new batts absorb too high

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lamplight
lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
my new rolls batts require a higher absorb setting, right now it's at 14.8 , so with temperature compensation i'm hitting 15.1+ on some days, this shuts off the inverter, and i just blew one of my 12v led lights. fortunately the 12v car adapter for my server works good on a wide input, its been fine.

anyone have any tips? I can work around the LED lights easily enough now that i know better, but i might be absorbing for 2-3 hours each day and with no inverter during peak harvest time its more than a little inconvenient. other than lowering my absorb which i think i'll have to do, does anyone have any other tips? i know i could get some converters for the smaller stuff, but i dont know if theres one that will handle 1500+ (110v) of current.

in another post here i listed the min and max values for absorb, eq and float from rolls, and i have wanted to go on the high side of those ranges (also per suggestions from rolls) as my pv is on the low end of the charging scale. so im thinking i will lower my absorb to a usable point for now, and have the float and eq's be at the max settings recommended for the batts. any other ideas? surely this must come up for other people.

thanks as always and have a great weekend!

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  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
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    Re: new batts absorb too high

    Don't run the absorb that high. A lower voltage should be fine, just may take a longer time.

    Test your SG now after full charge and after running at lower voltage for a while. If it has not changed significantly then battery is getting enough charge.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high

    excellent advise thank you, will try that. going to have to actually :)
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high

    i'm considering even disabling the battery temp sensor so i can ensure im charging at the absolute highest level (closest to recommended) i can without tripping the inverter. since that would be 14.9v , with rolls recommending i be at 15v for a smaller PV system, I'm thinking this may be a good option.

    i'm figuring that my batteries are in a moderate, even temperature location (in the basement so never too hot or too cold), and that even with the battery temperature compensation i'm still within these ranges anyhow. makes sense to me... thoughts?
  • blackswan555
    blackswan555 Solar Expert Posts: 246 ✭✭
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    Re: new batts absorb too high

    I would not disable bat temp sensing, It is the internal temp that is important, not the ambient and can be very different,
    I would either set absorb time to 6 + hours or float voltage to same as absorb, Then keep a close eye on water usage, You may find ( sun / load dependant) that you could knock 0.1 v off your charge v and extend your service / EQ intervals.
    Have a good one
    Tim
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high

    thats sounding like a good idea... if i take both of your advise i can use the temp sensor , lower the voltage, extend the absorb time. 6 hours though?? phew... but still i hear what youre saying... extend it.. its at 2.5 hours now... the nice thing about these big rolls is there is a nice amount of space for fill height so watering schedule can be extended more than the smaller batts (if i forget , say..).
  • blackswan555
    blackswan555 Solar Expert Posts: 246 ✭✭
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    Re: new batts absorb too high

    Advice from a rolls tech for under panel`d or hard worked systems :D Keep a very close eye on your water usage till you get the feel of it, ( or get some hydro-caps aswell)
    Tim

    ps your coffee maker give your bats a very hard time, 1400 w = about 125 amps dc draw, that is way down around C/8
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high

    already got my new hydrocaps on, from nzaw&s :) thanks guys very much!
  • BB.
    BB. Super Moderators, Administrators Posts: 33,479 admin
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    Re: new batts absorb too high

    Which inverter are you using? Some list 15.3/30.6 volts as the cutoff voltage--although several inverter models list 16 volts as the high end of the acceptable voltage range. :confused:

    Is the set-point adjustable?

    Also, do you have the inverter and chargers "home run'ed" back to the battery +/- bus connection or does the inverter power come from/near the output of the battery charger, then those cables run to the battery bank (you get the voltage drop (increase in apparent battery voltage drop due to shared charger/inverter cable run)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high
    BB. wrote: »
    Which inverter are you using? Some list 15.3/30.6 volts as the cutoff voltage--although several inverter models list 16 volts as the high end of the acceptable voltage range. :confused:

    Is the set-point adjustable?

    Also, do you have the inverter and chargers "home run'ed" back to the battery +/- bus connection or does the inverter power come from/near the output of the battery charger, then those cables run to the battery bank (you get the voltage drop (increase in apparent battery voltage drop due to shared charger/inverter cable run)?

    -Bill

    Bill:
    samlex (labeled cotek or something though). its a hardcoded 10.5-15.0v operating range, it just disables itself outside that range. not settable.

    everything home runs to the battery. no shared cabling except 1' on the negative terminal where i had to splice some stuff due to the shunt install.


    BUT - i have good news, at least for myself :) I feel like an idiot but i just noticed that the msview software for configuring the tristar mppt has a Maximum Voltage Cutoff for JUST THIS REASON (voltage sensitive loads). so i set it to 14.99 and will put my charge rate back up to 14.9, leave on the temp compensation, and extend the absorb. I plan to try 4 hours absorb first , watch the water levels every week, see how it goes. I'm still glad I brought this up though as I learned a few things along the way.
    thanks for these great ideas and help.
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high

    Bill,

    btw, this is the inverter:

    http://www.invertersrus.com/sk1500-112.html
  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
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    Re: new batts absorb too high

    If your absorb voltage is too low for the particular battery, the battery life will (or may) be reduced due to sulfation.

    Maybe what you can do is to reduce the absorb voltage for regular, every day charging, (14.99V ?), and then just expect to NOT have the inverter running while you do an equalization charge on those batteries at regular intervals. You can turn off your LED lights at those times as well so you don't burn any more of those out.

    Or, get an inverter that can take the higher Voltage. It's usually the cheaper 12V inverters that have these problems.

    my 2 cents for today.
    boB
  • lamplight
    lamplight Solar Expert Posts: 368 ✭✭✭✭✭✭
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    Re: new batts absorb too high

    Ho , boB
    nice to hear from you. thanks thats just what i did: set it at 14.99. btw my upgraded system is using your little midnite 6 array combiner/disconnect/fusebox.. (forget what its called :roll:), nice looking and functional little box.

    its odd but its not one of the cheaper inverters (see above), in fact ive seen some of their standard (samlex) cheaper 12v sine wave inverters do allow up to 16v, but for some reason this one is only 15. anyhow i think this is a very doable workaround, 14.99, as opposed to the recommended 15v should be just fine. i'll keep the shorter (normal) absorb time of 2.5hrs at first , watch water and battery health and increase if needed as suggested here (great idea Tim!)
  • boB
    boB Solar Expert Posts: 1,030 ✭✭✭✭
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    Re: new batts absorb too high
    lamplight wrote: »
    Ho , boB
    nice to hear from you. thanks thats just what i did: set it at 14.99. btw my upgraded system is using your little midnite 6 array combiner/disconnect/fusebox.. (forget what its called :roll:), nice looking and functional little box.

    its odd but its not one of the cheaper inverters (see above), in fact ive seen some of their standard (samlex) cheaper 12v sine wave inverters do allow up to 16v, but for some reason this one is only 15. anyhow i think this is a very doable workaround, 14.99, as opposed to the recommended 15v should be just fine. i'll keep the shorter (normal) absorb time of 2.5hrs at first , watch water and battery health and increase if needed as suggested here (great idea Tim!)


    Samlex makes some good stuff. I think they should realize that some systems, such as yours, can run at higher than 15.0 Volts, especially with larger flooded batteries and the voltage they sometimes need to be charged at.

    Glad you like the MN boxes !
    boB