Solar Battery high pitched squeal hiss

Options
Karen_Outback
Karen_Outback Registered Users Posts: 2
in Off Grid Solar & Battery Systems #1
I have a whole house system that has been in place since 2007. Outback system, 24 panels, 12 4V 2 cell deep cycle batteries. I was doing regular maintenance (checking H20 levels) and I heard a noise from 1 of the batteries. It was not the usual inside the battery charging type noise, it was a sound like there was pressure being released slowly through one of the cells/side of one battery under the top. I unscrewed the cap of one side at a time, once I'd located which was the offending battery, and the noise stopped. I continued my checks and it started again, and stopped again after releasing pressure by unscrewing the cap of one cell of the battery. I have never had this happen in 7 years, is this one battery becoming defective? Do I need to look at some type of sealant or just keep a closer eye on it? Any ideas what it is and why it occurs? Thanks.
· Share on Twitter

Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Options
    Re: Solar Battery high pitched squeal hiss

    Welcome to the forum Karen.

    Battery caps aren't actually sealed, they're vented: no pressure should build inside. It sounds (literally) like the vent in the cap has become plugged so that there is pressure building inside and forcing its way out through the restricted cap vent. Wash the cap in distilled water and put it back. The noise should go away. If it doesn't (and it's probably most noticeable during Absorb stage) I'd check that cell Voltage and SG compared to the others; see if there's any indication that it is getting too hot which might indicate an internal short (and thus more gas produced).
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Options
    Re: Solar Battery high pitched squeal hiss

    if a cell is failing then its voltage will sag after a few hours of not being charged and will sag faster under load. you would have need of a dmm or dvm to measure the voltage for each to see if the one in question is failing. for instance 2.12v, 2.14v, then your cell in question showing 1.79v. there could also be other cells weak if this one has indicated a failure. the cells are older so if you find this cell much lower than the rest then it may be time to replace them all.

    of course it could be just that vent too, but I doubt it as it sounds to me like excessive outgassing from a bad cell.
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,448 admin
    #4
    Options
    Re: Solar Battery high pitched squeal hiss

    As above, what Niel and Marc said--sounds like a cell starting to fail. Note, this could be a "good cell", and there is another in the same string failing (would usually be a "shorted" cell).

    As suggested by Marc, take a volt meter (set to 20 volt full scale--NOT AMPS/CURRENT) and check the voltage of each cell, under charge, under load, and setting with no load/charging.

    Ideally, they should all be withing 0.03 volts of each other--If you find some high or low voltage cells (like >0.1 volt or larger differences), then you need to do some more research and figure out what is happening.

    The nice thing about 2 volt cells, is you can measure the voltage of each cell.... The 6/12 volt batteries typically have their cell connections sealed and you cannot measure their individual voltages.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #5
    Options
    Re: Solar Battery high pitched squeal hiss

    Hi Karen,

    Believe that Cariboocoot, that most likely this one cap is somewhat plugged, and rinsing or even soaking it, and then rinsing it in a stream of Distilled Water should resolve this, at least for some time.

    There is one cell here that does this, and the soak/rinse did the trick. These batteries use Water Miser (tm) caps -- the yellow & green ones with plastic beads inside. Have felt that this type cap is somewhat more susceptible to this orifice reduction, and a bit of whistling during EQ in particular. This cell in the bank here has been hurt a bit during a deep-ish discharge, so have been charging it separately with a single-cell charger, which causes this cap to need to deal with more emissions than its neighbors.

    It is possible that this cell is gassing more than its sisters, which may or may not be an indication of possible trouble ... as others note, keep an eye on its water consumption, and voltage during high rate discharge, charge and in the AM with light loads before charging begins.

    But, it looks like these batteries have served well. Good Luck, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
    · Share on Twitter
  • Karen_Outback
    Karen_Outback Registered Users Posts: 2
    #6
    Options
    Re: Solar Battery high pitched squeal hiss

    I dipped the cap in d. water and replaced. No whistling anymore. Water consumption as usual for all cells, so it looks like the mystery is solved. EQ yesterday evening went fine. Thanks for everyone's help. This continues to be a learning process.
    · Share on Twitter
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Options
    Re: Solar Battery high pitched squeal hiss

    glad to hear the cell was not failing.
    · Share on Twitter

Categories