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Axpert 5Kva and battery questions


Abnormal
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Hi

 I am considering setting up a UPS system to power a few items. The main objective would be to provide lighting during outages and run the fridge, alarm and garage door.

 

I have done a calculation but don’t seem be able to find it now.

Possibly around 1200W for lights (max) but less than half of them are usually on

Maybe another 300w for the fridge

Maybe another 200w for other stuff alarm etc.

The DB board is currently separated so that one circuit has lighting loads fridge and garage doors.

The plugs are on another circuit.

 

 

Inverter I am looking at buying an Axpert KS KVa 4000kW PWM model.

For now it would simply be connected to Eskom and some batteries for backup.

Maybe later I will add a PV array.

 

It seems like a better idea to run this on the lighting loads only to prevent an overload scenario.

What would happen if I run this inverter on all loads instead of isolating it and

load exceeds the 4000kw limit. Would it switch over to Eskom power should the max load be exceed or would it shutdown?

 

Then Batteries, I have read up info on

Lead acid

Lead GEL

AGM

Lead crystal

LPF

 

But I am uncertain which may be best. i.e. cheapest with most available Amp hours to be used during an outage but does not necessarily need to have the capability to be cycled as many times.

  

How does 4 x 12v 170AH Narada batteries compare to

1 x Pylon US2000B 2400KW in terms of capacity?

 

   

Would the Narada batteries be 170Ah x 48v = 8160 at 50% DOD = 4080KWh capacity

vs 2400kw capacity on the Pylon

 

 What would be a recommended setup for this scenario? 

Which batteries should i consider?

 

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9 minutes ago, Abnormal said:

Inverter I am looking at buying an Axpert KS KVa 4000kW PWM model.

For now it would simply be connected to Eskom and some batteries for backup.

Maybe later I will add a PV array.

I would not power anything except perhaps the smallest gate motor with a PWM. The losses due to the in-efficiencies PWM will more than justify spending a little extra for a MPPT model.

13 minutes ago, Abnormal said:

IIt seems like a better idea to run this on the lighting loads only to prevent an overload scenario.

What would happen if I run this inverter on all loads instead of isolating it and

load exceeds the 4000kw limit. Would it switch over to Eskom power should the max load be exceed or would it shutdown?

 The inverter will go into bypass mode if you overload it (subject to you enabling that feature). I would try and keep the inverter below 80% of its rated capacity. I don't have any empirical evidence but I think many inverters' lifespans are shortened due to high loads.

20 minutes ago, Abnormal said:

 But I am uncertain which may be best. i.e. cheapest with most available Amp hours to be used during an outage but does not necessarily need to have the capability to be cycled as many times.

  

How does 4 x 12v 170AH Narada batteries compare to

1 x Pylon US2000B 2400KW in terms of capacity?

 

   

Would the Narada batteries be 170Ah x 48v = 8160 at 50% DOD = 4080KWh capacity

vs 2400kw capacity on the Pylon

 

 What would be a recommended setup for this scenario? 

Which batteries should i consider?

 

Your maths is spot on (what is a decimal between friends). What needs to be included is that you would want to discharge the Pylon to 80% so the Pylon's capacity would be 1.920 kWh The difference between them would be the number of cycles.

If you do not need the capability for many cycles then standby batteries will be the answer. If however you plan/need to have numerous cycles I don't think a Pylon can be beat.

You battery bank size is determined by your over-night load.

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Hi Thanks for the Quick response Chris

 

There is a fair difference in price.

KS 5KVa PWM = R6k and  

MKS 5Kva MPPT = R11k from what i can find.

 

Don't know if or when I would do the PV array as I wanted to start with just back up power.

PWM is just for for solar charging right? Conversion back should be the same?

Is MPPT that much better, from what i read it seems to be marginally better. But of course I have no experience at all. 

 

So 2x Pylons at 3.840KWh :) are going to be about the same capacity as the 4 x 170AH 12v batteries.

Are there options for standby batteries which may be cheaper? Those Narada's were around R5k each.

Will the Axpert be fine with charging the Pylons?

 

If I really go all the way and get 2 x Pylons then I may as well get a PV array and get some savings as well.

Was initially looking for the cheapest option to keeps the lights running :)  

 

 

 

 

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58 minutes ago, Abnormal said:

There is a fair difference in price.

KS 5KVa PWM = R6k and  

MKS 5Kva MPPT = R11k from what i can find.

 

Don't know if or when I would do the PV array as I wanted to start with just back up power.

PWM is just for for solar charging right? Conversion back should be the same?

Is MPPT that much better, from what i read it seems to be marginally better. But of course I have no experience at all. 

A MPPT is 30% (or greater) more efficient than a PWM. Fine for small applications but comes back to bite you on the arse on bigger installs. Both PWM and MPPT are technologies associated with solar charge controllers so they both for solar charging.

1 hour ago, Abnormal said:

So 2x Pylons at 3.840KWh :) are going to be about the same capacity as the 4 x 170AH 12v batteries.

Are there options for standby batteries which may be cheaper? Those Narada's were around R5k each.

Will the Axpert be fine with charging the Pylons?

The difference is the residual energy. The Naradas  will give you an extra 50% in an emergency whereas the Pylons on 20%. Other than this extra capacity to be used when the chips are down not normal cycling the lead acid batteries hold no advantage over LiFePO4. I would still if your aim is to have backup power go with the Naradas. They are in fact standby batteries. If you want to cycle then I would go with the Pylontech. 

Axperts have only been approved for use with Pylons in the last 9 months and there are some tweaks I would make  but essentially yes Pylons and the Axpert are compatible.

 

 

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1 hour ago, Abnormal said:

MKS 5Kva MPPT = R11k from what i can find.

So 5k to add an MPPT? Get the PWM model and buy a Victron BlueSolar MPPT (or SmartSolar) later. Well, to get the same capacity that way will cost more, but it buys you time.

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Plus one on what Plonkster said.

Will add though, the batteries, you are looking at a number of years on standby on both ranges.

The question you have to aks yourself, when, or if, you want to go solar?

If no, not for a long time, like 5+ years, the go for the cheaper batteries. Even Royals if you can find them quite a bit cheaper than Naradas. 

If yes, in a year or two, do not go for Naradas or any cheap battery. You will try and sell it all and buy new.

Most of us have bought on what we researched, we where advised. Yet in the end, once we started, the whole thinking changes. Believe that, we have a oil tanker full of T-Shirts here. :-)

That is only on the batteries. The PWM / MPPT, that stands as Plonkster said. Save the money now, buy later If you go for panels.

Chris Hobson has endless experience on Axpert implementation and best uses, him being off-grid and all. You cannot get more real life experience than that.

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On 2018/06/08 at 10:05 PM, The Terrible Triplett said:

Chris Hobson has endless experience on Axpert implementation and best uses, him being off-grid and all. You cannot get more real life experience than that.

It is a bit like spending most of your day in the kitchen - eventually you'll learn how to use the Snackwich maker.

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