etc, a task I was not up for. I've sold 4 of the good batteries, made a jump starting cart with 2 more and scrapped two. I did mean that I had to bite the bullet for new batteries. I got 2 Freedom won eTowers with a total of 8Kwh usable energy. I cycle them daily and set my ESS SOC% to 40%. The lowest they went one overcast morning with dishwasher and washing machine running was 29% so I must say it was a worthy investment. It shaved my electricity bill with more than a R1000 per month.

 

1 hour ago, Czauto said:

Spent hours on special chargers, tricks and tips to desulphate the battery but with no success.

All kinds of fancy chargers are just snake oil.... Just overcharge it with a higher voltage, if it heats up too much in the process your battery might be beyond repair. There might be a shorted cell. If it does not let through any current just apply more pressure with a higher voltage till it starts conducting. You should hear it bubbling inside.

 

Like I said I experimented on a 7AH gate battery and I simply charge it with a normal bench power supply. I was actually shocked that it worked so well.

 

I also tried with a dead car battery, but could not get it to the point where it would crank the engine. Maybe my bench PSU could also not supply enough amps? (I think the limit is somewhere between 7-10A) There was a marked improvement in the power it had but still failed and after two equalisation attempts I also traded in the old battery for a new one. Your mileage might vary.

 

If you are going to scrap a bank of 4 x 200AH batteries because 1 is faulty then it is worth a try. 

Surely you must have some friends with a Bench PSU? 

 

Edited March 18, 20224 yr by iiznh
mmm

4 hours ago, WernerH said:

Should i rather bite the bullet and upgrade the Inverter as well?

Lots of people seem to have the GoodWe Units.

- Are these good?

- are they Hybrid units that are able to draw and prioritise power from solar/batteries/grid and to consumables/batteries/grid as per Imeon? - think so

- My only other worry is that the Imeon was able to output up to 6kw + when grid was up.  Every now and then i exceed 5kw and get closer to 6 (even 7) kw for short periods (oven, kettle and microwave on at the same time).  Can the Goodwe's reach this level of power output or are they capped at 5kw?

No I think your inverter should do fine, plenty people run successfully from lithium without needing communication

Goodwe is a good inverter it can grab shortfalls from the grid (have not used it myself but hat was what I was told) similar to what your inverter does. Sunsync/Deye is also very popular. Most of those have features to prioritise where power shortfalls should be sourced

 

Also the Voltronic (Axpert) range doing load balancing as I call it.

So….  Bought a battery capacity tester from Banggood that runs the batteries under a configurable load and measures capacity…. Turns out they are are stuffed.   Running to 11.8v at 20 Amp load estimate:

- 1 at around 10% capcity

-1 at around 15% capcity

- 2 closer to 30% capacity

 

Now trying to desulphate using the tricks mentioned above by running 10 amp load and over voltage into the batteries to see if i can eat some extra use out of these batteries - but getting ready to upgrade to Lithium - it is inevitable.

 

Will update on how much more i can get from them.

Edited May 28, 20224 yr by WernerH

Must be doing something horribly wrong.

after trying to desulphate, the capacity has actually dropped by around 30%…

 

ahhh

 

3 hours ago, WernerH said:

after trying to desulphate, the capacity has actually dropped by around 30%

If your capacity drops that much then your battery does not have electrolyte left. Is there a cap to add water?

Also you should not add a load to the battery when charging. You fully charge the battery. Then up the voltage to 15.5 - 16V and charge it for another 5-10 hours. 

If it does not take any current (less than 1A) then you can try to up the voltage for a short time so 20V or even 25V. Monitor the amps and temp of the battery, (stop if the battery heats up too much) a dead battery will likely take 0.1 - 1Amp. Higher voltage might let some of the deposits break loose, you might see current flowing. 

I have had some success but mostly failure.

Decided in the end that lead acid is a waste of time if you compare it to lithium. You will not regret upgrading

 

Some good videos on this topic

2 hours ago, iiznh said:

If your capacity drops that much then your battery does not have electrolyte left. Is there a cap to add water?

Also you should not add a load to the battery when charging. You fully charge the battery. Then up the voltage to 15.5 - 16V and charge it for another 5-10 hours. 

If it does not take any current (less than 1A) then you can try to up the voltage for a short time so 20V or even 25V. Monitor the amps and temp of the battery, (stop if the battery heats up too much) a dead battery will likely take 0.1 - 1Amp. Higher voltage might let some of the deposits break loose, you might see current flowing. 

I have had some success but mostly failure.

Decided in the end that lead acid is a waste of time if you compare it to lithium. You will not regret upgrading

Thank you for this video, think i watched it a few months ago and watched the other 2 videos earlier this week.

unfortunately it is a sealed Lead Acid battery, so don’t have access to add more water.

 

i unfortunately don’t have the patience required to wait before steps and wanted to get the batteries back up before tomorrow load shedding (even if only at a fraction of rated capacity).  Hopefully the waiting isn’t that important.

I did the following:

- Charged using standard battery charger

- over charged using a bench PSU at 10a for around 8 hours.

- batteries started warming up at some of the cells (not boiling hot, Luke warm). Maintained around a 16.8v charge at 10a.

- let battery sit for a few hours to settle

- tested capacity using capacity tester at 20a

- repeated another time.

 

is that roughly right?

 

I do however think that i am going to need to upgrade - getting some quotes for the Freedom Won 10/8.

 

 

thanks again.

On 2022/05/28 at 9:10 PM, WernerH said:

is that roughly right?

 

I do however think that i am going to need to upgrade - getting some quotes for the Freedom Won 10/8.

Yes it does sound right, you might need to perform 3-4X the whole operation. Repeating it dislodge more deposits.

I had some good results on a "sealed" lead acid (gate motor battery). Once you pop off the plastic cover there where rubber vents where I could refill the water.

I tend to agree that lead acid is not worth the effort. Took almost all my lead acids back for recycling.

Just get lithium, you will be amazed how much power they store and how forgiving they are when combined with a BMS. FreedomWon is a good choice