DCS 12V 75AH (LITHIUM)
DCS 12V 75AH (LITHIUM)
Ultra-Safe
Explosion-proof / No leakage
Stable
Low Internal Resistance / Proven Stability
Long Life
Ultra-long cycle life
Guaranteed A Grade
Contracted A Grade cell supply
DCS Batteries are the ideal replacement & upgrade from AGM, Gel or other lead-acid batteries for any application. DCS gives you the ability to upgrade your current batteries to lithium-ion technology that can deliver a minimum of 2500 cycles and has tremendous advantages in weight, performance, reliability and service life compared to traditional lead-acid batteries.
Backed by a 4 year warranty.
Availability: In Stock
$999.00 AUD
The DCS 75Ah batteries come in a small footprint and pack a big punch with a 2C discharge rate, which means these little batteries can run a 1800W inverter!
- Cell status showing real-time cell balancing operation
- BMS MOSFET temperature (great info when you are winching or running a large inverting load or your trolling motor to know how hard you are pushing the electronics).
- SOC% estimate (using impedance tracking – the App learns the SOC after the first 10 cycles)
- Battery pack voltage and cycle count
- Amp meter – showing charge and discharge current
- Connectivity distance up to 10m
- Now there is no need to install battery monitors or shunts in boats, campers or vehicles. You have all the info you need at your fingertips.
- The SOC estimate is accurate on single batteries, the more batteries that are expanded in parallel, the less accurate the SOC becomes.
- This free application provides the perfect tell-tale about the battery packs’ state of health as it ages
- Assists installers & integrators to quickly diagnose any system issues
DCS 6AWG 230mm Parallel Cables with M8 Ring Terminals
Click Here for more information
What will a DCS 12V 75Ah battery run?
| Specifications: | – |
|---|---|
| Nominal Voltage | 12.8V |
| Nominal Capacity (1Hr) | 75Ah |
| Case Dimensions (L x W x H) | 260mm x 169mm x 175mm |
| Weight | 8.60 Kgs |
| Cycling voltage | 11.5 ~ 14.6V |
| Charge voltage | 14.0 ~ 14.6V |
| Float Voltage | 13.5 ~ 13.7V |
| Maximum Charge Current | 75A |
| Recommended Charge Current | ≤50A |
| Maximum Discharge Current | ≤150A |
| DCS BMS (internal) | DCS active cell management system, over/under voltage, over current charge/discharge, low/high temperature protections, satisfies the AS/NZS 3001.2:2022 lithium battery standards |
| Cell Chemistry | DCS 3.2V 5.0 – 7.2Ah Cylindrical (LifePO4) |
| Cycle Performance | 2500 Cycles @ 100% DOD ≥ 80% Capacity Retention @ 25°C |
| LCA | 750 |
| Ingress Protection | IP54 |
| Case | ABS (flame retardant plastic) |
| Operating temp Range | -30 to +110 degrees C |
| Terminals | Top Mount M8 Stainless steel / Copper |
| Parallel Connections | Up To 10 |
| Series Connections | No |
| Warranty | 4 years | 3 years under bonnet |
| Certifications | UN 38.3, UL 1642, IEC 62133 & 62619, CE |
DCS High Performance 2C Charge & Discharge Curves
DOWNLOAD APP (DCS LFP)
DCS Bluetooth Technology powered by DCS LFP, this APP is only for DCS LFP batteries which is based on BLE 4.0 technology. Every DCS battery pack comes standard with our detailed battery monitoring via Bluetooth.
This App provides comprehensive monitoring for DCS LFP batteries, including:
- SOC%
- Time Remaining
- Battery pack voltage, Power & Current
- Battery Management MOSFET temperature
- Individual Cell Status with balancing indicators.
- Connectivity distance up to 10 meters.
- Every DCS battery pack comes standard with our detailed battery monitoring via Bluetooth
Learn More About the DCS LFP APP
Click Here to Watch the App Overview Video
| Battery Terminal Configuration | RHP – Right Hand Positive, LHP – Left Hand Positive |
|---|
Battery User Guide
Battery Installation Locations
DCS Batteries that are in a sealed traditional style battery case are IP rated 54 unless otherwise specified.
As there is a considerable amount of electronics inside the battery cases, it is important that these batteries are protected from the ingress of particles and water.
IP54 means that there is partial protection against dust & similar particles & protection against splashing water from any direction for a minimum of 10 minutes.
IP54 MEANS THE BATTERIES ARE NOT WATERPROOF
Our DCS Slimline battery range is IP rated to 53 unless otherwise specified.
IP53 means that there is partial protection against dust & similar particles & protection against splashing water up to 60 degrees from the vertical with limited ingress permitted for 3 minutes.
IP53 MEANS THE BATTERIES ARE NOT WATERPROOF.
DCS batteries should be installed and operated in a location that will not exceed the specified operating temperatures.
Make yourself aware of the new requirements that relate to battery storage, IP ratings and venting. Australian / New Zealand Standards (AS/NZS 3001.2:2022)
Do Not
- Install DCS batteries underneath a vehicle or caravan, or any other external location that is exposed to the atmosphere unless it is fully contained inside a suitable battery housing that will prevent the ingress of particles & or water. Also, sufficient mechanical / structural protection is needed to prevent damage from rocks and debris during recreational vehicle travel.
- Pressure wash or hose your batteries. You can wipe them down with a damp cloth if needed.
- Submerge your batteries in any fluids.
- Install DCS batteries near high heat sources, e.g. exhaust manifolds or turbo chargers.
Operating Temperatures
Each battery has a designated operating temperature range depending on the cell type used.
Our under bonnet Hybrid battery range (using cylindrical cells) is designed to work in ambient temperatures between -30°C to 110°C. Do not operate outside of this temperature range.
Our 12V 180Ah auxiliary batteries have an operating temperature range of -30°C to 60°C. The DCS BMS will not allow these batteries to operate if the 60°C is exceeded.
The DCS BMS will not allow a frozen Battery that is below 0 degrees Celsius to be charged. Charge will only be allowed when the ambient temperature of the battery cell is back above 0°C.
Discontinue the use of a battery immediately if the battery becomes excessively warm whilst in a resting/standby state.
Please check the specifications for the recommended operating temperatures of your particular battery on the DCS website.
Securing your battery
Your battery must be secured to prevent movement. Restraints must prevent any movement under a pulling force of twice the battery weight.
The recommended hold-down bracket torque is 4 N-m. or 3.5 lb-ft.
Care has to be taken to prevent the battery lid seal/gasket from deforming when securing the battery, which could affect the IP rating of the battery. Do Not over-tighten the battery holding clamps.
Battery Charging
Use only approved Lithium-Iron Phosphate specific chargers for your battery’s nominal voltage, chemistry and maximum charge rate with the correct charging stage voltages.
All DCS 12V cylindrical cell packs to be charged at:
14.4V Bulk
13.5V Float
The DCS 12V 180ah Auxiliary prismatic cell pack (SKU: DCS-12V-180ah) to be charged at:
14.2V Bulk
13.5V Float
Be aware some chargers have fixed charging voltages and cannot be adjusted.
Check the charger specifications for charging voltage levels & charging profiles before purchasing.
Alternator Charging
Our under-bonnet dual battery systems, 80ah Extreme & Slimline range, can be charged directly from the vehicle’s alternator, providing that they are the only battery chemistry being charged.
For example, you cannot parallel a Lithium battery to a lead acid battery and charge from the alternator.
This type of set up has to be separated by using a DC-DC Charger.
If you are parallel connecting batteries together, they have to be the same chemistry, nominal voltage, capacity and age.
Each battery has a maximum charge current listed in the specifications table that should not be exceeded; otherwise, permanent damage could be done to the battery.
When the batteries are parallel connected together, this doubles the amount of current the batteries can be charged at.
For example, our DCS 180ah (2 x 90ah ) dual battery system. The maximum charge current is 80 Amps per battery. So 2 x 80A = 160 Amps. This means you can charge these batteries provided your alternator’s max. output does not exceed 160Amps.
Before choosing a battery, check the maximum output current your alternator can produce and also find out the Cold Cranking Amps (CCA) needed to start your vehicle.
Your factory alternator is generally the best alternator to use, and there is no need for high output aftermarket alternators.
Check the specifications table on the DCS website for the particular battery you are interested in, and look for Lithium Cranking Amps (LCA).
If the LCA meets or exceeds the CCA for your particular vehicle, then the battery is suitable for your vehicle.
Parallel Connected Batteries
Connect Battery 1 Positive to Battery 2 Positive
Connect Battery 1 Negative to Battery 2 Negative ( This cable is extremely important as some vehicles use the chassis as a negative link, which is prone to failing due to corrosion, which causes a high resistance. )
In Balance Wiring
When you have batteries that are wired in parallel, as described above, it is good practice to wire your loads and inputs in balance.
What this means is, for example, to connect loads & inputs positive to the first battery e.g. Battery 1 and the negative loads & inputs to the last parallel connected battery e.g. Battery 2.
This is important when using an inverter that can have a high current draw so that they evenly draw from the parallel connected batteries.
Storage
If you are not going to be using the battery for some time, charge the battery fully to a 100% state of charge using the correct charging profile and voltages.
Disconnect everything off the battery terminals, and it can be left in this state for up to 3 months.
After 3 months, cycle the battery, fully discharge the battery (11.5 volts), then fully charge the battery, and the battery can then be left in this state for another 3 months.
Do Not
- Use a lead acid charger / maintainer on a Lithium battery.
DCS LFP App
Every DCS LFP battery pack comes standard with detailed battery monitoring information via Bluetooth. (BLE 4.0 Technology)
The app can be downloaded to Android or iOS devices that are Bluetooth enabled.
Comprehensive battery monitoring information for DCS LFP batteries include
- SOC%. (State Of Charge)
- Battery pack voltage, Current & Power
- Time Remaining
- Individual Cell Voltage Status
- Battery Management MOSFET temperature
- Connectivity distance up to 10 metres.
Renaming Your Batteries Using The App
- Open the DCS LFP app and connect to the battery.
- Tap on the three horizontal lines on the top right hand corner of the screen.
- Input Password. 736263 > OK
- Name ………… > OK
- Refresh the battery list by tapping the circular arrow.
- Select custom and your battery will now appear in this section.
Modifications
Do not attempt to alter, modify or repair any part of the battery.
Any modifications to the battery will void your warranty.
Fully Discharged Battery
The BMS will emergency open the circuit of the battery terminals to protect the cells. Typically, you will see 3 - 4 volts across the battery terminals when using a multimeter. The BMS needs a 12V supply with at least 1A of current to release and wake up from a cell emergency protection state.
Most mains chargers with a lithium profile will do a slow recovery charge, as will most solar regulators. Some chargers on the market today that are advertised as ‘lithium’ compatible still don’t have the firmware to do a slow recovery charge to release BMSs. If you have a charger that will not wake up the BMS, the easiest way to wake it up is to connect an unregulated solar panel directly to the battery terminals; however, ensure all loads are disconnected before you do this. Having said that, every system should have a suitable low cut-off voltage to shutdown loads/accessories so that the batteries are not fully drained.
“Batteries cannot be left flat/empty; if the low voltage cutoff is triggered, the battery pack should be fully charged as soon as possible. If access to a suitable charger is not possible, disconnect all loads from the battery terminals. The warranty will be void if the battery pack has been left in a low voltage cutoff state for longer than 14 days.”
The most important thing is to isolate everything from the battery terminals, as cables/loads connected to the terminals cause more power drain as the FET gates have to remain closed to cull the accessory standby loads connected to the battery pack + offset BMS standby power consumption.
Electrical Installations Standard ( AS/NZS 3001 . 2 : 2022 ) For Transportable Structures which includes Recreational Vehicles, Caravans etc.
Please note AS/NZS 3001 is made mandatory by electrical legislation in each state and territory.
The new standard includes requirements for “connectable electrical installation batteries” covering any battery that is installed with the primary purpose of supplying the living / accommodation features of a transportable structure, which includes recreational vehicles and caravans etc.
Below is a brief summary of some of the new requirements.
Lithium - Ion Batteries
- The location must be appropriate to ensure that the battery operates within the manufacturer’s defined operating temperatures and IP rating.
- Batteries must be located in a position that prevents any vented gases from entering a habitable area of the recreational vehicle. Any vented gases have to be vented externally from the vehicle. ventilation openings have a minimum vent area requirement, which is calculated based on the ratings of the battery. Any opening into the interior (habitable area) must be provided with an air seal.
- Any metallic service lines (eg. Gas, Diesel, Water etc.) located near the battery must be at least 300mm. clear of the battery terminals or must be shielded with dielectric material to prevent against short circuits.
- A battery must be secured to prevent movement. Restraints must prevent any movement under a pulling force of twice the battery weight.
FAQ
Lithium Ferrophosphate (LFP) is a flame retardant, stable, safe and proven cell chemistry that has a very good energy density around 325 Wh/L. This cell chemistry can be engineered for various applications by adjusting the ratio of elements to provide high performance characteristics. E.g. the DCS marine battery range runs 2C cells, which means our little 75Ah battery will discharge comfortably at 75Ah x 2C = 150A. The DCS 80Ah Extreme runs 10C cells which means the 80A can comfortably discharge at 80Ah x 10C = 800A but is of course limited to lower currents due the the Battery Management System.
LFP also has very good cycling durability between 2,000 ~ 12,000 cycles can be achieved depending on how well the cells are managed, and the lowest rate of capacity loss (aka greater calendar-life) compared to other lithium cell chemistries.
Battery cells are simply a bunch of resistors with the ability to store energy. A 100Ah battery pack has a different resistance characteristic compared to a 50Ah battery pack, that theoretical difference in resistance is 2:1. So if you connect a 100Ah battery in parallel to a 50Ah battery there is no way for these two batteries to equalise and therefore you can’t charge them correctly. So for example connecting a 60Ah calcium starting battery to a 120Ah AGM via a VSR (Voltage Sensing Relay) you cannot charge both batteries correctly and from that day onwards you are prematurely destroying both battery packs. Same theory applies with lithium’s it’s still a battery pack.
What’s the solution? A DC-DC charger, you now have a permanent point of isolation (meaning that both batteries are never connected to each other in parallel). The DC-DC charger takes the surplus power from battery A (engine) and chargers battery B (aux/house). This device now allows any battery capacity and or chemistry to be used.
Yes you can, but lithium’s have a different voltage curve, so you would still need to use a programmable VSR to dial them in correctly. You would also need to ensure the batteries are programmed to never exceed a 10%SOC variance, any larger and you risk damaging the BMS's. These devices also draw a lot of power when engaged to so it’s best to run the two batteries in permanent parallel and run a load disconnect instead of a VSR.
Lithium battery cells have a super low resistance so are very easy to charge and very efficient. This level of efficiency means you can charge them at very high C rates. For example if you look at the charge rate of a 100Ah AGM battery the recommended charging current will be around 25A, which is a 0.25C charge rate. If you consider the DCS 12V 100Ah Lithium battery it can be charged at up to 70A which is a 0.70C charge rate. This means you no longer need to consider DC-DC chargers as you can connect our batteries directly to high power charging devices such as suitable alternators, or large buck boosters. For example our popular dual 90Ah battery system for boats and 4WD vehicles, can be connected to alternators up to 160A.
Because our batteries are internally voltage regulated and because our BMS has such a high sustainable peak discharge current they will do an amazing job of equalising very quickly.
The BMS will emergency open circuit the battery terminals to protect the cells. This means there is no longer any resistance in the system. The BMS needs a 12V supply with at least 1A of current to release and wakeup from a cell emergency protection state.
Most mains chargers with a lithium profile will do a slow recovery charge as will most solar regulators. Some chargers on the market today that are advertised as ‘lithium’ compatible still don’t have the firmware to do a slow recovery charge to release BMS’s. If you have a charger that will not wakeup the BMS, easiest way to wake it up is to connect a unregulated solar panel directly to the battery terminals, ensure all loads are disconnected before you do this. Having said that every system should have a suitable low cut off voltage to shutdown loads/accessories so that the batteries are not fully drained.
"Batteries cannot be left flat/empty, if the low voltage cutoff is triggered the battery pack should be fully charged as soon as possible. If access to a suitable charger is not possible, disconnect all loads from the battery terminals. The warranty will be void if the battery pack has been left in a low voltage cutoff state for longer than 14 days."
Most important thing is to isolate everything from the battery terminals, as cables/loads connected to the terminals causes more power drain as the FET gates have to remain closed to cull the accessory standby loads connected to the battery pack + offset BMS standby power consumption.
Use the following settings:
Charged voltage 14.0V
Tail current 4%
Charged detection time 1min
Peukert 1.05
Charge efficiency 98%
Current threshold 0.1A
C rates: refer to the battery pack capacity
Fully charge to 100% isolate everything from the terminals and leave for max 3 months and then cycle (fully discharge and fully charge) and leave again for 3 months etc…. Minimum 4 cycles per year to not effect the cells capacity.
The reason many factory batteries fall over after 9/12 months is because modern/smart alternators typically drop the alternators voltage output to 13.5/13.6V. This voltage is not high enough to charge wet/calcium/lead acid batteries so from the getgo they are destined to fail prematurely. They are typically under charged to around ~80%SOC at these voltages.
So what happens when DCS Hybrid batteries are connected to smart alternators? Exactly the same thing they get charged to around the same 80%SOC. However because LFP has no memory effect that's perfectly fine. By only charging to 80% you are further improving the service life of our batteries. It's no not necessary to charge our batteries over 80%SOC. The only advantage is that you give the BMS a chance to detect full charge voltage and calibrate the SOC readout. So try to plug into mains once a week to fully charge your batteries, especially if your not running any fixed solar supply.
All DCS 12V cylindrical cell packs can be charged as follows:
Bulk: 14.4V
Float: 13.5V
The DCS 12V 180Ah Auxiliary prismatic cell packs (SKU: DCS-12V-180Ah) need to be charged as follows:
Bulk: 14.2V
Float: 13.5V
When the battery pack is discharged down to 11.50V the BMS resets to 0%SOC and now is placed in a relearning state - the pack must be fully charged continuously without stopping to calibrate again. Charge it on a mains charger to 14.60V.
Depending on the usage pattern, best to fully cycle the batteries once every 3 months to give the cells a refresh. To fully cycle a 12V pack discharge to 11.50V and charge to 14.60V.
BMS & CMS
Here at DCS, designing lithium batteries is not only our bread and butter, but we love this safe, stable, robust, and high-performance cell chemistry so much that we decided to develop our own range of Battery and Cell Management Systems in 2015.
DCS Battery Management System:
What was the objective? Well, the reason we embarked on this project was that all the basic Chinese designed BMS’s are just protection boards, and it is hard to call them a BMS when they don’t do any cell balancing or provide any means of programmability for various parameters and cell control. A lot of Battery Management Systems that we have tested were using inferior PCB engineering design techniques and poor components. That means continuous performance above 100A was more or less impossible, and reliability was also questionable when pushing above 100A with those Battery Management Systems.
Our key BMS objective was to develop a high-performance 200A BMS that could do;
- 200A continuous operations using high-quality components
- To have a minimal increase in temperature at peak output current (as these circuit boards are installed inside battery packs, limiting internal heat build-up that is crucial for the longevity of the battery cells).
- Designed for engine cranking applications, it has to deliver a minimum of 1200LCA’s for 10 seconds (because of the limited voltage drop with suitable lithium cells, it’s very easy to crank over modern engines. Most engines will start in under 1sec, so 10 seconds is plenty). CCA’s don’t apply to lithium batteries as this standard was developed for lead-acid batteries and needed to deliver 30 secs of cranking amps. When a lithium battery is controlled via a BMS, the correct terminology is LCA = Lithium Cranking Amps based on delivering 10 secs of cranking amps.
- Suitable for high temperatures applications, e.g. engine compartments. It will be stable up to 180 degrees C.
- Bluetooth and WiFi connectivity in order to develop a comprehensive app platform
- Pass MIL vibration testing standards (to open up the development of batteries for just about any application).
In a nutshell, the design needed to be tough and reliable for those who use them in the field with no room for error. The construction materials, coating and surfaces, assembly techniques are critical in designing a reliable system. After submitting our brief to all major leading manufacturers in Europe, Japan, USA and Korea, we assessed their expertise and ended up working with a leading and well known Japanese semiconductor manufacturer.
This is a typical Chinese 100A 4S BMS design
This is the DCS 4S 200A BMS
After three years of development, in early 2018, we were satisfied with the circuit board stress testing and released the first batch of our newly developed BMS’s right across our entire 4S (12V) & 16S (48V) battery range. At the same time, we hired an app development team to start working on the software integration to launch our first app platform. The first GEN1 BLE DCS BMS’s that featured Bluetooth chips were launched in OCT 2019. The app platform required a lot of tweaking both on the hardware and software front, and our GEN2 BMS’s were released in mid-2020 along with a more stable app platform with a new design scheme. Our latest GEN3 BLE BMS’s had been released in JAN 2021. The accuracy and stability of the DCS LFP App monitoring system is now very mature and refined. Some additional features had been added along with the ability to create custom battery names. We can produce our DCS BMS technology in any continuous rating range from 10A to 200A with our comprehensive BLE DCS LFP App platform.
DCS Cell Management System:
Having developed such an industry-leading and reliable BMS, it made no sense to combine the cell balancing system together with the BMS. So with our many years of experience in designing and maintaining lithium batteries, we have developed a stand-alone CMS to compliment our BMS. CMS? What? OK, so there are two ‘theories’ of cell balancing in the lithium world passive and active. Passive balancing is a cheap inferior method of cell management as it can burn resistors in an attempt to bleed cell strings. In contrast, active cell balancing is a more complex and efficient balancing technique that redistributes charge between battery cells during the charge and discharge cycles.
Passive balancing has two fundamental setbacks;
- Heat: We don’t want unnecessary heat build-up inside a battery pack. The less internal heat, the lesser the impact on the battery cells over time
- Resistors have a limited service life, and once they fail game over, you have no cell management. But more importantly, they can fail in such a way in which they will keep drawing power and eventually destroy the cells.
Active balancing is the only way to manage lithium cells correctly. There are many ways to design an integrated circuit (IC) to actively manage cell strings. At DCS, we have tested well over 10 different methods of active balancing IC’s over the years and, in the end, again decided to develop our own active management circuit boards with the best-combined techniques based on our stress testing. Our in house PCB design engineer Max, designed our circuit boards to again meet the following criteria:
- High current movement (our latest boards now achieve 3.7A dynamic movement per channel)
- Thermal management to ensure the boards remain reliable in harsh environments
- Be able to withstand maximum current and thermal loads to ensure long term reliability
- Fail-safe design, if any component fails, it won’t compromise the battery pack (not consume power from the battery cells)
This is the DCS 16 channel CMS
There are, of course, some other software features and parameters, which we can’t disclose on this page to the public, as well as some very fancy hardware. But what our latest 04 channel and 16 channel CMS’s do is they can easily manage up to 1000Ah battery banks. So, for example, if you wanted to use our 16 channel CMS’s you could run a 51.2V 1000Ah single battery pack, which would be 51.2kWh in size! The DCS 15kWh batteries are just shy of 300Ah in capacity, so one can only imagine the tight CMS control these batteries are under, and that’s why we back them with a 10 year / 80% capacity warranty.
The DCS 16 channel 59.2A active cell balancing system is so powerful that it will change the battery storage market forever. With this system, the lithium market will continue to dominate for the foreseeable future. Of course, all DCS batteries now feature both our BMS & CMS circuit boards.
We design all our own PCB hardware and the circuit boards are tested to withstand a minimum of 10 years of severe abuse. This video is the MIL-STD 810G Method 514.6 which includes 4 procedures for different modes of vibration.
How to wire batteries correctly
CELL SAFETY INFO - Why LiFePO4 (LFP)?
Lithium Ferrophosphate (LFP) is a flame retardant, stable, safe and proven cell chemistry that has a very good energy density around 325 Wh/L. This cell chemistry can be engineered for various applications by adjusting the ratio of elements to provide high performance characteristics. E.g. the DCS marine battery range runs 2C cells, which means our little 75Ah battery will discharge comfortably at 75Ah x 2C = 150A. The DCS 80Ah Extreme runs 10C cells which means the 80A can comfortably discharge at 80Ah x 10C = 800A but is of course limited to lower currents due the the Battery Management System.
LFP also has very good cycling durability between 2,000 ~ 12,000 cycles can be achieved depending on how well the cells are managed, and the lowest rate of capacity loss (aka greater calendar-life) compared to other lithium cell chemistries.
WHY YOU CANNOT USE A VSR BETWEEN TWO DIFFERENT BATTERIES CAPACITIES & CHEMISTRIES?
Battery cells are simply a bunch of resistors with the ability to store energy. A 100Ah battery pack has a different resistance characteristic compared to a 50Ah battery pack, that theoretical difference in resistance is 2:1. So if you connect a 100Ah battery in parallel to a 50Ah battery there is no way for these two batteries to equalise and therefore you can’t charge them correctly. So for example connecting a 60Ah calcium starting battery to a 120Ah AGM via a VSR (Voltage Sensing Relay) you cannot charge both batteries correctly and from that day onwards you are prematurely destroying both battery packs. Same theory applies with lithium’s it’s still a battery pack.
What’s the solution? A DC-DC charger, you now have a permanent point of isolation (meaning that both batteries are never connected to each other in parallel). The DC-DC charger takes the surplus power from battery A (engine) and chargers battery B (aux/house). This device now allows any battery capacity and or chemistry to be used.
What if both batteries are the same, can I run a VSR between exactly the same two batteries?
Yes you can, but lithium’s have a different voltage curve, so you would still need to use a programmable VSR to dial them in correctly. However these devices draw a lot of power when engaged to so it’s best to run the two batteries in parallel and run a load disconnect instead of a VSR.
The advantages of the lithium battery cell chemistry
Lithium battery cells have a super low resistance so are very easy to charge and very efficient. This level of efficiency means you can charge them at very high C rates. For example if you look at the charge rate of a 100Ah AGM battery the recommended charging current will be around 25A, which is a 0.25C charge rate. If you consider the DCS 12V 100Ah Lithium battery it can be charged at up to 70A which is a 0.70C charge rate. This means you no longer need to consider DC-DC chargers as you can connect our batteries directly to high power charging devices such as suitable alternators, or large buck boosters. For example our popular dual 90Ah battery system for boats and 4WD vehicles, can be connected to alternators up to 160A.
WHY CAN DCS BATTERIES BE CONNECTED IN PARALLEL WITHOUT ANY EXTERNAL COMMUNICATION SYSTEM?
Because our batteries are internally voltage regulated and because our BMS has such a high sustainable peak discharge current they will do an amazing job of equalising very quickly.
WHAT HAPPENS IF I FULLY DISCHARGE MY BATTERY TO EMPTY?
The BMS will open circuit the battery terminals to protect the cells. This means there is no longer any resistance in the system. The BMS needs a 12V signal with at least 1A of current to release and wakeup from a cell protection state. Most mains chargers with a lithium profile will do a slow recovery charge as will most solar regulators. Some chargers in the market today that are advertised as ‘lithium’ compatible still don’t have the firmware to do a slow recovery charge to release BMS’s. If you have a charger that will not wakeup the BMS, easiest way to wake it up is to connect a unregulated solar panel directly to the battery terminals, ensure all loads are disconnected before you do this. Having said that every system should have a suitable low cut off voltage to shutdown loads/accessories so that the batteries are not fully drained.
BATTERY MONITOR SETTINGS
Use the following settings:
Charged voltage 14.0V
Tail current 4%
Charged detection time 1min
Peukert 1.05
Charge efficiency 98%
Current threshold 0.1A
C rates: refer to the battery pack capacity
What is the best state/charge to store these batteries ?
Fully charge to 100% isolate everything from the terminals and leave for max 3 months and then cycle (fully discharge and fully charge) and leave again for 3 months etc…. Minimum 4 cycles per year to not effect the cells capacity.
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