Too hot to equalize?

Derik
Derik Solar Expert Posts: 82 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
I was going to use the long weekend to get my batteries up to snuff. They are currently all about 1.250. The forecast is for 100 degrees the next few days and my batteries sit outside in an insulated battery box that still get's some sun this time of year.

Is it too hot to equalize? I have 12 Trojan L-16 's
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Too hot to equalize?

    You really need to monitor the temperature of your battery bank...

    The absolute high temperature is around 120F (49C). Trojan battery manual (PDF) says the same thing.

    If the battery bank is much over 95F--You might want to wait until cooler temperatures.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Too hot to equalize?
    Derik wrote: »
    I was going to use the long weekend to get my batteries up to snuff. They are currently all about 1.250. The forecast is for 100 degrees the next few days and my batteries sit outside in an insulated battery box that still get's some sun this time of year.

    Is it too hot to equalize? I have 12 Trojan L-16 's

    If all the cells have the same specific gravity reading (within 0.010) you shouldn't equalize; Trojan recommends EQ on an "as needed" basis only. However, with an SG of 1.250 it sounds like they do need a good charge. L16's want good current available - 32 Amps for the 'A' series and 39 Amps for the 'B' series - and they also want fairly high Absorb Voltage: 14.8 on a "12 Volt" system.

    In that climate you should definitely have a good charge controller with a remote temperature sensor: the internal battery temperature could get quite high and need a fair amount of adjusting to the charge set points.

    One other problem you may see with high ambient temperatures is that panel output drops to the point where there isn't enough power to charge properly, much less reach elevated EQ Voltage. One of the many reasons why array size should always be rounded up to the nearest available configuration.
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  • Derik
    Derik Solar Expert Posts: 82 ✭✭✭✭
    #4
    Re: Too hot to equalize?

    Coot, I am making plenty of power just never had the time to equalize the batteries as they should be. Trojan says anything below 1.250 so I figured with the long weekend I would do it now.

    I put the batteries in service in May 2010 and they have never really been properly equalized. I have run the EQ off the mate but it was set for one hour. So the longest I ever did the EQ was 2 hours. SG is always about the same 1.255-1.250. I have only run the EQ maybe 3-4 times since SG has always been fairly high 1.250.

    I only use 4500 watts a day and make much more than that with 1800 watts of panels. I am making 1200 watts right now at 40 amps or so and it's 9:30 am. I will be into absorb soon for two hours and and then a 7 hour float.. or until the sun goes down.

    I use so little power my theory was that my panels aren't making max power, since I reach my absorb setting so early in the day 29.6 is reached by 10:00 am or so the finished at noon and then onto float. My panels only need to get up to about 1300 watts to maintain these voltage settings.

    So today the plan was to use a lot of power get the panels up to their max 1800 watts or more and then start to EQ in the afternoon.

    I do have a temp sensor on the batteries and have the FX80 with the flexware 500 and a mate.

    My belief is that this system is perfectly balanced I just need to run use more power and then fully charge the system. Currently low SG in the morning is 1.240-1.245. So I am cycling from 80% to 90% charge from low to high.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Too hot to equalize?

    Derik;

    You might want to set the FM80's Absorb time limit to 4 hours, just to be sure you're not cutting it short any particular day. I found the default 2 hour setting to be short. Have a look at what kind of Amps are being drawn during Absorb too. All too often these batteries aren't spending enough time in Absorb.
    To me, SG of 1.250 is low. Trojan recommends a temp corrected SG of 1.277. Now if your hydrometer measured 1.250 when they were brand new and fully charged (baseline reading) I wouldn't worry about it. But that's about 90% SOC by Trojan's reckoning. See if you can keep them in Absorb a bit longer and push the SG up.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Re: Too hot to equalize?

    The other questions--

    What are the absorb/float voltage settings on the charge controller, and are the cables between the charge controller and the battery bank fairly heavy and short (ideally, around 0.10 to 0.05 volt maximum drop).

    And do you have a remote battery temperature sensor?

    Also, how is your water usage?

    Your charging voltages (absorb and/or float) may be set a little slow or the controller is running hotter than the batteries and running the correction factor/charging voltage too high(causing low charging voltage).

    Equalization is not really used to recharge a battery bank... It is to bring up individual "weak"/under charged cells.

    If all the cells are all the same specific gravity, but low--look at the charging voltage.

    Assuming you have parallel strings of batteries, and only one string is low or high vs the rest--then look for dirty/loose/corroded battery connections.

    And, as always, check battery/cell voltages when under heavy load/heavy charging on look for the "odd man out" cells/battery that may have other issues.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Derik
    Derik Solar Expert Posts: 82 ✭✭✭✭
    #7
    Re: Too hot to equalize?

    No I am not trying to charge the batteries only going by what Trojan says which is when SG gets below 1.250 to EQ the batteries. I suspect I have some sulfation and think the charger will only get them so full since the charge controller is based on voltage.

    Coot I'll try to increase the absorb, I just cut it back from 3 hours to 2 since I started using more water than I wanted. I am adding water about every other month now. At 3 hours absorb it looked like it would be about every 6 weeks.

    I can make 13,000 watts a day and only use about 4000 t0 5,000. Charge controller is once again set at 27.6 float 29.6 absorb 2 hours and yes I have a temp sensor on the batteries. I have 4/0 cables about 11 foot.

    It's 1:20 panels are 124 degrees, batteries 94 degrees ambient 100 degrees. Panels are putting out 59 amps 1560 watts right now and I am in bulk. I have been running everything to see if I could get the panels up to their max. Which is 1935 watts. I have 9 215 watt panels.

    Thanks for the ideas.

    Derik
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