Well, I never expected this when I got home!

2twisty Solar Expert Posts: 199 ✭✭✭
Wife told me that she heard a loud "POP" sound, but that the power was just fine.

I came home to this:

Looks like something got a little toasty on that negative terminal and ignited the gasses in the battery.

Strangely enough, the bank was still functional!  Well...not really, but it didn't break the circuit and the middle cell was still trying to charge as evidenced by the bubbling.

Thankfully, I had a spare battery from my dead bank of batteries that was still holding a charge well and I was able to swap it in to get the bank back online quickly.

And double thankfully that nobody was out there when it ignited, since I'm sure it sprayed acid everywhere, too.


  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    edited December 2017 #2
    water down any evidence of acid before attempting diagnosis and repairs... and please put at least a piece of plywood over the bank for snow/rain protection. 
    I think you need to determine what caused the overheating and ignition, maybe the same or maybe not....
    there was a lot of heat in that cable shown in pic #1 and a lot of gas production to vent and explode...
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,440 admin
    I can't tell if the wire insulation was damaged by heat--or just mucked up over time (water, electrolyte, etc.). The copper crimp end looks pretty good--I don't see signs of overheating.

    About the only thing I can think of that would be caused by "you"... Water levels been ok in all cells (low water level can cause cells/exposed plates to behave badly)--Possibly cause excessive gassing/overheating when charging.

    If the case got cracked from handling (battery got moved/dropped/bumped--especially in cold weather and brittle case), could also cause loss of electrolyte...

    Dropping of a tool/something metal across the top of the battery bank? (accessible to kids playing around?).

    Otherwise, the wiring looked clean and the terminals looked fine.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2017 #4
    That negative terminal looks melted, heat travelled along the cable, the green jumpers appear to have UV damage, batteries should really be covered and not exposed to the elements. Good thing that was the extent of the damage, it could have been a lot worse with wood close by, do you have overcurrent protection, there must have been some serious current to melt the terminal, if in fact thats what happened,  i don't see a fuse.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I would make a baking soda solution to neutralize acid for clean up, and wear full protective gear.

    Any chance that battery was really weak, and got charged frozen?

    +1 on making an enclosure.
    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
  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    edited December 2017 #6
    Hot terminals don't ignite hydrogen gas (unless we are talking about much hotter than the melting point of lead and plastic).  But arcing caused by water across terminals can.    Keep your batteries dry!

    I am available for custom hardware/firmware development

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Odd, the wire is definitely overheated, but the copper strands visible. aren't oxidized.  Maybe the hot wire melted the terminal and the wire wobbling around in the puddle of lead, started an arc that lit the hydrogen.

    What sort of amps are going through that wire normally ?

    Lucky that's all that happened.
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    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Mike, good eyes on that melted post, missed it... saw the charred wire covering.
    Hope you are not in line of the current fires.
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    A poor crimp? or one that was stressed?  The other end of the terminal / wire bond that you can't see maybe the failure point?
    When I see different makes of cables in a battery system I am wary of this exact kind of event.
    The fires are way south of us and Mike, for a change this year Mr West!
    "we go where power lines don't" Sierra Nevada mountain area
    E-mail offgridsolar@sti.net