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    Default Mecer Inverter - 8 Batteries - Real World Figures

    Thought I'd post some examples from the office.

    When installing the system I did homework, and was convinced that 8 batteries would be more than sufficient, sad to say it is not.

    This is essentially our dedicated plug circuit, so only the computers are on it (no printers).

    About 1kw, 20amps.
    8 batteries in two banks of 4 (48v system)

    Loadshedding started just after 10am. If I leave all the lights on in the office the usage is just under 1.3kw (replaced lights with LED tubes from Makro). Just before 10:10 I switched off most of the lights, leaving on the absolutely essential ones on.

    10:10 - Battery 50.70v
    11:10 - Battery 49.10v
    12:10 - Battery 47.90v
    13:10 - Battery 47.10v
    14:10 - Battery 46.20v

    This means we are drawing the batteries down to below 30% which is not good. Busy finding out now if we could add another bank, but I am not sure if the inverter will be able to charge another 4 batteries.

    This exercise opened my eyes to the actual usage of for example lights. We had probably close to 40 fluorescent tubes in the office. I removed all the tubes, and in almost all the fittings replaced it with a single, or dual Phillips LED tube, this alone reduced our consumption by over 1kw.
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    Last edited by Dirk; 2019/03/20 at 02:12 PM.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Should a 48V system battery voltage not be around 54V fully charged?
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by Rudi.Oost View Post
    Should a 48V system battery voltage not be around 54V fully charged?
    Yes it is, but the moment when you switch does it show 48.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    What size are the batteries?
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by Prof View Post
    What size are the batteries?
    Probe M31PMF, 110ah batteries.
    http://www.probebattery.co.za/Produc...urpose-battery
    Last edited by Dirk; 2019/03/20 at 01:54 PM.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    From the top of my head I think there is something wrong with one of your batteries. I am not sure it should drop 4V when to load kicks in.

    Maybe one of the cells or batteries is damaged.

    Can you test each battery and make sure they are the same?
    Disconnect all the loads, and then switch the inverter on. Measure each batteries voltage. They should all be the same voltage.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Updated the first post with the last figure at 14:10.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Thanks for sharing your details on the system.

    Dirk at an average load of 20A over the 4 hour period those 8 batteries are not looking good out of a capacity point of view. I say this by comparing my own baby of 1 bat being discharged at 14A. The discharge took place before solar could really contribute much and also a test after 17h00 with about no sloar.
    Last edited by ekkekan; 2019/03/20 at 02:23 PM.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by Dirk View Post
    10:10 - Battery 50.70v
    11:10 - Battery 49.10v
    12:10 - Battery 47.90v
    13:10 - Battery 47.10v
    14:10 - Battery 46.20v

    This means we are drawing the batteries down to below 30% which is not good.
    The Volts you see is at load, not at rest
    To read Battery state of charge from voltage the battery must be without load at rest for at least an hour or more

    Meaning your system I guess is probably at 50% State of charge

    Note your top graph supports my comment
    Last edited by Dungbeetle; 2019/03/20 at 02:33 PM.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Yes definitely at load.

    I called Probe, they are confident that these batteries can run to 10.75v, so 43v, we ended load shedding on 46.2, so if that is the case then I am happy, unless the 4 hours suddenly become 6 hours, then we may have an issue.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by Dungbeetle View Post
    The Volts you see is at load, not at rest
    To read Battery state of charge from voltage the battery must be without load at rest for at least an hour or more

    Meaning your system I guess is probably at 50% State of charge
    Thanks for this piece of advice. I normally switched off my load at 12V under load which meand my bat was not even close to 50% DOD.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by Dungbeetle View Post
    The Volts you see is at load, not at rest
    To read Battery state of charge from voltage the battery must be without load at rest for at least an hour or more

    Meaning your system I guess is probably at 50% State of charge

    Note your top graph supports my comment
    100%, and believe it or not that el cheapo Inverter factors that in when it calculates and reports SOC.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by Dirk View Post
    Yes it is, but the moment when you switch does it show 48.
    20A x 4 hours = 80AH used.

    Batteries 2 x 110AH (at 48V) = 220 AH.

    So you used under half capacity. Consistent with the graphs above.

    ——————

    Your biggest problem with schedule 5 and higher load shedding is going to be getting back to 100% capacity between sheds.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Hi Dirk, is this the Mecer/axpert solar inverter? Do you have solar connected or does it charge from mains only?

    i am looking at this setup, mecer/axpert 5kv solar inverter with 2x 4 battery banks of 100ah each. Giving me 800ah 48v. With 1000watts solar coupled to mains. Will keep the oven and geyser on mains. Hoping to have the rest of the house on solar only by doing so. Total cost around R40k. System should pay for itself in 3 years or less. Will change geyser to solar eventually.

    Hopefully the solar will help as it charges constantly during the day while there is draw. Dont know if it will cover the draw 100% to have full batteries by sundown.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Dirk, buddy of mine runs 2 x 5kw mercer inverters in parallel. He had some issues and had to upgrade the software/firmware - U1 and U2 to fully charge his 3 banks of batteries. He was getting some funny readings.

    I would rather add solar pannels as the next step as you did not mention that you have pannels attached.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by LandyLove View Post

    i am looking at this setup, mecer/axpert 5kv solar inverter with 2x 4 battery banks of 100ah each. Giving me 800ah 48v. .
    Just remember because you have 4 in series per bank and 2 banks you actually only have 200Ah @ 48V=9.6kWh.

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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by ekkekan View Post
    Just remember because you have 4 in series per bank and 2 banks you actually only have 200Ah @ 48V=9.6kWh.
    I am so confused. So for how long will I be able to draw 2000 watts off 200ah @ 48V?
    this is what I measured directly after the power came on last night when all the fridges and inverter aircon started up. Sonit isnsafe to assume that it is more or less my maximum load without geyser and oven. I measured it by typing i001 into my prepaid meter.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by LandyLove View Post
    I am so confused. So for how long will I be able to draw 2000 watts off 200ah @ 48V?
    this is what I measured directly after the power came on last night when all the fridges and inverter aircon started up. Sonit isnsafe to assume that it is more or less my maximum load without geyser and oven. I measured it by typing i001 into my prepaid meter.
    TAKE THE AIRCON OFF THE INVERTER

    How long - 9600Wh of energy available. You draw 2000W. So basically about 4 hours.

    TAKE THE AIRCON OFF THE INVERTER

    Do that for a few weeks, then throw the batteries away and replace with new ones.

    TAKE THE AIRCON OFF THE INVERTER

    Realistically that 9600Wh should actually be about 2000Wh to 3000Wh, depending on the battery type. So 1 - 1.5 hours absolute max if on a regular basis.

    TAKE THE AIRCON OFF THE INVERTER

    --------------------------

    Did I mention

    TAKE THE AIRCON OFF THE INVERTER

    You cant run an Aircon off a battery unless you have a half a Bar system and very expensive batteries and deep pockets.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Just checking something here, my aircon is an inverter unit running off mains at the moment. Do you say that I will kill the batteries if I run the inverter a/c of the mecer axpert inverter system?

    What I am basically getting at is:
    i want to install a 5kva mecer inverter with 1000watt solar panels and 8x 100ah batteries in 2 banks. Giving me 200ah at 48V. (Hope ive got this right now)
    will this take my average 3bedroom home off eskom excluding the geyser and oven and aircons? Fridges, led lights, tv, alarm, cctv and plugs only.

    Will the 200ah be enough to last all night?
    Will the 1000watt solar panels be enough to keep the batteries full during the day?

    i dont want to spend a wheelbarrow full of cash and be disappointed with the outcome.

    i am not trying to go off-grid, i merely want to reduce my electricity bill by running low power appliances and fridges off solar while having the luxury of a UPS system.
    Last edited by LandyLove; 2019/03/22 at 08:47 PM.
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    Default Re: Mecer Inverter - 8 Batteries - Real World Figures

    Quote Originally Posted by LandyLove View Post
    Just checking something here, my aircon is an inverter unit running off mains at the moment. Do you say that I will kill the batteries if I run the inverter a/c of the mecer axpert inverter system?

    What I am basically getting at is:
    i want to install a 5kva mecer inverter with 1000watt solar panels and 8x 100ah batteries in 2 banks. Giving me 200ah at 48V. (Hope ive got this right now)
    will this take my average 3bedroom home off eskom excluding the geyser and oven and aircons? Fridges, led lights, tv, alarm, cctv and plugs only.

    Will the 200ah be enough to last all night?
    Will the 1000watt solar panels be enough to keep the batteries full during the day?

    i dont want to spend a wheelbarrow full of cash and be disappointed with the outcome.

    i am not trying to go off-grid, i merely want to reduce my electricity bill by running low power appliances and fridges off solar while having the luxury of a UPS system.
    If I can offer something here on saving. If you have space for say 4x300W panels you could go the grid-tied route so that the inverter takes the max the sun can offer and only take the rest from the GRID. You need not export by using a grid-tie. You could use the Goodwe which does this and also provide back up although at a reduced level than the 5KVA.
    Batteries are still a comsumable and adds cost big time if used off grid. Yes the negative is it only works when you have got an active grid.
    What I like about the Solis there is no load to consider on the inverter.
    Nothing wrong with using a Solis grid-tie and an Axpert for the back up portion with batteries if you don't go the Goodwe route.
    I hope this makes sense.!!!

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