16 minutes ago, FixAMess said:

Maybe that was too short a time to balance the batteries more would have been better.

All the pylontech batteries I have connected have had Over voltage issues which usually settle down after a few days/charge/discharge cycles.

You are making the same mistake as in the Luxpower thread from the other day. Connecting the batteries together on their own with no charging source will not balance them,they will only slightly balance between each other if you have a major SOC difference due to the flat charge curve of LFP. The correct way is to connect them and charge them up even if they have SOC difference , the packs balance between themselves at 89% SOC. The reason for these over voltage issues in the beginning is because the (15) cells in a pack is not yet full balanced. 

1 hour ago, onobeka said:

@Kilowatt, sorry to hear that :(.

Before going to voltage only, I was using the BMS communication to the inverter to manage the charging. The batteries got every day to 53.2 which is regarded as too high by the community. I've read on this forum that balancing happens at 3.48V (52.2V) which in case of us5000 is certainly not true, as I see a 30mV cell imbalance still after two weeks. I have 3xus5000. One battery is almost new (4cycles). I've charged it alone, and the other two, set them in parallel for 1h and then connected to the inverter. The new battery is set as master and when using BMS communication and the battery going to 53.2V, I can see that the BMS temperature of that battery is rising trying to balance the cells. I guess it's burning voltage of the higher cells while trying to charge the other(s). I can see that the higher voltage cell can reach 3.64V while the lower is trying to go above 3.5V. The cells in the other two modules are sitting at 3.54V. 

I went Pylontech for the sake of a solid BMS. I wish I didn't.

Maybe the Voltronic (Easun) bus is overreading the voltage, and the battery is not actually at 52.2V but lower, hence balancing will not happen there.

53,2V is not too high . Its too high if your specific inverter overshoots this value . You need that higher voltage to keep the cells in a pack balanced . If its overshooting with CAN comms you may need to switch to voltage settings and dial the voltage in so you get 53,2V at the batteries BMS. Sunsynk had this issue a while ago where it was overshooting to 53,5-53,6V. They have since corrected this in a firmware update and now it never goes over 53,15V ,absolute most 53,2V. I would just keep using CAN comms and cycle those batteries more. The cells in that pack will balance out over time. 

There are so many contradicting opinions on the Pylontech best practices that it's hard to pick one. I appreciate all opinions and I've tried this and that (probably most of the thigs I've read so far) and so far I cannot recommend somebody else what to do. I have little experience, only three units so far, added them gradually to my system. I had no issue with the first two. The third scared me a bit, seeing the BMS going to 48C on the first day with a cell at 3.64V and one at 3.4V ... now it's better, yet not flat balanced. 30mV imbalance is 0.008%. Not a big number, though.

21 minutes ago, Nexuss said:

Connecting the batteries together on their own with no charging source will not balance them

Will it not balance the batteries, but not the cells? That is the point I was trying to make..

Balancing of cells is an internal aspect. The reason I've connected them in parallel is to equalize SoC. I guess also that balancing is top balancing, so if there is current flowing from one battery to another while in parallel it means that one is charging (which is what happens), which also means that if the batteries are each close to 100%, there should be balancing going on, provided that the balancer is in it's balancing voltage range. I see no issue with having the batteries in parallel without an external charging source, this will happen at night with only solar charging or when the controller(s) are out of service for some reason. 

@Nexuss, "You are making the same mistake as in the Luxpower thread from the other day." <- where is the mistake in fact?

Edited October 11, 20232 yr by onobeka

10 minutes ago, FixAMess said:

Will it not balance the batteries, but not the cells? That is the point I was trying to make..

It will not effectively balance the packs no. As an example say you have a new battery which comes at 50% SOC and parallel that to a 80% SOC battery , they wont balance fully as there is not a big enough voltage difference for current to flow. You want to balance packs the same way you would when balancing the cells inside a pack and that is by charging them up to 3,55V-3,65V a cell. 

@Nexuss Do you know that for sure for Pylontech? I mean that they have to be above 3.55V to start the balancing? Pylontech recommends charging between 52.5 and 53.5V, which would mean that their recommendation is not balancing in most situations. 

15 minutes ago, onobeka said:

@Nexuss Do you know that for sure for Pylontech? I mean that they have to be above 3.55V to start the balancing? Pylontech recommends charging between 52.5 and 53.5V, which would mean that their recommendation is not balancing in most situations. 

It doesn't start at that voltage see my last post with the attachment. It's 50.4v

13 minutes ago, onobeka said:

@Nexuss Do you know that for sure for Pylontech? I mean that they have to be above 3.55V to start the balancing? Pylontech recommends charging between 52.5 and 53.5V, which would mean that their recommendation is not balancing in most situations. 

I am talking more about the LFP chemistry in general. They do not have to be above 3,55V to balance thats the absolute max they go to in a very balanced pack. As you can see in @Tinbum Images they start balancing pretty low at 3,36V if the delta is more than 30mV. The reason you want to be at the more steep part of the curve @ 3,55v is that a small balancing current makes a much bigger difference at this voltage than at the 3,4 range.

@Tinbum, @Nexuss, clear now! Thank you! I took another look into Tinbum's answer and I now see those values.

One additional question, are those values read by using something like BatteryView or MultiSIBControl? I would like to see something like that for my batteries as well. I tried googling it (only shallowly) and nothing relevant came up. Maybe I need to take a deeper look. If you could point me in the right direction, I appreciate it!

20 minutes ago, onobeka said:

@Tinbum, @Nexuss, clear now! Thank you! I took another look into Tinbum's answer and I now see those values.

One additional question, are those values read by using something like BatteryView or MultiSIBControl? I would like to see something like that for my batteries as well. I tried googling it (only shallowly) and nothing relevant came up. Maybe I need to take a deeper look. If you could point me in the right direction, I appreciate it!

Have a look at

 

Edited October 11, 20232 yr by Tinbum

On 2023/10/11 at 11:09 AM, hoohloc said:

Before giving up, contact Pylontech directly and see if they can help. Some times Segen just repudiate the claims only for Pylontech to accept the failure and honour the claim. With Segen, you will not win because they are only focusing on the events from the first year of use, when the battery failed almost three years later. To be honest, they should focus on what happened at the time of failure. It is good to look at the past history just to have an idea of how the battery was used but they still need to find out why it failed and also if you had two of them and the other one is still ok, then the issue is clearly with the battery and not how it was being used. This is just my honest opinion 

Maybe pull the logs from the other US2000 and share with Pylontech logs from both batteries.

@hoohloc I have sent off an email this morning motivating for a warranty replacement directly to Phylontech. I will provide feedback once I have received a reply. 

After reaching out to Phylontech in China, it looks like my warranty will be honoured. Thank you to all for the feedback and insight into this issue. Below is the email reply from China. 

Hi Quintus,

 

After rechecking your case, I agree that overcharging is not the main cause of battery damage. After inspection, although the battery has been impacted by large currents, the current alone should not cause damage to the cells.

 

Sorry for the wrong judgment I gave before, I will contact Segensolar to prepare a new battery for you. Please note that when using a Victron inverter, it is best to set the charging voltage to 52.5V.

 

Best regards,

Chris

13 minutes ago, Kilowatt said:

After reaching out to Phylontech in China, it looks like my warranty will be honoured. Thank you to all for the feedback and insight into this issue. Below is the email reply from China. 

Hi Quintus,

 

After rechecking your case, I agree that overcharging is not the main cause of battery damage. After inspection, although the battery has been impacted by large currents, the current alone should not cause damage to the cells.

 

Sorry for the wrong judgment I gave before, I will contact Segensolar to prepare a new battery for you. Please note that when using a Victron inverter, it is best to set the charging voltage to 52.5V.

 

Best regards,

Chris

This is really encouraging to see . Thanks for the feedback.

Interesting to see the voltage recommendation direct from pylontech.

30 minutes ago, Tinbum said:

Interesting to see the voltage recommendation direct from pylontech.

This is for Victron inverter, do not use that value as a standard for all inverters. Always refer to the battery manual for recommended values and if you want specific values for your inverter, contact them and they will give you the value. For My Growatt SPF5000TL, pylontech advised me to set the voltage to 53.2V

@Kilowatt Good to see that you came right with your claim. It is always better to contact the manufacturer directly if you have bought from Segen and the likes  

Edited October 16, 20232 yr by hoohloc

8 minutes ago, hoohloc said:

@Kilowatt Good to see that that you came right with your claim. It is always better to contact the manufacturer directly if you have bought from Segen and the likes  

Just sad that such a costly item can indeed have an error in judgement. 

Not the 1st or last error from a seller. 

Edited October 16, 20232 yr by Scorp007

11 minutes ago, hoohloc said:

@Kilowatt Good to see that that you came right with your claim. It is always better to contact the manufacturer directly if you have bought from Segen and the likes  

@hoohloc I was just going to accept the loss and walk away. So thank you for your advise to contact them directly, it has saved me a lot of money now. 

25 minutes ago, hoohloc said:

This is for Victron inverter, do not use that value as a standard for all inverters. Always refer to the battery manual for recommended values and if you want specific values for your inverter, contact them and they will give you the value. For My Growatt SPF5000TL, pylontech advised me to set the voltage to 53.2V

I know it was for Victron but Pylons recommendation in the manual and on the battery itself is a range.

I was wondering though, how you are supposed to set that, when the battery itself always set's it at 53.2v. Victron do change it in some of their units but if you don't have that and still use CAN or RS485?  (I do it by sniffing the  CAN messages and then adjusting them and sending them on to my inverters which are not Victron).

On 2023/10/10 at 5:07 PM, hoohloc said:

OP, you were hammering this battery in the first year of use. Was it the only one you had at the time? and then added the other two later on. This is the only explanation I can give with just having a look at the logs. You will not win this one with Segen 

I agree, from that data, the batteries got a hammering... it also begs the question of installers and sellers, why they often say, "oh, you can begin with this smaller battery pack for now, and add a battery later on when you can, or when your funds permit". In reality, this means you begin by hammering and abusing your current system from day-1 and by the time you increase your battery pack, the damage may be done and they have made a sale and will obviously not own up to such slyness. Note: no supplier names were mentioned to "protect the guilty"!😡

Am glad Pylontech actually came through and honoured the Warranty. That was going to be my next point of observation. I wonder how good other battery manufacturers will be in this regard such as Sunysnk batteries, Inverters, Freedom Won, BlueNova etc... or is this the power and influence of this forum being felt as we have so many who then would recommend "dropping" a particular brand?

Edited October 18, 20232 yr by Moffat
More info read on thread

On 2023/10/10 at 4:48 PM, Nexuss said:

How was these batteries wired up ? Do the logs of the other batteries also show those 50-60A discharge currents ? It almost seems like your packs were not sharing current equally as 60Ax3 would be a 180A draw which would be very unlikely from your two inverters. It doesn't look like the overcharging bothered it as much as those large currents. Your batteries are very much under spec for the system as the three of them are only rated for 87A continuous draw. Edit* I have also seen on other forums that Victron inverters can be quite Amp heavy and they recommend over-sizing the battery bank.

Why would your main breaker not trip if you were drawing such larger currents? If I remember correctly my house breaker is 60A. 

19 minutes ago, Kilowatt said:

Why would your main breaker not trip if you were drawing such larger currents? If I remember correctly my house breaker is 60A. 

The currents measured are on the DC side.

 

Edit

60A DC is 60a x 48v = 2.88KW

60A AC is 60a x 240v = 14.4KW

 

Edited October 19, 20232 yr by Tinbum