Sounds like you said the same thing twice.
No, I did not. Either you do not understand the charging modes or you are uninformed. I tried not be derogatory. Basically, you are ware of the modes but do not understand the modes or you have no knowledge of the modes or what you do know is incorrect. Those are not the same thing.
So you are telling me if I wake up to the battery monitor saying its at 95%, it reaches 100% by noon, and by 1 PM the charging current is 0.30 AMPs, on a 2s2p 200 AH battery bank, that it isn't full? If not, how long would you say to leave it charging on the 27.2 float voltage to consider it full?
My other system is still charging at 6 amps in boost voltage 29.2, so I know that one isn't 100% full. I've disconected it from all loads once during this month and let it charge for 2 days.
Go to the spec sheet, right hand side and note the charge curve, this was for the original 100Ah Gel battery in this thread.
https://www.renogy.com/content/RBT100GEL12-G1/GEL100-Datasheet.pdf
For 200Ah AGM, (I didn't dig for a Gel 200Ah), you go here
https://www.renogy.com/content/RNG-BATT-AGM12-200/AGM200-Datasheet.pdf
Below you state 800Ah of battery capacity but I'm not quite certain if you are using 100Ah batteries or 200Ah batteries (it does appear you possibly have 200ah). Will make a huge difference on charge rate. Any batteries in series do not increase total Ah capacity, it only doubles the voltage. Batteries in parallel will double the total Ah capacity. Note I said total Ah capacity, of which 50% is usable.
As full charge is reached and charger hits C.V. charge current should drop to .01CA. Note that Renogy states 13.6V to 13.8V for a full charge. 13.8V with 2 batteries in series would be 27.6V and not 27.2V. If you hold at 27.6V and rate is less than .01CA, then it should be fully charged.
Using the charge curve, from a 50% discharge, it should take 12 hours to fully charge the battery (double that with a 2P bank) starting at around .11CA.
The third system is used AGM batteries previously used by Sprint, I'm assuming for cell towers.
I don't have a battery monitor on that one, but I let it go to float before using it. Its currently powering 600W constantly during daylight hours, and seems to stay on float unless it gets cloudy. Again, how long would you recommend leaving this on float with no load to ensure full charge?
You should look up the manufacturers charge curve and the battery capacity. But basically the same, .01CA.
Regarding the sulfation, the charge controllers claim to run an equalization for 2 hours every 28 days, and the spec sheet for the batteries seems to agree with the charge controllers equalization voltage. The SCC manual says to have no load while doing this process, unfortunately I didn't catch it during that time,
Ahhh, the human error factor I mentioned above. It happens.
but the load was probably minimal. After moving and rebuilding these I will be diligent about the day I set them up so I can ensure this no load time happens. Any more input on the sulfation?
EQ on AGM is difficult due to not being able to measure cell specific gravity. I've seen where Enersys uses battery voltage, you do need to be accurate when performing EQ.
Flooded lead acid allows EQ over extended time frames as distilled water can be added as it may take many hours for cells to equalize and sulfation removed. For AGM, this option is not available so it becomes a case of EQ can actually damage the cells. For this reason, it is better to get full absorb charge into a AGM battery and not perform EQ unless the battery shows signs of sulfation such as decreased capacity. This does require occasional teardown and testing individual batteries for capacity.
Lastly, these batteries ended up being roughly $2500 for 8 200 AH batteries.
200Ah AGM from Renogy is $380 each. $3040 for 8
, so 800 usable AH for $2500. Your cheap EG4 (which I understand doesn't have a huge discharge amp rating),
1C discharge rating on a LFP battery and believe me, it won't suffer from the voltage sag seen with lead acid.
As for the EG4, I advocate for DIY myself, check out the links in my signature.
You say 800Ah. Let's just figure watts instead. 8x12x200=19,200Wh divided by 50%= 9600Wh usable
So for $2800 plus shipping (let's just say $3040 same as the Renogy) we get two
EG4 24V 200Ah= 5120Wh x 2= 10,240Wh x .90= 9216Wh usable
would only be 1/4 of that for the same price.
I just showed the price is just slightly more for the EG4 with less than 400Wh less capacity.
But the Renogy is rated to 750 cycles at 50% DOD, that comes to $3.33 per cycle. (Look at the chart for battery cycle life and DOD on the spec sheet) The EG4 is rated for 6000 cycles, that comes to $0.506 per cycle.
Is the lead acid really the better deal? If we compute per Wh over the expected lifespan of the battery, there is really no comparison. This doesn't even account for ensuring full charge is reached often with lead acid and desulfation.
I feel like I had to learn a lot to wire up these systems without adding learning LiFePO onto the list, so I don't regret getting these batteries for now. Maybe in a year I'll feel different.
Anyway, I certainly have much to learn, so please educate me on those questions?
I've just touched on a few things, I could build DIY batteries for much less than the EG4 with more capacity. $2313 for the 16 304Ah cells is 14,592Wh x .9= 13,132Wh usable