dead batteries?

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mshen11
mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
in Solar Beginners Corner #1
just want to confirm they are dead.

i was inherited mystery trojan 105T batteries. last weekend i charged and then equalized them. i forgot to check the voltage when they were done. this week i checked:

battery 1: 5.5V
battery 2: 6.2V

havent bought a hydrometer yet. im guessing these batteries are beyond dead... no chance of resurrection?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: dead batteries?

    Sounds like scrap metal to me.
    A good 6V battery would have a minimum resting charge of about 6.5V. What they measure immediately after charging is irrelevant.
    But yes; buy a hydrometer. Less than $10 at any automotive store (and other places) and worth it.
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  • mshen11
    mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    #3
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    Re: dead batteries?

    ok one is definitely dead. so what i can do w/ 1 used 6V trojan? that one still seems good.

    if i buy more batteries i obviously cant mix them.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #4
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    Re: dead batteries?

    even though the one may be good yet, it probably has suffered some cycle life and capacity losses. the other needs properly disposed of and maybe the cost of that can be offset by your selling the better one as i wouldn't add a new one to that one. you might break even in the deal so it wasn't a gift after all.:cry:

    idea.......
    do you know of anybody or anyplace that may use those power chairs or even golf carts because they may be willing to part with an older battery when they go to replace them and you could pair it up with this one.
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  • Just Me
    Just Me Solar Expert Posts: 48 ✭
    #5
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    Re: dead batteries?

    It wouldn't hurt to use one in series. Just like a flashlight; if one is dead or low, you can replace just one with a new one and still get decent light. In parallel, is a no no.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
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    Re: dead batteries?
    Just Me wrote: »
    It wouldn't hurt to use one in series. Just like a flashlight; if one is dead or low, you can replace just one with a new one and still get decent light. In parallel, is a no no.

    sorry, but an old and new battery is not recommended for being seriesed either as they would both have different capacities and characteristics causing a limiting of the overall capacity and causing charging to be uneven. it's a no no either way.
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  • Just Me
    Just Me Solar Expert Posts: 48 ✭
    #7
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    Re: dead batteries?

    You're right, I wasn't thinking about the charging aspect. :blush:
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #8
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    Re: dead batteries?
    mshen11 wrote: »
    just want to confirm they are dead.

    i was inherited mystery trojan 105T batteries. last weekend i charged and then equalized them. i forgot to check the voltage when they were done. this week i checked:

    battery 1: 5.5V
    battery 2: 6.2V

    havent bought a hydrometer yet. im guessing these batteries are beyond dead... no chance of resurrection?

    You could try another EQ cycle on the weak one, can't hurt much.
    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
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  • mshen11
    mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    #9
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    Re: dead batteries?

    how long does equalization last? i stopped it after 12hrs (all night run).

    also regardless of whether it actually got to full charge... batteries should drop to those voltages in 1 week on 60F no load temperature, right (even the good one dropped 20%?)


    another battery question: can i put my batteries on top of tiles (kitchen/bath tiles) in anticipation for acid spills. or will acid also eat right through that? what im trying to do is prevent my garage concrete floor from having holes.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #10
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    Re: dead batteries?

    The batteries should drop to their "resting voltage" in about 3 hours. Any further drop is probably the result of self discharge. If the drop is large over a week--then it indicates that the battery is probably failing.

    Equalizing should usually only be done for a few hours. Long and numerous Equalization just "boils" the water away (need to refill with distilled water). It may help the battery to recover some capacity---but is a roll of the dice as to how successful mutlitple equalization will help (after 12 hours of equalization--I would probably give up if the battery cannot hold a charge for a week).

    Most of the time excessive equalization will not help recover battery capacity--but there is the occasional report that a person has recovered an old fork lift battery (many times, it turns out there is one or two bad cells in a bank while the rest are still OK. Some large batteries allow you to wire around a bad cell (i.e., a 36 volt fork lift battery is rewired for 24 volts, or even replace a cell with one from another battery).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mshen11
    mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    #11
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    Re: dead batteries?

    um wait... on a prosine 3.0 you have to equalize manually.
    it doesnt turn itself off? do i have to stop this equalization process?

    also how 'expensive' to one's electricity bill is an equalization?

    note: i didnt see any loss of water
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #12
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    Re: dead batteries?

    Were the batteries bubbling and warm during the equalization? If they were not, at least, bubbling--then the equalization voltage may not be correct.

    You should also have a hydrometer to check the specific gravity across all cells... Any cells with low specific gravity are probably bad.

    By the way, you can put the batteries on tile or wood to protect the floor... Sulfuric Acid does not dry (just the water)--so you will need to wipe it up (if on the tile glaze) or the acid will be absorbed/neutralizes by the raw side of the tile or wood. You could put some plastic sheeting down to protect the floor underneath--if you want.

    Assume that anything next to the batteries will eventually be ruined by acid mist or spill (depending on how messy your batteries are).

    -Bill

    PS: Assuming a 10 amp charge into a 200 amp 12 volt battery (5% equalization; 60% inexpensive charger efficiency):

    10 amps * 15 volts * 1/0.60 cheap charger efficiency = 250 watts

    0.250 kW * $0.12 per kWhr = $0.03 per hour (rough estimate)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #13
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    Re: dead batteries?

    Take the batteries outside if you can: like Bill says, the acid can go all over and it's very dangerous stuff.

    The trick with equalizing is to measure the Specific Gravity before you EQ and after: you're looking for a change. Make that an improvement. :p

    So check each cell, write it down (some way you can remember which is which), then equalize and check again. With your two 6V 225A/hr in series I'd suggest you try an EQ Voltage of 15.5 for 2 hours. If you see an improvement, try again. At some point there will be no further improvement: that's the end.

    Don't be surprised if that one that's under 6 Volts is a loss.
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  • mshen11
    mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    #14
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    Re: dead batteries?

    thanks for the replies. anyone know about prosine 3.0.. if it should turn off automatically after it thinks its done w/ equalization?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #15
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    Re: dead batteries?
    mshen11 wrote: »
    thanks for the replies. anyone know about prosine 3.0.. if it should turn off automatically after it thinks its done w/ equalization?

    Xantrex does:

    http://www.xantrex.com/web/id/241/docserve.aspx

    Page 62:

    3. Monitor the battery specific gravity during equalization with a battery hydrometer.
    When all cells have a specific gravity of approximately 1.265, manually terminate
    equalization. Terminate the equalization charge by momentarily depressing the
    CHARGE ON/OFF push-button. As a safety feature, the Prosine will time-out and exit
    Equalize Mode after eight hours.     If the battery specific gravity is still rising and has not
    yet reached the target value when the charger exits equalization, restart equalization by
    holding the push-button for five seconds. To cancel equalization at any time, turn
    charger off.
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  • mshen11
    mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    #16
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    Re: dead batteries?

    i mustve missed that. so its ok as it equalizes (bubbles) to open up and draw liquid from the battery? as a newbie, im afraid of acid spews ive been hearing from various forum.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #17
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    Re: dead batteries?

    Yes it's okay to draw acid from a charging battery. But you're right; it is acid and it is dangerous. It will eat holes in things (like clothing, for instance) and you don't want to get it on your skin. Have some baking soda (neutralizes acid) and some water (rinse acid off) standing by.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #18
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    Re: dead batteries?

    Small acid spills are probably more of a pain in the butt as opposed to dangerous... Some on the skin, spilled on the floor will do a bit of damage (like a rash, damage finish on floor). The acid mist (if there is any) just causes everything to rust and corrode in hours that is nearby.

    Wear glasses or safety glasses and avoid causing sparks--especially when charging/equalizing. The hydrogen gas can blow the top of a battery and spray acid and plastic everywhere.

    Short circuits and explosions are the two things that worry me most. Shorts because it can be difficult to disconnect the read hot wire (if no fuse, breaker, or switch). Explosions because it sends stuff where it normally would not go.

    -Bill

    PS: Drawing electrolyte from a charging/equalizing battery is a bit of a pain... The electrolyte is "hydrogenated" and the small bubbles can stick to the float(s) and cause false (high specific gravity) readings. It may take a few sharp raps to the side of the hydrometer to knock the bubbles off.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mshen11
    mshen11 Solar Expert Posts: 185 ✭✭✭✭✭
    #19
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    Re: dead batteries?

    assuming it is inevitable... what are some pre-emptive ways to minimize them after the fact - like put them above large bathroom tiles and cover them on top with plywood casing or...?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,447 admin
    #20
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    Re: dead batteries?

    Placing the batteries on a sacrificial material (wood, brick, plastic) is a start... You can get a "battery box" (with venting) to contain the batteries and spills (and keep temperature up in cool climates).

    For some applications, we would sprinkle baking soda powder at the base of the battery to both limit corrosion and give an indication (fizz) if there was a leak/spill (keep powder from top of battery).

    Covering the top of the batteries with a piece of plywood or other material is actually a good idea--limits the damage from a dropped tool or soft drink can as people walk by. A short circuits on the top of the battery are the starting point for lots of other issues/problems.

    Not overfilling (or even slightly filling a bit below the "full" level) the battery leaves room for electrolyte "expansion" (heat, and "gas" bubbles) and prevents many of the messy battery top cleanups.

    Most of the battery issues are common sense once you have addressed the safety problems.

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