BYD BMS

[Killing]

I´am thinking about a hybrid inverter and maybe another, pure grid inverter. most hybrid inverters have a one-phase- power system.
at max. in Europe 3600W/220V, 16A AC.
Thats enough for the batteries and one string with 4KW PV is sufficient.

The second string can be used at the grid inverter. Later I will enlarge the PV generator on another roof and plug that
string in the grid-inverter, too.

 

[Coda]

I´am thinking about a hybrid inverter and maybe another, pure grid inverter. most hybrid inverters have a one-phase- power system.
at max. in Europe 3600W/220V, 16A AC.
Thats enough for the batteries and one string with 4KW PV is sufficient.

The second string can be used at the grid inverter. Later I will enlarge the PV generator on another roof and plug that
string in the grid-inverter, too.

I’m in a similar situation, though I have an almost useless 1kw grid tie system that was on the house when I bought it and I get some tiny payments from the electric company (it’s really almost nothing what they pay for a kwh though). So, Im going to upgrade to 4.5kw PV with a hybrid inverter (probably a Solis RHI 5KW 5G) which will give me an option to build a 16s1p 48v lifepo4 box later. I couldn’t care less about the £5 a month payments I get but once there is a battery everything will make sense.

 

[luisfcosta]

Yes - inside each BYD pack is 8 cells. Which makes 16 cells, in series. (and it's you are! )

Hi Jason
Thank you for this precious information and your contribution on this thread.
Honestly this helped me so much! I have 16 of these BYD packs and am starting to architect the whole thing (bracing myself)
On this note, do you have to open the packs to connect the cells in 16S or you just connect one pack to the other through the pack terminals?
I thought the 16S BMS would need each of the 16 cells to be in series.

 

[shorawitz]

Hi Jason
Thank you for this precious information and your contribution on this thread.
Honestly this helped me so much! I have 16 of these BYD packs and am starting to architect the whole thing (bracing myself)
On this note, do you have to open the packs to connect the cells in 16S or you just connect one pack to the other through the pack terminals?
I thought the 16S BMS would need each of the 16 cells to be in series.

I think we have the same BYD packs - mine are the 220Ah 24V packs. If you want 48V and you have more than 2, you have a few options. Parallel 1/2 of them to make a large 24V pack, do the same with the other 1/2, then series them. You only need 1 path to your DC equipment then. I have 8, so what I did was to series each pair making 4x48V batteries. I fused each 48V pair with a 100A fuse and disconnect. That way, I could work on each pair without taking down my system. You will still need a BMS for each 24V pack though. If you link them like I did, you don't need to spend much on the BMS's since you can take each pair out of service by throwing the disconnect.

I'm thinking of selling mine. I have new cells that I bought to build a 4P16S pack.

 

[jasonhc73]

Hi Jason
Thank you for this precious information and your contribution on this thread.
Honestly this helped me so much! I have 16 of these BYD packs and am starting to architect the whole thing (bracing myself)
On this note, do you have to open the packs to connect the cells in 16S or you just connect one pack to the other through the pack terminals?
I thought the 16S BMS would need each of the 16 cells to be in series.

One cable from one pack to the other (+ to - ) to make a 16-cell, 48V setup. A parallel setup of course doubles the AH and connected + to + and - to -.

 

[jasonhc73]

After 2½ years of use, I have a measured usable capacity of 60AH per pack.
Measured with a Victron SmartShunt.
Measured by charging to as full as the battery pack will go, 26.2V (3.3V per cell) (not really close to the self-limit of 3.45V per cell I set of 27.6V per pack)
And not discharging lower than 23.5V, (2.94V per cell)

I have 4 in parallel in a trailer. So basically 240ah of 24V for ~6 kWh. In a nice sunny day it will recharge in about 5 hours and last 2 weeks sitting idle (under trees with essentially no sun).

Here is my trailer:

Another Cargo Trailer setup.

This is now officially a legitimate sickness. My 4th off-grid system: The players: This setup is actually cheaper than going with a PWM Hybrid all in one unit 48V unit. I have AC input to charge the 48V batteries with shore power. (The 21.99 charger) A way more than I will use MPPT battery...

diysolarforum.com

 

[Supervstech]

After 2½ years of use, I have a measured usable capacity of 60AH per pack.
Measured with a Victron SmartShunt.
Measured by charging to as full as the battery pack will go, 26.2V (3.3V per cell) (not really close to the self-limit of 3.45V per cell I set of 27.6V per pack)
And not discharging lower than 23.5V, (2.94V per cell)

I have 4 in parallel in a trailer. So basically 240ah of 24V for ~6 kWh. In a nice sunny day it will recharge in about 5 hours and last 2 weeks sitting idle (under trees with essentially no sun).

Here is my trailer:

Another Cargo Trailer setup.

This is now officially a legitimate sickness. My 4th off-grid system: The players: This setup is actually cheaper than going with a PWM Hybrid all in one unit 48V unit. I have AC input to charge the 48V batteries with shore power. (The 21.99 charger) A way more than I will use MPPT battery...

diysolarforum.com

Wow... really? 60Ah? That sucks. I have 4 in a trailer, and I was hoping it was around 100Ah... they haven't been measured, but I know they are weak.
I've added 400Ah to my solar trailer, so now it should have between 600 and 700 if you are right.

 

[jasonhc73]

Wow... really? 60Ah? That sucks. I have 4 in a trailer, and I was hoping it was around 100Ah... they haven't been measured, but I know they are weak.
I've added 400Ah to my solar trailer, so now it should have between 600 and 700 if you are right.

I remember when they were sold as 5 kWh each. ? Well, anyways in my cargo trailer setup, the only thing they run all the time is the Solar Assitant PI computer, a WyzeCam, and a Google Assistant. If I didn't have the tree where I park it, the panels would keep them charged up indefinitely. I recharge my Ego Z6 and the Dewalt batteries. So they are good enough.

I could replace the entire set of packs with 1/8th the mass with new 280ah cells and have more energy storage! ? 600lbs vs 90lbs.

 

[Supervstech]

I remember when they were sold as 5 kWh each. ? Well, anyways in my cargo trailer setup, the only thing they run all the time is the Solar Assitant PI computer, a WyzeCam, and a Google Assistant. If I didn't have the tree where I park it, the panels would keep them charged up indefinitely. I recharge my Ego Z6 and the Dewalt batteries. So they are good enough.

I could replace the entire set of packs with 1/8th the mass with new 280ah cells and have more energy storage! ? 600lbs vs 90lbs.

Yeah, those beasts were a massive rip off. I too bought them expecting 5kWh each… I got a little compensation back, but wow, hard to believe they are 90% gone…

 

[bhavin66]

Not sure if the readings i am getting from victron smartshunt i just bought are correct but the first discharge cycle for 3 sets (6 batteries) connected to LV5048 gave me 392Ah that equates to about 130Ah per set of 2 connected in 48v setup. Not good but not as bad as 60Ah. will let the smartshunt monitor it from now on and see if i still get same readings

 

[jasonhc73]

Not sure if the readings i am getting from victron smartshunt i just bought are correct but the first discharge cycle for 3 sets (6 batteries) connected to LV5048 gave me 392Ah that equates to about 130Ah per set of 2 connected in 48v setup. Not good but not as bad as 60Ah. will let the smartshunt monitor it from now on and see if i still get same readings

I do limit my BYD packs to less than 3.45 per cell. 2 cells in the 32(4 packs) go way up if they get to 3.45V all on their own. The same sort of runaway happens to 6 cells if I go below 2.90V, they drop to 2.00V in seconds if I let the packs go below 2.85V.

That's kind of the nature of the beast though, totally random. I had 8 packs in a 48V setup running just fine for a year and was expecting nearly 40 kWh, but was never able to get more than 12 kWh of use out of my packs. ?

 

[bhavin66]

i installed around the same time as jasonhc73 and i think i am bit luckier. Another discharge and still 392Ah. i have my setup at 47V and 54V and i do see couple runaways 2.8v on low end and 3.8v on high end. May be i need to try balancing again. i dont have a BMS just one 1A active balancer connected to 3 sets in parallel.

 

[Coda]

3.8v

Are you sure? That's awfully high.