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Which batteries should I buy (rhetorical question)


Chris Hobson

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8 hours ago, plonkster said:

Remember to adjust the charge efficiency setting when switching from lead-acid to Lithium. The recommendation I got was to set it to 97%, but I noticed it fills up "early" every day and resets to 100% too often, so I gradually increased mine and it is now sitting at 99% and working well.

Yip, adjusted as per the manual that came with my BMV-702. Charge effeciency set to 99% and Peukert's exponent to 1.10 but i just noticed with the latest online manual that the Peukert's exponent must now be set to 1.05

image.png.a172b13deaac905e3166be40922b3f3e.png

What have you set your Peukerts exponent to?

8 hours ago, plonkster said:

You can sort-of see clearly when a LFP battery is full. The charge current just drops way down (under 1 amp) and within a few minutes the chargers will go to float. This is when most batteries balance cells. Some BMSes allow you to look at individual cell voltages and its interesting to watch it. In mine, I can see the voltages in one battery is higher than the other, and that one also feels warmer when you touch it. That's the passive balancing going on... it's bleeding off energy.

Yip, i'm noticing that as well. Is there a BMS monitoring tool that i can plug into the Pylontech's to check what is going on every cell?

 

4 hours ago, viper_za said:

@PurePower
Do the batteries connect to the inverter for any communication?

Nope, not for the Axpert inverter.

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3 hours ago, PurePower said:

What have you set your Peukerts exponent to?

It's also set to 1.05.

3 hours ago, PurePower said:

Is there a BMS monitoring tool that i can plug into the Pylontech's to check what is going on every cell?

I have Victron's Smart batteries with Bluetooth, so I can see cell voltages using VictronConnect. I have no idea how you do it or if it is even possible with the Pylons.

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  • 5 weeks later...

I'm also seriously considering some sort of lithium solution since my small 200ah bank has some bad batteries in it and I would like to make use of the full potential of my PV array.

Currently the Freedom Won 15/11 looks to be my best solution. They work out at +- R6700/kwH with the 10 year warranty. This included the cabling and the case. The power star inverter is also listed as a supported inverter and their offices are close by. 

The pylontech also looks quite nice and they are going for +- R6305 /kwH. They don't really need a case I suppose as they are in casing already. I like the modular design and the options that afford. The warranty is less than the freedom though. Not sure about compatability though but would probably work.  

I'm just not 100% sure if my setup is ready for it yet. I have the MLT Powerstar(UPS/Inverter). It supports Li battery types. My main concern is the Flexmax 80 Charge controller. Someone told me that should the li-battery isolate itself the MPPT sees the the capacitor of the inverter and you get a situation where the MPPT tries to match it's output voltage to the voltage of the capacitor and you get a runaway situation where the MPPT and inverter is damaged. Anyone heard of this sort of thing? I suppose the integrated inverters like the Axpert won't suffer this.

 

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On 12/23/2017 at 12:46 PM, Chris Hobson said:

So Santa (Father Chris(tmas) Russouw) has delivered a pair of Pylontechs to Graaff-Reinet. I will take pictures and give some feedback.

Hi Chris,

Please posts the photos when the Pylontechs are up and running. 

I purchased two but am waiting for the switches etc to arrive - only in middle January.

I intend using it as a backup with a 4kw Infinisolar Super inverter.

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20171222_211931.thumb.jpg.8c09bb14c8679f52dad5dbc0c23a966e.jpg

So they arrived Friday before Xmas and uncharacteristically I left the install to Saturday morning.

The assembly of the cabinet was the most painful part of the whole process. The cabinet is South African made and is robust and the build quality is good but assembly instructions were sparse and the supply of the wrong nuts and bolts compounded my problems. Fortunately there were enough of the right size nuts and bolts in my workshop (a rare occurrence) and the cabinet was assembled but really I would have expected better.

The installation of the batteries was fairly painless and connected the relevant wires. The removal of the existing lead acid batteries was the most difficult part of the whole process. I had forgotten how many cables and wires I had attached to the batteries -  HA 02, voltmeters, BMV and thermometers. The old AGM batteries have found a new home in a 24V Axpert system but I do not expect them to last more than 6 months or so. 

Having removed the previous bank the install was a doodle. The batteries are connected using Amphenol connectors which clip onto the batteries and make a satisfyingly audible click when seated. It took me longer to find my glasses and get down on my hands and knees than to connect up the batteries. Expanding the bank will be just as easy.

Commissioning the battery bank is child's play. You switch each battery on in turn and then press the start switch for the master battery - process completed.

20171223_122222.thumb.jpg.fdd44f7fa083679406287a219696c477.jpg

 I have reset the Axpert's programs (to the settings recommended by Pylontech) whilst both PV and grid were off and started running. In typical solar fashion we had a cloudy overcast day. I could immediately identify one of the advantages of Lithium was the higher charging rate. At one stage we hit 50A something I could never achieve due to the size of my LA bank. So the little bit of sunshine we did have I was able to capitalize on.

20171223_143853.thumb.jpg.7a87bbc99f384e40ffc8b5eec463485b.jpg

@PurePower and @weber have been corresponding and hope to bring you Pylontech 101 in the New Year. In the mean time I have adjust float to values as advised by weber. It appears that perhaps the manufacturers either don't fully understand the technology or they are having difficulty communicating their recommendations in English.

With only 2 Pylontech units and a house full I cannot go through the night on battery and a 3rd unit will need to be purchased in the near future, but that is the beauty of Lithium, I can now expand the bank as and when finances allow. I simply could not afford the big investment in a LA bank. Now I can do it piecemeal.

 

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On 12/26/2017 at 9:45 PM, Chris Hobson said:

20171222_211931.thumb.jpg.8c09bb14c8679f52dad5dbc0c23a966e.jpg

So they arrived Friday before Xmas and uncharacteristically I left the install to Saturday morning.

The assembly of the cabinet was the most painful part of the whole process. The cabinet is South African made and is robust and the build quality is good but assembly instructions were sparse and the supply of the wrong nuts and bolts compounded my problems. Fortunately there were enough of the right size nuts and bolts in my workshop (a rare occurrence) and the cabinet was assembled but really I would have expected better.

The installation of the batteries was fairly painless and connected the relevant wires. The removal of the existing lead acid batteries was the most difficult part of the whole process. I had forgotten how many cables and wires I had attached to the batteries -  HA 02, voltmeters, BMV and thermometers. The old AGM batteries have found a new home in a 24V Axpert system but I do not expect them to last more than 6 months or so. 

Having removed the previous bank the install was a doodle. The batteries are connected using Amphenol connectors which clip onto the batteries and make a satisfyingly audible click when seated. It took me longer to find my glasses and get down on my hands and knees than to connect up the batteries. Expanding the bank will be just as easy.

Commissioning the battery bank is child's play. You switch each battery on in turn and then press the start switch for the master battery - process completed.

20171223_122222.thumb.jpg.fdd44f7fa083679406287a219696c477.jpg

 I have reset the Axpert's programs (to the settings recommended by Pylontech) whilst both PV and grid were off and started running. In typical solar fashion we had a cloudy overcast day. I could immediately identify one of the advantages of Lithium was the higher charging rate. At one stage we hit 50A something I could never achieve due to the size of my LA bank. So the little bit of sunshine we did have I was able to capitalize on.

20171223_143853.thumb.jpg.7a87bbc99f384e40ffc8b5eec463485b.jpg

@PurePower and @weber have been corresponding and hope to bring you Pylontech 101 in the New Year. In the mean time I have adjust float to values as advised by weber. It appears that perhaps the manufacturers either don't fully understand the technology or they are having difficulty communicating their recommendations in English.

With only 2 Pylontech units and a house full I cannot go through the night on battery and a 3rd unit will need to be purchased in the near future, but that is the beauty of Lithium, I can now expand the bank as and when finances allow. I simply could not afford the big investment in a LA bank. Now I can do it piecemeal.

 

This looks like an nice setup,do like the cabinet,everything looks very much neat,if I may ask what did you do with all that exstra voltmeters?

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On 12/26/2017 at 4:09 PM, Tersius said:

Freedom Won 15/11 looks to be my best solution

 

On 12/26/2017 at 4:09 PM, Tersius said:

pylontech also looks quite nice

The FreedomWon guys are really pushing the envelope and they have a neat product with a good and capable BMS. Well... speaking from a Victron perspective that is, their BMS integrates really well and uses all the new bells and whistles that we have dubbed "DVCC".

It sounds to me that you have all the right reasons to support them. I'm told that the cells inside their battery are sinopoly cells, but maybe you should ask them, my info might be bad. Googling around a bit says Sinopoly used to be called Thundersky and the guys who are now Winston used to build batteries for them, and there is some litigation going on. You can look it up yourself if you want to and decide how you feel about that.

It's unclear what cells are used inside the Pylontech batteries.

That's basically the two things I'm usually interested in: How good is the BMS, and how good are the cells. I heard some interesting rumours about older BlueNova packs where the BMS was the trouble even though the Winston cells are fairly good...

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4 hours ago, Andries said:

This looks like an nice setup,do like the cabinet,everything looks very much neat,if I may ask what did you do with all that exstra voltmeters?

They are lying here on my workstation. I have ½ dozen new ones in the draw. You want to build some?

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18 minutes ago, Chris Hobson said:

They are lying here on my workstation. I have ½ dozen new ones in the draw. You want to build some?

I have 6 12v batteries with 1x victron battery balancer and want to monitor all the batteries,pm me your price please

thanx

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On 12/29/2017 at 6:41 PM, plonkster said:

 

The FreedomWon guys are really pushing the envelope and they have a neat product with a good and capable BMS. Well... speaking from a Victron perspective that is, their BMS integrates really well and uses all the new bells and whistles that we have dubbed "DVCC".

It sounds to me that you have all the right reasons to support them. I'm told that the cells inside their battery are sinopoly cells, but maybe you should ask them, my info might be bad. Googling around a bit says Sinopoly used to be called Thundersky and the guys who are now Winston used to build batteries for them, and there is some litigation going on. You can look it up yourself if you want to and decide how you feel about that.

It's unclear what cells are used inside the Pylontech batteries.

That's basically the two things I'm usually interested in: How good is the BMS, and how good are the cells. I heard some interesting rumours about older BlueNova packs where the BMS was the trouble even though the Winston cells are fairly good...

@plonkster Pylontech makes their own cells. I have also heard rumours about the BMS on the BLueNova giving problems. MLT stopped using BlueNova until it is sorted out. Not sure if it has been sorted yet.

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13 hours ago, Tersius said:

Not sure if it has been sorted yet.

They have a new "digital BMS" according to their advertisements, I assume it's sorted. The cells are Winston. But you should still consider the overall discharge rating, some manufacturers oversize their batteries by 20% while others size theirs smaller and use a C10 rating on the spec sheet. Both are good batteries, it's just that apples and oranges thing. 

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1 hour ago, plonkster said:

 But you should still consider the overall discharge rating, some manufacturers oversize their batteries by 20% while others size theirs smaller and use a C10 rating on the spec sheet. Both are good batteries, it's just that apples and oranges thing. 

Pylons have opted for a halfway house with charge/discharge of 0.5C (C2) rather than 1C (C1)  but it is not 0.1C (C10) but I am willing to live with the lower discharge. The maximum we have drawn (it is early days yet) is 25A which is 0.25C. I realise summer is giving me a buffer and I will need more Pylons come winter.

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2 hours ago, Chris Hobson said:

A visitor and I were looking at costing a Victron 48V 90Ah Lithium bank is roughly 4X the cost of a Pylontech 48V 100Ah Lithium bank. Prices vary from supplier to supplier but that is a large difference.

They are in a different league. They are in that bracket where you find things like the LG Resu batteries, but a little below Tesla and Daimler. Then you have to import them, and pay 14% VAT on top of the 110% rule they use, so an additional 25% on top after shipping. I don't blame anyone who think they are expensive, they really are.

But they can do sustained discharge rates of more than C0.5 (ie full to empty in less than half an hour). My 300Ah batteries can do a sustained 750 ampere, although they recommend staying under 300A :-)

In this case I think both Pylontech and BlueNova have a point: You don't do that kind of thing with a house. C2 is fine.

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2 hours ago, Chris Hobson said:

What do you run off them?

Oh, I've never been close to 100 amps, and my cables would go long before that... well the fuse would go after 150, but if it wasn't there the cables would be gone before then.

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On 11/23/2017 at 7:59 AM, plonkster said:

Remember to adjust the charge efficiency setting when switching from lead-acid to Lithium. The recommendation I got was to set it to 97%, but I noticed it fills up "early" every day and resets to 100% too often, so I gradually increased mine and it is now sitting at 99% and working well.

You can sort-of see clearly when a LFP battery is full. The charge current just drops way down (under 1 amp) and within a few minutes the chargers will go to float. This is when most batteries balance cells. Some BMSes allow you to look at individual cell voltages and its interesting to watch it. In mine, I can see the voltages in one battery is higher than the other, and that one also feels warmer when you touch it. That's the passive balancing going on... it's bleeding off energy.

Hi Plonky. I have the same issue with the BMV going to 100% SOC too early. Surely one needs to decrease the charge efficiency so that the BMV calculates that only 96 or 97% of charge is actually going to make into the battery as stored energy. Am I being dense?

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1 hour ago, Chris Hobson said:

Surely one needs to decrease the charge efficiency so that the BMV calculates that only 96 or 97% of charge is actually going to make into the battery as stored energy. Am I being dense?

No, I have the reverse of that problem. My batteries fill up, as seen from the charge current dropping off a cliff, but the BMV only shows 97% or something like that. Then it goes to float, from 28.4V to 27V, and because a lithium battery doesn't sommer drop voltage for nothing, it actually needs to discharge slightly to bleed off the extra voltage, so now it's at 96% on the BMV though it's technically full. Now usually it will reset back to 100% after a while, if your charged voltage is set correctly, but the fact that it fills up at 97% indicates that the batteries are more efficient than the setting on the BMV. If you spend a few days at partial charge, the problem compounds and the BMV shows lower than the actual charge, getting worse each day until it resets again. 

My BMV reset yesterday, from 95%. Today it again filled up at 99%, so 1% drift in a day. My BMV is set to 99%. In other words, efficiency appears to be more than 99%. 

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So looking at the specs of the Freedomwon 15/11 batteries they are 300ah with 200A continuous and 250A max. So C rate of 0.67 I suppose which is ok. More than what my 8KVA inverter can supply anyway, installed 32A breakers on the output although the inverter can do 62A drawing from mains and batteries at the same time.

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