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How to make a CHEAP Lifepo4 battery!

Batteries, razor

Esteban

Lifepo4 advantages over AGM GEL and Acid.

They weigh up to 3 times less than a conventional battery.
Equal amperes, They are much smaller.
They last more than 2000 discharge cycles 90/95% without getting damaged. (AGM/GEL 350/400).
They have a BMS for protection in case of short circuit, overheating etc..
No risk of explosions or gases inside the vehicle.
They charge much faster than a gel/agm battery.
The useful life is 10 times greater.

Lifepo4 VS Lithium Which is better and why

batteries lithium, Li-Ion or lithium ion have a voltage of 3.7v and are in a liquid state., which makes them quite dangerous and can explode if not treated well., overload, overdischarge.. etc..

Batteries Lifepo4 also called as LFP, lithium-ferrophosphate or iron phosphate, They have a voltage of 3.2v and are solid state so they do not explode.

They have been with us for a long time, Fortunately I have been able to see and test LifePo4 batteries first-hand, but before them, I have been through acid, deep cycle acid, agm and gel ones. Today, and according to my personal experience, If I had to buy a battery again, It's very clear to me, without a doubt Lifepo4, and as a second option GEl, especially the Ultracell, which gave me very good results.

Assemble a Lifepo4 battery economically

If you are here it is to know how to set it up, so I'm not going to let you down, after much study on the subject, search and compare, The best prices by far are in Aliexpress, buy them in Spain sincerely, I consider it a real theft for the prices they charge..

Material needed:

- BMS to control the load, discharge and balance the cells
- Lifepo4 cells
- copper terminals for cell union (sometimes they come as a gift with the cells)

Types of BMS, which to choose?

Hay 2 types of BMS let's say them “normal” and the “smart”

Los normal they are more cheap, They balance the cells and when it detects that one of them is at the 100% stop swinging. They also do not include a temperature sensor.

Then there are the smart o Smart BMS, These carry a microcontroller and balance the cells continuously until they are all at the same level. 100%, control the temperature, son but expensive, but it is worth investing a little more to have something much better, These can also be fitted with a Bluetooth module to configure the maximum charge and discharge voltages., turn off the battery and everything from the Android or IOS mobile itself.

With SMART BMS we will have greater control and they are safer than the others, We must keep in mind that the cells are not cheap and we have to take care of them, so don't skimp €20/30 on the bms.

For 12v vans and campers, among the options offered by sellers, we must choose one 4s, 12v y “common port” or common port, those of separate port They are also valid, but you would have to take the charging cable from the solar panel/alternator directly to the charging port.

The peculiarity of those with a common port is that we can load and unload in the same place, like common AGM or GEL batteries, being able to replace one with another without doing anything else.

How to connect the BMS to a LifePo4 battery

It is very simple, and I think the best way to explain it is to simulate that the BMS is a fuse, Let's say it would be installed in the middle of the negative cable that comes out of the battery.

Then we have a connector with 5 cables, As we have 4 cells, we would connect the black wire to the negative, and then in order each cable to the positive of each cell in cascade. I better leave a picture, It may seem complicated but it is actually very easy. Sorry for the quality of the drawing.. :p

This is the pack I currently use, The BMS is not like the one installed before, but I'm waiting for it to arrive to install it.

How to charge a LifePo4 battery

exist 3 shapes, through a charger o booster, through the vehicle's alternator, or with solar panels. You can use the 3 separate systems, or combine the 3 at once, depending on the circumstance you find yourself in.

The charging values are compatible with those used in lead batteries., come to agm. So it doesn't really matter how it's configured, your regulator swallows everything..

– You can configure your regulator with a voltage of 14.2v – 14,6v, but what would be recommended would be 14.2 Since at that voltage the cells are already completely filled and we would not stress the cells.

– The maximum low battery cutoff is 10v, although it would not be advisable to rush it so much as to reach that voltage., can be left at 11.5v (5% approximate load). If you download more, the bms itself would cut through its protection and leaving it discharged would end up damaging it.

If you want to make a portable version and charge it at home, you can use a fast charger like It is, or a slow one such as a typical Lidl car or something like It is something cheaper in GEL mode.