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Battery Value for Money


Lukey87

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Hi all, I have been keen to get going witha proper back up system and as usual just got started with it and never really planned/ costed it out properly.

So i have installed new db so far and split the essential from non-essential loads. Essential loads is all lights (all LED globes), fridge, Tv and two routers.

Already have 1 x Kodak OGX 5.48 (5kw, 48v) ready to be installed.

So i was just quickly (haha) going to buy 2 or 3 x Pylontech US 3000's with a cabinet and be done, right? Well that idea came to a halt when i realised i would have to drain my kids college funds to make this purchase:)))

Please help me with a plan B? Do I go with 4 x AGMs in series? Will I need to further parallel these with another 4 x AGMs... buying Pylontechs just seemed so neat, safe, reliable and convenient, but not worth the money given other priorities I have.

PS. Its just backup power at this point. Have not planned for solar at this point.

 

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Have you measured the wattage that your essential loads will draw? And what time do you want to power them?

If you are talking about roughly 400-500W (which would be my guess based on your description) for the typical loadshedding duration (2.5h), then a single 3.5kWh Pylon will be enough for you (500W x 2.5h = 1.25kWh vs the Pylon able to provide 2.8kWh @80% DOD)

I used to have a bank of lead acids when I initially installed my backup system in 2015. The batteries went through less than 50 cycles and by 2019 were basically dead (end of lifetime). Lithium batteries do not have the same problem of dying even without usage. I do not know what current lead acid prices are, but I would guess that a set of lead acids that at 50% DOD provide you with similar capacity as the Pylon @80% DOD will cost you more than half of the Pylon - which means that if you plan on keeping your system for more than the lead acids' expected lifetime, the Pylon will actually work out cheaper in the long run. Plus having the ability to (a) have something that is suitable for expanding your system with PV and (b) add more batteries as you grow your system 

That's also what I did: Replaced my lead acids when they were dead with a 1st Pylon, then added PV, and eventually added Pylons #2 and #3 

As long as the 2.8kWh usable capacity is sufficient and you can ensure that you do not draw more than 37A (approx 1800W) from your Pylon, I would strongly recommend that path

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2 hours ago, DeepBass9 said:

So start with one pylon, that should be cheaper than 4x lead acid batteries. As far as I am aware you can add pylontechs as time goes by. 

Thanks... was not sure if I could chance it with one. But maybe I can. 

So absolute worst case for 2.5 hours of LS I have worked out 3.9Kw. Well that is max i could possibly draw through my essential load circuit in that time, but absolutey uneccesary to do that. Total amps would be around 14A.

Hmmm... maybe 1 US 3000 is the way to go... Thanks!

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1 hour ago, wolfandy said:

Have you measured the wattage that your essential loads will draw? And what time do you want to power them?

If you are talking about roughly 400-500W (which would be my guess based on your description) for the typical loadshedding duration (2.5h), then a single 3.5kWh Pylon will be enough for you (500W x 2.5h = 1.25kWh vs the Pylon able to provide 2.8kWh @80% DOD)

I used to have a bank of lead acids when I initially installed my backup system in 2015. The batteries went through less than 50 cycles and by 2019 were basically dead (end of lifetime). Lithium batteries do not have the same problem of dying even without usage. I do not know what current lead acid prices are, but I would guess that a set of lead acids that at 50% DOD provide you with similar capacity as the Pylon @80% DOD will cost you more than half of the Pylon - which means that if you plan on keeping your system for more than the lead acids' expected lifetime, the Pylon will actually work out cheaper in the long run. Plus having the ability to (a) have something that is suitable for expanding your system with PV and (b) add more batteries as you grow your system 

That's also what I did: Replaced my lead acids when they were dead with a 1st Pylon, then added PV, and eventually added Pylons #2 and #3 

As long as the 2.8kWh usable capacity is sufficient and you can ensure that you do not draw more than 37A (approx 1800W) from your Pylon, I would strongly recommend that path

Thanks for the advice!

Think i covered your questions in reply to Deepbass9...

So that 1 x Pylon carried you through a load shedding section? What is the recharge time, if you know?

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6 hours ago, Lukey87 said:

So absolute worst case for 2.5 hours of LS I have worked out 3.9Kw

This would mean an average draw 1.56kW - which is close to what a single Pylon can provide for longer periods of time (37A x 50V = 1.85kW)

And if you did draw that amount for the full 2.5h than obviously a single Pylon would not suffice

6 hours ago, Lukey87 said:

So that 1 x Pylon carried you through a load shedding section?

Yes, at the beginning I only had my light loads on the inverter, which kept my load constantly under 700W for the duration of the loadshedding

Just keep in mind that you obviously have efficiency losses in the DC-AC conversion, which means that 100W of AC load do not equal 100W of DC load on your Pylon. So you want to make sure that you leave a bit buffer in your calcs

6 hours ago, Lukey87 said:

What is the recharge time, if you know?

Pylons do not like more than 37A either in either direction for an extended period of time. In theory that means, that you can recharge the Pylon in approx. 1.5h if you can provide it with exactly that charge (not sure how finely you can program the AC charger on the Kodak but on my Axpert I can only select in 10A increments, which means that I would only charge it with 30A and hence it would take a bit longer)

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18 hours ago, wolfandy said:

the DC-AC conversion, which means that 100W of AC load do not equal 100W of DC load on your Pylon. So you want to make sure that you leave a bit buffer in your calcs

I worked on 90% efficiency...

That is in the 3.9kw mentioned. 

Edited by Lukey87
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On 2020/06/21 at 10:14 PM, Lukey87 said:

So i was just quickly (haha) going to buy 2 or 3 x Pylontech US 3000's with a cabinet and be done, right? Well that idea came to a halt when i realised i would have to drain my kids college funds to make this purchase:)))

With the title of this thread being value for money: In the long run the Pylontechs work out cheaper than LA.

And cabinets are overpriced. I used R15 brackets to hang the batteries on the wall.

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6 minutes ago, Pietpower said:

With the title of this thread being value for money:

Yeah, good point. 

To be really honest, I am a bit OCD on neatness and the Pylontechs really look great:)

Call it confirmation bias, but guess I just needed your guys help to push me in the pylontech direction and justify it from technical, value point of view... maybe go with one to start out and just ration my power use in load shedding... guess we have got by with a led torch and 3 AAA batteries the past few years, so should do ok on one pylon for now;)

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2 hours ago, Pietpower said:

And cabinets are overpriced.

Absolutely overpriced. I use a Samson equipment rack at a fraction of the cost of those cabinets. As the Pylons are standard rack-mount size, no need to buy special cabinets

2 hours ago, Lukey87 said:

maybe go with one to start out and just ration my power use in load shedding

Definitely the best choice 

Just one word of warning: Once you start down this path, you will eventually end up spending more money. You will get by with a single Pylon, but then it would be really nice to have a 2nd one to run a couple of extra things during loadshedding. And then, since you already have the inverter and Pylons, you might as well add a few PV panels to start banking savings from the inverter/Pylon investment that you have already made 😝

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8 hours ago, wolfandy said:

Samson equipment

 

2 hours ago, Jaco de Jongh said:

server racks

Little wall-mount 6u cabinets can be had for under 2k if you shop around a bit. I bought a massive 48u case with wheels for 1.5k (second hand) and stuck my entire system into it. I definitely support shopping around and making a plan, cause after all... it's standard 19" stuff.

Look on geewiz.co.za, to name just one alternative.

Edited by plonkster
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