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Pylontech US2000B Plus

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I'm considering replacing my Trojan T105-RE battery bank with the Pylontech US2000B Plus batteries.

Could I get some feedback from the guys using them currently?

My bank is only a year old, what do you consider a reasonable price for them with three HA-02's?

The BMV says I have used roughly 700KWH's from the batteries and the midpoint deviation is 0.02V so basically like new.

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12 minutes ago, SolarNoob said:

The BMV says I have used roughly 700KWH's from the batteries and the midpoint deviation is 0.02V so basically like new.

Doing a bit of math here. That's roughly an 17kwh bank. 700 over a year is roughly 2kwh a day, Let's say 2/16 to make the math easy, that's around 12% DoD. So you've done 360 cycles out of a possible 2500 (educated guess) or 1 out of 7. So thumbsuck that bank should be about 85% new :-) So take that percentage of what you paid for them when they were new, and you have an upper limit of what you might get for them.

What I'd do is see if I can sell them on to a golf cart owner :-)

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15 minutes ago, SolarNoob said:

What is your opinion of the Pylontech?

I have no personal experience with them, but I haven't heard any complaints either, at least nothing that makes it past the first two helpdesk levels :-) It's a good battery. Compared to other LFP batteries (LG Resu for example) they have a fairly low continuous discharge current (C2 recommended), but that is usually perfect for home use.

The only complaint I heard is that the cables they supply with it might be a bit thin if you have 5 racks or more in parallel :-)

Yes, @Chris Hobson has such a battery in his setup now.

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1 hour ago, plonkster said:

The only complaint I heard is that the cables they supply with it might be a bit thin if you have 5 racks or more in parallel :-)

Jip I think the cables are rated at 120A and a 5 module stack could easily deliver 125A.  I would  have  4 or less in a stack and if you need more have 2 stacks and busbars.

Pylontech is one of the few OEM Lithium manufacturers being responsible for the entire production chain.

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1 hour ago, Chris Hobson said:

Manie tells me that during charge their temperature hovers around 30°C

Manie? Do you mean ICC is able to interface with the BMC in the Pylontech? 

 

1 hour ago, Chris Hobson said:

I love them

Good to know, thanks Chris.

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2 minutes ago, SolarNoob said:

Manie? Do you mean ICC is able to interface with the BMC in the Pylontech? 

Not yet.....:D. W ehave to give Manie some leeway. He was asked to interface with Pylontech for a corporate client. The spinoff is that he now knows how the beast works.

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4 minutes ago, Chris Hobson said:

Not yet.....:D. W ehave to give Manie some leeway. He was asked to interface with Pylontech for a corporate client. The spinoff is that he now knows how the beast works.

Fantastic! @Manie does great work.

I assume that means we wouldnt need BMV's any more?

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31 minutes ago, SolarNoob said:

I assume that means we wouldnt need BMV's any more?

In theory yes. In practice... some BMSes (I don't know about the pylontech specifically) are less accurate than a BMV. And others (LG Resu) doesn't go to 100%, they stop at a lower value (because it is better not to go all the way to the top every day). At least with Lithium batteries it is not as serious a matter as with lead acids. Just keep your cells at a healthy voltage and you're good.

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1 hour ago, plonkster said:

In theory yes. In practice... some BMSes (I don't know about the pylontech specifically) are less accurate than a BMV. And others (LG Resu) doesn't go to 100%, they stop at a lower value (because it is better not to go all the way to the top every day). At least with Lithium batteries it is not as serious a matter as with lead acids. Just keep your cells at a healthy voltage and you're good.

Will be interesting to compare the BMV to the BMS with ICC when its complete. I'm quite happy to keep the BMV

 

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55 minutes ago, SolarNoob said:

I'm quite happy to keep the BMV

 

I have kept mine. There is a difference between the LED SOC and the BMV SOC. I think the built in SOC takes into account balancing charge/discharge and so lags behind BMV SOC.

 

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5 hours ago, Chris Hobson said:

I have kept mine. There is a difference between the LED SOC and the BMV SOC. I think the built in SOC takes into account balancing charge/discharge and so lags behind BMV SOC.

 

Which setting did you change on the BMV? Just the battery efficiency or the peukert values too?

Did you follow the SOP Pylontech supplies for the installation on the axpert? Did you find the instructions adequate?

Have you perhaps done an install on the Infinisolar inverters with the pylontech's?

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7 minutes ago, SolarNoob said:

Which setting did you change on the BMV? Just the battery efficiency or the peukert values too?

Yip change the efficiency and Peukert values. Still busy fiddling. Lithium efficiency varies with charging rate so over weekend I fiddle and try get it better.

10 minutes ago, SolarNoob said:

Did you follow the SOP Pylontech supplies for the installation on the axpert? Did you find the instructions adequate?

Yes except I raised the low battery cut-off from 47.5V to 48.3V. Works well for me occasionally someone does something silly and then the inverter shuts off at about 30-40% SOC. Even the 47.5V is conservative the real minimum is about 45V but I don't want to be anywhere near that.I one caused the BMS to shut down the battery. We had a morning with drizzle and although the panels were producing there was still a deficit and we were using a couple of hundred Watts from the battery. The panels artificially raised the battery voltage but in fact they were near empty. With the raise battery cut-off voltage I can prevent it happening again. My float voltage is 50.5V based on some reading and recommendations from @weber. Pylon don't actually specify a float voltage.

20 minutes ago, SolarNoob said:

Have you perhaps done an install on the Infinisolar inverters with the pylontech's

No but I cannot imagine that it is any different. Just follow the SOP.

 

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18 minutes ago, Chris Hobson said:

My float voltage is 50.5V based on some reading and recommendations

Looking at the SOP for the infini, the image shows the float voltage should be set to 53.2V? is 53.2V too high? Please excuse my ignorance :)

 

Capture.JPG

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I quote correspondence with @weber.

"That's good to hear, Chris. The 50.5 ±0.2 V is 15 times 3.35 V to 3.38 V per cell, which is a distillation from a number of sources. Here are two web resources I have found very useful.

http://www-personal.umich.edu/~hpeng/DSCC2013_Weng.pdf
See figure 2 on page 3.

http://www.cse.anl.gov/us-china-worksho ... %20BMS.pdf
See the graph on the left of page 15."

 

The slightly lower float setting means that my batteries might not reach 100% SOC maybe 99.5% but I am more concerned not to stress the  LiFePO4 cells. Not running @Coulomb's dynamic charging algorithm I notice that the battery voltage rapidly peaks and overshoots slightly (for about 5 seconds up to about 54V) so to fall back to a lower voltage makes sense. 

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11 hours ago, Chris Hobson said:

The panels artificially raised the battery voltage

One of the issues I deal with a lot now is voltage drop on the cables. I have that issue on my own system, and also on some customer systems. Under full load (eg, doing 125 amps out of a 5-rack pylontech) there might be an 0.6V drop on the cable, so the inverter thinks we're lower than we really are. On the Victron kit we have something called Dynamic cut-off, which means it takes into account the current when it makes decisions about the voltage. Often the additional drop on the cable is enough to push us into cut-off even though the battery is still fine. When there is no load, a voltage below 50V could already be a bad sign, but at full load not only does the battery sag to below 48V, you also have to account for the voltage drop across the cable.

That's why we now recommend quite often that people put in the voltage sense cables (extra thin wires that is used only to read the voltage) to their inverters. We also have a software solution called SVS (shared voltage sense) whereby the inverter and solarchargers can track the voltage drop over their respective cables and compensate for it. All reasons why you really want something blue on your wall... :-P

2 hours ago, Chris Hobson said:

slightly lower float setting

When using a two-wire BMS (basically it has two relays that closes if the battery is low or high), the older Victron solution (using the two-wire assistant, or the same functionality in the ESS assistant) is to go to float when you get the signal that the battery is full. By setting a slightly lower float voltage, you get the benefit of both. It fully charges AND it backs off to a less-stressing voltage after that. So I concur with this advice.

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Gee wiz this is getting into higher grade French Polynesian spoken in tongues. 

Makes me think of the latest newest 1600cc diesel engines. Fuel consumption and power wise they make my 280TD with a inter-cooler(!) look and sound like a old lister engine that must be put out to pasture right this minute.

However, if you drive in far off places, exposed to any grade of diesel, even 100% biodiesel, diesel laced with paraffin (jip, I sometimes smell it in the exhaust) then the 280TD "lister" kicks some serous a..e all the way to Sunday and back.

You can never try that with the newer diesel engines ... no, do not try it at home either, trust me.

High tech batteries are awesome and the tech in them are getting seriously amazing to worry about small voltage drops versus the Trojan's i.e. 280TD.

3l Ford, 2l Coke and 1l Brandy ... voltage drop se gat man, gooi net bigger cables and lots more batteries. :D

All jokes aside. Listen carefully now ... Respect for the new tech.

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3 minutes ago, The Terrible Triplett said:

All jokes aside. Listen carefully now ... Respect for the new tech.

Wait until you've had a taste of this. It's the most amazing thing, after running lead acids for so long and seeing it drop to 23.9V at high loads, to see your LFPs sitting at 25.9V and you know its only reading below 26V because of the voltage drop on the cable!

:-)

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54 minutes ago, plonkster said:

One of the issues I deal with a lot now is voltage drop on the cables. I have that issue on my own system, and also on some customer systems. Under full load (eg, doing 125 amps out of a 5-rack pylontech) there might be an 0.6V drop on the cable, so the inverter thinks we're lower than we really are. On the Victron kit we have something called Dynamic cut-off, which means it takes into account the current when it makes decisions about the voltage. Often the additional drop on the cable is enough to push us into cut-off even though the battery is still fine. When there is no load, a voltage below 50V could already be a bad sign, but at full load not only does the battery sag to below 48V, you also have to account for the voltage drop across the cable.

That's why we now recommend quite often that people put in the voltage sense cables (extra thin wires that is used only to read the voltage) to their inverters. We also have a software solution called SVS (shared voltage sense) whereby the inverter and solarchargers can track the voltage drop over their respective cables and compensate for it. All reasons why you really want something blue on your wall... :-P

When using a two-wire BMS (basically it has two relays that closes if the battery is low or high), the older Victron solution (using the two-wire assistant, or the same functionality in the ESS assistant) is to go to float when you get the signal that the battery is full. By setting a slightly lower float voltage, you get the benefit of both. It fully charges AND it backs off to a less-stressing voltage after that. So I concur with this advice.

I have seen that on my pack. Large current draws dropping the voltages. Is this only due to cable lengths? I thought it was natural for a pack voltage to drop under high load. Luckily the Powerstar has the state of charge input from the battery so it doesn't try and float the battery back to higher voltages unless it's actually needed.

Quite fascinating all of it. Chart from this morning. My voltage drops are more than 0.6V...

amChart.png

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15 minutes ago, Tersius said:

Is this only due to cable lengths?

Length and thickness. But voltage drops are unavoidably, and at the metioned 150 amps on a 48V system, 0.6V represents less than 2% which is totally acceptable especially at such a high load. So I really would not try to address this by using thicker cable. That is exactly why voltage sense becomes such a useful feature the moment you move to Lithiums.

TTT is right, the old lead acids are simple in this respect. If you do that kind of load, the battery voltage drops by so much that you hardly worry about the drop on the cable. It does become more of a concern with LFPs though.

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16 minutes ago, plonkster said:

Wait until you've had a taste of this.

I do. :-) 

Hear the UPS click and all that when the fridge and freezer starts up same time, spiking quite high for the inverter that has to also power a constant base load of 700-800w.

2 minutes ago, plonkster said:

But voltage drops are unavoidably

Ditto. I have 35mm cables from batts to inverter. Even 50mm will make no difference.

3 minutes ago, plonkster said:

... lead acids are simple in this respect.

Old se dinges man. Nuwes. Not even 3 years old. :D

 

Running all I have on the brink most of the time, voltage drops have been with me since day one.

I am near paranoid with clean power to sensitive equipment, especially when on Eskom, not because I cannot claim, I just don't want to be bothered with that waste of time.

Like friend of mine lost a boatload of electronic stuff last week when their power dipped badly where he lives in PTA. Insurance claim is climbing daily as he finds more stuff fried.

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Gents i know you mention voltage drop here ..... and yes it does happen on cabling that isnt sufficient from source being the battery to the load being the inverter, and the V sense port on the victron is very important for making sure this is compensated for both on charge and discharge, but i must tell you something in relativity to the conversation, SOC determines voltage sag on Lifepo4, if you take a fully charged cell and discharge it fairly steady with a good current draw it will hold its own provided you not demanding alot out of it .... meaning you will see figures of around 3.2v per cell under load at a 80% soc .... but here is where it gets interesting try the same load at a lower soc say at 30% you will see the cells ability to deliver energy changes, the characteristics of Lifepo4 are such that the lower the soc % the more the sag at high demand, some cells are better then others in this regard, Sinopoly do sag more under low soc where as the likes of headway and Calb dont, be careful that you are not basing you voltage sag on the actual cells ability to delivery current at a low SOC %....

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On 2018/02/26 at 2:41 PM, SolarNoob said:

Will be interesting to compare the BMV to the BMS with ICC when its complete. I'm quite happy to keep the BMV

 

@plonkster  I have been running the Pylontechs with the BMV for a while now and I can report that the SOC reported by both is very close, no more than 1 or 2 percent difference in their readings.

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@SolarNoob

Do you upload to PVOutput?  It would be really nice to see your output and efficiency especially with the Pylontechs charging in the morning!

Thanks

Mark

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