12v Float and bulk charging setting, what should they be?

YostFMX
YostFMX Solar Expert Posts: 94 ✭✭✭
edited December 2015 in Off Grid Solar & Battery Systems #1
I have a Xantrex C60 charge controller, 615 watts of panels, running 12v system with 4 golf cart batteries. The charge controller has a float and bulk knob. Ive read the manual and its hard to understand where its supposed to be set for 77F degrees temperature. Ive just left it where it is at 13.5v float and 14.0v bulk. Is that correct? Ive been running it like that for about 3-4 years. Then in the book it has a chart to adjust + or - for temperature and at 77F it shows 00.0 change, but i need to find out what 77F should be set to! Please help.

The book almost seems to say it should be float 13.5v and bulk 14.8v. Bad instruction manual...
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  • 706jim
    706jim Solar Expert Posts: 519 ✭✭✭✭
    #2
    I ran the same default settings on a C40 for many years. (24 volt system with bulk at 28.0 and float at 27.0) Now with Trojan manual recommendations, I run bulk 28.4 and float 26.4. Your settings should be half of mine for a 12 volt system. Original batteries were GC's while new ones are L16's. I suppose, time will tell if the changes were warranted.
    Island cottage solar system with appriximately 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing due south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter which has performed flawlessly since 1994. Outback Flexmax 80 MPPT charge controller four 467A-h AGM batteries. Insignia 11.5 cubic foot electric fridge 1/4hp GSW piston pump. My 31st year.
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  • YostFMX
    YostFMX Solar Expert Posts: 94 ✭✭✭
    #3
    Ive had my batteries about 2 years, found the water was down on them to where you could see the fins, not sure they are going to last, fridge starting at night trips the low voltage breaker at about 2am :-( . Did i ruin them letting the water get too low? Any ways to make these batteries work good again?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    If you exposed the plates to air for any length of time--That pretty much kills the battery. With such low charging voltage (assuming that not 14.0 volts for days on end), then it sounds like not checking/adding distilled water often enough. Generally, if you have to add water more often than once per month--over charging. If you add water less often than once every 6 months--probably under charging. Roughly. every 2 months is about average.

    It is possible that you have a failing/failed charge controller too--Some problem where the charger was not actually holding the programmed voltage(s). Do you have a meter to confirm voltages at the battery?

    A DC Current Clamp DMM (like this "cheap" one from Sears) is really handy to have.

    http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P

    You should also have a hydrometer (rinsed out after use before putting away) to measure specific gravity too. It will help you figure out if the charging voltages/time are appropriate or not.

    http://www.solar-electric.com/midnite-solar-battery-hydrometer.html

    If you use something else other than distilled/de-ionized water, it is possible that contamination caused rapid water loss.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • YostFMX
    YostFMX Solar Expert Posts: 94 ✭✭✭
    #5
    Ahh i guess they are shot then :-( . I check the batteries and the water most of the time is fine, them one day i check and i see the plates :-( . How long should GC batteries last? 5 years?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    3-5 years is a good life for CG batteries. Our friends in Canada can do better (winter deep freeze/cold can slow battery aging).

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