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Category: Tech Tips
Balancers
When putting batteries in series for a 24V or 48V system it is a good idea to use a balancer. This balancer ensures that the voltages of all the batteries in the pack remain equal and balanced. Without a balancer, especially on lithium systems, the voltage of each of the 12V batteries can drift apart over time. Balancers help to minimise this effect and keep equal voltages across batteries.
The balancers we are talking about here are different to the balancers we use on lithium cells. These balancers balance between 12V batteries, not 3v cells.
BlueSolar vs SmartSolar
When buying Victron MPPT solar controllers you have two product lines to choose from, the BlueSolar range and the SmartSolar range. The key difference between the two is that the BlueSolar range does NOT have Bluetooth. The SmartSolar range has the smart features and can connect to your phone via Bluetooth. Yes that is definitely confusing, that’s why this tech-tip exists.
If you have happened to purchase a BlueSolar solar controller and want to change settings or add Bluetooth to it you can. You just need to purchase a VE.Direct Bluetooth Smart dongle. This will add the Bluetooth functionality to your device. You can also plug the controller into a Cerbo if you want an even cooler, more advanced setup.
Rail Profiles
We help a lot of customers with solar rail and solar panel mounting hardware. Sometimes people need to match rail or mounts with their existing system. In order for us to help you out best, it is always a good idea to bring a photo or sample of your mounting gear. The images shown above give you an idea of the various types, of very similar looking, solar mounting profiles.
The Grace style and Clenergy branded rails are the most common types of rail that we sell currently. We do, however, stock a large range of new and used profiles and mounting hardware to suit a wide range of brands and profiles.
Lithium Safety
At Alt-Tech we sell lithium iron phosphate (also called LiFePO4 or LFP) batteries.
These are just one of the various types of lithium-ion batteries that are available currently. Many people are aware of the risk of fire that lithium batteries pose, however, it is important to recognise the differences between the different chemistries. Lithium iron phosphate is a very safe, low fire risk, type of lithium. It does not present as much risk as some of the types of lithium batteries you often hear about.
GWL Group, a European battery manufacturer created an excellent video which demonstrates the risk posed by different lithium types.
https://youtu.be/Qzt9RZ0FQyM?si=WMTLvV9t5vP21_Yb
Calculating Watt-hours
Imagine you have a 100Ah 12v battery and a 100Ah 48V battery, which one stores more energy?
The 48V 100Ah battery stores 4x the power of the 12V 100Ah battery. How is this possible? Don’t they have the same 100Ah capacity?
Yes they have the same Amp-Hour rating, however, Amp-Hours are not the full story. In fact, amp hours are, in our opinion, not a very useful measure of a battery’s capacity. Watt hours are a far more useful measure of battery capacity.
Watt hours are similar to Amp-Hours in that they measure the storage of a battery. However, Watt hours are independant of the voltage of the battery. So where Amp-Hours measure how many amps can be supplied over time, watt hours measure how many watts can be supplied over time.
A 100Ah battery as we know will supply 1A for 100h.
A 100Wh battery will supply 1W of power for 100h.See how Watt-Hours are much more useful for determining how long you can run a certain wattage load. It is easy to see how a 100Wh battery can supply a 100W load for 1 hour. Watt-Hours remove the confusion assosciated with battery voltage and Amp-Hours.
There are two useful ways of calculating watt hours.
This first equation is useful for calculating the Watt-Hour storage of a battery:
Watt-Hours (Wh) = Battery Capacity in Amp-Hours (Ah) x Battery voltage (V)
Example:
100Ah x 12V = 1200Wh of energy stored
100Ah x 48V = 4800Wh of energy storedThis second equation is useful for measuring how many Watt-Hours a device might use over time:
Watt-Hours (Wh) = Power in Watts (W) x Time in Hours (H)
Example:
Running a 1000W load for 6 hours. How many Watt-Hours would that use.
1000W x 6 hours = 6000Wh or 6kWh
Can I Run My Lithium Battery With No BMS?
Our immediate answer is NO, ABSOLUTELY NO. But lets have a look at that a bit more…
Technically speaking, yes lithium batteries will output power even without a BMS. However, it is unsafe to do so. The BMS is a protection circuit. It protects the batteries from over-voltage, under-voltage, and sometimes also over-current and over temperature.
Running a lithium battery without a BMS is a safety hazard. Even if the batteries don’t vent or catch fire, the batteries will almost certainly be damaged and swell if discharged too much. Overdischarging or overcharging is a common way that a lithium battery can be damaged when not using a BMS. Running the battery even slightly too flat will severely reduce the capacity of the batteries.
So you may say why can’t I run a battery protect to protect my lithum battery? That is unfortunately not good enough for lithium. Every cell of a lithium battery needs to be monitored and protected. If even one cell goes over-voltage or under-voltage you will permanently damage the battery pack.
Using a lithium battery without a BMS is a bit like having a car without brakes. Sure the car drives just fine without them, however, it is an inevitable safety hazard.
So while yes, technically you can run your lithium battery without a BMS, for the relatively low cost of a BMS is it worth damaging thousands of dollars worth of lithium cells or worse?
Temperature Compensation
Temperature compensation is a feature of some high quality battery charging devices. It is a setting that allows the charger to adjust the charging voltage of the battery to suit the temperature of the battery. Most battery datasheets specify that the battery charge voltage should be reduced at high temperatures to prolong the battery lifespan.
Correctly setting the temperature compensation of your charger may improve the lifespan of your battery bank. The correct compensation value for your batteries should be available in the battery datasheet or from the battery supplier.
The value you are looking for is something such as -16.20mV/C (Victron Default).
Amps VS Amp-hours
Understand the difference between amps and amp-hours and how they affect one another.
Simple Explanation:
Amps (A):
Amps are like the amount of water that flows through a pipe. More flow = more amps.
Example: Lets imagine a pipe with a flow of 1 Litre per hour.Amp-Hours (Ah):
Amp hours are like the amount of water stored in a water tank (Litres). A larger tank has a larger capacity.
Example: Lets assume you have a 50L tank (Similar to 50Ah). If you had a flow of 5L per hour (Lets call this 5A) the tank would empty in 10 hours.Electrical Explanation:
Amps (A):
Amps are a measure of current in a circuit. Amps measure the amount of current flowing through a circuit at an instant in time.Amp-Hours (Ah):
Amp-Hours are a measure of capacity. Amp-Hours measure the amount of current (A) that have passed over time.
Calculation: Amp-Hours = Current (Amps) x Time (Hours).
Example: You have a fridge drawing 5A for an hour, you would have used 5Ah of your batteries capacity.Important note: While it may seem that a 48v 100Ah battery and a 12v 100Ah battery have the same amount of storage, this is not the case. A 48V battery has 4 times the amount of energy stored (watt-hours). This will be explored in a future tech tip.
Disclaimer: Never over discharge your batteries! Make sure that you dont exceed the maximum depth of discharge of the battery.
What are Watts?
Watts are a unit of power.
Power is defined as the instantaneous amount of energy delivered to a load. Watts should not be confused with watt-hours or kilowatt-hours. Watt hours are a measure of energy storage, which is a different topic to be covered in the future.
Power (Watts) = Volts (V) * Amps (A)
Lets consider a 10A draw from different battery voltages:
12V battery delivering 10A results in 120W of power.
24V battery delivering 10A results in 240W of power.
48V battery delivering 10A results in 480W of power.Lets now consider a 2000W load and different battery voltages:
2000W load on a 12V battery will result in a current draw of 167A.
2000W load on a 24V battery will result in a current draw of 83A.
2000W load on a 48V battery will result in a current draw of 42A.Sometimes running a higher battery voltages can have benefits.
– Being able to use smaller cables to run the same load
– Sometimes being able to use smaller devices to charge the same batteryIt is important to consider ALL factors when selecting a battery voltage. Higher voltage batteries are not always better, consider your use case and needs before deciding.
Disclaimer: ALWAYS remember to check your device’s specifications to ensure you don’t damage it by exceeding its capabilities.
VE. Smart Networking
Delve into the tech magic of VE.Smart Networking—a wireless interconnection using Bluetooth Smart technology, fostering seamless communication among your Victron products. How to Use:
Device Pairing: Effortlessly connect Victron devices through BLE. Up to 10 devices in the same Network. Sensor Integration: Attach a BMV monitor, SmartShunt, or Smart Battery Sense to Solar Chargers. Parameter Optimization: Witness Solar Chargers adapt charge settings based on real-time data from connected sensors. Advantages: Battery Health Assurance: Monitor voltage, temperature, and current, safeguarding battery longevity. Voltage Compensation: Counteract cable voltage-drop for precise charging. Temperature Adjustment: Adapt charge voltages based on real-time battery temperature. Current Precision: Enhance tail current setting precision for a more nuanced charge cycle. Synchronized Charging: Linking multiple SmartSolar chargers for a collective charging strategy. Limitations: Sensor Priority: Only one Smart Battery Sense or BMV per VE.Smart Network. BLE Range: Aligns with Bluetooth range experienced in VictronConnect. Sensor Caution: Connect one sensor type per battery, preventing overcharging or heating. Current limit: if limiting the total charging current is required, a GX device is needed to use the DVCC function. Note: for full information and step-by-step procedure refer to the official Victron documentation.