Newbie feeling lost 😞 Battery Balance issue

[Tinbum]

I think you need to look at it the other way round.

57/16 = 3.56v so if a cell is 3.75v it is over volt. (3.56v is more normal for a max charging cell voltage).

[nowty]

If they are the Extra 2000 batteries another online datasheet has very different voltage profiles, more akin to the standard 15 cell ones today.

https://www.renugen.co.uk/content/Renew ... ochure.pdf



Also Dannyg2325 says in his first post,
"Lids off and multimeter out, I started checking the 4 packs within each cabinet. The first pack on both batteries had the same reading of approx 9v, the other 3 packs on both were in and around 11v each. So I’m guessing that’s them all out of balance now."

Suspicious that both cabinets have a first pack of 9v and the rest at 11v. Sounds like there are 3 packs of 4 cells in series and a 1 with only 3 cells in series. And then with all packs in series with each other. Therefore they might have been all balanced but all of them just too low.

Dannyg2325 - Did the pack sizes all look like the same size ?, and could you even count the cells ?

We like a nice mystery here and we wont give up till we find an answer, could you send any pictures of the pylontech, or is there a model number ?

[Tinbum]

Yes very interesting. The modern ones have 3 packs. So that would make me think 4 cells in a pack as against verses 5 to a pack but as you say its strange re voltages.

Pylontech do seem to change their specs but not model numbers. Their latest US3000c and I think US2000c now have different hardware internally that now gets bricked if updated the same way as the older ones but you can only tell by the serial number.

My Tp-Link TL-ER5120 is now on version 4. It even looks different and will be bricked if you use any other versions firmware but still it's the same model number. Even if you look at the TP-Link website it shows the specs for the wrong version and wrong picture!!

[Dannyg2325]

Yes they are as per your picture Nowty, the Extra2000’s.
Definitely 4 packs in each cabinet, I’d assume they’re supposed to be nominal 12v each hence making 48v total.

I haven’t pulled the individual packs apart to see what the make up inside is (not that brave, nor felt the need haha)
Each pack that was 9v was the first battery connected to the main terminal, not sure if that makes any difference or not?

The remaining packs reading 11v I just assumed was because they had discharged too far.

I have a picture of one with the lid off if that helps, of course if you need anything else I can obtain/upload tomorrow

[Tinbum]

Think your right nowty. Look at the pack labels. 3 x US2000A and 1x US2000B.

[nowty]

I really don't know, I'm actually thinking they may be 16 (or even 12 cells with a higher voltage chemistry) now as each pack has an increment marking of 10V and they all look identically sized. This means I'm not going to provide a list of parameters that may prove to be wrong.

What I will say is whatever setting you were using, increase the "Set min discharge voltage by a volt or two in order for the pack not to discharge too far. That will override whatever DOD % you set as that will be all over the place in lead acid mode.

The pylontechs do have a lot of protections so its pretty hard to kill them as they current limit, alarm or shut down if you do something they don't like. The other thing I would say is don't add any other types of pylontechs in parallel with them as they may well have different operating voltages if they have a different number of cells.

[Dannyg2325]

It’s a tough one for sure.

I’ve reconfigured based on the data sheet you posted Nowty, but gone with 44v-54v to be on the safer side and not discharge too far.
It’s up and running again and charging away this morning from the solar, so I will keep an eye on things and see how it goes.

Working on the 80% dod I should be able to draw approx 3.8kwh from the packs all being well

Thanks for everyone’s input, greatly appreciated!
I feared I had discharged them too far, throwing them out of balance and having no way of rectifying it.
They didn’t cost me a lot of money to begin with, and bought them as a test really to see if it were worth it, so wasn’t soo bothered if they were now scrap.

I’d love to increase my bank to be less reliant on the grid as I’ve got plenty of PV to charge them, plus E7 durning the winter.

The 2 batteries I currently have, have made a huge difference reducing our leccy bills by more than half (along with a few other changes)

[nowty]

It’s a tough one for sure.

I’ve reconfigured based on the data sheet you posted Nowty, but gone with 44v-54v to be on the safer side and not discharge too far.
It’s up and running again and charging away this morning from the solar, so I will keep an eye on things and see how it goes.

Working on the 80% dod I should be able to draw approx 3.8kwh from the packs all being well

Your plan is sounds good, you can see how it goes and see how much power goes in and out of the batteries. You can also watch the LED status on the pylontechs themselves. Over time you may be able to widen out the voltage settings but your starting from a safer baseline.

Keep us up to date with how it goes.

[hoggy]

How did you get on with these?
I have a set of 3 currently (probably from the same source) on a Goodwe Inverter which can actually talk to the Pylontech Extra 2000 BMS fine.
(They also seem to go by the name of US2000A)
Mine are 2x 2016 and one from 2015.
They should have a sticker with Voltage ranges on them.

I can report from my experience with them that the Pylon BMS requests the following from the GoodWe Inverter:

Charge Voltage: 53.8V
Cut-Off Voltage: 45.5V
"Float" Voltage: 52.5V (52.0V)
Discharge current: 50A (40A)
Charge Current: 50A

Note: items in brackets are what I have set instead. Curiously the BMS overrules all the other settings, including Charge Rate which is a bit weird but I guess it thinks it knows best. I would prefer the Charge Voltage to be lower (which I can then adjust should I simply disconnect the BMS cable and run as lead acid) but by doing so you lose SOC so you can't win.
Perhaps they need slightly more volts to get the balancers to kick in compared to the newer Pylons. These are a bit of a rarity and I've struggled to find much about them internally.

PS this is the latest manual I can find on them (2014) https://www.nuvisionenergy.co.uk/image/ ... Manual.pdf

[Dannyg2325]

Hoggy, thank you for posting these settings!

I have it set as per your settings and it has worked faultlessly to this day.

I thought I had replied to you, until this morning when I realised I hadn’t. So apologies for my ignorance!

Thanks again for the help, greatly appreciated

Danny