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Simple "Lithium" UPS system


Richwost
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Greetings...

This has absolutely nothing to do with solar.  I need a very simple UPS system to run my LED TV, the Explorer and one led light.  No more than that. I have a 20kva Generator, but If I am watching a Test and the power goes off, I can switch to the generator - either automatically or manually (which I far prefer) - but I don't have to tell you how disruptive that is.  If I am out and recording the Boks, then I come back to fine absolutely nothing.

Now for the rub.  Those of you who know me from previous correspondence on the Forum (more than a year ago - hell how time flies) know that I am passionate about Lithium batteries.  I bought a 50Ah Lithium battery about 6 months as well as a special C-Tek lithium charger.  The battery is about half the physical size of a car battery.  I attach specs.

This battery cost me R10k and I bought it for a certain purpose which I've now decided against.  So I have a brand new Lithium battery being kept perfect by the Lithium charger for the UPS.

Where do I go from here?  I would really appreciate your help...

50ah battery.pdf

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Hi Richwost.

 

Sounds like a simple 12V inverter would work, but it isn't always so simple.

I don't know the specifics of your TV etc, but modern LED TVs use under 200W. I would think a DSTV decoder uses less than 50W and the LED light another 10W.

So lets say you need a 300W 12V inverter.

 

Your 50Ah Lithium battery has 480W of energy in it at 80% DoD. Should last 2h, more if the TV is off.

 

I would think a Victron Phoenix 800VA would be a good fit, but does not have a transfer switch

https://powerforum-store.co.za/collections/inverters/products/victron-phoenix-12-800-schuko-outlet

The Ctek lithium charger is a 5A unit. You will be drawing 20A from the battery, so recharging the lithium will take much longer.

 

The better option would be a Victron MultiPlus Compact 12V 800VA. This has a transfer switch and lithium charger built in!

 

https://powerforum-store.co.za/collections/inverters/products/victron-multiplus-c-12-800-35-16

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Another option would be buying a cheap 650VA UPS, under R1000, pulling out the Lead Acid battery and connecting the Lithium instead. For this setup, you don't want the UPS to charge the Lithium battery, so a diode would need to be connected between the UPS and the battery to prevent charging.

Edited by Travis
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10 minutes ago, Travis said:

For this setup, you don't want the UPS to charge the Lithium battery, so a diode would need to be connected between the UPS and the battery to prevent charging.

It might not even matter. Many UPSes have no three-stage charging anyway, instead just floating the battery at 13.5V (or thereabouts) permanently, and also has no real high power charging capacity either, so it might be perfectly adequate. If it floats too high, eg at 13.8V, what you could do is just add two back-to-back diodes to introduce a bit of a drop (0.6V typically) to get it closer to around 13.2V. It would have to be some pretty beefy diodes though, and they are going to dissipate a good 10W of heat at full load :-)

Of course, some kind of BMS solution or balancing or even just a temperature sensor with disconnect might still be a good idea. You don't want the equivalent of a large Galaxy S6 next to your television :-)

@PJJ, didn't you have a spare 800VA unit, or am I misremembering this?

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3 minutes ago, plonkster said:

It might not even matter. Many UPSes have no three-stage charging anyway, instead just floating the battery at 13.5V (or thereabouts) permanently, and also has no real high power charging capacity either, so it might be perfectly adequate. If it floats too high, eg at 13.8V, what you could do is just add two back-to-back diodes to introduce a bit of a drop (0.6V typically) to get it closer to around 13.2V. It would have to be some pretty beefy diodes though, and they are going to dissipate a good 10W of heat at full load :-)

Of course, some kind of BMS solution or balancing or even just a temperature sensor with disconnect might still be a good idea. You don't want the equivalent of a large Galaxy S6 next to your television :-)

@PJJ, didn't you have a spare 800VA unit, or am I misremembering this?

You are right. Especially on a spall UPS. Probably charges at <1 AMP for their 7Ah LA batteries.

 

According to the Relion website, the RB50 battery has a built in BMS.

 

This kind of UPS should be fine

https://www.rebeltech.co.za/8373-rct-850va-line-interactive-ups.html

 

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13 minutes ago, plonkster said:

@PJJ, didn't you have a spare 800VA unit, or am I misremembering this?

The guy where I bought mine from had 2, but both have been sold, but CurrentAutomation have a good price for the 12V 800VA Multi,  R5636 excl, so R6481 Incl

 

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I am smiling.

From 2 x 102ah cheap maintenance free batteries and a R1000 bucks cheap UPS to Lithium batteries and a Victron Multiplus, you guys forgot the BMV. 

Something about 'engineers' over-designing a simple and easy solution comes to mind. :D

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7 minutes ago, The Terrible Triplett said:

forgot the BMV

Don't need the BMV if you use a Multiplus and there are no DC-chargers. The Multi can keep track of SoC perfectly fine provided it does all the charging.

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1 minute ago, plonkster said:

The Multi can keep track of SoC perfectly fine provided it does all the charging.

You want quality, get a Multi. But I am not so sure about the +-20ms switch-over though, IF the DSTV or TV goes off, could be a dampener.

But dang bro's, it is expensive compared to stock standard off the shelf UPS for ad-hoc Eskom failures.

2 x 102ah batts will carry the DSTV and TV for a number of hours.

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5 minutes ago, The Terrible Triplett said:

20ms switch-over

Turn on the "UPS function". The 20ms switchover was on the older units, it's gotten better. The specs also says "less than 20ms", while many off the shelf UPSes can do a mere 16ms at best, so you will likely it's as good as a UPS these days.

The UPS function makes the Multi sync with the grid, but it also makes it more picky about the AC quality, which is why that option even exists.

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2 minutes ago, plonkster said:

The UPS function makes the Multi sync with the grid, but it also makes it more picky about the AC quality, which is why that option even exists.

Reminds me, a cheaper UPS has more protections than solar inverters.

For most solar inverters passes what comes in "as-is" out other side.

Therein my personal preference, which is NOT the solution here, of on-line UPS'es.

 

2 minutes ago, plonkster said:

The 20ms switchover was on the older units, it's gotten better.

The UPS'es are averaging on 20ms, but somehow they don't affect connected equipment in the stuff switches off.

But it can also happen.

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Depending what you want to do in future just some info . Power consumption Ds TV 30 watt .  40 inch Samsung led TV 85 watt . 32 inch Hi sense led  45 watt + 3-10 watt led light . A simple Square wave 600 watt inverter cost about R600 . If your charger is good  your battery should give about 3.5 hrs of use . These inverters is good enough vir TV and lights but useless for anything else . I was using it for years before installing solar with no problems just a light buzz when TV is switch on . 

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On 2018/06/25 at 9:02 AM, Richwost said:

Greetings...

This has absolutely nothing to do with solar.  I need a very simple UPS system to run my LED TV, the Explorer and one led light.  No more than that. I have a 20kva Generator, but If I am watching a Test and the power goes off, I can switch to the generator - either automatically or manually (which I far prefer) - but I don't have to tell you how disruptive that is.  If I am out and recording the Boks, then I come back to fine absolutely nothing.

Now for the rub.  Those of you who know me from previous correspondence on the Forum (more than a year ago - hell how time flies) know that I am passionate about Lithium batteries.  I bought a 50Ah Lithium battery about 6 months as well as a special C-Tek lithium charger.  The battery is about half the physical size of a car battery.  I attach specs.

This battery cost me R10k and I bought it for a certain purpose which I've now decided against.  So I have a brand new Lithium battery being kept perfect by the Lithium charger for the UPS.

Where do I go from here?  I would really appreciate your help...

50ah battery.pdf

I am using a similar solution for my NAS / router/Network switch for quite a while now  except I use a Victron Filax changeover which is fast ( https://www.victronenergy.com/transfer-switches/filax-2)

a 20 AH Lifepo4 with cheap Charge controller - https://www.ebay.co.uk/itm/6v-12v-Lead-Acid-3-6v-7-2v-NiMH-6-4v-12-LiFePO4-Li-Ion-solar-charge-controller/292584753349 with a 20 Watt panel 

and a generally good quality inverter with minimum fan noise - https://www.ebay.co.uk/p/Inverter-Power-Bestek-300w-DC-12v-to-230v-AC-Car-Converter-Electronic-Dual-USB/5017022038

why the wired combo ?-:)  most of the components were left over from my earlier projects except the charge controller 

 and I needed something to keep my internet/server  going when I am playing around with various assistant setups in the Victron 

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Many thanks to those of you who took the time to reply to my conundrum.  Is my mind now more clear on what to do?  Yes!!!  Diodes?  I had to refer to my Oxford Dictionary.  That convinced me further to say within my comfort zone!!  That normally means more money and less anguish.  

I think that the Victron 12V 800VA Multi (or even the 500VA) is what I will go for (thanks Travis) and I will get hold of Current Automation - thanks PJJ.  

My local friend who is big into alternative energy on his farm tells me that a UPS is the single most dangerous piece of equipment in your house and the one that is most likely to start a fire.  Not very comforting at all?  Would that be true of what I am proposing to do?  Naturally I will get the UPS professionally wired into the DB.  

I have now spoken to Current Automation, and their prices are unbeatable.  However I am going to buy mine in PE.  Higher price hopefully means that I will get backup from them - programming of the Victron etc.

Many thanks again.

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51 minutes ago, Richwost said:

Many thanks to those of you who took the time to reply to my conundrum.  Is my mind now more clear on what to do?  Yes!!!  Diodes?  I had to refer to my Oxford Dictionary.  That convinced me further to say within my comfort zone!!  That normally means more money and less anguish.  

I think that the Victron 12V 800VA Multi (or even the 500VA) is what I will go for (thanks Travis) and I will get hold of Current Automation - thanks PJJ.  

My local friend who is big into alternative energy on his farm tells me that a UPS is the single most dangerous piece of equipment in your house and the one that is most likely to start a fire.  Not very comforting at all?  Would that be true of what I am proposing to do?  Naturally I will get the UPS professionally wired into the DB.  

I have now spoken to Current Automation, and their prices are unbeatable.  However I am going to buy mine in PE.  Higher price hopefully means that I will get backup from them - programming of the Victron etc.

Many thanks again.

UPS' generally don't catch fire, but some cheap UPS don't have any protection on the battery line so if something goes wrong, it doesn't stop. More expensive UPS' have fuses, or polyfuses (in layman's terms, self resettable fuses). 

I have yet to see a UPS catch fire, and I've been in the IT game since 1997. BUT, it's not impossible. It's an electrical appliance and for that matter just about anything else with electricity could cause a fire. 

For your own safety, make sure you have ample protection. Fuses on the batteries, and overload protection on the AC side. Since you want to use Lithium, make sure you don't exceed the BMS' charge and discharge rates. The specsheet you have attached says it can charge and discharge continuously at 1C / 50A. Although you'll probably discharge slower / at lower Ampere, don't recharge at higher than 50Ah. 

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4 hours ago, SilverNodashi said:

I have yet to see a UPS catch fire, and I've been in the IT game since 1997.

Adding to your post.

Have posted on the forum somewhere pictures of where a UPS battery bank blew up. Literally exploded. Acid and parts of battery casing all over.

Over and above the fuses, from what I have seen the problem also can come from when the battery/batteries are shorting. Had a nasty burn from a bolt on a "perfect" (ito volts) battery that was building up some serious heat. Learnt that lesson touching that pole that day to disconnect the wire.

UPS'es need servicing and their batts checking, same as solar, maybe less frequent, depending on frequency of use.

Edited by Guest
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