Idiot's guide to a self build battery

[Joeboy]

A small note, thought i'd set up the hybrid inverter this morning to self defined parameters to see what the next mornings voltage would be. Went fine and the settings are in. As we know SOC is lost but I found that the inverter was also pulling a 1/2kW from the grid pretty much consistently. That won't do so I have reverted to Pylontech profile. I'll go back to user defined at 21.30 tonight and run it overnight. See if we can get those last 2V(in 48V mode) into the LF280's as a trial and then revert back to the Pylontech profile.

3.32 to 3.34V has been approximately where the LF280 packs have been charged to by the next morning, 49.8 to 50.1V. As I say this is a one time system test then i'll go back to Pylontech settings. Once Spring rolls around the Victron system will fill the LF280's even when the Pylontechs are not charging anymore.

Pylontech profile


Self define profile

[Lincs Robert]

That's the buckboard power supply professionaly cabletied to a bit of old board. Ran it up, tried the pot, all good.

Decided to check out the top voltage on the Pylontechs.

My batteries slowdown considerably after 88% soc, they can charge there for a long time then go quickly from 88% to 100%. Here's what I found.
88% SOC @ 51.3V
95% SOC @ 52.6V
100% SOC @ 52.9V
The above percentages are as indicated on the Goodwe hybrid inverter, there is lag so pinch of salt please.
Nonetheless, after it indicated 100%SOC the Victron continued to charge as did the grid and the solaredge, all of which I left doing their thing. At 53.3V the Victron shutdown and almost immediately the solaredge power was being exported. The grid charging had been off for about a minute by then as controlled by the Goodwe hybrid inverter.
Did another check after a few minutes and holding at 53.3V

Disconnected the can lead and the main feed leads to the stack and watched it self balance for about 6 minutes then all the Pylontech lights were out. A quick check of the voltage and it had fell back to 52.9V. Hooked it back up, reboot and all fine. I mention the change in voltage seen pre&post balancing to show that it does make a difference and is worth doing. I am choosing to do it on an annual basis even though its a small amount of power being redistributed (to be honest, I just like watching it do its thing).


The main thing I am taking away from this is that my particular Pylontech stack has a peak of 53.3V. Not sure what the rest of you guys top out at?

As each battery unit has 15 individual batteries within it in series I can take the 53.3V seen at 100%SOC and divide in by 15 which gives me a figure to stay below when balancing the new LF280 batteries on their Nov arrival. 3.553V being the figure.

That was fun.

A reply to a post from a couple of months ago! As you can see, I’m working through this saga working out all the pitfalls awaiting me for my own build - for which the batteries haven’t left China as yet. . Hey ho.

The reason I’ve replied to this particular post relates to the voltage of the fully charged Pylon stack - which Joe has stated for him is 52.9 volts @ 100%. So I’ve just measured mine (as it’s just finished charging using Go Faster). I only have 50.8 volts. My config is a LuxPower 3600 ACS with 5 x Pylons. Does anyone else have a similar config and would care to share their voltage please. I actually have this duplicated, 2 Luxes with 2 stacks of Pylon, the other stack indicates 50.7 volts. Those voltages are as indicated by the Lux app, actually measuring it with a cheapy DVM shows 50.4 and 50.5 respectively.

Seems to me as if I’m at least 2 volts down, should I be concerned & is there anything I need to do about it?

Cheers- Rob

[Tinbum]

Mine will go up to 53.2v at times but they don't stay their long at all.

[Joeboy]

That's the buckboard power supply professionaly cabletied to a bit of old board. Ran it up, tried the pot, all good.

Decided to check out the top voltage on the Pylontechs.

My batteries slowdown considerably after 88% soc, they can charge there for a long time then go quickly from 88% to 100%. Here's what I found.
88% SOC @ 51.3V
95% SOC @ 52.6V
100% SOC @ 52.9V
The above percentages are as indicated on the Goodwe hybrid inverter, there is lag so pinch of salt please.
Nonetheless, after it indicated 100%SOC the Victron continued to charge as did the grid and the solaredge, all of which I left doing their thing. At 53.3V the Victron shutdown and almost immediately the solaredge power was being exported. The grid charging had been off for about a minute by then as controlled by the Goodwe hybrid inverter.
Did another check after a few minutes and holding at 53.3V

Disconnected the can lead and the main feed leads to the stack and watched it self balance for about 6 minutes then all the Pylontech lights were out. A quick check of the voltage and it had fell back to 52.9V. Hooked it back up, reboot and all fine. I mention the change in voltage seen pre&post balancing to show that it does make a difference and is worth doing. I am choosing to do it on an annual basis even though its a small amount of power being redistributed (to be honest, I just like watching it do its thing).


The main thing I am taking away from this is that my particular Pylontech stack has a peak of 53.3V. Not sure what the rest of you guys top out at?

As each battery unit has 15 individual batteries within it in series I can take the 53.3V seen at 100%SOC and divide in by 15 which gives me a figure to stay below when balancing the new LF280 batteries on their Nov arrival. 3.553V being the figure.

That was fun.

A reply to a post from a couple of months ago! As you can see, I’m working through this saga working out all the pitfalls awaiting me for my own build - for which the batteries haven’t left China as yet. . Hey ho.

The reason I’ve replied to this particular post relates to the voltage of the fully charged Pylon stack - which Joe has stated for him is 52.9 volts @ 100%. So I’ve just measured mine (as it’s just finished charging using Go Faster). I only have 50.8 volts. My config is a LuxPower 3600 ACS with 5 x Pylons. Does anyone else have a similar config and would care to share their voltage please. I actually have this duplicated, 2 Luxes with 2 stacks of Pylon, the other stack indicates 50.7 volts. Those voltages are as indicated by the Lux app, actually measuring it with a cheapy DVM shows 50.4 and 50.5 respectively.

Seems to me as if I’m at least 2 volts down, should I be concerned & is there anything I need to do about it?

Cheers- Rob

Fair question Rob,the max as far as i know for Pylontechs is 53.2V That's not to say there isn't variance between our stacks or indeed measurement of those. We spoke a while back about the accuracy of inverter SOC and how much actual band is stored above a certain voltage. Defo diminishing returns.

Here's a thought from today. I am not maxing out my stack voltage in any way and know for a fact that I am not getting anywhere close to my LF280's max. I won't see that until May 23.

My point is that even at the lesser charge rate and volume provided to the parasite LF280's we still managed this today. Bear in.mind that the Pyontechs were a 14.4kWh stack.

18th Nov
90% soc & 1.8kWh
61% soc 8.7kWh
55% soc 10.3kWh
44% soc 12.3kWh
31% soc 14.5kWh discharged

As you can see I'm miles off the full charge potential but I'm OK with that as even the extra that bleeds over to the LF280's during the Pylontech charge window is enough to keep me happy. We'll see how it plays out in the Spring. TBH, the goodwe hybrid is a bit a**e when it comes to forcing it to do self defined charging. Epic fail actually.

My further point is that the true meat of it is in the middle of the stack voltage, not the extreme edges...Hope this helps?

[nowty]

The reason I’ve replied to this particular post relates to the voltage of the fully charged Pylon stack - which Joe has stated for him is 52.9 volts @ 100%. So I’ve just measured mine (as it’s just finished charging using Go Faster). I only have 50.8 volts. My config is a LuxPower 3600 ACS with 5 x Pylons. Does anyone else have a similar config and would care to share their voltage please. I actually have this duplicated, 2 Luxes with 2 stacks of Pylon, the other stack indicates 50.7 volts. Those voltages are as indicated by the Lux app, actually measuring it with a cheapy DVM shows 50.4 and 50.5 respectively.

Seems to me as if I’m at least 2 volts down, should I be concerned & is there anything I need to do about it?

Cheers- Rob

Where your batteries in standby (all leds off) or had the batts been in discharge for a short time ?, when you measured them.

50.7V or 50.8V on a pylontech is still about 97% or 98% SOC, i.e. they are still nearly full. If the bats are in standby (all leds off), you cannot measure the voltage correctly with a DVM because they partially shut down the output. You actually need a small load on them to wake them up.

If the pylontechs have been in discharge even for a few minutes they may have lost a couple of percent anyway and the voltage drops dramatically near the top end.

When you add your new cells in parallel, and say you set the charge voltage to 53.5V. The pylontechs will go into standby at 52.7 to 52.9V. Your Chinese stack will keep on charging to 53.5V (given enough time). In discharge the pylontechs will stay in standby until the voltage drops a little, then they will wake up. In fact, when the pylontechs wake up because of a small amount of hysteresis, you might notice the pylontechs charging again from your Chinese stack.

[Lincs Robert]

That's the buckboard power supply professionaly cabletied to a bit of old board. Ran it up, tried the pot, all good.

Decided to check out the top voltage on the Pylontechs.

My batteries slowdown considerably after 88% soc, they can charge there for a long time then go quickly from 88% to 100%. Here's what I found.
88% SOC @ 51.3V
95% SOC @ 52.6V
100% SOC @ 52.9V
The above percentages are as indicated on the Goodwe hybrid inverter, there is lag so pinch of salt please.
Nonetheless, after it indicated 100%SOC the Victron continued to charge as did the grid and the solaredge, all of which I left doing their thing. At 53.3V the Victron shutdown and almost immediately the solaredge power was being exported. The grid charging had been off for about a minute by then as controlled by the Goodwe hybrid inverter.
Did another check after a few minutes and holding at 53.3V

Disconnected the can lead and the main feed leads to the stack and watched it self balance for about 6 minutes then all the Pylontech lights were out. A quick check of the voltage and it had fell back to 52.9V. Hooked it back up, reboot and all fine. I mention the change in voltage seen pre&post balancing to show that it does make a difference and is worth doing. I am choosing to do it on an annual basis even though its a small amount of power being redistributed (to be honest, I just like watching it do its thing).


The main thing I am taking away from this is that my particular Pylontech stack has a peak of 53.3V. Not sure what the rest of you guys top out at?

As each battery unit has 15 individual batteries within it in series I can take the 53.3V seen at 100%SOC and divide in by 15 which gives me a figure to stay below when balancing the new LF280 batteries on their Nov arrival. 3.553V being the figure.

That was fun.

A reply to a post from a couple of months ago! As you can see, I’m working through this saga working out all the pitfalls awaiting me for my own build - for which the batteries haven’t left China as yet. . Hey ho.

The reason I’ve replied to this particular post relates to the voltage of the fully charged Pylon stack - which Joe has stated for him is 52.9 volts @ 100%. So I’ve just measured mine (as it’s just finished charging using Go Faster). I only have 50.8 volts. My config is a LuxPower 3600 ACS with 5 x Pylons. Does anyone else have a similar config and would care to share their voltage please. I actually have this duplicated, 2 Luxes with 2 stacks of Pylon, the other stack indicates 50.7 volts. Those voltages are as indicated by the Lux app, actually measuring it with a cheapy DVM shows 50.4 and 50.5 respectively.

Seems to me as if I’m at least 2 volts down, should I be concerned & is there anything I need to do about it?

Cheers- Rob

Fair question Rob,the max as far as i know for Pylontechs is 53.2V That's not to say there isn't variance between our stacks or indeed measurement of those. We spoke a while back about the accuracy of inverter SOC and how much actual band is stored above a certain voltage. Defo diminishing returns.

Here's a thought from today. I am not maxing out my stack voltage in any way and know for a fact that I am not getting anywhere close to my LF280's max. I won't see that until May 23.

My point is that even at the lesser charge rate and volume provided to the parasite LF280's we still managed this today. Bear in.mind that the Pyontechs were a 14.4kWh stack.

18th Nov
90% soc & 1.8kWh
61% soc 8.7kWh
55% soc 10.3kWh
44% soc 12.3kWh
31% soc 14.5kWh discharged

As you can see I'm miles off the full charge potential but I'm OK with that as even the extra that bleeds over to the LF280's during the Pylontech charge window is enough to keep me happy. We'll see how it plays out in the Spring. TBH, the goodwe hybrid is a bit a**e when it comes to forcing it to do self defined charging. Epic fail actually.

My further point is that the true meat of it is in the middle of the stack voltage, not the extreme edges...Hope this helps?

Yes, makes sense - thanks

[Lincs Robert]

The reason I’ve replied to this particular post relates to the voltage of the fully charged Pylon stack - which Joe has stated for him is 52.9 volts @ 100%. So I’ve just measured mine (as it’s just finished charging using Go Faster). I only have 50.8 volts. My config is a LuxPower 3600 ACS with 5 x Pylons. Does anyone else have a similar config and would care to share their voltage please. I actually have this duplicated, 2 Luxes with 2 stacks of Pylon, the other stack indicates 50.7 volts. Those voltages are as indicated by the Lux app, actually measuring it with a cheapy DVM shows 50.4 and 50.5 respectively.

Seems to me as if I’m at least 2 volts down, should I be concerned & is there anything I need to do about it?

Cheers- Rob

Where your batteries in standby (all leds off) or had the batts been in discharge for a short time ?, when you measured them.

50.7V or 50.8V on a pylontech is still about 97% or 98% SOC, i.e. they are still nearly full. If the bats are in standby (all leds off), you cannot measure the voltage correctly with a DVM because they partially shut down the output. You actually need a small load on them to wake them up.

If the pylontechs have been in discharge even for a few minutes they may have lost a couple of percent anyway and the voltage drops dramatically near the top end.

When you add your new cells in parallel, and say you set the charge voltage to 53.5V. The pylontechs will go into standby at 52.7 to 52.9V. Your Chinese stack will keep on charging to 53.5V (given enough time). In discharge the pylontechs will stay in standby until the voltage drops a little, then they will wake up. In fact, when the pylontechs wake up because of a small amount of hysteresis, you might notice the pylontechs charging again from your Chinese stack.

That makes sense, yes, the Pylon LEDs were all off.

Thinking about when I add the Chinese stack, I was planning on top balancing the new cells (in parallel right), and then reworking the busbars to the final, series, config to give the desired voltage. I’m not sure what that should be at this stage, but was thinking that it should be a bit less than the an almost full Pylon voltage - so let’s say 3.366 volts giving 50.5 when in series. So, with 50.5 on the Chinese stack, I was going to wait until the Pylons were @ 50.5v before throwing the Frankenstein switch, or perhaps even placing a low value resistance (an ohm or so) between the two positives to limit the current flow before throwing the switch. Hope that makes sense as a method? If I were to set the charge volts to 53.5v, as you mention, I’m assuming that this would actually be done by 53.5/15 = 3.566 as a cell voltage? My Lux unit is set to Pylon battery mode and surely I’d have to set it to lead acid mode and then set the max voltage? Is that even a setting I can change? I don’t recall seeing it before - but then again I’ve probably not looked in the right place.

Sorry about the ramblings here.

Thanks for the support chaps

[nowty]

Thinking about when I add the Chinese stack, I was planning on top balancing the new cells (in parallel right), and then reworking the busbars to the final, series, config to give the desired voltage. I’m not sure what that should be at this stage, but was thinking that it should be a bit less than the an almost full Pylon voltage - so let’s say 3.366 volts giving 50.5 when in series. So, with 50.5 on the Chinese stack, I was going to wait until the Pylons were @ 50.5v before throwing the Frankenstein switch, or perhaps even placing a low value resistance (an ohm or so) between the two positives to limit the current flow before throwing the switch. Hope that makes sense as a method? If I were to set the charge volts to 53.5v, as you mention, I’m assuming that this would actually be done by 53.5/15 = 3.566 as a cell voltage? My Lux unit is set to Pylon battery mode and surely I’d have to set it to lead acid mode and then set the max voltage? Is that even a setting I can change? I don’t recall seeing it before - but then again I’ve probably not looked in the right place.

Sorry about the ramblings here.

Thanks for the support chaps

Paralleling the individual cells up to initially balance them is fine as long as each cell is within about 0.2V. When connecting the stack up with the pylontechs the smaller the voltage difference the better but I have no problem connecting them with up to 0.5V difference (full stack voltage).

In practice you can get away with larger voltage differences but not for the faint hearted.

[Lincs Robert]

Thanks

I’ll think I’ll take an actual voltage that isn’t the LEDs off “100”, maybe slightly less than that. Or even wait for the Pylons to drop down to whatever the Chinese stack is at before throwing the Frankenstein switch.

It’s all quite some time away however, and I have lots & lots of prep to do in advance …….

[Tinbum]

Just make sure of your max voltage for the Pylontech. (Over 55v and they will require a new BMS).