The battery guide
How do I start up my BMS?
On new BMSs, there is a small button on the bluetooth puck. It looks like a diode light but it's a button. When you have connected the battery, you simply press the button and the BMS starts up. You do not need to connect the battery or have a charger connected.
How to start up your bms 2.0 (Update)
How to take care of your battery
How do I balance my cells?
The reason why you want to balance the cells is because you want all the cells in the battery to work equally hard. If you have a large imbalance in the cells, you will not get all the amperes that the battery has. It is usually because one cell will charge faster than the others. The BMS will switch off the charge when e.g. one cell is 3.65V, regardless of whether the others are only on e.g. 3.4V. If you have an imbalance between the cells, you can balance them, regardless of whether they are new or several years old.
There are several different ways to balance your cells.
1. You can connect your cells in parallel and use a charger that you can set to 3.65V. This will take time as charging usually takes place with 3-4A. If you have a 12V battery with 4 cells, it can take a week, which of course depends on the SoC (State of Charge) the battery had when you start charging. If you have a 48V battery with 16 cells, it can take several weeks. It is common to first connect the cells in series to charge it up as much as possible. Then you connect them in parallel to make a top balancing and then it doesn't take as long to charge the cells.
2. You use the balancing that is in the BMS and let it do the work. If you have a strong imbalance and the BMS is unable to restore the balance, you can plug in a balance card that does the job. The balance board will balance the cells when charging and discharging.
3. You can also set "high volt cell protect" to e.g. 3.3V and then gradually increase "high volt cell protect" to 3.65V. This is a time-consuming process and may need to be redone several times to be successful.
Choose the right setting for your BMS!
Assemble your own LifePO4 battery!
Assemble calmly, methodically and carefully. Ensure that the pole bridges do not come into contact with both the + and - poles of the same cell, then there will be a short circuit and the cell may be damaged.
Mount the BMS's temperature sensor and Bluetooth Dongle before connecting the BMS to the lithium battery.
If you want to hold the cells together, you can draw a round of tape around the cells, one round on the upper part of the cells and one round on the lower part of the cells. Feel free to use tape that is not elastic and can withstand a little heat, for example Kapton or Gorilla tape. It is also fine to use cable ties
Now put the pole bridge from the + pole on cell 1 to the - pole on cell 2 and screw in the screws loosely, just so the pole bridge is in place.
Place pole bridge no. 2 from the - pole on cell 2 to the + pole on cell 3 and screw in the screws loosely just so the pole bridge is in place.
Place pole bridge no. 3 from the + pole on cell 3 to the - pole on cell 4 and screw in the screws loosely just so the pole bridge is in place.
(For 24 V batteries continue in the same way to cell 8)
Fit the BMS blue cable labeled B to the pole of cell 1
Take the cable harness with a black cable and 4 red cables (NOTE for 24V 8 red cables) and for simplicity mount on cable lugs
Fit the black cable to the - pole of cell 1 (same pole as blue cable labeled B-)
Take the first red wire, it is the one directly next to the black wire and mount it on the + pole of cell 1 (Mount the red wire on top of the pole bridge)
Take the second red wire (the one immediately after the first red wire and mount it on the + pole of cell 2 (Mount the red wire on top of the pole bridge)
Take the third red wire (the one immediately after the second red wire and mount it on the + pole of cell 3 (Mount the red wire on top of the pole bridge)
Take the fourth red wire (the one immediately after the third red wire and mount it to the + pole of cell 4
(For a 24V battery, you continue in the same way with all the cables to cell 8)
The battery is now fully assembled and ready to use. When connecting to the application, the + cable to the power consumer and charger must be connected to the + pole on cell 4 and the - cable from the power consumer and charger must be connected to the black cable marked P- on the BMS.
Why should you have LiFePO4 and BMS?
In this video and text we will tell you about the lithium LiPePO4 cells and batteries that we sell.
There are large quality differences in lithium LiFePO4 cells and batteries. Lithium batteries have properties that in many ways make them more suitable for energy storage in e.g. boats, motorhomes, caravans, golf carts and lifts etc.
Lithium Iron Phosphate or in Swedish Lithium-Ion Iron Phosphate (LiFePO4).
Lithium batteries (LiFePO4) are significantly lighter
A Lithium battery weighs only 1/5 - 1/6 of what a Lead/AGM/Gel battery weighs for the same capacity.
If we take e.g. a 100AH battery. It weighs approx. 28 kg and a corresponding Lithium battery weighs 12 kg. If you have a battery bank of 4x100AH (28 kg), the vehicle will be 88 kg lighter if you choose a Lithium battery with the same capacity.
Higher energy density
Lead/AGM/Gel battery 12 volt of 100AH in reality gives 50AH, which means that you only get 50% of the capacity. If you have a 12 volt battery bank of 4 x 100 AH = 400AH x 50% = 200AH.
On a 12 volt Lithium battery of 100 AH you get 100% when consumed. If you compare the capacity of the different technologies, 4 x 100AH Lithium also gives 400AH. In other words, you get 200AH more with Lithium batteries. An alternative is to halve the number of batteries.
Without getting too technical, Lithium batteries have lower resistance, which means that they charge up much faster. This results in having to run the engine or generator for a shorter time. It is entirely possible to charge the batteries with solar cells during a day.
To give a comparison, it takes 8 hours to fully charge a 12 volt Lead/AGM/Gel 100AH. For a 12 volt Lithium battery 100 AH it takes 2 hours.
Lifespan is measured in Depth of Discharge (DoD) and how many repetitions a battery can discharge.
Lead/AGM/Gel Deep cycle – capable of 300-600 repetitions @ 50% DoD
LiFePO4 – 3500 repetitions @ 80% DoD
A Lithium battery has a lifespan that is roughly 6-8 times longer than a Lead/AGM/Gel battery.
Withstand deeper discharge
You should never discharge a Lead/AGM/Gel battery below 12 Volts. A quality lithium battery can be discharged to 10 Volts.
You should never go below 10V because it can damage the battery. For this reason, you must have a BSM (Battery Monitoring System) that shuts down the battery before it is damaged.
Lithium batteries can, for example, manage without a maintenance charge during the entire winter season, without problems. Lead/AGM/Gel batteries discharge to 80% in 4 months Lithium batteries discharge to 80% in 8 months.
LiFePO4 are free of lead, mercury and cadmium, as well as other toxic substances.
The properties we particularly want to emphasize are the lifetime and the propensity to accept charging.
LiFePO4 batteries have a very low self-discharge and do not need to be charged during the winter. Make sure the batteries are half charged or just below approx. 13.20 Volts. Then disconnect one connection to the batteries so that they absolutely do not have a consumer connected. In the spring, just connect the batteries and start.
If you look at the batteries during the winter and notice that the pole voltage has dropped a little, perhaps to 13.10V, that's completely fine. The pole voltage drops slightly as the temperature drops.
BMS (Battery Management System)
It is extremely important that each individual cell in a LiFePO4 battery is protected against over- and under-voltage and against over-temperature. A bad and/or undersized BMS can completely destroy the battery. A BSM must be aware that the battery is not exposed to overvoltage (14.6V) and not exposed to undervoltage (10V). In both cases, the BMS must protect the battery and switch off incoming and outgoing current. The BMS should be able to balance the cells so that maximum capacity is obtained from the battery.
Most manufacturers of lithium batteries state that they should be charged using so-called "CCCV" technology (Constant-current constant-voltage charger) to achieve the best results. This means that charging must provide a constant current during the charging process and that charging ends with constant voltage and decreasing current. This means that they can be charged with both low and high current. By low current we mean that it can take up to 10 hours to fully charge them and by large we mean as much charging current as the maximum recommended by the manufacturer.
Charging and discharging are measured in C against the battery's AH. If the battery is a 12V 100AH battery and the battery can be charged with 1C, this means that the manufacturer recommends charging with a maximum of 100AH. If it reads 0.1C, it will be 10% of 100AH, which means a maximum charge of 10AH.
When discharging, it can e.g. stand Max discharge current 4C and Peak discharge current 5C. That means 4 or 5 x 100AH = 400AH or 500AH discharge for shorter periods. It may be interesting to know if you have LiFePO4 as a starter battery or for winches, bow thrusters and windlass (large consumers for a short time).
For the vehicle owner, it is usually interesting to know how quickly they can be charged so that we can use the engine's generator optimally. A normal generator is very well suited as a charger. Our lithium batteries thrive with a charge that is regulated by the voltage regulator that is already in the generator. However, it works best if the regulator's final voltage is 14.4 Volts. Improvements may need to be made to an older electrical system to fully utilize the "fast charging" capabilities that lithium batteries offer.
COMPARISON BETWEEN AGM AND LITHIUM LIFEPO4:
AH or amp hours, is the capacity you get out of the battery. More AH, the longer you can be out without having to charge the battery or batteries.
2 x AGM 12V 250AH, gives 500AH but you only get 50% of the capacity out of a Lead, AGM or GEL battery. Lithium LiFePO4 gets all the AH that the battery has. For example. BatteryGo LiFePO4 12V 280AH also provides 280AH in capacity.
The comparison below is between old technology AGM (from a well-known brand) and new technology Lithium LiFePO4 batteries.
- A Batterygo LiFePO4 280AH battery provides more capacity and is 6 times lighter (23 kg) and takes up 6 times less space. Has 4 times longer life and is 7% more expensive compared to the capacity you get.
- Towing around an extra 132 kg all the time, what does it cost in extra fuel consumption?
- If you factor in the lifespan, the LiFePO4 280 AH battery is 334% cheaper.
- If you want more space, less weight and batteries that last a long time, Lithium LiFePO4 batteries are unbeatable.
- No lead, acid or other toxic substances, lithium can therefore be mounted lying on its side. 100% utilization of the capacity in the battery, compared to lead/Gel/AGM battery where you get 50% of the capacity.
- Extremely low self-discharge, can stand all winter without charging.
- Safest lithium technology, no risk of fire in case of overcharging or in the event of a crash.
- Can be connected in both series and parallel