Blew the caps off

billybob9
billybob9 Registered Users Posts: 141 ✭✭
in Old Battery Tech Discussions #1
Couldn't get a charge to hold on one of my 6v batteries which was number 1 of my 24 volt group. My new EPEVER controller was already in line and I wanted to test it out, so I fired up the system with one very low battery. Everything was looking fine until I turned on my small fridge and my 1000W Inverter tripped off. After a few tries, I took out two 6v batteries and replaced it with a 12v battery out of my truck. Now my 24v system was supporting the fridge and charging the batteries. Everything looked OK as I checked out the controller and later as the sun went down, shut off the fridge and went  inside for dinner. After dinner I checked on the system and found the truck battery in a puddle of water with the caps blown off. I probably damaged the battery but it still worked. Live and Learn....BG  
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #2
    What was the AH rating of the 6 volt vs 12 volt batteries? Assuming that the 6v batteries were 2x or greater AH capacity, the truck battery was basically equalized at (probably) a pretty high current. Lots of gassing/bubbling, and could have had gotten pretty hot too (depending on current, time, etc.).

    Series connected batteries need to be very similar (or ideally matched) AH capacity, or bad things can happen (and series connected batteries need to be similar state of charge too--Or the high SoC cells will get over EQ'ed too).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #3
    If your truck battery was fully charged and the two 6 volt batteries were not then the truck battery got a serious overcharge,  count yourself lucky.  Next time be sure that all batteries in a series string are at the same s.o.c.

    word of caution.....hydrogen gas mixed with oxygen as in batteries gassing burns at 6350 feet per second....it's rather dramatic.....remember the pictures from Fukushima Nuclear Power plant.....the explosion....hydrogen gas and oxygen from the dissolving zirconium fuel rod cladding......
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #4
    Bill
    Not sure of AH on the truck battery ( 10 yr old ) it only reads 850 cold cranking amp on the battery side. The 6v Interstate golf cart batteries are 235 AH ( So they say ). There probably was a difference in Battery charges .


    Tecnodave

    Yeah, that was really stupid of me to do that but now it just might save someone else, since it's never been mentioned. I should have know better. I once told a doctor he had the wrong bottles and Oxygen was the green ones..Thanks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #5
    The truck battery was probably 80-100 AH (assuming the truck was a typical gasoline powered pickup)...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #6
    Yeah, Ford F-150. But one last thing. If the battery is shot and I put it on the battery charger which has an automatic shut off when fully charged. Will it keep charging because it is damaged and doesn't get to that point ?  Thus blowing up again.  Thanks....BG
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  • Tecnodave
    Tecnodave Registered Users Posts: 437 ✭✭✭✭
    #7
    Check electrolyte levels and keep an eye on it, check sides near top for temperature, if it's getting hot too fast then it got damaged.  Do you have evidence of an hydrogen explosion.....besides blowing off the caps it will bulge out the sides of the battery.  Sides of the battery should be flat. Usually the ends bulge out first as the separators between the plates will expand when damaged. 
    2 Classic 150, 2 Kid, 5 arrays 7.5 kw total  2ea.  2S6P Sharp NE-170/NE-165, 1ea. 12P Sanyo HIT 200,  2ea. 4/6P Sanyo HIT 200, MagnaSine MS4024AE, Exeltech XP-1100,  2 Banks L-16 battery, Rolls-Surette S-530 and Interstate Traction, Shunts with whizbangJr and Bogart Tri-Metric, iCharger i208B  dc-dc buck/boost converter with BMS for small form lithium 8S 16650 or LiFePO4,
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #8
    Usually, your battery will achieve full changing voltage. And an automatic charger will stop.

    Things that can make the prediction false include shorted cell and high leakage current.

    More or less, if you see a constant float charging current over 2% of battery capacity (80 ah x 2% = 1.6 amps), assume the battery is bad and could eventually catch fire (over heat, boil dry,  arc with hydrogen and oxygen inside, etc.).

    Obviously a worst case scenario, but one that is more likely if those conditions are present.

    Also many automotive chargers have poor voltage control and or high charging voltage (for fast charging) which is its own set of issues.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • billybob9
    billybob9 Registered Users Posts: 141 ✭✭
    #9
    Tecnodave
    With caps off tried to check electrolyte level that was stated on one site as 1 cm above plates and another that said Interpolate meniscus at 1cm above plates. Hard to see with small holes unlike the golf cart batteries but I think I'm close. No bulges or abnormalities that I can detect so here goes. Thanks

    Bill
    As I'm charging now and hoping for no worse case scenarios as you have mentioned. I've read all your possibilities and will probably just put it back in my truck, start it up then unplug it and drive to Costco for a new one. Hopefully my alternator will get me there ( or will it ). I don't want it blowing up in my truck.  BG
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #10
    If the batteries puked fluid, that was electrolyte, and you replacing it with distilled water.   That will reduce somewhat, the capacity.
    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 ||
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    edited May 2019 #11
    If you can start your truck, you should be able to drive there (assuming less than 1 hour, daylight/no headlights, etc.). You can use your headlights (if bad weather), assuming your alternator is OK. Just trying to suggest taking less risk/loads on the one battery (pull up to a light, engine RPM drops low, alternator fails to keep up with current draw, and ignition/engine computer drops out).

    From my experience, the battery may not start the truck once you turn it off (bring jumper cables--if needed)... Or the battery can work 1-2 weeks and then in just one moment, go dead and not start the engine again (older batteries that have been taken dead, then recharged).

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