So, new lifepo4-bank and new SMART BMS from Daly, how can this go wrong?
According to the sales representative of the lifepo5-cells the lot was matched and balanced. My obvious questions were:
A) matched how
B) balanced, top or bottom
when the reply arrived as
A) by voltage
B) both
I knew this was going to get ugly...
Ok, yes, the eve cells are good, but no tool works well without proper handling and maintenance.
8pcs of 280ah cells, ~7kwh, will keep everything running for 4days in winter time (without charging). Never mind B. How much can I loose? A couple of ah? Maybe... but that showed itself to be the least problem I encountered,
I have an inverter. It’s a voltronic clone, it’s great, I love it. But it pointed out an annoying issue by itself when the new bank and bms was installed.
the smart bms from Daly works great. Really up to spec. When a cell (during charge) hit the treshold, BOOM; the charge mosfet shut.
Perfect!
or?
So petrol generator is running (I’m in Sweden, we only have sun almost never), and it’s pushing 60 amps to the 8s bank), impressive right?
One of the (top AND bottom balanced) cells hits the treshold, and the charge mosfet shut and what? The inverter shut down! Error 08, blabla bus overvoltage. Non-recoverable in software. Pitch black! So while I have ice bears roaming around the yard I need to disconnect the bank to reset the inverter. the perimeter fence is down, this is bad!
I’m ok. Don’t worry, they seldom attack if they are not hungry!
After some investigation I found out that IF the charge current is ~20A+ when the chgMos shut, the inverter enter this state. When the current is =that high= the inverter cannot handle the disconnect. The battery side of the inverter goes 33v+ which is way over the specs, hence producing the error.
I was kinda annoyed, almost angry for a week or two, both at DALY, since they have such a HARD shutdown and also at EASUN since they could not handle such a HARD shut down, but after a bit of thinking I realised that:
A) Daly hw is acting accordingly
B) Yes, the Inverter should maybe handle this but
C) it is mainly due to my unbalanced bank, Sorry, no, my Bottom AND top balanced pack.
Which the bank in reality is neither....
I came to the conclusion that IF the bank was top balanced this issue would never surface.
If the bank was top balanced and the bank hits 3.65, the charge current would have gone down to levels that the inverter could handle.
hence, top balancing.. so how do I do this... according to numerous guides and prowse videos, the trick is to parallel charge all cells to 3.65v until no current is drawn (-ish)
I really don’t have the energy or time or 3.65v-power source to to this, it’s not gonna happen!
what I DO HAVE is a big ass dump load that came with the worthless wind turbine controller. I bought some year ago.
it’s one ohm, BUT you can hook into it anywhere, hence lower the resistance by just scratching the surface and attaching a lead.
Ok, I admit it was a tedious process, but it worked. I fired up the generator and had an eye on the cells voltage when charging and when it went over 3.35v I put the plan in action:
I attached wires with connection “clamp” to the dump load, at 1/4, which should give me around 0.25ohm. That will generate ok balancing current, like ~ 3.2/0.25 =>~13A.
whenever I saw a cell being at higher voltage then the other cells I attached the clamps to the cell until the other cells came along. In the beginning it took a while but the more charge the cells got, the faster it went. In the end it was almost like a puzzle game to get it to perfection. I had to cut the charge current to 10A to keep up, but after an hour or so “gaming”, the current dropped to zero and the voltage of each cell was within 4mV.
hopefully error 08 will not appear again! ?
According to the sales representative of the lifepo5-cells the lot was matched and balanced. My obvious questions were:
A) matched how
B) balanced, top or bottom
when the reply arrived as
A) by voltage
B) both
I knew this was going to get ugly...
Ok, yes, the eve cells are good, but no tool works well without proper handling and maintenance.
8pcs of 280ah cells, ~7kwh, will keep everything running for 4days in winter time (without charging). Never mind B. How much can I loose? A couple of ah? Maybe... but that showed itself to be the least problem I encountered,
I have an inverter. It’s a voltronic clone, it’s great, I love it. But it pointed out an annoying issue by itself when the new bank and bms was installed.
the smart bms from Daly works great. Really up to spec. When a cell (during charge) hit the treshold, BOOM; the charge mosfet shut.
Perfect!
or?
So petrol generator is running (I’m in Sweden, we only have sun almost never), and it’s pushing 60 amps to the 8s bank), impressive right?
One of the (top AND bottom balanced) cells hits the treshold, and the charge mosfet shut and what? The inverter shut down! Error 08, blabla bus overvoltage. Non-recoverable in software. Pitch black! So while I have ice bears roaming around the yard I need to disconnect the bank to reset the inverter. the perimeter fence is down, this is bad!
I’m ok. Don’t worry, they seldom attack if they are not hungry!
After some investigation I found out that IF the charge current is ~20A+ when the chgMos shut, the inverter enter this state. When the current is =that high= the inverter cannot handle the disconnect. The battery side of the inverter goes 33v+ which is way over the specs, hence producing the error.
I was kinda annoyed, almost angry for a week or two, both at DALY, since they have such a HARD shutdown and also at EASUN since they could not handle such a HARD shut down, but after a bit of thinking I realised that:
A) Daly hw is acting accordingly
B) Yes, the Inverter should maybe handle this but
C) it is mainly due to my unbalanced bank, Sorry, no, my Bottom AND top balanced pack.
Which the bank in reality is neither....
I came to the conclusion that IF the bank was top balanced this issue would never surface.
If the bank was top balanced and the bank hits 3.65, the charge current would have gone down to levels that the inverter could handle.
hence, top balancing.. so how do I do this... according to numerous guides and prowse videos, the trick is to parallel charge all cells to 3.65v until no current is drawn (-ish)
I really don’t have the energy or time or 3.65v-power source to to this, it’s not gonna happen!
what I DO HAVE is a big ass dump load that came with the worthless wind turbine controller. I bought some year ago.
it’s one ohm, BUT you can hook into it anywhere, hence lower the resistance by just scratching the surface and attaching a lead.
Ok, I admit it was a tedious process, but it worked. I fired up the generator and had an eye on the cells voltage when charging and when it went over 3.35v I put the plan in action:
I attached wires with connection “clamp” to the dump load, at 1/4, which should give me around 0.25ohm. That will generate ok balancing current, like ~ 3.2/0.25 =>~13A.
whenever I saw a cell being at higher voltage then the other cells I attached the clamps to the cell until the other cells came along. In the beginning it took a while but the more charge the cells got, the faster it went. In the end it was almost like a puzzle game to get it to perfection. I had to cut the charge current to 10A to keep up, but after an hour or so “gaming”, the current dropped to zero and the voltage of each cell was within 4mV.
hopefully error 08 will not appear again! ?
