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  1. #1
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    Default What batteries for a 5kva inverter/charger

    I have a 5 kva axpert type inverter.

    At the moment I have 2 x 100ah semi-deepcycle batteries connected in series as its a 24v system.

    I only use it to power my alarm system , Wifi router and small 32" led tv and only for load shedding and power cuts.
    In the beginning the batteries would last about 5-6 hours but now a year later they only last 2-3 hours before the low voltage cutout of the inverter kicks in.

    Now my question is should I just expand on the current battery setup ie add 4 or 6 more 100ah batteries

    OR

    Should I go with 2 x 200ah gel batteries

    OR

    Should I go lithium and if I go lithium what size should it be.


    I would like to be able to run the alarm, tv and wifi for at least 8-10 hours for when we have long power cuts (seem to happen more often) and not have to replace the batteries every year.

    Any input would be appreciated

    Thank You

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    Default Re: What batteries for a 5kva inverter/charger

    At which voltage does it cut out?
    Please supply the individual voltages of the two batteries as they are now?
    Are the batteries identical products?
    This will assist in answering your post.

    Are the 5KW Axperts not 48V systems?
    Last edited by Subok; 2021/01/27 at 02:58 PM.

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    Default Re: What batteries for a 5kva inverter/charger

    You probably have Royals. Some people has/had issues with Royals not living up to expectations.
    Last edited by Spiceman; 2021/01/27 at 03:25 PM.
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    Default Re: What batteries for a 5kva inverter/charger

    Sounds like you run a very small load from a large inverter, a 1kva inverter would have used much less battery power than a 5kva use without a load.

    How many Watt's does the inverter show when you are running the load?
    Also check battery cycles vs soc.

    Say your usage is 200w and you run that for 10hours it is 2000w or about 83ah, so in such a case 2x 200ah will do to keep battery discharge at about 40% max
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    Default Re: What batteries for a 5kva inverter/charger

    Do you run the system monthly ? Batteries must work.
    There is no task too simple for some people to complicate !



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  6. #6
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    Default Re: What batteries for a 5kva inverter/charger

    My 2 cents, actually what I'm busy with right now.

    Quote Originally Posted by HiluxRoux View Post
    ... alarm system , Wifi router and small 32" led tv and only for load shedding and power cuts.

    ... expand on the current battery setup ie add 4 or 6 more 100ah batteries
    OR
    Should I go with 2 x 200ah gel batteries
    OR
    Should I go lithium and if I go lithium what size should it be.

    I would like to be able to run the alarm, tv and wifi for at least 8-10 hours for when we have long power cuts (seem to happen more often) and not have to replace the batteries every year.
    IF this is it, lets take some "big" numbers:
    Alarm = 10w
    Wifi = 10w
    TV = 50w
    = 70w
    Round up to 100w, then double that because you may add cellphones and what not later.
    = 200w

    10 hours = 10 x 200w = 2000wh

    24v: 2 x 200ah batteries = 200ah x 24v = 4800wh x 50% (lead acid 50% DOD) = 2400wh, fits the bill.
    24v lithium bank = 100ah x 24v = 2400wh x at 80% DOD = 1920wh, also fits the bill.

    Lithium IF treated right, good BMS, will last 10-15 years.
    Lead acid, maybe 5 years depending on frequency of use etc.

    But here is the thing: Why spend the monies on lithium if you don't use them every single day?

    Alarm is on 24/7.
    Wifi is on 24/7.
    TV maybe wot, 6 hours per day?

    I would have gone and bought a 12v 500VA Multiplus and a MPPT and some panels, and take the entire shebang off-grid, using lithium batteries.
    And If there are extended bad weather, the Multiplus has a charger, so use Eskom to top up.
    Or, get it al in place, then the MPPT and panels later.

    Ps. As I'm typing this, I'm busy balancing (top and bottom) a 200ah 12v 2nd Life lithium bank, having horse traded a 12v 500va Multiplus and a 12v 120amp BMS.
    My idea is to take 200w off-grid as far as possible with this little pure sine wave inverter and its 20amp charger.
    With solar only recharging the batteries daytime, the MP charger there as a backup, in case.

    Why spend monies if one cannot have some fun too along the way?
    Last edited by the_terrible_triplett; 2021/02/01 at 09:06 AM.
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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by Subok View Post
    At which voltage does it cut out?
    Please supply the individual voltages of the two batteries as they are now?
    Are the batteries identical products?
    This will assist in answering your post.

    Are the 5KW Axperts not 48V systems?
    Without these answers we will all just speculate

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    Default Re: What batteries for a 5kva inverter/charger

    My humble guess it is a 48V system.
    Or maybe a 3Kv inverter.
    Last edited by optics; 2021/01/27 at 06:33 PM.

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    Default Re: What batteries for a 5kva inverter/charger

    The core parts are in red ...

    Quote Originally Posted by HiluxRoux View Post
    I have a 5 kva axpert type inverter.

    At the moment I have 2 x 100ah semi-deepcycle batteries connected in series as its a 24v system.

    In the beginning the batteries would last about5-6 hours but now a year later they only last 2-3 hours before the low voltage cutout of the inverter kicks in.

    Now my question is should I just expand on the current battery setup ie add 4 or 6 more 100ah batteries

    OR

    Should I go with 2 x 200ah gel batteries

    OR

    Should I go lithium and if I go lithium what size should it be.

    I would like to be able to run the alarm, tv and wifi for at least 8-10 hours ...
    Based on the above ...
    Quote Originally Posted by Subok View Post
    Without these answers we will all just speculate
    The bank is done, replace one battery or add more, the remaining 1 y/o battery will draw the rest down faster.

    Having stated 2 x 100ah batteries ...
    Quote Originally Posted by optics View Post
    My humble guess it is a 48V system.
    THIS makes sense 3kva ... but still inconsequential, the batteries or a battery is EOL - because of overuse.
    Quote Originally Posted by optics View Post
    Or maybe a 3Kv inverter.
    Core question is: Which route to go ito new battery bank ... just though I'd share.
    Last edited by the_terrible_triplett; 2021/01/27 at 08:27 PM.
    Political Correctness
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  10. #10
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    Default Re: What batteries for a 5kva inverter/charger

    24 V 3kVA can still do Lithium batteries. You are just limited in terms of available options.

    One 2.4 kWh battery will probably do 5 hours in your scenario
    So I guess a 4kWh if you go DIY
    Last edited by Tiaan Pot; 2021/01/27 at 10:13 PM.

  11. #11
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    Default Re: What batteries for a 5kva inverter/charger

    Here is a quick view of what I was talking about, running off-grid with a small system.

    Picture one shows no Eskom used (Shore), now and then a teeny little bit pushed back into the house circuits ( -5w at the time), as it is connected to a wall outlet.
    Can also see the current power usage. My 2 screens and Intel server sits between 150w - 180w.

    Picture two is where I tell it to only recharge from 10am tomorrow morning for 11 hours, i.e. until 9pm AND because of this feature, no batteries are used during this time.
    Should be charged easily by 5pm at 20amps (+-280w).
    Times will alter between summer and winter.

    Picture three are the settings to use the lithium bank to a min SOC of 30%, so not pushing them hard at all.
    When SOC of 30% is reached I'm normally in bed, Pc off, so inverter reverts back to house grid tied power.
    Because the main system powers the entire house at night, I don't want to use batteries to recharge batteries, therefor the 10am Scheduled Charging setting.

    Notes:
    I use Victron's free ESS software on a Raspberry Pi to make all of this happen automatically.
    This first test run is done using one 12v 100ah bank.
    The 2nd 12v 100ah bank is still in assembly stage.

    I said before recharge via solar.
    Because the little MP is plugged into a house socket, the house being grid tied, by 10am I have a bit of spare solar power which means effectively the power comes from the panels via the main 5kva grid tied inverter into the house circuits.

    Why? Because I can ...

    Joking!!!

    It is a Hobby,
    this is our new camping system.
    So I though, why waste the lithium batteries? Why NOT use them every night?
    When we do go camping, my Pc is off, so I simply pick up the little setup and off we go.

    Still need a MPPT that can charge at 20amp, with panels to match, to recharge at the camp site. ... later ...
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    Political Correctness
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    Saw this in a pub - no idea why the wife does not see it so:
    I'm not opinionated ... I'm just always right!

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  13. #12
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    Default Re: What batteries for a 5kva inverter/charger

    I like TTT's idea best.

    Just something to ponder as well, the other day a friend bought two 200Ah gel batteries for his 24V system, for something like R2000 more he could have had a 150Ah 24V second life lithium battery. Same capacity, much smaller and lighter and a much much longer lifespan makes spending that R2000 more worth it.
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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by bigboy529 View Post
    I like TTT's idea best..
    Thank you.

    Ran for 4 hours on the 100ah 12v 2nd Life bank to 30% DOD with +-165w load.
    Recharged in 3:35 hours at 20amps back to full using 100% solar only.
    Took 340w to charged (538w - 198w = 340w)
    Considering changing it to 100w, that it can slowly charge the entire day ... will test that once the 200ah bank is in.

    Picture 1: Details from the 12v 500va Multiplus, recharging whilst powering the loads. No Eskom used, 100% solar.
    Picture 2: Details from the 48v 5kva Multiplus II, power the house, heating a geyser and charging the little 500va.

    The camping system works beautifully .. "grid tied", solar recharged and all that.
    I'm smiling!
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    Last edited by the_terrible_triplett; 2021/01/28 at 03:12 PM.
    Political Correctness
    Political Correctness is a doctrine, fostered by a delusional illogical minority, rabidly promoted by a unscrupulous mainstream media which holds forth the proposition that it is entirely possible to pick up a turd ... by the clean end!

    Saw this in a pub - no idea why the wife does not see it so:
    I'm not opinionated ... I'm just always right!

  15. #14
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    Default Re: What batteries for a 5kva inverter/charger

    Yes sorry it is 3kva 24v inverter charger

    Its silver calcium semi deep cycle batteries identical and bought new bit less than a year.

    I do not know the voltage at cut out. Will check next time.

    It has a 30a charger integrated and 60a solar (not in use atm)

    Someone suggested that the charger is to big and may have damaged batteries 🤷🏼#♂️

    Its only being used as a ups atm so only when load shedding or power cuts.

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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by HiluxRoux View Post
    Someone suggested that the charger is to big and may have damaged batteries 🤷🏼#♂️
    Definitely possible if the settings where not correctly set.
    Also the fact that they could have been run too low to frequently.
    Political Correctness
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    Saw this in a pub - no idea why the wife does not see it so:
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  17. #16
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    Default Re: What batteries for a 5kva inverter/charger

    With settings for AC charge of 2, 10, 20 and 30A it is up to the user/installer to adjust the current as it seems like the solar side is not used. For the 48V unit. The 24V only has 20 and 30A settings.
    I would rather have the strong charger and set lower value than have a smaller charger.
    Last edited by ekkekan; 2021/01/28 at 09:02 PM.

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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by the_terrible_triplett View Post

    24v: 2 x 200ah batteries = 100ah x 24v = 2400wh / 2 (lead acid 50% DOD) = 1200wh to 50% DOD - need 4 x 200ah batteries.
    24v lithium bank = 100ah x 24v = 2400wh x at 80% DOD = 1920wh
    Just a quick glance it seems on the lead acid you applied 50% twice. 2 x 100Ah to 50% DOD yields 1200Wh. Should the 200Ah not yield 2400Wh to 50% DOD?

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  20. #18
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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by ekkekan View Post
    Just a quick glance it seems on the lead acid you applied 50% twice. 2 x 100Ah to 50% DOD yields 1200Wh. Should the 200Ah not yield 2400Wh to 50% DOD?
    Yes he did, well spotted.

    To make things even worse , the 2 x 200AH gives more than twice the capacity and safety factor for a rainy day than 1 x 24V 100AH Lithium.

    --------

    When it comes to these choices it really is horses for courses. Li is OK for daily cycling, but Lead Acid performance is far superior for UPS/Standby/Leisure duty cycle.
    Last edited by Fluffy; 2021/01/30 at 06:44 PM.
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  22. #19
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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by Fluffy View Post
    Yes he did, well spotted.

    To make things even worse , the 2 x 200AH gives more than twice the capacity and safety factor for a rainy day than 1 x 24V 100AH Lithium.

    --------

    When it comes to these choices it really is horses for courses. Li is OK for daily cycling, but Lead Acid performance is far superior for UPS/Standby/Leisure duty cycle.
    At least with lithium batteries we have moved away from the Ah rating - which only tells half the story.

    Except for smaller lithium batteries that's stil on Ah and not kWh
    Last edited by Tiaan Pot; 2021/01/30 at 08:45 PM.

  23. #20
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    Default Re: What batteries for a 5kva inverter/charger

    Quote Originally Posted by Tiaan Pot View Post
    At least with lithium batteries we have moved away from the Ah rating - which only tells half the story.

    Except for smaller lithium batteries that's stil on Ah and not kWh
    The other half of the story will be that the lead acid (2 x 200Ah) would have provided 4800Wh vs 2400Wh for the lithium for the rainy last 7 days.

    Each one has it's place. Daily cycling vs storage for rainy days. One of the few long periods in summer time with low PV.
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    Last edited by ekkekan; 2021/01/31 at 01:11 AM.

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