LiFePO4 Batteries - An introduction
LiFePO4 (pronounced life-poh-four) stands for Lithium (Li), Iron (Fe) Phosphate (PO4).
LiFePO4 batteries are a marvel of modern technology and manufacturing.
They are not the same as Lithium Ion batteries – LiFePO4 is inert when it comes into contact with water.
Whereas everyone knows these days that Lithium-Ion cells are highly reactive to water and can catch fire.
This makes the LiFePO4 cells a much more suitable and safer solution when considering for marine use.
Customers always ask questions about the longevity and performance of the lithium batteries we use.
So we’ve produced this article to try and answer these questions in a way which will give insights into this.
Rechargeable Lithium battery technology has come a long way in recent years, and lithium batteries are a marvel of modern technology and manufacturing.
Low voltage devices that can make use of battery power are now everywhere.
Therefore it makes sense to standardise and package batteries to run these devices efficiently, and reduce waste.
And batteries can be produced cheaply due to economies of scale.
This article explains how lithium batteries are put together and packaged.
It’s so that our customers can learn for themselves how effective the batteries are to power their engines.
Lithium batteries require some care if we want to get the maximum life and performance out of them.
And here we provide tips on what steps should be followed to take good care of the batteries.
Also, why these steps are important to the health of the batteries.
What's so special about Lithium Batteries
The standard form for the Lithium Ion batteries is a cell.
This cell called the 18650 cell.
The 18650 cell is slightly larger than a standard AA cell
(see the picture for comparison).
The cells are each usually a standard voltage of 3.675V.
They can range from 2 Amp Hrs (Ah) to 4Ah in power.
A lot can be researched about these cells.
For example, Wikipedia. has some good articles
How are they packaged?
The 18650 cells can be packaged together in banks:
- When wired in series, this will increase Voltage (eg. 3.675v, 7.35v, 11.02v, 14.7v, 29.4v, etc…)
- When cells (or banks) wired parallel, will increase Ampage. (eg. 2.2Ah, 4.4Ah; 6.6Ah; 8.8Ah)
The picture illustrates a 29.4V /6.6Ah battery:
- A bank of 8x 3.675V / 2.2Ah cells in series will deliver 29.4V max (or 24V nominal).
- A pack of 3 of these banks wired in parallel will deliver 6.6Ah.
- This pack would be called 8s3p (ie. eight cells to a bank in series, three banks in parallel
And so it goes: Cells > > Banks > > Packs
What's a BMS?
BMS stands for battery management system.
It is a circuit board attached so the pack (see pic).
Its purpose is to protect and regulate each of the cells.
The BMS ensures no cell runs below a min of 2.7V, or above a max of 4.2V, for optimum life:
- Below the 2.7V threshold, a chemical reaction may occur that can damage the cell.
- Above 4.2V Li-Ion cells may overheat, which is dangerous for the cell, and for the pack.
- LiFePO4 however is much more stable in this respect.
The max. Volts of a bank is the sum of all the cells.
If one cell dies, the max. Volts of the bank is reduced.
The lowest voltage bank sets the max. Volts of the pack.
Having many cells protects the pack from any cell failing.
But if one cell in one bank becomes damaged,
it will reduce the maximum Volts of the pack.
Even a Tesla uses these standard 18650 cells – about 7,000 of them in the floor pan of the car.
For example a Tesla Model S uses a standard 3.66V / 3400mAh cell within modular battery packs.
The configuration of each module is 6s74p, or 444 cellsAnd there are 16 modules.
That means there are 7,104 cells in total, to deliver 85 KWh.
Caring For Lithium Batteries
It is important that lithium battery cells are maintained well.
This means ensuring that the power of any cell is not allowed to run down below its minimum threshold voltage.
Below this threshold, a chemical reaction occurs within the cell which can permanently damage the cell.
What this post shows is how intricate the lithium battery packs are, and how critical it is to keep them recharged.
Even if you are not using the battery for extended periods.
What does motorzoo do?
motorzoo offers a diverse range of electric outboard motors. Our budget range of trolling motors, from 1hp to 3hp:
- See our 12V-01×0, 48V-01×0, and 48V-02×2 models.
And our high performance range, from 5hp to 20hp:
- See our 48V-03×0, 48V-06×5, and 48V-11×5 models.
These models have some unique patented features.
You may need a 1hp trolling motor, or a 20hp power plant. We can provide right-size solution for your power needs. You can also find user guides for our engines online here. You will find that our motors compare very favourably. If you want to know more, shoot us a question.
Want to Find Out More?
Please just fill out the enquiry form, and we will respond.
Alternatively, you may prefer to speak to us. Call (1 3000 76268)