Hey folks,
As I said I finally got my 302 Ah CATL cells form Michel! ( big thanks there!) Now I need to hook them up!! ( so excited)
I know there are couple of good write ups out there, but I seem to have lost my links for them also. I was hoping some folks might have some specific advice for my situation.
These calls are replacing my 8 CB6 Amg Lead acid batteries on our0-off grid home. It is a 48 V system with an existing Midnight Change controler.
The batteries are in a well insulated external shed that mostly stays above 32* F most of the winter in Wyoming but not a guarantee.
I have Buss bars,
Questions:
1 Will the midnight Controller work? any settings that will need to be Changed?
2 What is the best/ recommendations for a 16 cell BMS? (the Cells will need to to reach 48 V)
3. Are there Low current draw heating mat options to protect the cells if it gets cold?
4. What else should I be aware of?, Places I can get into trouble, avoid fires etc...
Thank you all for your help and pointing me in the right direction!
For current best practices on top balancing cells, please watch the video and download the PDF at the following page: Top Balancing Cells Using a Low Cost Benchtop Power Supply If you are interested in a more general tutorial of what balancing is about and *Why* to balance, check this out...
Hey folks,
As I said I finale got my 302 Ah CATL cells form Michel! ( big thanks there!) Now I need to hook them up!! ( so excited)
I know there are couple of good write ups out there, but I seem to have lost my links for them also. I was hoping some folks might have some specific advice for my situation.
These calls are replacing my 8 CB6 Amg Lead acid batteries on our0-off grid home. It is a 48 V system with an existing Midnight Change controler.
The batteries are in a well insulated external shed that mostly stays above 32* F most of the winter in Wyoming but not a guarantee.
I have Buss bars,
Questions:
1 Will the midnight Controller work? any settings that will need to be Changed?
Depends on the current you need to pull from the batteries to power your system, e.g., 4000W inverter; 4000W/48V = 83A. If you have meaningful surge on your inverter, and you anticipate using it, then you should size the BMS for the surge current.
I can find out the surge load, it is a soft start pump with smart controller, not the mechanical pressure switch, but still is our biggest load.
any recommended sources for 200 amp BMS?
Not exactly sure off the top of my head, I will check when i get home in a few days. It is a big black one that mounts on a wall,
so probably the classic 150 or 200
Many of us use Midnite Classics, no problem but there is a bit of tweaking of course. It works better if you also have the WizBangJr so you can set your EndAmps to 15.1A for a 302AH pack.
You will have to be careful with the settings and ensure that your Voltage Offsets in the Classic are correct between what the SCC sees and what the "Actual" voltage is at the battery terminals, even a 0.5V difference can result in problems with charging and stats accuracy. There is a Gotcha Here of course. During Charge Cycle, be it SCC or external charger, the offset to both Voltage & Amperage will be higher and during Discharge the opposite is true and the offset will be lower. For stats accuracy, stay closer to the "discharge" offset on the SCC and compensate for the difference with the charge voltage settings. *NB* On the Inverter Side, you will want to adjust settings relative to the Discharge Offset difference so that it cuts off at the Actual Battery Voltage and not what it "thinks" is the correct voltage. Unlike Lead Acid batteries which are more "brute force"and can tolerate more differences, Lithium Based batteries are less polite, as they are Millivolt & Milliohm sensitive.
The BTS is no longer required as the Midnite can't do anything about Batt temp. Apparently, some have used the BTS as a temp sensor and with Aux1 & Aux 2 to opti-couplers to trigger a warmer. * There is no simple way to tell a Classic to stop charging @ 32F and a BMS should cut off charging at 0C/32F.
Additionally, the charge rate should be restricted to below 0.25C until 10C/50F (75A for 302AH) after which up to 0.5C or 151A can be applied to 90% SOC max, at which time CV charges the balance to 100%.
My Midnite Classic-200 Charge Controller settings (Rev.Dec.2021) All equipment MUST BE Voltage Corrected & Calibrated (VERY IMPORTANT) see link in my signature on how to do it.
Divide Values X2 for 12V. Multiply X2 for 48V. Absorb: 27.5 for 15 minutes (3.4375vpc) (some call this boost) Equalize: OFF Float 27.4V (3.425vpc) MIn Volts: 22.0 (2.750vpc) Max Volts: 28.7 (3.5875vpc) Rebulk Voltage: 24.0 (3.000vpc) End Amps: 14A (*1)
(*1): End Amps is calculated from the Highest AH Battery Pack in a Bank. IE: 200AH X 0.05 = 10A 280AH X 0.05 = 14A. NB: Victron Forum discussion says EndAmps = TailCurrent
Coulumbic Efficiency / Battery Status Meter Efficiency for LFP = 99%.
This get's the bank charged to full with high amps (Constant Current) and then float (Constant Voltage) tops off so the cells are on average between 3.400-3.420. I am running 7/24/365 so float is used up by the Inverter + provides whatever the packs will take to top off. * Do Not forget to adjust for Voltage Offsets between Actual Voltage @ Battery Terminal & at Solar Controller.
BMS Options are many now it is generally recommended to DERATE them so for a 200A BMS you'd be looking for a 250A so as to not push them to the design limits and to allow for the occasional surge potential. 48V/250A can support 12,000W or 240V/50A or 120V/100A uncorrected. Currently the more popular brands of BMS' in use are JBD or JK-BMS, QUCC and some prefer Daly. Features, Functions and Capabilities of course affect the cost but a Smart BMS with a BlueTooth Interface so you can manage / monitor your battery system is prudent. Myself, I am in process of changing all of my BMS' to JKBMS with 2A Active Balancing, 150A, BlueTooth, RS485&CanBus here is the link to the different versions of these: https://www.aliexpress.com/item/1005003104573871.html
There are some additional links in my signature which would be helpful, the Assembly Tech Guide also has extended voltage charts and charging info as well. Some more midnite stuff too.
Not exactly sure off the top of my head, I will check when i get home in a few days. It is a big black one that mounts on a wall,
so probably the classic 150 or 200
Maybe when you make it back home you can shoot me a pic or two of your ground mount. We get BIG WIND and are getting ready to ground mount some panels where they will get 70 mph winds, and most likely more.
I can find out the surge load, it is a soft start pump with smart controller, not the mechanical pressure switch, but still is our biggest load.
any recommended sources for 200 amp BMS?
We have a fridge only unit, and a small chest freezer, which we keep outside, we have several small circulations pumps for our radiant floor system, all off which we have on timers so none of it runs till we have sun on the panels. we have washer , but also don't use it unless it is sunny.
That was the plan, form what i could tell it would be good up grade form our 8, 200 amp hr AMG CB6's which seem to do mostly what we needed when they were new.
We have a fridge only unit, and a small chest freezer, which we keep outside, we have several small circulations pumps for our radiant floor system, all off which we have on timers so none of it runs till we have sun on the panels. we have washer , but also don't use it unless it is sunny.
That was the plan, form what i could tell it would be good up grade form our 8, 200 amp hr AMG CB6's which seem to do mostly what we needed when they were new.
If your main breaker is 60A @ 240VAC that is 14,000 Watts (gross uncorrected.) which provides 2 legs of 120VAC/30A.
I have a GrundFos SQ5 Deoo Well SoftStart pump that runs on 120VAC. It kicks on at 40PSI @ 550W stages up 3 stages and finishes at 52PSI @ 1100W. It is 260' Deep, fills a 50 Gallon Pressure Tank then it goes another 75' to the house. There are two filters, a sediment filter & fine filter as well and no one ever notices a pressure drop.
Many Pumps and AC Units, even Fridges can be converted to SoftStart but it depends on the type of motor.
I also have Radiant Heating within my Frost Protected Slab Foundation and boy do my Ol Bones love it, sure makes for less creaking & crunching between the joints, and always having a warm bed to lay down is Sweet... Anyone without Radiant Heating Experience will not understand that statement... The Radiant System also uses a Variable Speed GrundFos pump that uses very little power as well.
Additional Clarity on my Settings from above.
I run my Production system with 3x 24V/280AH & 2x 24V/175AH Battery Packs and I have utility packs for use in my Toolshed & elsewhere also LFP. My preference is to keep them within the Working Voltage of 3.000-3.400 Volts per Cell as that is the Very Flat Working Voltage Curve. The Maximum Allowable Voltage (Gross Voltage) is 2.500 absolute minimum and 3.650 the Absolute maximum. Between 2.50-2.90 and 3.425-3.650 only represents about 7-10% of "Gross Capacity".
What is Gross Capacity? A cell's genuine capacity for a 280AH A+ cell will typically test out as 290A +/- and be capable of delivering 280AH "from the working voltage range alone". Grade B or Bulk Cells "MAY" test out at 280AH Gross from 2.500-3.650 BUT be only capable of 270AH +/- for the working Voltage Range. Some will even test at a lower Gross Capacity.
Almost all vendors will sell Grade: Bulk (brokered cells with unknown provenance), B or A+ (most often from brokers or contracted buys from manufacturers (no original QR codes). They most often VOLTAGE & IR (Internal Resistance Test) cells at the usual storage Voltage 3.200, this is NOT MATCHED OR BATCHED. Matched & Batched cells are tested through 3 cycles with tests being done every so often during a Charge / Discharge cycle and repeated in the opposite. Once complete the cells are matched so that at the same Voltage Points they exhibit the same IR so they remain even / close throughout their working cycle. This is a costly process that adds cost but is totally worth it.
* One of my 280's is Matched & Batched cells, they stay within 10-14mv from 2.800-3.450 and only start to deviate once that those points. The Bulk Cells will be deviating much more at those ends, sometime in the extreme can be up to 1mv per AH of capacity.
Sorry. I do not do ONE LINE responses to drag things out due to an incomplete or minimal response to drag out a thread to a huge massive pile of one line answers that end up causing confusion by page 5 or 6. WHY & Context is important, especially with small details.
Helping Folks does require the application of W5H. Who, What, Where, When, Why & How as applicable.
Some Ponderances:
With LFP, you can always add another Battery Pack in Parallel later without ANY ill consequence - It ain't Lead \\YAY// !.
Batteries in Parallel add AH Storage Capacity AND will divide & share Load & Charge relative to each packs capacity.
You CAN put different Capacity Battery Packs together in parallel BUT try to keep them as close as possible, the less difference the better (easier to manage).
LFP / Lithium in General is also quite sensitive to Voltage & Amperage differentials as it is NOT Brute Force Tech like Lead Acid & Variants. To this end, ensuring that Voltages are compensated where required and that everything is properly Calibrated is essential.
Some quicky tips:
- Use identical wire (Gauge & Length) from battery terminals to the DC Bus and through E-Panel to Inverter.
* Keep DC Wires close together to cut "Noise" EFI and magnetic fields.
- ! Every Lug, Fuse, Breaker, Shunt, Bolt, Battery Terminal will add resistance and as such will contribute to Voltage & Amperage DROP ! YES, Amperage Too ! and one MUST be aware of that when working out your settings.
- Fuse Each Battery Pack, can be done at Battery Terminal, or In-Line or at the BusBar if using a common DC Bus System.
- IF installing Multiple Packs to build a Bank, it is best to try & match them so that ANY Pack can operate as "The Last Man Standing" as a standalone pack that can run your system should any cutoff for any reason. This is the Fail Over Fault Tolerance that one can gain with LFP/Lithum based packs within a battery bank. This means each battery pack having a BMS capable of doing so, keeping them consistent / identical certainly makes like a lot simpler and you (and family) happier campers.
Good Luck, Hope it helps and that the One Liner responses stop and that you actually get full answers to your questions. I am no longer as active here as I used to be but do check in regularly.
Steve
This is my install of a custom set of battery warmers from Ultra Heat. I had contacted them through email asking about a warming profile for LiFePO4 batteries. They responded with a design to my specifications, including warming pads that fit my batteries exactly. While I initiated the...
There are many different pads used by forum members. There are a few threads where someone throws out a pad and we knock it down as being too hot, so be sure to read their entire thread.
The reason I went with Ultra Heat is they have pads that are specifically for batteries and they custom made pads to fit my exact specifications. Yes, it was expensive.
