A question about safety concerns around Hydrogen outgassing from 6V batteries

djdenali
djdenali Registered Users Posts: 11
We have a tiny system---one 85W PV panel on the roof with 2 US 2200 6V batteries that are in a screen room into which we just moved into for sleeping. The room is about 10 by 20 with screens covering about 2 of the total wall space. The batteries are on a shelf about 3 feet off the ground about 5 feet from where we sleep---in a 'normal' height bed.

So,

1) Is Hydrogen (or other off-gassing) dangerous? Does it sink (the screens start about 4 feet off the ground and go to the ceiling)? if so, this means less potential for gas movement?

2) If we move the batteries outside, and move the Suncontrol 20 Control charger with it, would it take less energy to put the inverter right near the batteries and leave it on all the time OR run a wire run from the battery to the place where the inverter is currently (in the house, on the other side of a wall about 5 feet from the batteries) and turn it on and off only when we need it --We only turn the inverter on when we use it as the lights are DC and run directly off the "Load" wire from the control charger. Our AC draw is small--electric shaver, computer occasionally, blender wand in the morning for smoothies...

If this is not enough information, let me know what else would be helpful...

thanks,
dj

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: A question about safety concerns around Hydrogen outgassing from 6V batteries

    Hydrogen is flammable, but not hazardous (as long as there is still lots of oxygen in the room). Hydrogen itself is much lighter than air and will rise (and out through your screens). It is not like propane which (heavier than air) can settle and be an explosion hazard in a basement/etc.

    With a screen room, your biggest danger is probably if somebody lights a cigarette next to the battery caps during the day (when charging) or drops some metal on top of the battery wiring--It could cause a battery explosion (and spray acid around). That you do not want.

    Otherwise, when charging (and the battery is bubbling), you can get an acid mist that will have a "sulfur" smell. In a screen room as you describe, it probably would not be a problem at all. Many people have a battery bank in their garage and never have any problems.

    Just build a small box around the whole battery, or at least a cover to keep people away from the battery caps/wiring and everything should be OK. Just do not keep anything "valuable" right next to the batteries (books, electronics, etc.) as the acid mist could damage those. (it is not a lot of acid mist--but if you have looked in a motor vehicle and see some corrosion on the cable ends and the steel around the battery--That sort of stuff can occur).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: A question about safety concerns around Hydrogen outgassing from 6V batteries

    What BB said. And I'd also like to add that your 85 watts, is just barely able to keep a float charge on the batteries, if you use much power at all, it will be days before the tiny panel can recharge the big batteries and the batteries may degrade.
    Using a generator to top off batteries might be a good idea on a weekly basis. And adding distilled water to the cells too, when they are low on fluid.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: A question about safety concerns around Hydrogen outgassing from 6V batteries
    mike95490 wrote: »
    What BB said. And I'd also like to add that your 85 watts, is just barely able to keep a float charge on the batteries, if you use much power at all, it will be days before the tiny panel can recharge the big batteries and the batteries may degrade.
    Using a generator to top off batteries might be a good idea on a weekly basis. And adding distilled water to the cells too, when they are low on fluid.

    My thoughts exactly. In fact my first thought was how little H2 that panel could produce at the best of times.
  • djdenali
    djdenali Registered Users Posts: 11
    Re: A question about safety concerns around Hydrogen outgassing from 6V batteries

    Much thanks for the well thought out responses. Most helpful and reassuring. enjoy your days...
  • BillBlake
    BillBlake Solar Expert Posts: 49
    Re: A question about safety concerns around Hydrogen outgassing from 6V batteries
    djdenali wrote: »
    Much thanks for the well thought out responses. Most helpful and reassuring. enjoy your days...

    It reminds me of a story from way back in ('09) :-)
    Or was it 1915.

    It's Don Gentry talking about 1909 if you follow the Link.
    Far as I heard the Edison Ni-Fe battery factory cranked back up in 1908
    after being closed for several years to make improvements.
    So 1909 would have been the 2nd Generation of Ni-Fe cells.

    <SNIP>

    The submarine chosen as the test bed was the E-2.

    There was one important difference between

    leadacid batteries and the alkaline battery.

    Lead-acid batteries gave off hydrogen while they discharging

    while the alkaline battery gave off hydrogen while charging.

    Edison and his engineers claimed that the same venting procedures in place for lead-acid batteries would work for the
    alkaline version.

    In August (1915), the E-2 tied up at the Brooklyn Navy Yard. Workmen removed the existing batteries and
    installed 240 Edison cells.

    The E-2’s captain was Charles “Savvy” Cooke who felt Hutchison’s ventilation and cooling system was inadequate.
    Cooke wrote letters through the
    chain of command for months warning of the dangers of hydrogen gas – they were ignored.

    During the next several weeks, several small explosions occurred in the battery compartments.
    Hutchison dismissed the detonations as insignificant but agreed to conduct accurate measurements
    of hydrogen gas.

    Cooke was disappointed when the Bureau of Steam Engineering reported only infinitesimal amounts
    of hydrogen in the
    battery wells.
    Feeling that any level of gas was a concern, Cooke went so far as to make his own changes to
    the ventilation system drawings.

    When Hutchison learned of this, he complained and the changes were discarded.
    In December, power profiles of the new batteries indicated insufficient capacity.
    To remedy this, Hutchison decided to force the batteries
    through a complete charge and discharge cycle
    (to thicken the current generating chemical layers on the plates).

    To do this, he would connect both groups of cells together, connect them to the eard’s power supply and drive them
    though the sequence in single day.
    During this cycle, the boat’s electricians would monitor performance and water the cells.

    With all the cells linked together, it was possible for some of them to discharge completely and
    then to begin charging again

    using current from the remainder of the cells still in the discharge phase.

    During laboratory trials, Edison’s engineers noted that such “reversed cells” generated hydrogen
    at a much higher rate than usual.
    Hutchison, aware of the tests, apparently didn’t recognize their significance in the E-2’s application –
    a fatal oversight.

    On Friday, January 15th, EM2/c Otto was carrying an empty water barrel up to the deck to refill it.
    As he straddled the hatch trying to get the barrelthrough, there was a muffled thump followed by a
    forced that spun him into the air.
    Cooke, aboard the tender Ozark one dock away, heard the noise
    and ran to a window where he saw a puff of dirty white smoke emit from the E-2’s main hatch.
    He rushed to dock #2 where the E-2 was tied up.
    By the time Cooke reached the boat, thick black smoke was billowing from all hatches
    and debris was scatter about. To his horror, Cooke saw one of
    the E-2’s electricians down on the deck, his right leg severed at the hip.
    Ignoring the danger, Cooke lead a group of men down through the main hatch where they heard
    people moaning and calling for help. Unfortunately, the dense fire and smoke prevented them
    from rendering assistance at that point. Returning to the dock,
    Cooke ordered fire hoses to be directed at the boat’s interior.

    He found Otto wandering aimlessly nearby and sent him to the hospital.
    After ordering gas masks and fans, he reentered the boat with another group of volunteers.
    Moving quickly, rescuers found more survivors, and more bodies – four total, with ten injured.

    The initial investigation concluded that a hydrogen explosion was to blame.

    Favoring the Edison battery, Navy Secretary Daniels rejected these conclusions and ordered a formal inquiry.

    The inquiry nearly ruined Cooke’s career who, although absolved of any blame, was reassigned
    him to a landlocked supply ship in Boston Harbor.
    It would not be until December 1918 that Cooke would command another submarine – the R-2.

    Eleven months later, he would received orders to take command of one of the new S-boats.
    Soon after, he and his crew would make submarine history aboard the S-5.

    [The above was condensed from the recently publish “Under Pressure”, an excellent book on
    the S-5 sinking and crew recovery by AJ Hill—Don]

    http://www.fieldlines.com/index.php/topic,146754.msg1010056.html#msg1010056

    BillBlake