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Posted

I am trying to put together a QUALITY small system for load shedding. Something a bit better and more modern than a mass produced trolley  with lead acids and noise and modified sine etc (not that these solutions do not serve an important function)

So if someone can help - the system I have in mind (for my staff) is something like this:

Charger: Blue Smart IP65s Charger 12/5(1) 230V            approx R 1.6k 

 Battery: Blue Nova 13V Battery 22Ah = 286Wh                  approx R1.94k

Inverter:  VICTRON PHOENIX 12/375-230V VE.               approx R 2.1k

manual switch over.

 This is a system of very high quality even though very small - I cannot provide a staff member with a kind of bonus that collapses in a year. The quality is more important than the size or multi function utility.  Ie not cheap skate stuff. Also in a year I can add a battery and later maybe panels etc. It is a capital investment

However, no auto switch over   !!!

This is a major problem. I know without any doubt that the system will be used during a load shed and then forgotten on! It will then run down to zero and harm the batteries and also not be ready for the next load shed and ends up as a major disappointment for me and them. 

I need an ATS!!

Can someone assist with advice?

  • 3 weeks later...
Posted (edited)

I would also add a battery protector to not rely on the BMS to cut out on low voltage. The Victron is far less than a R1000.

At 360W draw from the inverter the battery could be flat in 40min.

Edited by Scorp007
Posted

You mean i can make do with a smaller inverter?

what do you mean "The Victron is far less than a R1000."  The charger or the inverter? Available for less than R 1000?

Tx for your help.

 

Posted
3 hours ago, Clivevan said:

You mean i can make do with a smaller inverter?

what do you mean "The Victron is far less than a R1000."  The charger or the inverter? Available for less than R 1000?

Tx for your help.

 

I meant the Victron battery protector at less than R1000 to prevent the battery from discharging too low. The battery would cost a few times the price of the battery protector.

Posted

Yes quite right.  But the economics is maddening. The upshot of adding all the bits and pieces is a unit with a small high quality cost effective battery; a small high quality cost effective panel/inverter/controller and comparatively VERY expensive automatic transfer switch, battery protection, fuses, etc. The latter category of items cannot be downscaled.

So I end up tempted to break my own rule and buy cheap or go easy on battery protection etc🥴 Only to create the same problems so many people suffer with trolley backups or fancy looking off-the-shelf back-up units.

Posted

I have just last week build a circuit that you can use for battery protection. You need to add a starter relay that can carry 100A.

Search for TL431 Circuits on google. I could not believe how easy it is to build.

All the parts including a 10A relay to drive the 100A starter relay was about R100 

I used a small multiturn pot and adjusted it to switch off at 12.2v which is about 60% of an AGM if you run a lithium you can adjust it to where you want it to cut off.

I know it is not a Victron battery protector but if you have to build 10 of these you will  be able to do it cheap. 

you can Add a contactor that is driven by the incoming AC the moment the contactor gets incoming AC it pulls in supply the plug with AC when the AC fall away the contactor will open and the  NC line can be used to switched the Starter relay connecting the battery. I know this is a nasty way to do this but it works. 

 

Posted

There is an easy way to do ATS, but it will be somewhat dangerous. You need to have a dead time switching between the two supplies - as they will not be in phase with each other. Honestly, I suggest looking at a 500VA Multiplus - it adds about R3500 to the cost, but in the long run it will be worth it IMO. (and also a bigger battery, the 20A discharge rate is a bit limiting. Or look at the Freedom Won or BSL alternatives, IIRC they have higher discharge rates)

Posted
2 hours ago, Clivevan said:

Thank you gentlemen. Appreciate your assistance.

Interesting suggestions to get to a simple solution of providing 350W of power during LS.

I agree with @P1000

If making a auto change over and it fails and the grid and battery power AC meets then even the best inverter is fried.

When providing for staff a self contained UPS box and battery will still be the easy way. If it does not work as intended only 2 items to check. The adjustable discharge level inside some units remains a winner. It is the reason why I think the trolley units got a bad name. But then looking at the number of happy vs unhappy the trolley stands out as a great product. KISS 🤔

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