diy solar

diy solar

all off grid is a gamble

Daddy Tanuki

Solar Wizard
Joined
May 11, 2021
Messages
1,807
after 10 years offgrid it seems to me that all offgrid is a gamble I run magnum inverters, morning star inverters and sharp panels, and ali babba batteries this is a 4k setup that I am now expanding to 8k as of this post). at the same time I am also converting to lithium (LiFePo4's). my agm's lasted to about 1000 cycles, still trying to figure out why they died so quick, i had a lightening strike, and the possibility that the charging algorithm is not correct (though in line with the battery sellers instructions). Though I am almost sure its due to the low quality of ali babba/alipresss battery's or my settings. One last try with CALB cells are now in the works. a friend in thailand spent 2.5 years on these calb cells and is still working not sure now much more I can stand as a hobby. i can get all all the power needed from my solar setup, and when the sun is strong I can pump power like you would not believe out of the magnum inverter... it depressing at times. (no sponsorship no buyin's of any sort). (I am dyslexic so f you if you are a spelling or grammar Nazi.)


ken
 
1000 cycles is almost three years, so depending on the quality of the batteries and how much they where used, I am not sure I would be super disappointed.

Can you share details on your current setup?
 
For the AGM batteries I used, last page of this manual shows 1000 cycles to 50% DoD is where capacity drops to 80% of original.


How deep were your cycles?
Of course, by "died" you probably mean much worse than 80% capacity.

My batteries cost me $0.25/kWh of capacity.
Looks like the 280 Ah cells people use for DIY, together with BMS, cost about $0.10/kWh capacity. And cycle life is expected to be about 10x as long as my AGM.

If you assemble the pack well (good contact between cells), keep it at moderate temperature and have reasonable charge rates, should last a long time. Like a decade of deep cycling.

"Lightning strike"
One vendor who claims EMP hardened products tested competitor's products. Some died when given a pulse of over-voltage. One continued to operate, but battery voltage from the charge controller was too high. Check how your equipment is performing post-strike.
 
I’ve been lucky (knock on wood ) I’m on my 4th system and they all still work .
I lost a tracer 40 amp cc a few years ago but that’s it .
My sail boat had gel battery’s that lasted 5/6 years
I use cheep sams club golf cart battery’s , I have some going on 6 years now with just minimal EQ ing and watering .
My cabin has 16 GC battery’s on there third year they cost less then 1500 bucks and I spend a hour maintaining them
4 times a year , mostly just watering and checking SG .
I’m hoping to get 6 ears out of them .
I may switch to lithium for my next set, but I should have 3 or more yers left on the set I have now .
It all good her so far
 
11+ years off grid, no unplanned outages, with a well engineered system. I run heavy loads daily in the summer, pumping irrigation water and winter, I run a generator for the cloudy days.

all in the planning and choice of gear
 
I was told if I treated them good I could get 500 cycles before they dropped to 80%. So I think 1,000 cycles is pretty good. :)
Now my lifepo cells should last me the rest of my life. ;)
 
... still trying to figure out why they died so quick, ...

The capacity should go down slowly as they age. If it drops suddenly, (one day you have X amp hours, the next day they won't hold a charge) there may be a short in one of the batteries that are dragging them all down. As others have pointed out 1000 cycles isn't bad for lead-acid depending on DoD, but might be worth getting the batteries tested.
 
1000 cycles is almost three years, so depending on the quality of the batteries and how much they where used, I am not sure I would be super disappointed.

Can you share details on your current setup?
TS MPPT 60 x 4, sharp 200 watt panels x 20, and JASolar 200 watt panels x 20. Magnum MS4448 pae x 2 600 a/h battery bank (ali babba batteries) batteries were 12 VDC 200 A/H x 12 wired in a series parallel setup. first two years showed equal drain from all batteries when tested with a DC clamp ammeter then about at the 2.5 year mark we had a lightening strike that took out my inverter and several of my neighbors lost fridges, and water heaters due to the same lightening strike. at that time i installed the 2nd inverter that I had planned on paralleling and sent the original out for repair. about 3 or 4 months following this during the winter I noticed that the volts were dropping hard at night and then the system started dropping out at about 4am in the morning (at this time it was mid winter and very cold) when I tested the batteries in the Am it shoed that one battery on every series pack was down by about 1 volt compared to the other three IE: 3 out of twelve batteries one each in the series set were lower by about 1 volt. pulled those batteries and reassembled packs with good batteries after cleaning buss bars and then sat down and did a full charge using a separate charger along with a slight overcharge (on purpose). it did nothing and the three batteries did the same thing the following morning AM. I dropped the bank from 600 to 400 and a week later the same thing occurred, one battery out of the four was lower. checked and cleaned buss bars again, nwo down to 200 a/h at 48 volts and these batteries seem OK, but 200 amp hours does not cut the mustard so I ordered the LiFePo4's. on average i was drawing an average of about 150 amp hours form a 600 a/h bank per night. was it the lightening strike? was it improper charge setting's due to piss poor communications from the China supplier? was it a temperature issue (too cold of charge or discharge)?

short of being made of money and being able to buy 1000's of components from china I see no way to actually ensure that you are getting a quality product. personally i cannot afford battle born or any of the other current name brand batteries nor would I. unfortunately here in japan there is nobody that offers a reasonable priced lead acid (golf cart style for instance) everything here in japan is all about screwing over whomever you are selling too.. china is the same.
 
The capacity should go down slowly as they age. If it drops suddenly, (one day you have X amp hours, the next day they won't hold a charge) there may be a short in one of the batteries that are dragging them all down. As others have pointed out 1000 cycles isn't bad for lead-acid depending on DoD, but might be worth getting the batteries tested.
understood, my camper has a small system that is going on 10 years and still working fine. matter of fact this year the batteries just started to show issues, but these batteries were not cheap chinese ones, they were 1200 USD per battery made in japan ones. the system in the house uses the same quality components and the settings were similar due to same chemistry but not exactly the same.the batteries were the major difference. charge controllers, inverters, panels wireing practices were all the same... only real difference were the batteries and the fact that the camper is not grounded like the house/shop system is. its on all rubber tires so no real ground path unless jump from body to ground. (also not at same location so no lightening.) so hard to quantify what the difference was... was it lightening.. cheap batteries? a combo of the two?
 
I was told if I treated them good I could get 500 cycles before they dropped to 80%. So I think 1,000 cycles is pretty good. :)
Now my lifepo cells should last me the rest of my life. ;)
500 hundred cycles to 80% DOD yes... but when you are only cycling to a 25% DOD then you should get many more. hence my confusion. my camper is somewhere around 3800 cycles on AGM but as its not used everyday most "cycles" were only 1 or 2% DOD with most of the time spent in float. until last year I could run them to a full 80% DOD when camping but this year no such luck.. two system used differently totally differnt results.

Like I said a total gamble.
 
500 hundred cycles to 80% DOD yes... but when you are only cycling to a 25% DOD then you should get many more. hence my confusion. my camper is somewhere around 3800 cycles on AGM but as its not used everyday most "cycles" were only 1 or 2% DOD with most of the time spent in float. until last year I could run them to a full 80% DOD when camping but this year no such luck.. two system used differently totally differnt results.

Like I said a total gamble.
OOPS, I must have missed you saying 25%. Sorry.
Yes I think it was the lightening then. :)
 
Without mentioning your Specific Brand (Make Model #) of your batteries no one will be able to answer anything.
Saying they are Alibaba/Aliexpress batteries means NOTHING ! That is like saying they are EBay or Amazon batteries. Thousands of independent vendors selling whatever on those sites.

AGM / Standard Heavy Lead can work easily for a decade BUT a slight bit of abuse shortens it quickly. Abuse can be anything from bad Temperatures to not watering to over discharge or charge and more... If the system is not well protected and takes a lightning hit, that can also cook batteries even with a momentary hit before a protection devices cuts the line.

until last year I could run them to a full 80% DOD when camping but this year no such luck.. two system used differently totally differnt results.
The "GOLDEN RULE" with Lead/AGM is to NOT go below 50% DOD for maximized life. You were using these to 80% DOD for some time. Your answer for the short lifespan is right there ! This likely weakened one or two complete batteries dragging the rest down with them, this would not be unusual or unexpected with that kind of over use.

I myself started with Rolls Surette Heavy Deep Cells, designed for purpose batteries. I over discharged them a couple of times, they got "frozen" litterally once in a discharge state, 6 years later they are sickly but still functional yet about 1/2 the capacity. I did water & maintain them but just a few incidents and whomp, the big dollar investment takes it.

AGM or Standard Lead batteries have Cells as well between the posts, if one cell within the battery goes bad, the entire battery is pulled down but in turn that weaker battery pulls down the entire bank, because with this chemistry, the Lowest Denominator rules the bank.

My Lead Bank is now a secondary backup bank. I've replaced the 24V/428AH/22kWh Lead bank with 910AH/23kWh of LiFePO4 (which charges in the same amount of time and cost me the equivalent of replacing the 8x S550 Lead Batteries for only 214AH useable) Within the next week I'll have completed my migration & implementation to a 24V/1190AH/30.4kWh.

Things are NOT such a GAMBLE !
80% DOD is intentionally beyond 50% limitation for lead based batteries.
Well known products & materials used will only result in a more reliable system. Garbage In = Garbage Out.
Blaming a Nationalty ? Seriously ?? Everyone Anyone can make Good or Bad... Black & Decker, Porter-Cable, DeWalt ALL owned by the same Investment House, the products are made in the same Factories in China but tools designed in the US... B&D = CRAP while DeWalt is better... WHO IS AT FAULT ? Designer or Sub-Contractor making it ??

We buy a LOT of stuff from offshore, NOT just China but we look at the Brand/Maker reputation, known history, user / buyer experiences etc.. Due Diligence when making a large investment. No one buy's "No Name Brand" critical components, like fuses, breakers or batteries.
 
My under standing is Lightning can do strange things to a System .
I don’t get a lot of Lightning where I am.
it’s hard to know what’s going on with the AGM batteries flood batteries can have the SG checked a couple times a year .
Having 3 strings allso hides battery issues , it would not take long for one battery to drag down a system especially in winter.
last winter I had one battery that seamed to lag behind , I was charging every 2 or 3 days and using 40% or a little more or my capacity.
I may have one bad cell that dosent seam to charge the same as the rest .
I was tempted to swap the one battery out but never did .
there is a guy in my area that has 24 GC battery’s stashed in his basement , he bought them in 08 I think and they are still supplying power he thinks they have 70% capacity left .
 
12V 200Ah wired 4s3p for 48V 600Ah
Cycling 25% DoD would be 150 Ah, 7.5 kWh

The AGM brand I use is supposed to give a bit over 2000 cycles to 25% DoD. Some brands might be half that, some FLA much longer life.

You said the loss of capacity was observed a few months after lightning strike. Previously, had you observed the battery still had full capacity by occasionally cycling it deeply? Or did you measure rest voltage after having drawn 7.5 kWh overnight, and observed that it still looked like 75% SoC? Because AGM, you couldn't measure SG like you would for FLA.

If you weren't aware while it was happening, could be capacity was continually degrading. Initially 600 Ah so your 150 Ah draw was just 25%, but later 50% and 80%, eventually drained at 4:00 AM.
Once capacity dropped to the point where cycling was deep, they would degrade more rapidly. Once a cell was imbalanced, it would remain undercharged and degrade faster.
Some AGM vendors do recommend equalization when capacity loss is observed. I have some automotive AGM which had low resting voltage and this process brought it up a bit. Not sure if they actually equalized, or if the batteries just weren't being properly charged by alternator or battery charger.

Alternatively, could lightning have affected charge controller? Have you confirmed that charge voltages are correct? If it stopped charging to the correct absorption voltage, then battery wouldn't be maintained as well.

4x TS MPPT 60
If any under-charged the battery, others should still deliver full charge. If any overcharged the battery it would be overcharged.


Settings ... communication from Chinese supplier ...
Some charge controllers are more sophisticated than others. Some work by voltage alone, while others track amp-hours as well. Certainly the settings (volts, absorption time) need to be correct for the batteries. Default VRLA settings of my inverter/charger were close, but I adjusted them slightly for what battery vendor recommends.

Batteries were $1200 (each?, 200 Ah at 12V)
What brand/model? Link to data sheet?
My SunXtender are 400 Ah at 6V, so same capacity. L16 size, 120 lbs each. They cost $600 each. I have 8 of them, 8s for 48v.


When you switch to lithium, you'll no longer have the problem that less than full charge causes degradation. So long as you set max/min charge correctly, SoC won't harm the battery.
What temperature will the batteries live at? If LiFePO4 is kept at moderate temperatures, it can accept full charge current.
How big a back are you putting in? Likely only half as big as the AGM or less, since they can be cycled more deeply.
Maybe 16, 208 Ah cells for 13,400 Wh?

You've got 40 x 200 = 8000W PV panels.
That was about 0.25C for your AGM. Hopefully within recommended charge rate, which does vary by brand/type.
That would be around 0.5C of 13,400 Wh LiFePO4 bank, which should be OK at room temperature.
If battery gets close to zero degrees C but not quite to low-temperature disconnect, acceptable charge current is probably around 0.1C, 1340W, 28 A. If you exceed that while LiFePO4 is very cold, would shorten life.
Probably easiest way to avoid that is keep battery in a warm location, and set low-temperature (charging) disconnect at a temperature where 0.5C is acceptable.
 
Without mentioning your Specific Brand (Make Model #) of your batteries no one will be able to answer anything.
Saying they are Alibaba/Aliexpress batteries means NOTHING ! That is like saying they are EBay or Amazon batteries. Thousands of independent vendors selling whatever on those sites.

AGM / Standard Heavy Lead can work easily for a decade BUT a slight bit of abuse shortens it quickly. Abuse can be anything from bad Temperatures to not watering to over discharge or charge and more... If the system is not well protected and takes a lightning hit, that can also cook batteries even with a momentary hit before a protection devices cuts the line.


The "GOLDEN RULE" with Lead/AGM is to NOT go below 50% DOD for maximized life. You were using these to 80% DOD for some time. Your answer for the short lifespan is right there ! This likely weakened one or two complete batteries dragging the rest down with them, this would not be unusual or unexpected with that kind of over use.

I myself started with Rolls Surette Heavy Deep Cells, designed for purpose batteries. I over discharged them a couple of times, they got "frozen" litterally once in a discharge state, 6 years later they are sickly but still functional yet about 1/2 the capacity. I did water & maintain them but just a few incidents and whomp, the big dollar investment takes it.

AGM or Standard Lead batteries have Cells as well between the posts, if one cell within the battery goes bad, the entire battery is pulled down but in turn that weaker battery pulls down the entire bank, because with this chemistry, the Lowest Denominator rules the bank.

My Lead Bank is now a secondary backup bank. I've replaced the 24V/428AH/22kWh Lead bank with 910AH/23kWh of LiFePO4 (which charges in the same amount of time and cost me the equivalent of replacing the 8x S550 Lead Batteries for only 214AH useable) Within the next week I'll have completed my migration & implementation to a 24V/1190AH/30.4kWh.

Things are NOT such a GAMBLE !
80% DOD is intentionally beyond 50% limitation for lead based batteries.
Well known products & materials used will only result in a more reliable system. Garbage In = Garbage Out.
Blaming a Nationalty ? Seriously ?? Everyone Anyone can make Good or Bad... Black & Decker, Porter-Cable, DeWalt ALL owned by the same Investment House, the products are made in the same Factories in China but tools designed in the US... B&D = CRAP while DeWalt is better... WHO IS AT FAULT ? Designer or Sub-Contractor making it ??

We buy a LOT of stuff from offshore, NOT just China but we look at the Brand/Maker reputation, known history, user / buyer experiences etc.. Due Diligence when making a large investment. No one buy's "No Name Brand" critical components, like fuses, breakers or batteries.
sorry Ioften confuse DOD with SOC. I rarely drew more than 150 amp hours from a 600 amp hour bank
 
I will take photos of the failed batteries along with the ones in the camp which lasted right at 10 years. in so far as the settings they gave me float and cycle use voltages and I set the solar controllers off of that.

In the camper I use the bogart trimetric to monitor the batteries with the efficiency set at 97%. On the cabin I used the magnum BMC with the efficiency setting at auto.
 
Have to agree with the others, if you can possibly afford lithium, then do it. I've tried a variety of "deep cycle" flooded and AGM batteries, and none of them delivered even the 50% capacity for lead. More like 35-40% is typical. And they really do not like to be deeply discharged, frozen, overheated, overvoltaged, go right down the list.

(Plus it's been my suspicion that mass-produced lead batteries for automotive or other uses have generally declined in quality in recent years. Just a suspicion, and the industry will deny it, but I know a lot of people who replace their car batteries every year or two.)

Where I live in California lightning is VERY rare. But I've lived in other parts of the US southwest where thunderstorms are a routine occurrence in the summer. If you have ANY kind of problem with lightning damaging electronics, absolutely put a good lightning rod on your house roof, connected directly to a new ground stake.
 
12V 200Ah wired 4s3p for 48V 600Ah
Cycling 25% DoD would be 150 Ah, 7.5 kWh

The AGM brand I use is supposed to give a bit over 2000 cycles to 25% DoD. Some brands might be half that, some FLA much longer life.

You said the loss of capacity was observed a few months after lightning strike. Previously, had you observed the battery still had full capacity by occasionally cycling it deeply? Or did you measure rest voltage after having drawn 7.5 kWh overnight, and observed that it still looked like 75% SoC? Because AGM, you couldn't measure SG like you would for FLA.

If you weren't aware while it was happening, could be capacity was continually degrading. Initially 600 Ah so your 150 Ah draw was just 25%, but later 50% and 80%, eventually drained at 4:00 AM.
Once capacity dropped to the point where cycling was deep, they would degrade more rapidly. Once a cell was imbalanced, it would remain undercharged and degrade faster.
Some AGM vendors do recommend equalization when capacity loss is observed. I have some automotive AGM which had low resting voltage and this process brought it up a bit. Not sure if they actually equalized, or if the batteries just weren't being properly charged by alternator or battery charger.

Alternatively, could lightning have affected charge controller? Have you confirmed that charge voltages are correct? If it stopped charging to the correct absorption voltage, then battery wouldn't be maintained as well.

4x TS MPPT 60
If any under-charged the battery, others should still deliver full charge. If any overcharged the battery it would be overcharged.


Settings ... communication from Chinese supplier ...
Some charge controllers are more sophisticated than others. Some work by voltage alone, while others track amp-hours as well. Certainly the settings (volts, absorption time) need to be correct for the batteries. Default VRLA settings of my inverter/charger were close, but I adjusted them slightly for what battery vendor recommends.

Batteries were $1200 (each?, 200 Ah at 12V)
What brand/model? Link to data sheet?
My SunXtender are 400 Ah at 6V, so same capacity. L16 size, 120 lbs each. They cost $600 each. I have 8 of them, 8s for 48v.


When you switch to lithium, you'll no longer have the problem that less than full charge causes degradation. So long as you set max/min charge correctly, SoC won't harm the battery.
What temperature will the batteries live at? If LiFePO4 is kept at moderate temperatures, it can accept full charge current.
How big a back are you putting in? Likely only half as big as the AGM or less, since they can be cycled more deeply.
Maybe 16, 208 Ah cells for 13,400 Wh?

You've got 40 x 200 = 8000W PV panels.
That was about 0.25C for your AGM. Hopefully within recommended charge rate, which does vary by brand/type.
That would be around 0.5C of 13,400 Wh LiFePO4 bank, which should be OK at room temperature.
If battery gets close to zero degrees C but not quite to low-temperature disconnect, acceptable charge current is probably around 0.1C, 1340W, 28 A. If you exceed that while LiFePO4 is very cold, would shorten life.
Probably easiest way to avoid that is keep battery in a warm location, and set low-temperature (charging) disconnect at a temperature where 0.5C is acceptable.
after 10 years offgrid it seems to me that all offgrid is a gamble I run magnum inverters, morning star inverters and sharp panels, and ali babba batteries this is a 4k setup that I am now expanding to 8k as of this post). at the same time I am also converting to lithium (LiFePo4's). my agm's lasted to about 1000 cycles, still trying to figure out why they died so quick, i had a lightening strike, and the possibility that the charging algorithm is not correct (though in line with the battery sellers instructions). Though I am almost sure its due to the low quality of ali babba/alipresss battery's or my settings. One last try with CALB cells are now in the works. a friend in thailand spent 2.5 years on these calb cells and is still working not sure now much more I can stand as a hobby. i can get all all the power needed from my solar setup, and when the sun is strong I can pump power like you would not believe out of the magnum inverter... it depressing at times. (no sponsorship no buyin's of any sort). (I am dyslexic so f you if you are a spelling or grammar Nazi.)


ken
sorry i often confuse DOD and SOC. basically I was drawing about 1/4 of the available capacity according to a Magnum Battery monitor with shunt. I know its not as good as a bogart, but it should do the basics. I was (according to magnum) fully charged almost every day. there were a few days with snow, or heavy cloud cover etc. that kept me in the not quite fully charged range but that was less than one day of a week. for the guy SHOUTING about brand of battery, I have no fricken clue.... they are definitely not what you run.. they were alibababa batteries claiming this that and the other so it was a gamble. asking what battery a person bought from alibabba is like asking which variety of paid women you prefer.. so please go back to the batteries you prefer and have a nice day. every battery from china has a different name depending upon which who is selling that battery. This is a given, we all take our chances and pay the price.
 
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Where I live in California lightning is VERY rare. But I've lived in other parts of the US southwest where thunderstorms are a routine occurrence in the summer. If you have ANY kind of problem with lightning damaging electronics, absolutely put a good lightning rod on your house roof, connected directly to a new ground stake.

And install surge arrestors. Some of my inverters come with replaceable MOV. Those apparently wear out after a number of hits. A couple different technologies with varying performance are available, ideally have multiple kinds.

Midnight makes devices appearing to protect between each pair of terminals [Line, Line, Ground] or [PV+, PV-, Ground]. They have LED to show protecting/failed. Presumably strikes to utility powerline somewhere is the biggest concern, and then nearby strikes can couple energy into your array wiring. Maybe lightning rods above the array can prevent it from getting a direct strike, don't know if that would exceed what the protection can absorb.
 
And install surge arrestors. Some of my inverters come with replaceable MOV. Those apparently wear out after a number of hits. A couple different technologies with varying performance are available, ideally have multiple kinds.

Midnight makes devices appearing to protect between each pair of terminals [Line, Line, Ground] or [PV+, PV-, Ground]. They have LED to show protecting/failed. Presumably strikes to utility powerline somewhere is the biggest concern, and then nearby strikes can couple energy into your array wiring. Maybe lightning rods above the array can prevent it from getting a direct strike, don't know if that would exceed what the protection can absorb.
I bought the Midnite solar SPD's had no problems hooking them up on the inlet side of the solar controllers, but could not get them to work on the output side of the inverter.... still trying to figure that out. have no inlet side power source. The inverters, batteries etc. are at the shop but do have a long run of buried power wire from the shop to the house.
 
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