Please recommend a charge controller for this system...

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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #32
    Re: Please recommend a charge controller for this system...

    Hi Reg,

    I do not run AGMs, but, personally, if I were you, I would connect your batteries as a bank and cycle them a few times (at a minimum).

    There will always be small differences between each battery that comes off a production line, and it often takes some number of cycles for each one to settle in.

    I realize that you are trying to have a perfect solution, by doing every thing perfectly, but perfection is very, very difficult to achieve, and seldom requierd.

    Just MHO, of course. 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.
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  • halfcrazy
    halfcrazy Solar Expert Posts: 720 ✭✭✭
    #33
    Re: Please recommend a charge controller for this system...
    RegGuheert wrote: »
    Unfortunately, I got to learn what venting sounds and smells like first hand today. While the Classic set points ARE adjustable over a very wide range, I learned that it is fully capable of ignoring your settings and charging at other voltages instead. When I programmed three 6-V batteries to charge at 21.6 volts the Classic promptly pushed them up over 25.6V and they were bubbling and hissing furiously. Fortunately I was right there and this only continued for about two minutes. One thing I will say about the venting I saw today: there was NO heat involved. Somehow I had always imagined heat.

    After a frantic call to MidNite they were able to duplicate the problem. After some head scratching on their part they were able to determine the cause of the problem. It turns out that if you are doing temperature compensation on your batteries, there are upper and lower limits which are separately enforced, so if you set absorb or float outside those limits, your settings are COMPLETELY IGNORED. So be careful if you are charging an odd number of 6V batteries with a Classic controller and be sure to adjust your temperature-compensation limits to include the operating voltages you are using. I had no idea there even were limits on the temperature compensation! MidNite says they will work to change the firmware to try to prevent this problem in the future.

    Thanks for your assistance with this Ryan and boB!

    Everyone will be happy to know that Reg gets the credit for that one the new code prevents the Minimum temperature compensated voltage from being greater than the Float voltage set point.
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