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rachelsdad
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# Posted: 12 May 2020 06:21
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The learning never stops.
Of course waiting till the last minute...a few weeks actually..
I have a new battery bank of 4 24 volt Volt Batteries. My integrated charge controller/Inverter cabinet MidNite Solar MS2024 came with a flash drive owners manual and all of the pages that deal w/settings are blank save for headings.
I'm sure MidNite will answer my email of this morning as to how to change the settings in the unit.
The batteries have a range of 18-25.2 and my CC range is 18-34..so I can get all of the goodness out of them.
Does anyone have a suggestion for settings for the batteries?
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Nobadays
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# Posted: 12 May 2020 09:04
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If I recall... you are using 24v Chevy Volt modules from Creeky. Can he help with settings? I don't run a Midnite Solar SCC so not much help there....but a quick search looks like you can download a pdf on that unit.
The caution here is that 34vdc your SCC can put out.... don't get up there or bad things will happen!
With the Volt modules it is best to stay away from the top.... and IMHO the bottom when setting charge parameters. I'm not sure where the "knee" is on your 24v modules. On our 48v modules it is at 42v, any discharge below that will drain the modules quickly and could damage them. So we set the LBCO at 42v (I have never let it get that low before kicking on the generator... 42.6v was lowest.) On the charge side, my understanding is they can be easily damaged by overcharging, this will at the very least shorten their life.... at the worst cause overheating and results we'd rather not talk about! Again not sure on the 24v modules but on our 48v's (top is 50vdc on them) we do not charge beyond 48.1vdc. At that point we go from bulk charge to absorb (lithium don't really need an absorb charge but with my SCC it was easier to set up as 3 stage), absorb for only 5 minutes then float at 48.0vdc. If I recall Creeky doesn't exceed 48v.... but he will dip to and below 42v on a rare occasion.
We feel like they will last longer if we stay off the bottom and top. With our current 12kw of storage/ use we rarely dip below about 46.5 (80% full) on a daily basis. So we are using off the top 20%. Winter is when we can go 2-3 days without charging, then we start dipping toward the LBCO.... that's why we installed 4kw more storage this spring... in preparation for next winter.
Let us know how it goes!
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rachelsdad
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# Posted: 12 May 2020 09:42
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I agree completely with staying within the low sides top and bottom.
I overlooked all the google searches for the CC alone as I have this wall mounted integrated unit. Perhaps that will help..duh!
Ooops, here is what I got from them:
To program the Classic for Lithium batts ….
Set the Absorb charge voltage (Charge/Volts).
Set the Float charge voltage (Charge/Volts):
If no Float is desired, then set a low Float value, such as 20V, and the Classic will rest after the Absorb charge cycle ends.
Set the Absorb charge time, usually very quick, like 4-6 mins (Charge/ChgTime).
Turn the temperature compensation off by setting the temp coefficient factor from a common -5mV to “Disabled†(Charge/T-Comp
Not seeing any setting advice for Bulk....
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rachelsdad
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# Posted: 12 May 2020 14:01 - Edited by: rachelsdad
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Well Todd from Midnite got back to me, I forgot to mention, the flash drive which contained the Owners manual was missing a few chapters...guess which...
EDIT: I guess I did mention that 
He led me to the right pdf for my unit, (bundled CC & Inverter), and the "keystrokes" to change the program for charge rates.
Going up Friday to open the place up!
Thanks Nobadays!
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Nobadays
Member
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# Posted: 12 May 2020 14:06
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Not sure there is... or needs a bulk charge setting. My understanding is, especially with these Volt modules- lithium in general, they will take a high rate of charge. So whatever your SCC will put out based on your panel output - IS - your "setting".
Not knowing your SCC, my [u]guess[/u] is once your state of charge (SOC) hits your set Absorption voltage it will then regulate charging to maintain that voltage for the set length of Absorption (say 5 minutes), then it will switch to Float and maintain the set Float voltage. I know my SCC also has a setting that at "X" SOC it will resume bulk charging.... the cycle begins again. However, I have never seen it resume bulk. We have never put such a demand in the system that the power from the panels can't support the draw on the system.... therefore we deplete the modules to that point.
Hope this helps.... and someone will add to/correct me if I'm not correct. My experience is primarily with my Schneider SCC and cheapo Chinese controllers.
I would say, read, read, read. Then maybe hit the DIYsolar forum and ask there. Some really knowledgeable folks on there.
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rachelsdad
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# Posted: 13 May 2020 05:48
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Sorry NBD you're correct, no bulk setting.
I'm going a little haywire here. I've been reading up but frankly still a little, (lot), nervous about this conversion.
Funny, as tricky as it was to unhook and re hook all the cables up on the eight batteries, at least i had done it several times...now I'm even questioning how to do a parallel hook up...Nerves I know.
cable gauge, where does neg from CC go on batt bank vs pos? Same battery...opposite ends of bank??? Conflicting info out there..
Driving myself nuts
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Nobadays
Member
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# Posted: 13 May 2020 09:07
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Negative to negative/ positive to positive for parallel... voltage stays same amps increase.
I prefer running both positive and negatives to a busbar first... #2 cable. In my case all the negatives run to regular busbars (I have 2 - 4 place bars - 6 modules - connected by a short 4/0 cable) then 4/0 from the busbar to the inverter. The positives go from the modules to a Squqre-D QO load center where each connect onto a 35amp AC/DC breaker (the QO series are the only AC breakers rated for DC as well) - those of course connect to the load center busbar and 4/0 cable from there to the inverter.
SCC positive and negatives hook to the respective busbars.
By connecting to busbars with your module leads I'm told this helps eliminate uneven drain from the modules(same with batteries). If you link all of them together and draw from the end.... your more likely to draw first from the nearest module, power draw reducing as you recede back to the furthest module. My understanding is that if you don't use busbars then connect to the center of the string to help eliminate uneven draw.
BTW.... you don't really need a load center/ breakers for the positive side, a busbar for those would work as well. NOTE, be sure to fuse - appropriate size for your calculated max current draw - between the modules and the inverter.... preferably near the modules.
Hope this makes sense and is helpful.
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rachelsdad
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# Posted: 13 May 2020 11:10
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It certainly helps..and makes sense.
I think I'd prefer to connect to center string...less to mess with.
On more question if I may.
What size nuts for the terminals? I'd hate to have to walk into a hardware store, (with a mask on due to NYS Covid 19 regs), carrying an odd shaped package?
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rachelsdad
Member
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# Posted: 13 May 2020 12:00
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Well, I really did not want to bother him but
Creeky has come to the rescue!!
I believe he says it like this: Huzzah
Nobadays, I'd like to thank you for the help as well
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Nobadays
Member
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# Posted: 13 May 2020 15:33
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No problem! Not sure of nut size but I think metric as they take a 10mm socket.
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