Go to the Northern Arizona Wind & Sun - Online Solar Store

Announcement

Collapse
No announcement yet.

charging frozen batteries

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • charging frozen batteries

    I have read that lead acid batteries should never be charged when they are frozen.

    I have 4 T-605's that are stacked tight against each other and I have one inch of foam insulation around them. They are in a exterior battery bay that is not heated. I have been fine until recently it's been well below freezing for several days and will be several more before it warms up.

    Not knowing how cold they where I tried to charge them with the xantrex inverter. The charger went straight from BULK to FLOAT and skipped the ABSORB stage. I tried several times and got the same result. I shot the battery terminal with a non contact thermometer and it said 27*F. I assume the batteries wouldn't charge properly because they are frozen.

    The batteries where at 12.2V when I tried to charge them. How bad did I hurt the batteries?

    What to do from here? I was thinking about bringing the batteries in until they warm up to 40*F and trying to charge them again.

    How do you keep a exterior ventilated battery bay warm when it's this cold out?

    Did anyone else wake up to frozen pipes this morning I'm heading for Mexico next winter
    2 80w Solarex / 4 40w Arco's on a Zomeworks passive tracker / 4 Trojan T-605's wired for 420ah at 12V / Xantrex c40 / Xanterex RV 2012M / Honda powered Coleman 3500w generator

  • #2

    Re: charging frozen batteries

    Re: charging frozen batteries

    Doesn't sound good. 12.2 volts means around 20-30% charge, if that. Frozen temps kill the electrolyte when voltage is low like this. Providing the plates where not damaged too bad, an electrolyte replacement may be in order. I'm sure you'll get plenty of opinions/suggestions, but in the mean time, get them batteries to someplace warmer than freezing.

    All you can do is bring the batteries into a warmer environment (above freezing) and try to charge them. Good luck and let us know what happens.
    Green Power Maniac's Ezine Page

    Comment


    • #3

      Re: charging frozen batteries

      Re: charging frozen batteries

      Be careful when you bring them in... A frozen battery can have its case cracked and when thawed, the electrolyte will drain out.

      If the batteries were that discharged such that they can freeze at 27F--then they where near dead and my have sulfated/failed from being stored at less than ~75% State of Charge for a long time.

      A 40% State of Charge battery should freeze around -16F. Either your battery is near 0% SOC, or you have some other issue (poor electrical connections, failed cell, failed controller, or something else).

      -Bill
      20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

      Comment


      • #4

        Re: charging frozen batteries

        Re: charging frozen batteries

        If the batteries are at +27F, and have any charge on them, they are likely not frozen.

        BUT you might have one cell that is weak, and one cell in a bank could be frozen. When was the last time they were charged, and last equalized ?

        http://www.windsun.com/Batteries/Battery_FAQ.htm

        Do you have a remote temperature sensor for your batteries, so the charge controller knows what the battery temp is ?

        If your batteries are in cases, you could try adding warm water to the spillage area, and see if that warms them up enough. Or get a glass thermometer, and actually dip it into a cell. Or just open a cap, and peek into the cell with a flashlight, if you see fluid, all should be fine.


        Originally posted by westcoastslider View Post
        I have read that lead acid batteries should never be charged when they are frozen.

        I have 4 T-605's that are stacked tight against each other and I have one inch of foam insulation around them. They are in a exterior battery bay that is not heated. I have been fine until recently it's been well below freezing for several days and will be several more before it warms up.

        Not knowing how cold they where I tried to charge them with the xantrex inverter. The charger went straight from BULK to FLOAT and skipped the ABSORB stage. I tried several times and got the same result. I shot the battery terminal with a non contact thermometer and it said 27*F. I assume the batteries wouldn't charge properly because they are frozen.

        The batteries where at 12.2V when I tried to charge them. How bad did I hurt the batteries?

        What to do from here? I was thinking about bringing the batteries in until they warm up to 40*F and trying to charge them again.

        How do you keep a exterior ventilated battery bay warm when it's this cold out?

        Did anyone else wake up to frozen pipes this morning I'm heading for Mexico next winter
        http://tinyurl.com/LMR-Solar
        http://tinyurl.com/LMR-BigLug
        http://tinyurl.com/LMR-NiFe

        Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
        Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

        Comment


        • #5

          Re: charging frozen batteries

          Re: charging frozen batteries

          Batteries would have to be at zero charge - 10 volts or so - to freeze at 27 degrees. So either it got a lot colder than you think, or there is something else wrong with the batteries.
          Northern Arizona Wind & Sun Forum & Website Administrator

          Comment


          • #6

            Re: charging frozen batteries

            Re: charging frozen batteries

            If they have been on some solar charge, or if they were left fully charged, it is possible that they are fully charged already, hence going from bulk to float without absorb. If you have a battery temperature sensor, it may be telling the charger to ramp down the charge current.

            A battery with anything but pure water in it won't freeze at 27f. 50% charge won't freeze until nearly -20, fully charged won't freeze until well below -50f.

            Check each cell with a hydrometer or volt meter.

            Tony

            Ps, we routinely leave batteries over the winter @ -40 with out trouble.

            Second, don't charge a frozen battery,,, but I don't think yours are frozen.
            Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

            Comment


            • #7

              Re: charging frozen batteries

              Re: charging frozen batteries

              OK sorry for the confusion. I'm really new to all this. A quick visual check showed that none of the cells where actually frozen. I didn't know electrolyte had a lower freezing point than water.

              Doesn't sound good. 12.2 volts means around 20-30% charge, if that.
              The voltage charts I have seen say 12.2v = 60% and 11.6v = 20% No charge or discharge for 6 hours.

              No battery temp sensor on the batteries.

              The batteries are drawn down to 12.4v on a daily basis and recharged by the panels. If I get no sun I'll let it go to 12.0v before starting the generator to recharge. They never sit below 12.0v. Last EQ (which was the first time ever for some two year old batteries) was two weeks ago.

              Why do you think the charger skipped the ABSORB stage? I know I didn't get a good charge on them.

              If I maintain a good charge is it safe to leave them outside? High of 18*f today and back down to 0*f tonight.
              2 80w Solarex / 4 40w Arco's on a Zomeworks passive tracker / 4 Trojan T-605's wired for 420ah at 12V / Xantrex c40 / Xanterex RV 2012M / Honda powered Coleman 3500w generator

              Comment


              • #8

                Re: charging frozen batteries

                Re: charging frozen batteries

                Battery voltage changes as the temps change, and that can be fooling your charge controller. You NEED a remote temp sensor to properly charge your batteries.
                http://tinyurl.com/LMR-Solar
                http://tinyurl.com/LMR-BigLug
                http://tinyurl.com/LMR-NiFe

                Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
                Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

                Comment


                • #9

                  Re: charging frozen batteries

                  Re: charging frozen batteries

                  You can also put a load on them and see if they 'behave'. Sometimes you have to draw a battery down a bit before you can charge it up.

                  Trick for automotive charging. Really dead batteries won't draw current from automatic chargers, so hook up the charger and turn the lights on so that the charger starts producing current, then turn them off. It'll drop back to zero, but then will start slowly charging up. This is because of the charger, though; not the batteries.
                  1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

                  Ohm's Law: Amps = Volts / Ohms
                  Power Formula: Watts = Volts * Amps

                  Comment


                  • #10

                    Re: charging frozen batteries

                    Re: charging frozen batteries

                    Cold batteries need a higher charging voltage (one reason a Remote Battery Temperature Senor can help in cold weather).

                    Measuring battery voltage for state of charge is only accurate if the battery has sat for 3 hour or so.

                    Have you done a temperature corrected specific gravity measurement of all your cells yet?

                    -Bill
                    20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

                    Comment


                    • #11

                      Re: charging frozen batteries

                      Re: charging frozen batteries

                      On a side note,,,,

                      I think that if you are routinely drawing them down to 12.0, I think you are drawing them down to far. 12.0 is about 45% depending on temperature. Most folks don't recommend drawing down to a max of 50%, and then getting them back to 100% as soon as possible. Personally, I prefer to only draw down 20%.

                      Batteries that sit for more than a day or two at 50-80% soc are just asking for sulphation.

                      If you haven't read these yet I suggest that you read: http://www.windsun.com/Batteries/Bat...of%20Batteries
                      http://www.batteryfaq.org/

                      Tony

                      As for leaving them out side, IF they are kept fully charged, a battery in a box outside will be fine. Think of it this way. Your automobile battery rides around in the un-heated, subject to slipstream engine compartment, subject to cold temps and they do fine. -40 or even -50 in the north is not unheard of and our vehicles have lead acid batteries. (getting them started is another issue, preheat, block heaters, 0w5 oil etc).
                      Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

                      Comment


                      • #12

                        Re: charging frozen batteries

                        Re: charging frozen batteries

                        Originally posted by icarus View Post
                        On a side note,,,,

                        I think that if you are routinely drawing them down to 12.0, I think you are drawing them down to far. 12.0 is about 45% depending on temperature.
                        Actually, that may not be so. To the OP, are you talking about 12V under load or at rest? I would assume that you mean under load since you mention 12V as the lowest voltage. In which case it's tougher to tell what the actual SOC might be. If the batteries are getting down to a low of 12V under say a C/20 load, that would put the SOC pretty close to 75% (roughly, depending on all conditions). A heavier load could pull the batteries down to 12V momentarily when they are at a much higher SOC...
                        Last edited by hillbilly; December 7th, 2009, 12:08. Reason: typo
                        Off the grid, in the Sierra Nevada with 1200+/-watt "mongrel" PV array, 700AH surrette battery (ailing health), Outback MX60 charge control, VFX 3524 inverter, Generac 7.5kw generator, Honda eu2000 generator, also a Biolet dry composting toilet and small but growing organic garden... oh yeah and 2 GREAT dogs! Thanks for the forum

                        Comment


                        • #13

                          Re: charging frozen batteries

                          Re: charging frozen batteries

                          HB, Westcoatslider mentions in his post #7 about "no charge or discharge for 6 hours".


                          So I assume from that that he knows the difference. To your point however, battery state of charge is a tough nut to crack. Arriving at a absolute number is pretty hard, coming up with a "close enough" number is pretty easy if you pay attention to some parameters. (and have a good battery monitor).

                          Tony
                          Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

                          Comment


                          • #14

                            Re: charging frozen batteries

                            Re: charging frozen batteries

                            Thanks for all the help. I think I was over reacting to the cold temps. This is my first winter off the grid and I'm still learning about solar power.

                            I did get some temp comensated SG readings before the EQ I have not checked them since.

                            1.22 1.23 1.23
                            6.40v
                            1.23 1.23 1.23
                            6.45v
                            1.24 1.26 1.24
                            6.41v
                            1.24 1.24 1.235
                            6.44v
                            The batteries where at 44*F SG is temp compensated but voltage is not.

                            I rarely actually see 12.0v. We get a lot of sun and I'm very careful about power consumption when the sun is not out.
                            Last edited by westcoastslider; December 9th, 2009, 7:52. Reason: make SG easier to read
                            2 80w Solarex / 4 40w Arco's on a Zomeworks passive tracker / 4 Trojan T-605's wired for 420ah at 12V / Xantrex c40 / Xanterex RV 2012M / Honda powered Coleman 3500w generator

                            Comment


                            • #15

                              Re: charging frozen batteries

                              Re: charging frozen batteries

                              So it's getting colder. -20*F the last two nights. Highs in the teens. The batteries are at 4*F this morning. Not having a battery temp sensor I was hoping to manual adjust voltage in the c-40 to compensate.

                              The Trojan web site called for the batteries at 80*F to absorb at 14.8v and float at 13.2v. That seems like a high absorb voltage and a low float voltage. Is that where you guys charge your Trojans?

                              They also mentioned that for every 10*F below 80*F the charge voltage should be .028v higher per cell.

                              So 80*F - 5*F= 75*F bellow standard charge temp
                              7.5 * 0.028 (higher voltage) * 6 (cells in a 12v bank)= 1.26v higher charge voltage at 5*F

                              Starting at 14.8 and adding 1.26 gives me a absorb at 16.06v and float would be 14.46v.

                              The c-40 can only go up to 15v for absorb and 14.5v float. So I have the voltage maxed out on the controller and I'm hoping for the best.

                              I see a battery temp sensor for both the c-40 and the 2012 in the near future.
                              2 80w Solarex / 4 40w Arco's on a Zomeworks passive tracker / 4 Trojan T-605's wired for 420ah at 12V / Xantrex c40 / Xanterex RV 2012M / Honda powered Coleman 3500w generator

                              Comment

                              Working...
                              X