Do not use clamps on outdoor battery connections.

softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
Don't use clamps on indoor battery connections either of course. Clamps may be useful for telling if a solar installation is working properly. It may be tempting to delay replacing the clamps for another day. We all know how that may go...

With two separate solar arrays feeding power to an extra large freezer, I got even more complacent. Figuring I would notice if one solar array quit charging its battery bank.

Just completed a whirlwind tour involving four ~3000 mile round trips to the California Bay area. You already know what happened right? Both solar arrays quit charging its battery bank due to corrosion at the clamps. Good thing that over 2400 pounds of batteries did not go below 22.2 volts. Caught it in the nick of time.

Note: This board did a lot for my original 48 volt solar installation which continues to perform flawlessly.....knock on wood. So I intend to give the board updates in my ongoing solar journey. The plan is to relocate from our neo kakistocracy (bad government) and escape to freedom on a large, old sailboat. Next stop? Finding a marina on the Sea of Cortez for my 26' S2 sailboat. It is a good boat but too small for liveaboard world cruiser.

Hope the old gang is living the dream.
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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Comments

  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    softdown said:
    Don't use clamps on indoor battery connections either of course.
    Never mind that.  Don't use outdoor battery connections OR clamps, ever.  All battery connections should be inside a structure that keeps dirt, dust, water and humidity away from the battery terminals.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    edited June 2017 #3
    softdown said:
    Don't use clamps on indoor battery connections either of course.
    Never mind that.  Don't use outdoor battery connections OR clamps, ever.  All battery connections should be inside a structure that keeps dirt, dust, water and humidity away from the battery terminals.
    Know of any nifty such structures?  I'm a prole, not a plutocrat. Not in the surveillance business. We like to call our manufacturing endeavors "aerospace" and "cyber". The purpose is hunting humans and/or mining data about humans.

    Keeping dust and humidity out?
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    What kind of clamps did you use that failed?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    softdown said:
    Know of any nifty such structures?  I'm a prole, not a plutocrat. Not in the surveillance business.

    Keeping dust and humidity out?
    There are plenty of IP65 rated enclosures out there.  Heck, a basic well designed shed will give you most of that.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    BB. said:
    What kind of clamps did you use that failed?

    -Bill
    Cheap ones. They looked good but I think they are copper coated tin. Very thin copper at that. They did last for close to a year however. This is a dry climate of course. The corrosion happened very fast by the way. Seemingly while I was out of town.

    Being as rusty as an old nail, I applied both charge controllers to the main forklift battery. The larger MPPT charge controller seems to have killed the smaller PWM controller. This is why I never really went pro. Thousands of traps to fall into.

    As for the shed, one of the problems with a 1650 pound forklift battery is moving it about. It could have destroyed me twice while I was moving it through sand and ice. Another problem with 24 volt forklift batteries is they can be tall and thin. Not an especially stable structure.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Like this (don't know about material in this clamp)?

    httpcontentinfoautozonecomznetcsproduct-infoenUSepm05512image3
    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Possibly the battery got over charged and/or over filled before you left (electrolyte flooded top of cell)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    BB. said:
    Like this (don't know about material in this clamp)?

    httpcontentinfoautozonecomznetcsproduct-infoenUSepm05512image3
    -Bill

    The clamps looked like jumper cable clamps but much smaller. Maybe 4" in length. The corrosion had likely been creeping and I figured "What the heck, both arrays are working."

    I did add water via the water miser caps a couple weeks ago. The possibility of some water boiling over does present. Yet I think it was just creeping corrosion. A detective would look suspiciously at the water addition event without doubt.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • EstragonEstragon Registered Users Posts: 4,495 ✭✭✭✭✭
    Creeping corrosion, like the kind that lurks in standing rigging and brings the mast down in a blow?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    Estragon said:
    Creeping corrosion, like the kind that lurks in standing rigging and brings the mast down in a blow?
    Ughh.....every sailors worst nightmare. My corrosion was more visible than that. I just figured I had a good safety belt with two systems and they both worked pretty recently.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Jumper cable/alligator clamps are highly unreliable, especially if there are high currents involved.

    Highly recommend that only bolted connections be used for battery/bus bar connections.

    Petroleum jelly, various battery corrosion treatments work well too.

    - Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    BB. said:
    Jumper cable/alligator clamps are highly unreliable, especially if there are high currents involved.

    Highly recommend that only bolted connections be used for battery/bus bar connections.

    Petroleum jelly, various battery corrosion treatments work well too.

    - Bill
    600 watts and 360 watts are the rough currents that were involved. Seemed kind of small to me. One set of clamps had significantly more corrosion. Not sure which at this time.

    How does really thick grease do? For fending off the elements that is?
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Helps prevent corrosive gases/mists from settling on the metal surfaces (what you can see/clean) and wicking down the joints (and even up the strands of cable--Where you cannot see).

    10-20 Amps of DC is still not a great connection to make with jumper cable type clamps. A couple of folks have tried just starting up an AC Inverter using jumper cables for temporary connections--And the inverter failed to start.

    And even it if you get it to work short term, long term reliability is going to be poor (between corrosion and even thermal cycling, a bit of tugging on the cables during servicing, etc.).

    Not saying that Jumper Cable/Clamps will never work--But it can be a headache.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bill von novakbill von novak Solar Expert Posts: 891 ✭✭✭✭
    softdown said:
    600 watts and 360 watts are the rough currents that were involved.
    Those are powers, not currents.  600 watts at 24 volts is 25 amps - and that's a lot for that tiny contact point (edge of clamp against terminal.)
  • littleharbor2littleharbor2 Solar Expert Posts: 1,629 ✭✭✭✭
    BB. said:
    Helps prevent corrosive gases/mists from settling on the metal surfaces (what you can see/clean) and wicking down the joints (and even up the strands of cable--Where you cannot see).

    10-20 Amps of DC is still not a great connection to make with jumper cable type clamps. A couple of folks have tried just starting up an AC Inverter using jumper cables for temporary connections--And the inverter failed to start.

    And even it if you get it to work short term, long term reliability is going to be poor (between corrosion and even thermal cycling, a bit of tugging on the cables during servicing, etc.).

    Not saying that Jumper Cable/Clamps will never work--But it can be a headache.

    -Bill

    Plus it sounds like he was using those portable battery charger size clamps. Not much bite on those.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    My internet persona must be bottom 10% stuff, sorry.  Thought I might get 1-2 "hey's". Zero?

    Hope the old gang is living the dream.....pt II.

    Anybody know of a sweet marina deal on the Sea of Cortez? Hopefully within 400 miles of USA. I have a heavy 24' adjustable trailer and very large 4WD truck. The adjustable trailer plates range from ~10" to ~54" with two sets. Thought a marina/boat company might be interested.... I know....wrong board.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Softdown--Thank you for letting people know about the issues of failing battery clamps in wet locations/exposed to weather.

    I was just asking for some details--Because I was unclear about that kind of clamp you were using.

    And I am very happy that you caught your batteries before they were ruined.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • littleharbor2littleharbor2 Solar Expert Posts: 1,629 ✭✭✭✭
    softdown said:

    Anybody know of a sweet marina deal on the Sea of Cortez? Hopefully within 400 miles of USA. I have a heavy 24' adjustable trailer and very large 4WD truck. The adjustable trailer plates range from ~10" to ~54" with two sets. Thought a marina/boat company might be interested.... I know....wrong board.
    The only marina within 400 miles of the border is in San Felipe. It's mostly a commercial marina. Basically its a breakwater for the shrimp boats to get behind. All the pangas trailer in and out of the water and with the fishing ban in place now you don't see many pangas either. What are your intentions for the trailer?

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • LumisolLumisol Registered Users Posts: 374 ✭✭✭
    I don't even use clamps on my car batteries. lol
    At one time I had a deep cycle marine battery that did dual duty in my car and my boat, so it had quick release mechanisms on it for fast swapping.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    softdown said:

    Anybody know of a sweet marina deal on the Sea of Cortez? Hopefully within 400 miles of USA. I have a heavy 24' adjustable trailer and very large 4WD truck. The adjustable trailer plates range from ~10" to ~54" with two sets. Thought a marina/boat company might be interested.... I know....wrong board.
    The only marina within 400 miles of the border is in San Felipe. It's mostly a commercial marina. Basically its a breakwater for the shrimp boats to get behind. All the pangas trailer in and out of the water and with the fishing ban in place now you don't see many pangas either. What are your intentions for the trailer?
    I have previously traveled to a Mexican marina that wasn't that far away. Can't remember the name. Guayama/San Carlos is about 250 miles as well. Somebody here has a brother with a boat business somewhere in Mexico. I am bad with names though.

    The EZ-Loader trailer came with the boat. It has 64 support points so I can dry dock the boat without damaging the hull. Plus transport to the Sea of Cortez. The boat is too large to constantly transport unless you enjoy towing 14' tall loads.

    Having spent another $800 getting 4' steel plates drilled with 56 holes plus tires, I am interested in earning something with it. Plus the multiple ~3000 mile round trips to the bay area.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    BB. said:
    Softdown--Thank you for letting people know about the issues of failing battery clamps in wet locations/exposed to weather.

    I was just asking for some details--Because I was unclear about that kind of clamp you were using.

    And I am very happy that you caught your batteries before they were ruined.

    -Bill
    Thanks Bill! Lots of risk in being gone half the time. It was pretty exhausting. My boat came with three 12 volt marine batteries measuring 1, 2, and 5 volts. The 2 volt battery took a good charge and is "usable" as a boat battery. I think the batteries are all at least eight years old and have not been used at all. The elderly previous owner moved the boat eight years ago and didn't really lift a finger after that. Except for paying slip fees for eight years.

    Bringing back a battery measuring 2 volts was quite surprising. The other two batteries show a "bad cell" that prevents taking a charge. I have cranked a 65hp outboard for a very long time with the battery that measured 2 volts. I bet it would easily start a V8 many times. Not saying it is fine, just saying that it is rather shocking to be this useful after draining to 2 volts. It was kept in the Cali Delta, a cool, humid environment. Probably never really used.

    The mood on the board doesn't seem overly festive?
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • littleharbor2littleharbor2 Solar Expert Posts: 1,629 ✭✭✭✭






    I have previously traveled to a Mexican marina that wasn't that far away. Can't remember the name. Guayama/San Carlos is about 250 miles as well. Somebody here has a brother with a boat business somewhere in Mexico. I am bad with names though.


    A ha. Mainland Mexico, I forgot about that. Never been there. Heard  the cartels rule the area. That's enough to keep me out.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 540 ah @24 volt AGM battery bank. Plenty of Baja Sea of Cortez sunshine.

  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited June 2017 #24
    Was wondering where you were, what you were doing and so forth, kind of missed you,  glad to hear about your dreams coming true, so many say what they are going to do, but talk is cheap, money buys the wiskey. I retired at 24 to travel the world on a motorcycle, through Africa, Europe and the Americas, went back to work at 38 and re- retired at 55, not rich by any stretch of the imagination but confortablly settled in the tropics, where I belong. Don't loose sight of your dreams, we're only here once, never die with regrets someone once told me when I was about 17, now a farmer in Thailand  trying to be self sufficient, one of my dreams, and about 70% so far.

    During my travels I took the back roads from San Felipe south along the Sea of Cortez, not much happening in the way of marinas but very beautiful, met some American folk at camps along the way but it seemed La Paz was the next real port. This was in 1989 so things may have changed. San Felipe was/is a playground for rich American weekend tourists with over inflated prices but my information is dated.

    Often I wonder if perhaps I ran into  @littleharbor2  along the way, it's a small world anything could have happened. Have a great time doing what it is you are planning, best of luck 
     
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    mcgivor said:
    Was wondering where you were, what you were doing and so forth, kind of missed you,  glad to hear about your dreams coming true, so many say what they are going to do, but talk is cheap, money buys the wiskey. I retired at 24 to travel the world on a motorcycle, through Africa, Europe and the Americas, went back to work at 38 and re- retired at 55, not rich by any stretch of the imagination but confortablly settled in the tropics, where I belong. Don't loose sight of your dreams, we're only here once, never die with regrets someone once told me when I was about 17, now a farmer in Thailand  trying to be self sufficient, one of my dreams, and about 70% so far.

    During my travels I took the back roads from San Felipe south along the Sea of Cortez, not much happening in the way of marinas but very beautiful, met some American folk at camps along the way but it seemed La Paz was the next real port. This was in 1989 so things may have changed. San Felipe was/is a playground for rich American weekend tourists with over inflated prices but my information is dated.

    Often I wonder if perhaps I ran into  @littleharbor2  along the way, it's a small world anything could have happened. Have a great time doing what it is you are planning, best of luck 
     
    Traveling the world on a motorcycle takes a free spirit and plenty of courage. It was a very different world at that time. Were you an American at the time? We used to be welcome almost everywhere as we all know. A monstrous government given to pathological bullying and genocide with extreme prejudice has changed all that.

    Mexico has suffered from a prolonged psy-ops campaign. The vast majority of the violence is contained in a few areas such as Juarez....if I understood the experienced correctly.

    With Japan hosting the next Olympics, I am preparing for an onslaught of anti-Japanese psy-ops. We constantly play the victim card while running roughshod over almost all but the plutocrats with their umbilical cords frequently and firmly attached to the US Treasury. #RoadsAreForProles in America. Half of the highway rest areas are closed, construction zones everywhere with almost no construction happening, and potholes that may separate tire plies.

    Thank you for the encouraging words!
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    We try for technical discussions rather than "social media". Not that there is anything wrong with that. :)

    Every so often, somebody tries for a "joke or two"--And it does not always work (language/location confusion, short posts, no body language to read).

    Here is what passes for an engineering/math joke:

    The integral of 1/cabin is "log(cabin) + C

    Person 1: What's the integral of 1/cabin with respect to cabin?
    Person 2: A log cabin.
    Person 1: No, a houseboat; you forgot to add the C![9]

    And then I go on to explain the joke is still wrong--The mathematically correct answer is a natural log (ln) Cabin + C

    I cannot believe I have explained it again--This joke always did bother me because of the confusion between Ln and Log (typically base 10 logs vs base e (2.71828…) Ln).

    https://en.wikipedia.org/wiki/Mathematical_joke

    Funny, huh?

    We do have other sub-forum like the "in the weeds" section--Where discussions do not have to be solar based and could be more fun. But when have you heard the expression "as fun as a barrel of engineers"?

    Please feel free to start something "over there".

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    Sorry for meandering. My vision of the net seems to differ from many. Many who complain of the incredible endurance required to read an off topic paragraph.

    Back on topic now. The PWM charge controller seems to have been killed by the MPPT controller. The MPPT controller appears to be working properly but the forklift battery voltage has failed to increase after the first couple encouraging hours (of getting the strings working again).

    Betty the goat has figured a way to circumvent the obstacles. Wondering if her walking about has damaged the string output. I sure get rusty fast these days. Thinking I know why government often forces retirement at 55. Guess I should  measure voltage input at the charge controller.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Actually--Your "discussion" (thread), you take it where you wish.

    I try to advise other posters taking a thread "off topic" so that we stay more focused on the original poster's system/questions/observations (aka start their own thread--Bits and Bytes are cheap). But that is just to avoid confusion--Not any overall editorial meme.

    The PWM controller should not have been damaged by the MPPT controller... In general, the two controllers only have one common electrical connection--The +/- battery bus.

    If you, for example, were to attach a single solar array to both the MPPT and PWM controllers, you could end up with damage--But mostly caused by the Vmp-array and Imp-array values--Not because of the action of the MPPT controller itself.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,509 ✭✭✭✭
    BB. said:
    Actually--Your "discussion" (thread), you take it where you wish.

    I try to advise other posters taking a thread "off topic" so that we stay more focused on the original poster's system/questions/observations (aka start their own thread--Bits and Bytes are cheap). But that is just to avoid confusion--Not any overall editorial meme.

    The PWM controller should not have been damaged by the MPPT controller... In general, the two controllers only have one common electrical connection--The +/- battery bus.

    If you, for example, were to attach a single solar array to both the MPPT and PWM controllers, you could end up with damage--But mostly caused by the Vmp-array and Imp-array values--Not because of the action of the MPPT controller itself.

    -Bill
    You freely dispense so much great advice. Perhaps I simply have poor connections to the battery that the PWM is connected to. Using 1/4" bolts that I retightened this morning. Long been amazed by how electricity can fail to complete a circuit in spite of a large contact area. Then shock you because you are "too close".

    Two days ago, the PWM was working fine. Then it "lost its battery connection". I reasoned that the MPPT killed it. Connected it to another battery bank with 1/4" bolts. Will try sanding...
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • Marc KurthMarc Kurth Solar Expert Posts: 875 ✭✭✭✭
    Bringing deep cycle batteries from very low voltages is commonly done.

    It is a myth that a couple of extreme low voltage visits will destroy all lead-acid batteries. The key is time at low voltage. When the time is measured in weeks and not months, the odds of recovery to 80% to 90% storage capacity increase dramatically.

    I have "saved" many 12v batteries that were brought after sitting at 2v to 4v for several weeks. Many are still operating well two years later. The method of bringing them back up again varies dramatically depending upon the type and brand of battery.

    Marc



    I always have more questions than answers. That's the nature of life.
  • BB.BB. Super Moderators, Administrators Posts: 32,088 admin
    Part of the successful vs unsuccessful recovery issue may be--A difference between all cells going to near zero volts (i.e. self discharged, and/or well balanced cells), vs when a load is left connected and one or more cells is taken to zero volts then is reversed biased (starts to recharge with negative voltage across the cell) by the other cells in the series string that still have energy left to drive current.

    The reverse charging of a cell appears to lead to a "quicker death" than a cell (or group of cells) that were take to near zero then recharged withing a few days or weeks... Months at zero volts, a different issue.

    Plus, perhaps Marc Kurth can answer, I have read that AGM batteries do not sulfate as badly/quickly as a poorly maintained flooded cell (that is not "stored" for months at >~75% state of charge). Your comments?

    -Bill "in my humble observations" B.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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