Did I destroy my battery bank??

sunnyman · October 2017

Hi all. I am new to this forum. Sorry for such a long question on my very first post but I am about to replace my battery bank and unlike my first purchase, I will be spending as much as is necessary to buy the right product this time around. I guessed that I must give as much detail as possible if I want anyone to help me.

So the question is: Did I destroy my first battery bank with bad design or did I just buy cheap batteries which simply could not handle the job?

My off-grid adventure started a little less than 2 years ago. Now it has come to a temporary halt since it seems like I have gradually destroyed my battery bank. I am not sure if this is due to a set-up flaw or if I purchased inferior batteries (at 100 Euros each (brand new) they were not expensive at all).

The batteries are 8 Banner (Energy Bull) Deep Cycle Flooded Lead Acid Batteries – (Product literature is attached) They are made in Austria. K5/75Ah K20/100Ah K100/110Ah
Battery bank – 24V (4 parallel pairs in series but hard-wired) – I got this way of hard-wiring batteries from an eBook called Solar Secrets by Peter Lindemann.

Image: https://us.v-cdn.net/6024911/uploads/editor/ff/64uowcwaqzck.jpg

I used to top up all the batteries (a daunting task) with distilled water roughly every month. Interestingly, not all the cells lost their water at the same rate. I am not sure if this has to do with some of the caps leaking more than others or due to internal resistance of defective cells that was boiling the electrolyte. My next battery bank purchase will focus on ease of water topping. I have seen good examples of this in FIAMM and Hoppecke for example.

The array is made up of 6 Hyundai 255W panels (Model: HiS-S255MG) – Total 1530 Watts (Product data attached)
Setup: 3 strings of twos

Morningstar Tristar MPPT 60A – (No need to attach anything since everyone knows this one)
Connected via Ethernet to my PC. Very cool seeing real-time data and history etc. Occasionally (in early Springtime when the sun is bright but the air is still a bit chilly), it happened that the current limiter (at 60A) kicks in.
Below are a couple of screen-shots showing typical operational data.

Maybe this is irrelevant to my question but the inverter is a Kaco KI2000 2KW off-grid inverter (Made in Germany) which is transformer based.

I am in Malta (Europe) with the following sunshine data. My average power consumption is 5KW per day.

Image: https://us.v-cdn.net/6024911/uploads/editor/9u/7jvuz87wcm05.png

Any help, suggestions (and also shooting me down) from experienced members would be greatly appreciated.
Thanks.

Image: https://us.v-cdn.net/6024911/uploads/editor/m0/wio85etnn5za.png

Image: https://us.v-cdn.net/6024911/uploads/editor/fi/hicg07imr8ib.png

Photowhit · October 2017

We have not heard what the current situation is. I guess the batteries aren't holding a charge over night. It's fall and you have less charging hours/shorter day and you failing to hold a charge through the night. Do you use a backup generator?

Thank you for all the information. If 5 Kwh's is a year round load, I would want a larger array/battery bank. It looks like you have 4 month with solar isolation of less than 4 hours. You can see from your 'snap shoot' that the array is producing about it's maximum wattage at about 1200 for a 1530 watt array that's not bad. but when charging your batteries it will have to maintain voltage about 20% higher than the resting voltage of the battery so the battery can only store about 1 Kw of energy, I understand that European starting batteries are a not the Lead Calcium of US batteries, but in your battery info the information that "Thanks to the use of robust grid structures, special mass compositions and pocket separators with glass web cover, the Energy Bull offers up to three times the cycle resistance of standard starter batterie" Would make it appear that it is being compared to other starting batteries and not to other deep cycle batteries.

I think the starting batteries in Europe use Selenium alloyed to the lead to make the plates stiffer. I don't know the characteristics of lead selenium alloy's, though I think they do have somewhat better cycling.

It's very hard to have even resistance across 4 strings of batteries, This is where I would start looking. It appears that batteries 7 and 8 are a string that is right next to the junction/battery leads. It appears that the last battery on the 'red/+(?)' string is also the 2nd to last battery on a black string. I can't follow how they are organized, but it doesn't look correct on first glance.

Have you done equalizing? I see the graph shows equalizing, but I don't understand the chart well, does this indicate that you have had 219 minutes of equalizing and only 43 minutes of absorb, in the 24 hour period between 1yr/334 solar noon and 1yr/335 solar noon? If so, I would think equalizing was done when the battery bank was not fully charged. Have you take specific gravity readings of your batteries cells to determine what cells are weak?

If you were looking for a system that handle 5Kwh's a day and wanted 1 days autonomy (days without sun) and wanted to stay in the top 40% You would want a battery bank to handle about 8 kwh's (2 nights and 1 day) of discharge to 60% State of Charge or about a 20 Kwh's of storage. Top 50% about 16 Kwh's of storage. You have 8 - 100 amp hour 12 volt batteries or 8 x 100 x 12=9600 watt hours or 9.6 Kwh's.

softdown · October 2017

Are your batteries the K5s, K20s, or K100s? The fact that you presented data for all three is a clue that your understanding of batteries needs a charge.

As Photowit alluded to, it appears that your inverter/charge controller charging cables are attached to adjacent batteries in the upper left. Your battery cabling system appears, to me, to be quite substandard. I also wonder what gauge the cabling is?

Four parallel strings is two more than is generally recommended. However, I may bet that more life may be rendered from the battery bank by a complete overhaul of the cabling system.

All batteries must receive ~ the same charge from the inverter. You can use 2/0 copper for serial connections, 4/0 is suggested for parallel connections....which you have four of.

Then again, I may be wrong. Perhaps your cabling system is acceptable but it certainly does not look proper from here.

Cells will use water at different rates. My experience is that stronger, healthier cells use the most water. Also....it certainly appears to me that your batteries are not receiving equal amounts of current from the charging source. Not even close.

What is your battery bank voltage at the start of a typical day? I have not noticed yet data that shows low voltage at that time?

Have you measured specific gravity? That is very useful for telling you of weak cells.

Don't jump from my input only...I am suffering a sub-standard day here.

mike95490 · October 2017

while others are talking about multiple parallel strings of batteries I would suggest considering upgrading to a 48 volt system that would require fewer parallel string to get the same watt-hours of storage. you may have to rewire the solar array to get the needed 80-90V to fully absorb and equalize the batteries.

softdown · October 2017

mike95490 said:

while others are talking about multiple parallel strings of batteries I would suggest considering upgrading to a 48 volt system that would require fewer parallel string to get the same watt-hours of storage. you may have to rewire the solar array to get the needed 80-90V to fully absorb and equalize the batteries.

I would tend to disagree with this suggestion. A 1500 watt solar array is an ideal size for a 24 volt system.

Why re-invent the wheel when a spoke adjustment may be all that is needed?

Almost always best to keep it simpler when fixing a problem....I love simple. Considering that modern technology is prone to breakage when looked at from an inappropriate angle. I may be surprised is we ever get back to the moon, let alone "Men on Mars". #GrumpyOldFk'r

mike95490 · October 2017

4 parallel strings is wrong. If larger capacity batteries can't be sourced, shuffling the cells around to 2 strings @48v is still the same watts in & out, but it eliminates 2 pesky parallel strings, and reduces total wire amps (less copper loss)

> A 1500 watt solar array is an ideal size for a 24 volt system
why ?? If batteries are dying from chronic undercharge, that specific 24v system is either overloaded, or under panelled.

if batteries are dying from poor current sharing, then that needs to be addressed

sunnyman · October 2017

Thank you so much for your replies. I appreciate it. I will try to answer all the questions and make things clearer.

Yes, photowith, you guessed right. The batteries do not hold a charge overnight. I dismantled them and where I normally revive dead batteries with a battery rejuvenation technique, this time I did not succeed not even with a single one of them. Two of them even have damaged cells because they are reading 7 and 9v! During charging, these two get much hotter than their colleagues. So what I am left with is boat anchors here!

On a day with optimum conditions, I even get a maximum wattage far greater than 1530W actually! Here is one example :-

Image: https://us.v-cdn.net/6024911/uploads/editor/9y/qtujbv9jf5t8.png

I don't blame you for not following the wiring. I had a hard time with it too. I am attaching the page from the book I consulted on this. Then I figured out the best layout to achieve this circuit but to have the least possible connecting cable length to reduce both losses and cost. Yes you are right about batteries 7 and 8. They are the ones leading to the charge controller and the inverter.

Equalizing is done automatically by the Tristart MPPT every month or so. Also as you can see from the page of the book I have shared, they claim that with this way of wiring you get automatic equalization. Yes those figures are the duration in minutes of the phases. No I never took specific gravity readings. I always assumed that since I never saw spillage and I regularly topped up with distilled water, the electrolyte never was an issue in my mind.

softdown
I gave that battery data to show the real capacity. Many brands just say 100AH but they do not specify at which discharge rate. If you discharge by C20 you get a different capacity than if you discharge at a C5 rate. I got those figure from page 26 of the brochure uploaded. My model is the 957 51.

The copper cabling is 12mm in diameter. It was the thickest I could find locally. I frequently touched them to see if they are hot but never felt them so even when 50+ amps were being pumped from the MPPT. The store that sold me the cables kindly let me borrow a heavy-duty tool to crimp the connectors. Then I covered them with heat shrink. I guess I could have done a better job. At the beginning of a typical day the battery voltage would be anywhere between 11 to 12 volts depending on the season.

mike95490
I actually thought about going 48v when I buy the new battery bank. Although I am aware of that table where it says that a 1.5Kw array should be 24V, I never understood why it is so. If this conventional wisdom has a sound reason, I might consider adding another 2 panels just to be able to go 48V. The charging current will go down and so be more efficient. Both the Tristar controller and the Kaco inverter can handle 48V.

The batteries I am viewing right now would cost me 4 to 5K Euros for the same punch that I have now, which as I already said cost me only 800 Euros. I guess there must be some difference between these in terms of quality.

mcgivor · October 2017

The maximum battery voltage is, in my opinion, too low for cyclical use with a PV charging system, understandably the battery manufacturers recommendations are to use a 14.4 V maximum charger, but that would be for a grid charging system, as outlined in the literature, eventually the battery would become fully charged, but not in the limitations of solar charging. The constant deficit of discharge over recharge will lead to sulfation, imbalance of cells over time, the reason some cells use more water than others, it's is a slow process which usually rears it's head when it too late. Taking SG readings is of paramount importance, it will indicate when something is not right and something needs to be corrected, kind of like blood pressure monitoring.
Why do I know this? Because I made the same mistake, using 28.8V bulk /absorption to charge a 24V system, thinking it was sufficient, it's not, fortunately I realized the errors before loosing the bank, but that's a long story
Using low capacity batteries in parallel is a recipe for disaster, I would totally agree with @mike95490 , 4 parrallel strings is hard to manage, perhaps they can be recovered, perhaps not, but don't feel bad because most/all have learned these bitter lessons. When a replacement bank is selected, Hoppecke as an example stated, use 2V cells with a large capacity to form a single string, get a hydrometer, if you don't already have one and look after them.

softdown · October 2017

Which batteries are bad? 1 and 2 perhaps?

At one point you indicate that batteries drop to ~ 11 or 12 volts overnight. That is both a big difference and not indicative of lost batteries. Then you tell of batteries showing 7 and 9 volts. Readings that low are highly indicative of bad cells.....which equals bad batteries. Which do more harm than good.

I'd use 2 volt batteries this time. Perhaps 6 volt if switching to 48 volt.

Accepted "dogma" regarding voltage:
Under 1000 watts = 12 volt system
Under 2000 watts = 24 volt system

Those are not my numbers....those are common numbers in the industry in my experience. I tend to favor higher voltage at lower watts than "dogma". Though not a fan of redesigning the wheel when a spoke adjustment may fix the problem.

12 volt batteries were the wrong choice for this configuration. I think most of may have chose the wrong batteries the first time. I know that I did.

This board is mostly comprised of solar pros. Bringing a different perspective than a typical solar homeowner I think.

Estragon · October 2017

IMHO, the best design for a new bank (which it sounds like you need), has a single string of batteries in whatever size is needed. The size is arrived at by considering your loads, and the extent to which you're willing and/or able to charge with generator.

A single string has the advantage of completely avoiding any parallel wiring problems, and makes checking SGs and water levels as easy as possible (fewest number of cells). You really have to check SGs regularly. This is the best way to assess overall health of the bank, and lets you catch problems in charging regime or individual cells early enough that corrective action can be effective. With a large number of cells, the task is much more of a chore, so tends to get done less often or not at all.

Photowhit · October 2017

Please just burn that book!

Wiring can promote equal resistance across a battery bank, part of the equal resistance would include where the energy is coming into and out of the battery bank. This is not noted in the wiring diagram hence this shows a lack of understanding. So burn the book. Do not pass it along to another person! You would be just passing along bad or improperly presented information. I say that because he does say " The truth is, the currents always seek out the lowest resistance path..." but fails to explain that the wire is what adds resistance, so if you connect to one battery and the current has to pass through wires to get to other batteries there is more resistance.

Here is a link that explains how to set up multiple strings for equal resistance;
http://www.smartgauge.co.uk/batt_con.html

Multiple string will always be more trouble than a single string, once they get out of balance, there becomes easier and harder paths for the current to flow. Batteries are 2 volt cells, a 12 volt battery is just a string of 6 2v cells. As @softdown and @mcgivor have suggested a single string of 2 volt cells eliminates the worries of parallel strings of batteries. You can also find large traction batteries typically used for forklifts that are made up of a string of large 2v cells, but they are very heavy.

Specific gravity is the only way to determine the true health of a battery. Get a hydrometer and learn to use one. Wattage above the panel rating isn't uncommon in 'edge cloud' events and momentary instances. Typically panels will produce about 75% of their panel rating once they are hot...

softdown · October 2017

Photowhit said:

Please just burn that book!

Wiring can promote equal resistance across a battery bank, part of the equal resistance would include where the energy is coming into and out of the battery bank. This is not noted in the wiring diagram hence this shows a lack of understanding. So burn the book. Do not pass it along to another person! You would be just passing along bad or improperly presented information. I say that because he does say " The truth is, the currents always seek out the lowest resistance path..." but fails to explain that the wire is what adds resistance, so if you connect to one battery and the current has to pass through wires to get to other batteries there is more resistance.

Here is a link that explains how to set up multiple strings for equal resistance;
http://www.smartgauge.co.uk/batt_con.html

Multiple string will always be more trouble than a single string, once they get out of balance, there becomes easier and harder paths for the current to flow. Batteries are 2 volt cells, a 12 volt battery is just a string of 6 2v cells. As @softdown and @mcgivor have suggested a single string of 2 volt cells eliminates the worries of parallel strings of batteries. You can also find large traction batteries typically used for forklifts that are made up of a string of large 2v cells, but they are very heavy.

Specific gravity is the only way to determine the true health of a battery. Get a hydrometer and learn to use one. Wattage above the panel rating isn't uncommon in 'edge cloud' events and momentary instances. Typically panels will produce about 75% of their panel rating once they are hot...

That http://www.smartgauge.co.uk/batt_con.html link is so sneaky. Those are all 12 volt battery configurations. I went to use it on my newest 48 volt bank before that discovery. It was pretty embarrassing at the time. That link either fooled everybody or people sure kept silent.

24 volt forklift battery would be a good choice if you have the ability to replace a bad cell. Most do not. Hence......2 volt cells would be a great choice.

WaterWheel · October 2017

Another battery option to minimize strings would be to use four 6v L-16 sized batteries. If they are rated at 400 amp/hrs (20 hr rate) you'd have the same sized battery bank on one string. Or by adding a 2nd string you'd double your battery bank size with 2 strings instead of your current 4 strings. Two strings are much easier to balance than 4 strings and by using large 6v batteries you'd have a lot fewer cells to water.

But all of this is a mute point without a SG (specific gravity) meter. Get one and test all the cells. That will go a long way towards understanding where each battery is and help you spot problems early.

sunnyman · October 2017

softdown
Sorry for not explaining myself well. The 11 to 12 volts in the morning was when the system was in its glory and I was feeling as free as a bird not needing the grid any more. I actually used to see 22 to 24 on the Tristar monitor. If the voltage drops below 22 the inverter switches off to protect them.
Batteries 3 and 6 are the really damaged ones. Battery 3 is now actually showing 4V and the other 9V. If you are interested, I can upload the discharge graphs of all the batteries that I plotted one-by-one with my Westmountainradio CBA IV.

Estragon
Yes it is looking like that is my best option. My dilemma is between 24V or 48V If I go for 48V I will have to beef up the array and maybe change its configuration too to get the ideal voltage and charging current per cell.

Photowith
LOL! I will delete the book. To burn it I will have to burn my PC and that will not do.

Thank you all so much for your input. So since right now I have 400AH @ 24V and keeping in mind that I should make it slightly more,(I will have to add a couple of panels {if they still make them}) it looks like my choice is between
- Qty 8 of 6V batteries in series (400AH or so each) or
- Qty 24 of 2V cells in series (400AH or so each)

I hear that Rolls are the best but I am liking the Hoppecke because you can see inside and they have this AquaGen thingy which looks promising. I have some pain association with opening 48 caps topping up the cells every month and peering down with my flash-light to see the level. They also supply their own connecting cables which look like copper bars.
http://www.off-grid-europe.com/batteries/flooded-lead-acid/hoppecke/hoppecke-5-opzs-solar-power-520-2v
https://www.hoppecke.com/fileadmin/Redakteur/Hoppecke-Main/Products/Downloads/AquaGen_en.pdf

The FIAMM do not look too bad either and they too allow you to see the level from outside.
http://www.off-grid-europe.com/batteries/flooded-lead-acid/fiamm/fiamm-lm-350-2v-flooded-battery

Photowhit · October 2017

softdown said:

That http://www.smartgauge.co.uk/batt_con.html link is so sneaky. Those are all 12 volt battery configurations. I went to use it on my newest 48 volt bank before that discovery. It was pretty embarrassing at the time. That link either fooled everybody or people sure kept silent.

No, the information is good for any voltage. A 12 volt 'battery' is really a string of 6 lead acid batteries. So if you want a 48 volt battery, just replace the battery show with identical 'strings' of whatever size you want. 6 - 8volt batteries for a 48 volt string. Then drop in your 'string' into the diagram. It's the idea of equal resistance across the strings of cells, so use equali size wiring between the cells making up the string.

softdown said;

24 volt forklift battery would be a good choice if you have the ability to replace a bad cell. Most do not. Hence......2 volt cells would be a great choice.

Cells are replaceable in forklift batteries, it's just not simple. They will be under warranty for as long a period as I would be comfortable replacing a battery in a system. In general you don't mix old and new batteries.

Estragon · October 2017

If you go to 48v, you'll likely be shopping for a new inverter as well. If you don't need 48v to run big loads like pumps, you may want to stick to 24v.

softdown · October 2017

As for the original question.....it is hard, for me, to place most of the blame on the batteries. Inferior batteries are very prone to developing bad cells it seems. But that cabling arrangement really placed them at a distinct disadvantage. That cabling arrangement belongs in "How Not to" instead of a "How to" book.

If you do add panels, you want them to match your existing panels if possible. Larger panels will lose their extra capacity when added to existing panels.

I seem to remember feeling rather fearless when considering major additions. That was a few years ago. Now I am old and trying to delay the Grim Reaper by hiking 10-15 hours/week. Todays six hour hike dang near kilt me with the long, torturous climb at the end. But that is....another story.

Raj174 · October 2017

sunnyman said:

softdown
Sorry for not explaining myself well. The 11 to 12 volts in the morning was when the system was in its glory and I was feeling as free as a bird not needing the grid any more. I actually used to see 22 to 24 on the Tristar monitor. If the voltage drops below 22 the inverter switches off to protect them.
Batteries 3 and 6 are the really damaged ones. Battery 3 is now actually showing 4V and the other 9V. If you are interested, I can upload the discharge graphs of all the batteries that I plotted one-by-one with my Westmountainradio CBA IV.

Estragon
Yes it is looking like that is my best option. My dilemma is between 24V or 48V If I go for 48V I will have to beef up the array and maybe change its configuration too to get the ideal voltage and charging current per cell.

Photowith
LOL! I will delete the book. To burn it I will have to burn my PC and that will not do.

Thank you all so much for your input. So since right now I have 400AH @ 24V and keeping in mind that I should make it slightly more,(I will have to add a couple of panels {if they still make them}) it looks like my choice is between
- Qty 8 of 6V batteries in series (400AH or so each) or
- Qty 24 of 2V cells in series (400AH or so each)

I hear that Rolls are the best but I am liking the Hoppecke because you can see inside and they have this AquaGen thingy which looks promising. I have some pain association with opening 48 caps topping up the cells every month and peering down with my flash-light to see the level. They also supply their own connecting cables which look like copper bars.
http://www.off-grid-europe.com/batteries/flooded-lead-acid/hoppecke/hoppecke-5-opzs-solar-power-520-2v
https://www.hoppecke.com/fileadmin/Redakteur/Hoppecke-Main/Products/Downloads/AquaGen_en.pdf

The FIAMM do not look too bad either and they too allow you to see the level from outside.
http://www.off-grid-europe.com/batteries/flooded-lead-acid/fiamm/fiamm-lm-350-2v-flooded-battery

I have a LiFePO4 battery bank , and do not have as much experience with lead acid banks as the other members who have responded to your post. However, the FIAMM battery, to which you have provided a link, appears to be made for UPS service and may not be a good choice for your application. Other forum members may verify this.

Rick

sunnyman · October 2017

Estragon
My inverter handles 48V too. I am thinking about going for 48V to lower the currents.
If I understand this well, if I am to add another 2 panels (since my new battery bank will be a little bigger) I would have to raise the voltage so as not to exceed my 60Amp limit on my MPPT controller. Right now the maximum voltage from my array is about 60V. My voltage limit on the CC is 150V. So if I add another 2 panels I will have to re-wire them in strings of 3 to get a maximum of 90V
As it is, my setup already comes near to this current limit. In fact the CC sometimes kicks in the current limiter.

Rick
Thanks for your observation. I am actually more inclined towards the Koppecke. I don't know much about Lithium Iron except that they are smaller, lighter and much more expensive. I feel more comfortable with the old flooded cell. :-)

Photowhit · October 2017

sunnyman said:
My inverter handles 48V too. I am thinking about going for 48V to lower the currents.

This is very rare, I seriously doubt that your inverter handles 24 as well as 48 volts. They may make inverters that handle either, but both is very unusual. Could you post a link or provide a make and model?

Estragon · October 2017

I suppose it may possible to build an inverter that could be field rewired to a different input voltage, but like Photowhit, I suspect it can't.

The inverter appears to be out of production, so couldn't immediately find a manual. I did find a datasheet for the series though, and there were different part numbers for 24 an 48v models. That doesn't completely rule out the possibility of field rewiring, but does suggest otherwise. Unless your manual has explicit instructions for changing input voltage, I would assume it's only capable of 24v.

If so, adding a second charge controller would likely be much cheaper than replacing the inverter. It would also have the benefits of running them at reduced currents (less heat - longer life), and some redundancy for when one does fail.

If it can be rewired, there are advantages to 48v though.

sunnyman · October 2017

I am uploading the data sheet I was given when I was quoted the unit back in 2011. You can see the hand-written price of the sales guy.
My model is the KI200. As you can see it states 24 or 48V.
There is no operation manual. You may find this strange but it does not exist for this model. I wrote to KACO in Germany about this and they sent me a 1 page joke describing the LCD display! LOL!
The data sheet is quite clear to me but in light of what you are telling me I better ask them before I make any decisions.

littleharbor2 · October 2017

Could it be that you could order that model in a 24 OR 48 volt configuration? Is there any labeling at the DC connection points stating It is set up for a particular voltage?

Photowhit · October 2017

sunnyman said:

I am uploading the data sheet I was given when I was quoted the unit back in 2011. You can see the hand-written price of the sales guy.
My model is the KI200. As you can see it states 24 or 48V.
There is no operation manual. You may find this strange but it does not exist for this model. I wrote to KACO in Germany about this and they sent me a 1 page joke describing the LCD display! LOL!
The data sheet is quite clear to me but in light of what you are telling me I better ask them before I make any decisions.

Here is a link to a info sheet that says in English, "Available versions inputvoltage";

http://www.arestipower.gr/xmsAssets/File/Inverters/Kaco/KI_series.pdf

Photowhit · October 2017

While your link doesn't have a double asterist by the voltage this German(?) version does stating at the bottom "** modelli Differenti"
http://www.discandenergies.it/DATA-INV/Kaco/KACO_Scheda tecnica inverter per impianti a isola KI 250 KI1000 KI2000.pdf

sunnyman · October 2017

Photowhit you could be right. That pdf is in Italian.
If you see the datasheet I was given there is also the ** and it is referred to the note "different inverter types". However only the output voltage is marked with a **. This of course is because they have a model for Europe (240V) and another for the US (120V). It could also be that the missing ** beside the 24v/48v on my datasheet is a mistake. I will have a word with them just in case.

WaterWheel · October 2017

I'm no expert but I suspect hooking 48v to that inverter may produce "the magic white smoke".

sunnyman · November 2017

Came to mind to look up the graphs below.
When I bought the batteries, before I assembled them into the system, I fully charged them one-by-one and discharged them at a C20 rate while plotting their discharge. With hindsight I should have seen that they were not as brand new as the shop posed them to be. They should all have given near 100Ah since they were supposed to be brand new no? They all gave a different result. Also in most of them, the discharge was not a smooth curve.
I guess I was too eager to put everything together and start the adventure.
In the next post I will post the same thing but after I dismantled the bank after a little less than 2 years.

Battery 1 - 89Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/tm/phuwrtcmn6ua.jpg

Battery 2 - 82Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/xi/m9z9iuo2b7cf.jpg

Battery 3 - 83Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/8s/vaeeuxfyf2pb.jpg

Battery 4 - 89Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/m0/49801hsf3o32.jpg

Battery 5 - 81Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/fd/7fvtq7exqbkt.jpg

Battery 6 - 76Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/gj/8v8yicv3usci.jpg

Battery 7 - 85Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/n7/1trgewxtpism.jpg

Battery 8 - 83Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/16/qfoogfjx0iax.jpg

sunnyman · November 2017

You can see the state in which each battery ended in the following graphs.
The discharge started from a "fully charged" battery.

Battery 1 - 26Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/wk/cs0onl49xnh8.jpg

Battery 2 - 26Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/re/vugpglx2cukp.jpg

Battery 3 - Totally dead

Image: https://us.v-cdn.net/6024911/uploads/editor/qj/ea7eq9yx8144.jpg

Battery 4 - 25Ah

Image: https://us.v-cdn.net/6024911/uploads/editor/mf/m5umklblgl4a.jpg

Battery 5 - 17Ah

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Battery 6 - 1Ah

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Battery 7 - Totally dead

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Battery 8 - 2Ah

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softdown · November 2017

I'm not sure that two years is a real bad deal for the price that you paid. Now you are thinking about spending ~ six times more?

I would bet the batteries would have done significantly better with a more equitable cabling system.

Battery prices vary considerably by region but 100 Euro/battery seems pretty darned cheap. Isn't that about $150 USD?

sunnyman · November 2017

That is actually $118 USD.
But as you can see from the graphs, I did not get brand new batteries. They must have been sitting on the shelf longer than necessary. And the local agent's service is terrible. I told him that a new battery should read 13.2V and he told me I was talking rubbish!
When it came to the CC and charge controller I went for the good brands and cost was not an issue.
When it came to the batteries my instinct told me right from the beginning that this will all be a learning process for me and I don't regret the decision.
I will send them for re-cycling now. I will keep one of them for experiments. For a long time now I have been meaning to perform the experiments in Ed Leedskalnin's book.

Thank you all for your comments. I really appreciated it.
As payback to the forum I will try to answer some newbies' questions to the best of my limited knowledge and my pain-associated experience.

Did I destroy my battery bank??

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