About This Manual
All material appearing in this SOK SK48v100-NCBT Owners Manual is protected by copyright under U.S. Copyright law and is the property of Current Connected, LLC or the party credited as the content provider. Do not copy, reproduce, distribute, publish, modify, create derivative works, or in any way exploit any such content, nor may you distribute any part of this content over any network, including a local area network, sell or offer it for sale, or use such content to construct any kind of database or PDF. You may not alter or remove any copyright or other notice from copies of the content on Current Connected, LLC’s website. The content provided on the website may not be used to misrepresent, purposefully neglect, or maliciously misuse information provided herein in any way. Copying or storing any content except as provided above is expressly prohibited without prior written permission of Current Connected or the copyright holder identified in the individual content’s copyright notice. For permission to use the content in this manual for anything other than its intended purpose, please contact [email protected].
Unauthorized use or misuse of the content shown in this manual without written permission will be punished to the fullest extent of all applicable laws.
Use of this manual
This manual is not a substitution for proper training. The intended use of this manual is to provide guidance and reference for the use of products sold by and associated with Current Connected, LLC. All materials mentioned in this Training Manual range in technicality and require varying competency levels and expertise. Therefore it is recommended to seek proper training before using products seen and mentioned in the training manual.
Reading and understanding all safety guidelines and instructions is essential before use, connection, installation, or maintenance. Failure to comply with the policies and instructions can lead to property damage, injury, and/or death. Remember that past performance is not indicative of future results. The many variables in the materials listed in these training documents can be unpredictable if not managed and maintained correctly.
This manual does not cover all details or variations in the equipment. It does not claim to provide every possible contingency met in connection, installation, operation, and maintenance. Please contact the Current Connected, LLC. Support Team if further information is desired or problems arise. Current Connected, LLC. will not be held liable for damages or injuries sustained from improper use of the above-mentioned.
We thank you for the continued use of Current Connected, LLC. as your resource, and we hope this Training Manual will better assist you in understanding your project and enable you to meet your goals.
This manual is not intended to be printed on paper, as sections of this manual are interactive and will not function when printed on physical media. For the best user experience, you should refer to the web version of this page directly.
SOK Battery is a dedicated LiFePO4 manufacturer based out of Zhuhai, China. SOK has a long history of delivering both the highest quality battery and safest overall design at a value conscious price point. This trend continues with the release of the SK48v100-NCBT, a true Grade A+ Lithium Iron Phosphate (LiFePO4) battery pack designed to be easily installed into standard 19” EIA server-rack type battery enclosures or the custom-built SOK Server Rack.
A 16S (48v nominal) 5.12 kW-h LiFePO4 battery bank is paired with a digital battery management system (BMS), to provide automated and maintenance free battery operation, with a typical lifespan of over 4000 cycles. Contrary to the advanced version (SK48v100) this is a budget friendly alternative that has some features omitted, such as a LCD display, CAN/RS485 communication, and a pre-charge circuit.
The SK48v100-NCBT is ideal for small and medium off-grid or mobile energy systems that simply need raw energy storage, without any remote monitoring, data reporting, or inverter communication. CAN/RS485 communication features are great when paired with specific inverters that support closed-loop communication, but pose significant added cost to systems that do not support or require closed-loop communication. If you are looking for high-quality energy storage without skipping quality or safety, this battery is the best choice.
The SOK engineers plan future serviceability into the initial design of all battery assemblies. On rare occasion, products in the real world can fail, depending on the usage, environment, and build quality. Failures can be caused by shipping damage, installer error, downstream equipment malfunction, natural aging, and unavoidable environmental factors such as lightning.
Competing batteries on the market are not designed for serviceability, being permanently assembled using techniques such as IR-Laser Welding of aluminum cell-interconnection busbars, plastic injection-molded cases, and permanent epoxy potting. These processes are great for single-use disposable products, but a poor choice for systems expected to last decades. When parts within these permanently assembled packs fail, the entire module is rendered useless and needs to be disposed of as E-waste and replaced as a complete unit. Any attempt to service would certainly void your warranty and the likelihood of a successful service is slim to none.
SOK Battery believes that these products are an investment and should not be thrown away if something goes wrong; products should withstand the test of time. The SOK Battery SK48V100-NCBT is engineered so that every single part within the battery pack can be field serviced and replaced by either an authorized service agent, or the end customer. This means less downtime and lower repair costs to the end-customer, as well as a decreased environmental impact.
SOK Battery is the leader in battery technology, paving the way for many battery manufacturers to follow.
The SK48v100-NCBT features bluetooth functionality for troubleshooting and diagnostic purposes. This is useful for troubleshooting a fault with the system, but is NOT a replacement for a proper system battery capacity monitor such as a SmartShunt or a BMV-712.
Mobile App Download
Documentation for the ABC-BMS app is soon to be available from SOK battery. When this documentation is made availabe, we will add a hyperlink in this section.
Shipping & Receiving
Allowable Shipping Methods
Due to the nature of these batteries, they must be shipped by truck freight both to the customer as well as any returns to Current Connected. Each unit is over 100lbs, which excludes typical ground methods such as FedEx / UPS.
The SK48v100 server rack battery is a Lithium battery. Despite the inherent safety of LiFePO4 chemistry, Lithium batteries are considered class 9 hazardous materials and require appropriate UN3480 lithium battery handling & labeling. This means they cannot be transported on passenger aircraft or through the US Postal Service and must be packaged appropriately. If you need to ship your batteries for any reason, please contact Current Connected in advance for assistance with shipping.
Freight Forwarder Documents
Your new lithium battery is packaged using special materials to meet transportation standards. Please retain a set of this material should you need to pack and send your battery in the future e.g. for relocation or warranty claims. If the original packaging is not available, please contact your place of purchase or Current Connected to order a replacement set.
Each box is conveniently built with 2 hand-holes on each side because each box must be lifted by two people to relocate into the unboxing location. To protect the product, keep it in the original box until the time of permanent installation.
- Batteries are heavy! Team lift ONLY.
- If any strong smells are present, it could indicate internal damage. Stop and contact your place of purchase immediately
- Use a multimeter and measure from each terminal to the case to ensure that no internal damage has occured in shipping
Inspecting for damage
Carefully inspect the boxes inside and out for any dents, crushed cardboard/foam or strange odors. If any of these are observed, stop and contact your place of purchase immediately.
Removing batteries from boxes
The safest way to remove the battery from the box is to open the top of the box, remove the accessories & foam inserts, then carefully cut along the 4 vertical edges with a box cutter making sure not to cut/scratch any of the product inside. Fold down the 4 sides to create access space for two people to safely pick up the battery. The battery can then be carried by the two handles on the front. It can be moved in any orientation except for upside-down (top lid facing toward the ground).
After unboxing, we highly recommend that you power on the BMS per the power-up procedure covered later in this manual to make sure your battery is fully functional at the time of receipt. If you have a product that is dead-on-arrival (DOA) then contact your place of purchase to start a warranty claim.
Notice: We have isolated a situation in which internal damage has caused DC voltage to be present on the case of the batteries leading to difficult-to-trace faults. When unboxing, use a multimeter and measure from each terminal to one of the case screws to ensure that no internal damage has occurred. If you intend to use rack ears, install them before performing this test. If voltage is present, STOP IMMEDIATELY and contact Current Connected before continuing.
Installation: Planning your location
Protected From Damage
Batteries and solar components (Inverters) should be located in secure locations not subject to physical damage. Batteries installed in garages must be protected with bollards or similar to prevent damage caused by a vehicle collision.
Moisture / Humidity
As for most electronics, extreme humidity & condensation is not good for long term performance or integrity. Avoid environments that have condensing humidity and be especially cautious in locations near the ocean where salt spray may be present, as this can cause accelerated degradation that wouldn’t be covered by warranty. If a high humidity application is expected, install the batteries in a sealed / outdoor rated enclosure.
Proximity to Equipment
When compared to AC wiring, Low-voltage DC systems are very susceptible to voltage drop. Long cable runs between batteries and inverters can lead to premature low-voltage shutdown when heavy loads are turned on. For optimal performance, keep your batteries as close to your inverter/charge controllers as possible.
LiFePO4 batteries generally have a very strong tolerance to varying temperatures. However, if you install these batteries in extreme environments their performance and operation may be internally limited. Additional environmental consideration should be taken based on your climate.
Extreme Cold Charging
The SK48v100 battery is equipped with 6 temperature sensors – 4 of them measure the temperature of the cells, 1 measures the temperature of the high-power section of the BMS, and the final sensor is an environmental temperature sensor. These sensors are important for controlling the operation of the BMS, since charging in extreme cold is bad for the longevity of the cells. If any of the 6 sensors detect a temperature below -5°C (23°F), then the BMS will stop allowing charge to enter the battery, while simultaneously still allowing discharge to occur, if demands require discharging.
Extreme Cold Discharging
Contrary to charging, discharging in extreme cold does not present a risk to the cells quite like charging does. The battery can safely discharge down to -20°C (-4°F), although you may notice a reduced capacity (as much as 40% below its rating) and discharging at a voltage lower than normal. Once the battery returns to a normal temperature, this capacity will be restored and the voltage will cycle as expected. As strange as it may seem, if discharging in temperatures below 32°F, you may observe the voltage increasing as the battery is emptied. This is caused by the small amount of heat inside of the cells freeing up the flow of ions through the electrolyte inside the cells. Here is a very in-depth study in case you are interested: https://mdpi-res.com/d_attachmen….
This product is not a notable source of heat. It can operate without active cooling in most environments. The battery can charge in ambient temperatures up to 113°F and discharge in temperatures up to 140°F. The built-in BMS will automatically prevent charging / discharging in environments not suited for operation. Never exceed an ambient temperature of 150°F.
Installation: Mounting Batteries
Mounting without racks
This battery is very versatile, and can be used in may applications aside from the typical server rack use. Should you choose not to use the rack, there are many different orientations you can use the battery. When determining a location for installation, you must pay special attention to make sure the battery cannot fall, bounce, or slide, or otherwise move.
Battery Orientation – Stationary
In a stationary application, the SOK 48v battery can be installed in any orientation with the exception of upside down, as viewed from the front panel. This means installation on-end, sideways or even face down would be perfectly acceptable.
Battery Orientation – Mobile Application
In a mobile application, vibration and jarring is a much bigger concern. For this reason, we recommend installing the battery flat. When we say flat, we mean exactly how it would be oriented when installed into a server-rack.
The batteries may be stacked without a rack up to 3 units high. Further stacking poses a crush hazard to the battery on the bottom. When stacking without a rack, it is essential that the batteries be secured in such a fashion that they do not slide off of each other.
Author’s Note: Design changes are being implemented to future production of this battery that will allow for significantly improved use without a rack. Until these changes have been finalized, this will remain as a placeholder for direction regarding the new design implementations.
Installing in Racks
To prevent a tip over hazard, racks of all types should always be loaded from bottom to top, as illustrated in the diagram. Battery racks & server racks containing batteries must be anchored to the floor and have added earthquake brackets to prevent being tipped over. Not all manufacturers include outriggers or other means of appropriate tip-prevention, but they must be added for safe installation.
Since the SOK Battery can fit into a wide variety of standard EIA racks, we cannot predict the implications of every possible installation. Common sense must be exercised by the installer to ensure safe practice, such as keeping the center of gravity low and remaining within the weight rating of the rack the batteries are installed in.
SOK Battery Racks
19″ EIA Server Racks
When using a third-party EIA server rack for your batteries, you must use rails at minimum (full metal rack shelf is preferred) to support the full weight of the battery. The front rack ears are only meant for preventing the battery from sliding out of the front of the rack. Damage caused by opting out of using rack rails is not covered by warranty.
Batteries can be installed with one battery directly above another without a rack space between them (no cooling requirement).
- The front rack ears are only meant for preventing the battery from sliding out the front of the rack.
Video: Securing & Loading racks
The SK48v100-NCBT utilizes a very simple BMS that offers basic protection to the battery. It does not however, have advanced features like automatic current limiting or an automatic pre-charge circuit like the SK48v100 model includes.
Common in Inverters, battery chargers, and solar controllers is a sizable bank of capacitors on their DC bus to smooth out any ripple that may cause interference with normal operation.
When you apply a voltage across a capacitor it initially appears to be a short-circuit, that is, the voltage across the capacitor is zero and the ability to pass current is infinite. If there is very little resistance in the circuit, such the instant action closing of a circuit breaker, then the current will be extremely high for a brief instant while the capacitors charge. LiFePO4 Batteries in general have a very low internal resistance, especially when compared to lead-acid batteries. This means that it is easy for very large currents to be delivered instantaneously.
The sudden high current (known as an inrush current) can cause damage to various components such as circuit breakers, fuses, BMS units, and the capacitors themselves. Unrestricted, this inrush current will certainly exceed the current ratings of the equipment involved and lead to significant damage.
NOTE: If you overcharge the battery to the point that the BMS stops allowing charging, and immediately have a major inrush or short-circuit before the protection has cleared, permanent BMS damage will occur that is not covered by warranty. For this reason, we recommend connecting batteries to your system at their factory charge, or no greather than 50% SOC (approx. 51.2Vdc).
How to manually pre-charge
You will need approximately a resistor between 10 and 30 ohms, rated at 10 watts or greater. These are readily available: Amazon.com Mouser.com
You will also want to use insulated tools during this process.
- Thorougly inspect the system for any miswiring (loose connections, short circuits, reverse polarity) and correct any issues before proceeding.
- Assuming you are still installing the sytem, you will ned to leave one of the main negative cables leading to your battery bank disconnected.
- Switch all 48v DC circuit breakers and/or disconnect to the “ON” position. Do not turn on the on/off toggle switches on your inverters, just the breakers in the high-current DC path leading to them
- Hold your pre-charge resistor with one side making connection to the main negative cable you removed in step 2, and the other side touching the negative terminal the cable would normally connect to (see video below for example)
- Quickly remove the pre-charge resistor and make the final connection, torque to spec (15 ft·lbs).
- Your inverters now should be good-to-go, turn on their on/off toggle switch.
Equipment Setpoints & recommendations
- Charge Current for fast charge: Up to 80A (Per Battery)
- Absorption Voltage: 57.6v recommended; up to 58.4v max
- Absorption Time: 15 Minutes
- Float Voltage: 55.2v
- Low Voltage Shutdown: 48v
If you are running a generator and have ample charging capacity, you are better off running a higher charge current to get the batteries topped off as quickly as possible. Fast charging will reduce the runtime of the generator, leading to decreased wear & tear as well as increased fuel efficiency. The increase of wear on the cells by using a higher current when generator charging is miniscule compared to the increased wear & maintenance on a generator from additional runtime, that your money is better spent fast charging.
If you are providing normal everyday charging with solar, that’s when it would be better to reduce the charge current closer to the target of 63A or less. Areas having more than 4 hours of sun exposure can charge as low as a 25A (C/4) rate and still reach a full charge while experiencing minimal wear.
Not every charger allows you to dial in the exact voltage you need. Some only allow for coarse adjustment via DIP switches, as an example.
57.6v is the most optimal absorption voltage, however if the charger doesn’t let you program this voltage, anywhere from 57.6 up to 58.4v is still safe and within normal operating parameters for these batteries.
If any cell within the pack reaches a full charge too quickly (due to being out of balance), the BMS will restrict charging to the entire pack to allow that cell to be discharged by the BMS (balanced), and when the cell is back within a normal range the BMS will stop restricting charging. While some say that lithium batteries don’t need absorption, if absorption never takes place, then the battery may not be fully charged because charging has ended before the BMS has had a chance to correct any cell imbalances.
The float voltage is not actually a charging voltage; it is a voltage that can be provided by a charger that matches the resting full-charge voltage of the battery. Some chargers allow float to be disabled, however we do not recommend doing so. By leaving float enabled and set at the recommended voltage, the charger (whether solar or grid) will provide the power to loads FIRST, and the battery will make up for any additional current demanded by the loads.
Floating in this manner will prevent discharging the battery while ample charge is available – whether coming from Solar, Grid or Generator. If floating was disabled or set to a lower voltage, then the battery could be significantly discharged when the user thinks that it’s been connected to a charger and should be full and ready to go. This is contrary to the float-charge of a lead acid battery, as a lead acid battery will self-discharge when sitting and must be continually be fed charge current to keep it topped off.
Note: when batteries are operating in closed-loop communication mode, there is no “float” mode – when loads require power they receive it from the source, and if discharging of the battery occurs, then the battery recharges to 100% and the charging process ends until recharging is required.
Low Voltage Shutdown
We suggest stopping discharge at 48v. The battery won’t cut off until 46v, however if you set your low voltage shutdown at 46v, then there is a strong chance that the battery will shut down before the inverter/load, which can cause a situation where the battery is difficult to get restarted. Some chargers require presence of battery voltage on the terminals before they will turn on and begin charging.
“RST” Reset button
The reset button on the front of the battery offers a method to reset overcurrent protection. If for any reason the battery has had more current drawn than rated, this can be pressed with a small screwdriver or paperclip to clear the protection. Please note that this will not shut down the battery as it would with other models of SOK batteries.