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diy solar

EG4 6500EX 120/240 Setup, 48V 105kWh Battery & Overkill 100A BMS Install

PreppenWolf said:
I am glad I was not the only one to have this theory. I legit typed the same exact hypothesis to Ben. I agree I believe it "remembers" being below threshold and will not revert until setting 13 is hit. Because Solar interrupted that process, it was sending all the solar to the battery and remaining in bypass, but because Solar is priority for charging, the AC In was shutoff until Solar stopped producing.

Because I am very interested in testing this hypothesis, I am letting it grid charge to 54V. It's at 53.7 now so I should have my answer before I go to sleep.
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Now that you both mention this, I believe in my testing that I’ve experienced the same thing as well. Until you hit that “back to battery” voltage, the system will keep dripping you back to bypass mode.
 
Ty from SS did reach out thus morning at 830. This is what I sent him back.

Hi Ty,

The "issue", if we can call it that, is resolved. The unit charged to the Setting 13 value of 54V, then flipped back to battery mode. It is an odd behavior that the unit has this remberance and reverts back to grid even after solar interrupts. In my opinion it would make more sense to only utility charge until solar was available and do a check "Does solar exceed demand by X%". If yes, cancel grid charge and only solar charge. If solar dips below needed output, resume battery oitput. Then only grid charge again if the battery dips below setting 12 again.

Others may not desire that behavior, so I leave it to you guys to take it and discuss. I think at minimum there should be a note added to the manual under setting 12 "If this setting is triggered, battery priority will not be restored until battery charging reaches setting 13."

For records, my settings:

01 - SBU
02 - 120A
03 - UPS
04 - USE
06 - LRE
07 - TRE
09 - 60
10 - 120
11 - 60A
12 - 48
13 - 54
16 - SNU

Max PV input voltage is 450V, average during this time of year 230V as I have shading.
 
I'd lower setting 11 to 2A, unless you want some utility charging. Setting 12 to 44V, and setting 13 to 48V to 50V unless you have a circumstance where you want grid charging such as a snowstorm coming with possible outage. If you have enough battery capacity, I'd move these as low as possible. If you have some cell balance issues at the lower SOC, adjust accordingly.
 
I'm keeping Setting 12 at 48V due to the number of outages we have being so rural in a forest area. My wife and I both have home offices, so being able to have some backup at all times is important to us.

As we are currently still seeing sun at a low angle in NH, I'm not prepared to reduce the grid charging down. I'd rather fill the battery occasionally during a week of clouds/snow and just eat the grid charge to let the batteries cycle. It's not happening often, only 5 cycles since commissioning and one of those I forced due to predicted ice storm.
 
I was hoping to have a new high today as I removed some trees last weekend. Woke up and it was clear skies, then some clouds rolled in around 10. February single day high is 45.3kWh.

I will post up monthly production totals by editing the OP and adding a post to note an update has been made for people to have data for my area.

Some trees removed:


 
How much of that Feb jump would you attribute to the trees coming down vs the regular increase as you get closer to spring?
 
Well encountered a setup error on my part today. Finally had several days of big production with clear skies after 3ft of snow last week. Topped off the batts early this morning, then the shortcoming arose.

My units kept toggling batt charging on and off. Long and short of it is I had too tight of a tolerance on my BMSs. I was setup 3.700 disconnect and 5sec/3.650V reconnect.

I'm adjusting 3.700V disconnect and 3.450V reconnect to leave more settling room. Will report back how this works out before changing anything else. I likely will have to tweak the 6500 settings as well.
 
I use 3.65V for high voltage limit and bank charge voltage is set at 56.5V. On the Batrium, I see it reads 0.1V less on the display, the cells never go above 3.50V. I've never seen the 6500EX go into Float, it slows down charge for absorb as 56.5V is close, then bypass (balancing) on the Batrium begins. Cells are held at the 3.5V until the SCC quits charging. I've thought about lowering it some, the problem is the Batrium has a preset voltage for LFP-Long Life for bypass to begin at 3.5V and I can't change it.
 
PreppenWolf said:
Yes.
Click to expand...
I've actually ran into something similar a few weeks ago. I was messing with something and my cells were outta balance. As soon as the one cell would clear the HVD setting, charging would ramp right back up again and that cell would peak shutting down the pack again.

I would be cautious about charging to 3.7v. Every cell spec sheet I've seen has always stated 3.65 max for LifePo4.
 
Yeah I'm contemplating options today. Obviously I chose "aggressive" parameters on both. I still want as much maximum absorption as possible, so I'm will to accept there is going to be cycling on/off that occurs when the bank is full. Here in the NH we're in the wet season and there will be a lot of cloudy days over the next 4-6 weeks.

Lowering the 6500s charging voltage is likely the way to find a sweet spot that keeps the banks open and instead throttles charging.
 
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