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1 hour ago, Speedster said:

The PUP is lead acid while the Ratel is lithium

I assume you believe that Li-Ion is superior to lead acid for all applications?

The following is from another esteemed contributor on the 4x4 Community forum: https://www.4x4community.co.za/forum/showthread.php/339295-What-batteries-for-a-5kva-inverter-charger

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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5 minutes ago, Richard Mackay said:

I assume you believe that Li-Ion is superior to lead acid for all applications?

The following is from another esteemed contributor on the 4x4 Community forum: https://www.4x4community.co.za/forum/showthread.php/339295-What-batteries-for-a-5kva-inverter-charger

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.

Having the batteries float at near 100% they behave very differently. I have a ratel (415 I think) that I was expecting to be in need of new batteries by now - about 2 years of service. It still manages to carry me through about 4h15 of power. When it was new it could do just about 4h30.

SLA also have a standby life - usually this figure is available in the datasheets of batteries designed for UPS use (unlike lithium). The life depends on float voltage IIRC, but it usually works out to about 18-24 months. If I had an SLA system instead of the ratel I would almost certainly have to replace the batteries by now.

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2 hours ago, P1000 said:

Having the batteries float at near 100% they behave very differently. I have a ratel (415 I think) that I was expecting to be in need of new batteries by now - about 2 years of service. It still manages to carry me through about 4h15 of power. When it was new it could do just about 4h30.

SLA also have a standby life - usually this figure is available in the datasheets of batteries designed for UPS use (unlike lithium). The life depends on float voltage IIRC, but it usually works out to about 18-24 months. If I had an SLA system instead of the ratel I would almost certainly have to replace the batteries by now.

Li-Ion batteries aren't too fussy about theire stat of charge. (They actually say you should partially discharge them when storing them)

SLA batteries get hammered if left in a discharged state and yes, they only last a couple of years. However they only cost a fraction of Li-Ion (if bought new) 

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27 minutes ago, Richard Mackay said:

Li-Ion batteries aren't too fussy about theire stat of charge. (They actually say you should partially discharge them when storing them)

LiIon for longer term storage should be discharged to 50% SOC, this is usually the state the come from the supplier, they should not be put away at full charge or near empty.

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36 minutes ago, Richard Mackay said:

Li-Ion batteries aren't too fussy about theire stat of charge. (They actually say you should partially discharge them when storing them)

SLA batteries get hammered if left in a discharged state and yes, they only last a couple of years. However they only cost a fraction of Li-Ion (if bought new) 

The point I am making is that Li-Ion don't like to be kept at 100% SOC - which is why you should store them at 40-50%.

SLA batteries also have a life when kept at 100% SOC, usually 18-24 months. Which is why most computer UPSs last about that long.

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8 hours ago, Richard Mackay said:

I assume you believe that Li-Ion is superior to lead acid for all applications?

The following is from another esteemed contributor on the 4x4 Community forum: https://www.4x4community.co.za/forum/showthread.php/339295-What-batteries-for-a-5kva-inverter-charger

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.

Lithium ion outperforms SLA in every aspect except maximum current draw. In every other scenario the only reason one should even consider SLA is due to costs (or incompatible legacy hardware). Also, despite lithium ion being more expensive upfront it is almost guaranteed to be cheaper over the lifetime of the battery. 

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30 minutes ago, Speedster said:

Lithium ion outperforms SLA in every aspect except maximum current draw. In every other scenario the only reason one should even consider SLA is due to costs (or incompatible legacy hardware). Also, despite lithium ion being more expensive upfront it is almost guaranteed to be cheaper over the lifetime of the battery. 

If this were true then we would see Li-Ion batteries replacing all lead acid batteries which is not the case. If you have gleaned this information from a reputable source please refer us to this source.

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LiIon != LiFePO != LiFePO4 != LiTiO there's various nominal voltages spanning close to 2V between this lot, some will happily do a 10C discharge and potentially more without it being outside their specs or damaging it, in fact LiTiO's seem to be good for potentially 10-thousands of cycles at pretty extreme 5C and more charge and discharge rates. SLA is not a starter battery usually and if it is, its usually not a deep discharge design good for solar power storage, most Lead Acid batteries for solar storage are specced for 0.1C or 0.2C charge/discharge rates, but if you've got a 48V 200Ah bank, then drawing a kWh to max 1.8kWh may be within spec for this, check the manufacturers data. Either way, the draw back of most Lead Acids is that we use 12V or 6V batteries, without having access to the individual cells so when there's a problem, with one cell, you can't do much about it, unless you actually have individual 2V cells interconnected which you can swap or exchange to make up your battery, For this reason, I'd recommend using either 2V cells, 24 of them, thank you, to make up the lead acid battery one would want to use or, go for the Lithium variant that blows back your hair and would also allow you get to individual cells, in case the fan is struck by the inevitable, So homebrew you batteries from individual cells with BMS, mandatory for the Lithium side and maybe even a BMS to keep those Lead acids balanced and keeping you appraised of their state, this BMS, for the lead acids, one would probably also need to homebrew.

 

PS. Read what I mean, not what my fingers seem to type, damnit....

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Here is Battery University on the subject of lead acid batteries:

Lead acid stands its ground as being a robust and economical power source for bulk use. Even though Li-ion is making inroads into the lead acid market, the demand for lead acid batteries is still growing. The applications are divided into starter batteries for automotive, also known as SLI (20%), stationary batteries for power backup (8%), and deep-cycle batteries for wheeled mobility (5%) such as golf cars, wheelchairs and scissor lifts. 

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2 hours ago, Richard Mackay said:

Here is Battery University on the subject of lead acid batteries:

Lead acid stands its ground as being a robust and economical power source for bulk use. Even though Li-ion is making inroads into the lead acid market, the demand for lead acid batteries is still growing. The applications are divided into starter batteries for automotive, also known as SLI (20%), stationary batteries for power backup (8%), and deep-cycle batteries for wheeled mobility (5%) such as golf cars, wheelchairs and scissor lifts. 

I'll humour you.

 

For starter batteries, lead acid does well due to the required current draw (as mentioned in my post earlier. Stationary power backup lead acid only survives due to cost. You'll struggle to find any reputable solar installer who recommends SLA over lithium. And as for wheeled mobility, https://relionbattery.com/blog/best-golf-cart-batteries-lithium-ion-lead-acid

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23 hours ago, P1000 said:

Having the batteries float at near 100% they behave very differently. I have a ratel (415 I think) that I was expecting to be in need of new batteries by now - about 2 years of service. It still manages to carry me through about 4h15 of power. When it was new it could do just about 4h30.

SLA also have a standby life - usually this figure is available in the datasheets of batteries designed for UPS use (unlike lithium). The life depends on float voltage IIRC, but it usually works out to about 18-24 months. If I had an SLA system instead of the ratel I would almost certainly have to replace the batteries by now.

How many devices are you supplying from this mini UPS?

Is it only for the ONT and WiFi?

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On 2021/02/23 at 9:39 PM, Richard Mackay said:

The list of devices are all low voltage devices (not 220V)

This provides an opportunity to power these devices directly at the voltage they require. The advantages are enormous: Smaller (cheaper) batteries providing the same backup time as the huge inefficient UPSs & batteries. 

Those devices would be mostly driven from 230AC at the moment. So I assume that, for example, the LED lights have a little rectifier and transformer in side them. How do you get the DC Voltage to them?

My garage door and electric fence both actually work off a battery. The battery is charged by mains, but the devices actually run off the battery, which is why they keep working when the power is down. 

So what are you proposing here? Where possible modify the devices so that they are driven by the battery and have something to charge the battery from grid?

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1 hour ago, Richard Mackay said:

How many devices are you supplying from this mini UPS?

Is it only for the ONT and WiFi?

Quite an elaborate setup - fiber converter, mikrotik router and wifi router. Usage is in the order of 7W at the DC end IIRC. So the boost converter is quite efficient. When the batteries are charged, consumption from the wall is roughly 11W.

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6 minutes ago, P1000 said:

Quite an elaborate setup - fiber converter, mikrotik router and wifi router. Usage is in the order of 7W at the DC end IIRC. So the boost converter is quite efficient. When the batteries are charged, consumption from the wall is roughly 11W.

Do you have any devices being powered bu PoE?

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35 minutes ago, Richard Mackay said:

Do you have any devices being powered bu PoE?

Not in an official manner. The fiber converter has it's 12V running over 2 pairs, data over the other 2 - so "power over cat6" perhaps. My Ratel has no PoE output either.

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2 hours ago, Bobster said:

Those devices would be mostly driven from 230AC at the moment. So I assume that, for example, the LED lights have a little rectifier and transformer in side them. How do you get the DC Voltage to them?

My garage door and electric fence both actually work off a battery. The battery is charged by mains, but the devices actually run off the battery, which is why they keep working when the power is down. 

So what are you proposing here? Where possible modify the devices so that they are driven by the battery and have something to charge the battery from grid?

Yes. We have a 220V grid but many devices run on low voltage DC. Generating 220V by an inverter (powered by a battery) only for that voltage to be reduced down to 12V is inefficient. Inverters draw a lot of power when running off battery even if there's no load connected to it.

So rather power these devices directly with the low voltage DC they require (typically 12V) This is way more efficient!

If the device already has a battery then ensure it works throughout the power outages by increasing the battery size/charger   

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