Advice on Slogie's system

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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #32
    Re: Advice on Slogie's system
    Aguarancher wrote: »
    if you don't already have a hydrometer. you should be able to get one locally at the solar store where you got your parts or an auto parts store. Also pick up a gallon of distilled water. When you have these both in hand, come back here first and ask for further instruction on it's operation. Good Luck

    This is where I would start. Most auto part stores should have a hydrometer, they won't be much of an expense at all. It would be nice to check a cheap one against a more expensive one to verify that it's reading correctly.

    Understand that your batteries will be happy to kill them selves for you! Discharging them regularly below 50% State of Charge will be hard on most flooded batteries. 21 volts for a LVD is pretty low so if your kicking out by running a microwave you might be at a reasonably low SOC. I have a similarly sized battery bank, and I can over load my 1800 watt inverter before triggering a Low Voltage Disconnect unless my batteries are well below 50% SOC. You might have other things running that create a combined large load in the morning...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #33
    Re: Newbie needs advice on off grid system
    slogie wrote: »
    So, I know my Schneider inverter does have battery monitoring capabilities but the control panel is sold differently and the dealer does not have it in stock right now.
    Most of the major inverter manufacturers do not build the controls into their inverters, and require the separate purchase of the controls. There are two very good reasons:
    1) the inverters are stackable.... if you had 4 of those inverters, you wouldn't want to pay for 4 built-in control panels.
    2) Many folks want remote control of their inverter. With a separate control panel, you can mount it remotely if you wish.
    slogie wrote: »
    But from reading the books, I realize that the default LVD is 21.0V. I don't know if that is a correct level or if it can go lower.
    That is dangerously low from your battery's perspective.

    Suppose your inverter has a 3500 watt load and is 90% efficient. That means it is drawing 3888.89 watts from the batteries. Watts is Volts X Amps, so if your battery voltage at the time of the load is 24.0 volts, the current will be 162.04 amps. As the battery voltage drops the amps must go up to maintain the same power. When the battery gets to 21 volts the current is 185.19 amps. This is the limit of what your inverter can handle... the 21 volt LVD is to protect the inverter, not the batteries.

    Most full featured inverters, such as yours, have a LVD that is adjustable and can be set to a level that actually protects the batteries. Of course, you need a control panel to change the LVD.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Grinnin
    Grinnin Solar Expert Posts: 39 ✭
    #34
    Re: Newbie needs advice on off grid system
    slogie wrote: »
    So, I know my Schneider inverter does have battery monitoring capabilities but the control panel is sold differently and the dealer does not have it in stock right now. But from reading the books, I realize that the default LVD is 21.0V. I don't know if that is a correct level or if it can go lower.

    Seeing that I really don't know about these battery monitors, could any of you provide the name of a good one that I could try to find out here. Because, as you have all said, it would be great to know the level of the battery if it is really full or if it is really drained in the mornings so as to have an idea of what I have consumed from it throughout the night.

    21.0V is pretty low. There is no single "correct level" but for someone new to PV you probably don't want to set it lower.

    When I looked for info about your Schneider control panel, I didn't see any mention that it includes an amp-hour meter. It probably does. You'll probably want to confirm that. It may be "common knowledge" but I'm just not familiar with the Schneider inverters.

    Two common battery monitors are Bogart Engineering's Trimetric and Xantrex's LinkPro. I have a predecessor to the LinkPro. In winter I often wish I had the Tri-metric since it counts "days since last full charge" which may be more important in Maine than in Jamaica.

    There may be better monitors available now.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #35
    Re: Newbie needs advice on off grid system

    There is Nothing wrong with a Shunt based monitoring system, except in your case it's just a number / level of your batteries at some given point in time. It is NOT a integrated number that your Inverter / Charger that can use to control it's operation, those number's are going to be in Volts that your Combox or SCP have programed into them as a level of significance. As you mentioned the LDV, that is Volts. Your system will operate as a hybrid without the sell feature. Are you going to be up watching a battery monitor at 3:00 in the morning when the system says that this load is to big for the batteries to handle alone ? The Inverter will tell system to add some Grid Support to help with the load. To get the system to work automatically you to have Integrated controls, without them all you have is a cobbled up bunch parts than mean nothing to each other and numbers. As I mentioned before the Support features will only work if you have a Xantrex AGS on the Zanbus, without it the Automatic features will not work. Same is true if you intend to use the dod or soc as a trigger points you have to have integrated battery management.

    Battery Health is very Important. You mentioned the LDV set as a Default of 21v, that is very low and only serves as a low disconnect point for your Inverter Protection. Depending on the Voltage sag, maybe around 23.5v could be the setting required. ( notice that is in VOLTS and comes from the system voltage and not a shunt based stand alone Battery Monitor ). Yes you do need to get a hydrometer and watch the charge / discharge level of your batteries. I am suspicious of the Batteries you listed, in that they may not be a type that will give you longevity.Based on what you posted it would seem that you have been pulling them way below the 50% dod and that will kill them quickly, but without the system working correctly and the proper equipment that is going to happen and often.

    This is not about spending your money on a bunch of useless equipment that won't integrate into your system.

    http://solar.schneider-electric.com/product/conext-combox/

    http://solar.schneider-electric.com/product/conext-system-control-panel-scp/

    http://solar.schneider-electric.com/product/conext-battery-monitor/

    http://solar.schneider-electric.com/product/conext-automatic-generator-start-ags/
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