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Deep discharge test of 6 different capacity and BMS batteries

Quattrohead

Quattrohead

Solar Wizard
Joined
Oct 13, 2021
Messages
3,978
Location
Florida
I have 4 ex Felicity Solar 10kw batteries now with a JBD BMS, 1 DIY 14kw with a JBD BMS and another DIY 14kw with a JK BMS.

Almost otally off grid all electric home in central Florida. It has been cloudy here for the past several days as a front has stalled over us, morning sun and heavy afternoon storms.
I decided to not chicken out and connect the grid again and see how far I can take the batteries, just as a matter of interest.

Bat 1 14k JBD = 19%
Bat 2 14k JK = 26%
Bat 3 10k JBD = 25%
Bat 4 10k JBD = 24%
Bat 5 10k JBD = 26%
Bat 6 10k JBD = 26%
 
Just over 1 hour later, solar input ramping up 4.5kw currently -

Bat 1 14k JBD = 23%
Bat 2 14k JK = 29%
Bat 3 10k JBD = 28%
Bat 4 10k JBD = 27%
Bat 5 10k JBD = 29%
Bat 6 10k JBD = 29%
 
Weather better today, almost 6 hours later.

Bat 1 14k JBD = 73%
Bat 2 14k JK = 73%
Bat 3 10k JBD = 73%
Bat 4 10k JBD = 72%
Bat 5 10k JBD = 73%
Bat 6 10k JBD = 74%
 
Thanks for sharing your experience.
I am testing my 304A in parallel with a 100A tomorrow starting with similar voltages but with totally different BMSs the 304A being based on the Seplos 200E and the Odipie 100A running a Daren BMS.
Do you connect them by rs485 regardless of what BMS they run on?
Unfortunately, I have no access to the Odipie since the can bus doesn't seem to be compatible with Victron and I have not yet found a monitoring software for it so I am unsure about using the rs485, any suggestions?
 
Logic28 said:
Unfortunately, I have no access to the Odipie since the can bus doesn't seem to be compatible with Victron and I have not yet found a monitoring software for it so I am unsure about using the rs485, any suggestions?
Click to expand...
I run my 304 pack with a noncommunicating 100Ah paralleled and it's no problem. The 100Ah just follows along. I don't worry if their SOC gets out of sync in the middle range. They still top out together fine.
 
hwy17 said:
I run my 304 pack with a noncommunicating 100Ah paralleled and it's no problem. The 100Ah just follows along. I don't worry if their SOC gets out of sync in the middle range. They still top out together fine.
Click to expand...
YES! Ah!
Its odd how many leave off the energy h indicator and write the energy discharge notation...
 
hwy17 said:
I run my 304 pack with a noncommunicating 100Ah paralleled and it's no problem. The 100Ah just follows along. I don't worry if their SOC gets out of sync in the middle range. They still top out together fine.
Click to expand...
Thanks, yes I've heard that before and I shall try again today since the first time also mine followed along for some time but all of a sudden one day the smaller one started discharging much much faster.
 
Logic28 said:
Thanks, yes I've heard that before and I shall try again today since the first time also mine followed along for some time but all of a sudden one day the smaller one started discharging much much faster.
Click to expand...
My thoughts would be 1. Is the 100Ah getting out of balance in which case it could be separated and held at a full charge to balance. 2. Are you expecting the SOC to follow closely in the mid range, my 100Ah was at 50% yesterday while my 304Ah said 20% but I don't mind that.
 
I've been running them all day starting with similar voltages and just looked at their status now:
100A Odipie registering 73% SOC with a cell max delta voltage of 3 mA
304A Seplos BMS based at 80% SOC and you can see the Cell voltages yourself here:

screenshot_20240330-212122-png.205930
Screenshot_20240330-212112.png


I'm curious to see what will happen during the night but I fear that not much will change having such low loads at that time, perhaps a cloudy day will show more.

Interestingly this time I have not connected the Seplos Can bus to the Cerbo as I've had two previous issues that are still unknown so I want to test the two batteries purely in parallel with no communication whatsoever
 

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One month later - I've been running the two battery packs without any communication with each other or from the Seplos to Venus and I've never had any issues since.
However, as stated in my other post here
https://diysolarforum.com/threads/multiplus-ii-warnings-alarms.83127/page-2#post-1078933
I seem to receive multiple warnings from the VE Bus, DC ripple, Overload and occasionally low battery all when the load is not particularly high and when the batteries are generally around 80/90%.
 
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