Diluted electrolyte and low SG

SolarMusherSolarMusher Solar Expert Posts: 176 ✭✭✭
Hi all,
I have a problem on a rolls battery bank (flooded/700Ah/48V), which had been overfilled up to the top last November. Gravity reached 1.245 with a few 1.250 after 12 hrs 64V EQ last week but yesterday it was showing a low 1.230 after a full charge and 100% SOC (no loads). After a month, and several charges/discharges, cells are still at top level with too much water. PV is 3 kwh, Classic is 59.2V with a Whizbang end current set at 9A and 3hrs absorb time, gen is set to auto-start at 70%/100% (for now I’d like to avoid draining these batteries deeper). I’m afraid that this guy would end to kill these batteries when powering large loads (inverters are Magnum PAE 8.8kwh) with such a weak gravity. Of course this guy had been warned and the bank was performing great when installed, but…
I’m wondering what the real state of charge of these batteries is and what would happen when a diluted electrolyte drops too frequently under 1.200…? So what could I trust in, SG or SOC or nothing in this unusual case? What would be better, longer absorb time or frequent equalising to try to evaporate all this water?
Any thought appreciated.
Happy new year.
Erik

Comments

  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Diluted electrolyte and low SG

    Longer Absorbs would be my choice. The low SG's will not hurt anything except for a little lower capacity and that your not using anyway @ 70%. This the very reason I top-up the electrolyte when commissioning. Rolls seem to take those long EQ's to get a rise to start with 12 hrs on a new one doesn't seem out of the question. 1.255-1.265 is a normal 100% range.
  • SolarMusherSolarMusher Solar Expert Posts: 176 ✭✭✭
    Re: Diluted electrolyte and low SG

    Hi Bc,
    I was thinking about longer absorb too rather than EQ, but I'm afraid of very low temp that could prevent the propane gen to start at 70%, -32°c to -37°c for the next three days... too cold this winter! Problem is that this 70% SOC doesn't match the SG. I just hope that this false 70% SOC could start the gen before SG really drops under 1.200.
    I've now installed gen batteries (x2) inside a heated shed to take a chance whith low temp but I was not thinking of such regular low temps when I did it!
    So, you're thinking that it could only affect bank capacity and not its life?
    This bank was commisioned in september and I equalised because SG had dropped too low around 1.150, not enough sun, too much snow and too cold for batteries to start the gen.
    Erik
  • BB.BB. Super Moderators, Administrators Posts: 32,004 admin
    Re: Diluted electrolyte and low SG

    You might want to get a smaller gasoline genset (usually much easier to start when cold) to run a pre-heater for your larger propane genset.

    The smaller gasoline genset may be small enough that you could (if needed) pre-heat it from your main battery bank without too much power usage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Diluted electrolyte and low SG

    Erik, with low temps like that what is the SG adjustment factor? or did your SG numbers include the adj?
    I like Bills suggestion, a smaller \inverter gen, so you can do a long absorb.

    HNY to you all , glad we are having a very warm winter here this year, mostly just under 0*C, but lots of snow!!
    Eric
     
    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
  • SolarMusherSolarMusher Solar Expert Posts: 176 ✭✭✭
    Re: Diluted electrolyte and low SG
    BB. wrote: »
    You might want to get a smaller gasoline genset (usually much easier to start when cold) to run a pre-heater for your larger propane genset.

    The smaller gasoline genset may be small enough that you could (if needed) pre-heat it from your main battery bank without too much power usage.

    -Bill
    Hello Bill,
    I've tried to start my own gasoline gen (100% synthetic oïl) yesterday evening and I can't even pull the rope ;). I could start it only after a 1 hour fight.
    Just kidding but I was more thinking to add a spare gasoline gen on manual transfert switch that could be used only when too cold for a propane gen to start.
    When I stayed far up to the north, we brought the gen in close to the stove to warm it for one hour and brought it back outside to start it!
    Eric, these battery bank is located inside a heated shed so temp is steady at 15, 20°c.
    Erik
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Diluted electrolyte and low SG
    Hello Bill,
    I've tried to start my own gasoline gen (100% synthetic oïl) yesterday evening and I can't even pull the rope ;), we brought the gen in close to the stove to warm it for one hour and brought it back outside to start it!
    Wow! What viscosity motor oil are you using? Sounds like it's pretty thick stuff when cold. Synthetic or not, thick molasses won't lubricate an engine, and makes it very difficult to start.
    Sounds like you should be using 0W30 in Winter. The "0" indicates it flows very easily when cold and will get up there among the moving parts providing lubrication until the engine warms up (starting a cold engine is normally when most engine wear takes place because the oil is too thick), and the "30" indicates that when hot, it never gets thinner than #30.
  • SolarMusherSolarMusher Solar Expert Posts: 176 ✭✭✭
    Re: Diluted electrolyte and low SG
    Wow! What viscosity motor oil are you using? Sounds like it's pretty thick stuff when cold. Synthetic or not, thick molasses won't lubricate an engine, and makes it very difficult to start.
    Sounds like you should be using 0W30 in Winter. The "0" indicates it flows very easily when cold and will get up there among the moving parts providing lubrication until the engine warms up (starting a cold engine is normally when most engine wear takes place because the oil is too thick), and the "30" indicates that when hot, it never gets thinner than #30.
    Hi Wayne,
    I know that, but I use this gen only for charging when temps are a bit warmer (snowing), I fill it with 5W30 Synthetic oïl for winter, it's usually fine. If I had to start it at any time in a day when -30°c or below, I'd use 0W30 synthetic, of course. In the past, we lived for 15 years at 6 hours from the next town where synthetic oil was just a dream, you know these crazy places where even twisted and rusty nails are still useful because of no other choice, sometimes in winter we had to drive 300km pushing snow with the truck ;). At this time we didn't have all this solar stuff available and needed the gen, that's why we brought it in to warm it.
    Wayne, did you ever start a truck that has been parked for a week at -40°c without a block heater? It's funny, synthetic oïl or not. It's about the same as if it was crystal made.
    Erik
Sign In or Register to comment.