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Questions tagged [lifepo4]

All related to lithium iron phosphate (or LFP) batteries

11
votes
2answers
4k views

Does TI's LiFePO4 CV-free fast charge method reduce cell lifetime?

TI claim that you can charge LiFePO4 cells by CC (constant current) charging as usual but to a higher than usual voltage (eg 3.7V rather than the usual 3.6V for LiFePO4) and then step transition to a ...
10
votes
3answers
22k views

Using LiFePO4 battery as car battery

I've had an idea of using LiFePO4 battery as replacement for car battery, since 4 of those in series make nominal 12.8V which is very close to standard 12V voltage. And depending on the cell we can ...
6
votes
1answer
7k views

LiFePo4 vs LiPo

I'm planning on building an Ebike and I am not quite sure what type of battery I should get. What are the bigger differences between the two? I have Googled, but I don't understand the answers. I ...
5
votes
1answer
2k views

Solar powered single cell LiFePo4 charger circuit

As a follow-up to this question I've come up with this schematic for a solar powered battery charger: Subcircuits, from left to right: Solar cell (just a voltage source), 12V, 10W. Buck regulator ...
4
votes
2answers
3k views

How to fast charge a Lifepo4?

Disclaimer: I hope that I have not carelessly overlooked a previous post that answers this question; but I definitely have tried, and still find myself a little lost. Situation: I have 15 A123 ...
4
votes
1answer
1k views

18650 LiFePO4 Cell UVP/OVP Under/Over Voltage Protection

The vast majority of existing ancillary protection IC's available (such as Seiko) are not compatible with LiFePO4 chemistry due to the lower operating voltage. And the few vendors selling iron-...
3
votes
1answer
49 views

LiFePo4 cell risk of explosion during cool down

A 3 Ah LFP cell is charged to 100% at 25°C temperature. What happenes if I cool down the charged cell to -20 °C temperature? At -20 °C the cell can store only 2 Ah. Does it mean, the cell is ...
3
votes
1answer
1k views

Solar powered charger circuit for a single LiFe cell

I'm looking for a solar powered charger circuit for a single LiFePo cell. The load is a low power MCU with some sensors attached, and when sufficient solar power is available, it should be used to ...
3
votes
1answer
919 views

LiFePo4 2 Cell Series Charging with MCP73223

I want to make a charger for two LiFePo4 cells in series. As I'm aware, charging cells in series may be problematic, due to slight differences on each cells, that may charge one and not the other, ...
3
votes
1answer
90 views

How to drain LiFePO4 battery?

I am using a tracer battery BP2603(12V,3.5A) to turn on my camera. The camera needs 12V and it consumes max 3A. Maximum voltage the camera can accept is 13.5V. But I've found that when the battery is ...
3
votes
1answer
130 views

LiFePO4 lithium iron-phosphate cells - OK to dip?

I want to try epoxy-dipping a PCB with an 18650-sized LiFePO4 cell. This is for a low-power application and is slow-charged, so thermal is a non-issue. Before doing anything unforeseen dangerous, is ...
3
votes
1answer
875 views

Battery charging for DIY laptop

I am building a DIY laptop, and I need a battery pack that will allow me to use and charge my device as you would any modern laptop, i.e. by connecting a regular 12-19V DC power brick to a panel ...
3
votes
1answer
476 views

Lifepo4 current limiter with supercapacitor in parallell

I am making a LiFePo4/supercapacitor-hybrid. Spike current draw can reach 300A for a few seconds. The LiFePo4 batteries I am using is rated for 100A max discharge rate. In order to make sure the ...
2
votes
3answers
264 views

How many large format LiFePO4 cells can be connected in series?

Is there any real reason why I couldn't connect 320 LiFePO4 cells in series (for a nominal 960Vdc)? Or is there some limitations within the pouches inside the cells? Like to see your thoughts!
2
votes
4answers
6k views

What are the problems with LiFePo4 float charging? How should I charge them?

I can't find any reliable info on float charging LiFePo4 cells. It's quite clear that it's not possible to float charge Li-ion and Lipo cells, but LiFePo4 looks like quite different technology. I'm ...
2
votes
1answer
562 views

Short-circuit xPyS LiFePO4 batteries

I have a LiFePO4 battery connected in 2P4S configuration. What happen if one of the batteries is short-circuited? The other batteries will also be short circuits, or this will be result in the venting ...
2
votes
1answer
345 views

Raspberry PI 3 - LiFePO4 power supply

I'm working on a mobile computer unit with a Raspberry PI 3 motherboard. The computer unit needs to run on battery so i can bring it with me anywhere. I'm going to solder both the battery pack and ...
2
votes
1answer
573 views

18650 Li-ion modular battery packs

I was searching around for batteries to use in my personal electric scooter project. I've found some LiFePO4 that has sufficient capacities like: http://en.winston-battery.com/index.php/products/...
2
votes
0answers
153 views

Load Sharing/Isolation Circuit with ADP5063

I'm designing the battery power/charging circuit for the Reform DIY laptop which uses a (big) LiFePo4 cell. For the charger IC I've now settled on ADP5063 as it seems simple and can charge with 1.5A ...
1
vote
3answers
490 views

Charging batteries directly from 117 volt wall socket

It has occurred to me that almost no battery charger would be required if the battery pack was of the same voltage as grid supplied power. I build electric bikes, and the voltage on these has been ...
1
vote
2answers
1k views

MOSFET for reverse polarity protection of a LiFePO4 battery powered circuit?

I am looking to protect my circuit from a reverse polarity event. I found suggestions for using a MOSFET, particularly a p-channel type. Does anyone have a specific recommendation for a device to use ...
1
vote
5answers
9k views

Using Li-Po or LiFePo4 for diy motorcycle battery

Basically just after opinions on using LiPo or LiFePo4 for building a diy motorcycle battery. My current lead acid battery just died and i'm sick of replacing them after 1-2 years. Background info - ...
1
vote
1answer
327 views

Can I float charge LiFePo4?

Is it ok to take the output of a solar panel (no MPPT, but de-rated) and pipe it into a switching regulator at say, 3.45v? The output of the regulator would go into my micro, an STM32F103 and a ...
1
vote
2answers
240 views

LiFePO4 Batteries Discharge Fast After Recharge

On my application I have four 200 mAh LiFePo4 cells, configures as sereies of two parallels, thus achieveing a 6.4V battery. I understand this cells in series need balancing, I would like to leave ...
1
vote
1answer
227 views

BQ24650 or BQ24620 for LiFePO battery charger | Solar powered + Grid powered

I am designing a Battery Charge controller for our 12V LiFePo battery. Power input is: a. Solar Panel 80W @ 12V (Vopencircuit=21.33V, Vmaxpower=17.78V) OR b. 18VDC grid power. Either one power ...
1
vote
1answer
741 views

Will LiFePo4 work with ESC for LiPo?

Im just a little bit confused wether if LiFe batteries will work the same with an ESC (Electronic Speed controller) Whats making me confused is that in the description they only talk about LiPo ...
1
vote
1answer
186 views

LiFePO4 cells - self-balancing in series or parallel?

I am building various banks / packs from individual prismatic LFP cells, nominal 3.2V each. New and pretty large, 60-400AH. I have a good power supply, charge each cell independently, Bulk stage CC ...
1
vote
1answer
1k views

LiFePo4 Battery Charging for Maximum Cycle Life with Solar Panels

The problem is charging lithium iron batteries for "maximum Cycles" with a solar charge controller wile using loads? I have a PowerSonic 45 amp hour LiFePo4 battery for my Caravan house battery. I ...
1
vote
1answer
2k views

What is the maximum static voltage of LiFePo4 batteries?

I've been working with a pack of batteries from a DIY electric vehicle. The batteries in the pack are LiFePo4 chemistry and were chosen for safety (greater resistance to thermal run-away), flat ...
1
vote
2answers
59 views

LFP Cells - Case to internal thermal resistance

Semiconductors often specify thermal resistance from case to the junction, but LFP battery cells do not seem to specify this. Instead, they refer only to a generic 'maximum operating temperature'. ...
1
vote
1answer
407 views

Charging LiFePO4 at low voltage - how do you know when to stop?

I've read that the most typical approach to charging, is to provide as much current as you'd like (lower current causing less loss of capacity over time), and to stop when the cell reaches 3.6V. The ...
1
vote
0answers
91 views

Boost converter voltage drop when charging battery

I made a 4s battery pack made of 18650 LiFePO4 cells that I'm planning to use for a mobile computing hobby project. My plan for charging it is to use a salvaged power supply from a computer along ...
1
vote
0answers
59 views

How can I balance 2 separate LiFePo4 batteries?

On my boat I've got devices that run on 24V and others that run on 12V. Seeing as how the alternator, wind generator and solar panels are all generating 24V, I guess it's fair to say that this is ...
1
vote
1answer
21 views

VDC booster effect on LiFePo battery run time?

Looking for info to devise a solution for a mobile video rig. I work in the film industry and it would be VERY beneficial to run my video cart from battery power, as opposed to always having to plug ...
1
vote
1answer
24 views

changing 6v lead blocks by 3,2v LiFePo4 cells

I need to replace a lead battery system with a LiFePO4 element system. the existing system is 48V 240Amp and consists of 8 Trojan T145 6V Batteries with 240Amp in the C20, the idea is to replace this ...
1
vote
0answers
267 views

Help needed with over discharge circuit on LifePo4 12V car battery replacement

I'm putting together a LifePo4 battery pack with the intention of replacing the 12V lead acid battery in my 4WD. So far, what I've got is the following. 4 x 10 Ah LifePo4 batteries (38120 Headway) in ...
1
vote
0answers
434 views

LiFePO4 solar charging problems (amateur question)

My application is primarily portable ham radio operation. I chose a self-balancing, 4.5 Ah, 12.8V, 4s3p LiFePO4 battery pack, a 28W panel and an MPPT solar charge controller with extremely limited ...
1
vote
0answers
129 views

Switching in parallel high-capacity LiFePo4 battery packs during discharge cycle

I have two, possibly three 48V-nominal 50Ah Lithium Iron Phosphate battery packs used for E-bikes (16S cells, 2.5kWh capacity each). The packs have BMS circuitry which limits discharge to 50A (...
0
votes
2answers
263 views

Deciding on lithium battery chemistry, lithium ion (protected) or Lithium Iron Phosphate (no protection) Safety is critical

I am designing a product requiring high power and energy storage capability. I have narrowed down the selection to two (most cost effective) systems: a 3s system of protected 18650 lithium ion cells (...
0
votes
1answer
1k views

LiFePO4 in cold: charging

I have used LiFePO4 batteries, only in discharge mode, by down to -15 deg C (charging was done 'back to the warmth'), and they worked fine. But from what I read it looks like Li-* batteries do not ...
0
votes
3answers
2k views

Powering an Arduino Pro Mini 5V and a 3.3V nRF24L01+ Transceiver from One Small Battery

I'm trying to power an Arduino Pro Mini 328 5V/16MHz with a single battery, preferably a LiFePO4 for safety purposes (it doesn't need to be more than around 300 mAh). However, I'm connecting a ...
0
votes
3answers
287 views

3 watt LED plus LiFePO4 battery (1 cell), no resistor, no regulator. Is there anything wrong with this?

I read that you should "always" have a resistor in series between an LED and its power source. But what if the power source already has its voltage set to a suitable max for that particular LED? Why ...
0
votes
2answers
80 views

Determining Faulty Lithium Batteries in Battery Pack

I am having some difficulties with a 72V 200aH LiFePo4 battery pack that I am using in conjunction with an EMUS BMS. The BMS indicated some of the batteries were not charging properly, I corresponded ...
0
votes
3answers
486 views

LiFePo4 Slow charging 100 AH OK?

I'm working on a solar project that involves using 4 100AH LFE (LiFePo4) cells to supply 12 volts. The LFE cells indicate the charge rate should be between 0.3C and 2C, which is a lot of current. ...
0
votes
1answer
186 views

Load sharing between 3.3V regulator and LiFePo4 battery

I am trying to design a supply for a relatively low power (<100mA) device with a LifePo4 (14500 format) battery and a USB input. Everything is running at 3.3V, and therefore I would like to avoid ...
0
votes
1answer
80 views

LiFePO4 battery in sealed container

I'm making a project/rc boat to map the bottom of a lake and therefore I need a relatively big battery (say 12V 10Ah) for the operation and electronics of the small boat (propeller motor + telecoms + ...
0
votes
1answer
543 views

LiFePO4 BMS low charge rate disconnect

As my commercially purchased, 12V 4s3p LiFePO4 battery pack approaches full charge (3.65V per cell, 14.6V for the pack), the internal BMS disconnects the battery at a charge rate of 0.02C. What ...
0
votes
1answer
372 views

LiFePO4 16-cell stack precision dc volt measurement LTC2400 MUX

I would like to build a highly precise volt meter (5 digits; e.g. +/- 1mV) to measure each cell voltage in a LiFePO4 battery stack of 16 cells (<60V). I am content with measuring the cell between 3 ...
0
votes
1answer
143 views

Boosting Peak Draw spec on LiFePO4 using Capacitors

Attempt to replace a 4.5Ah 12V Pb battery with LiFePO4 for a Profoto Acute B flash generator I have a detailed writeup here... Previously I had used a Tenergy drop in Li replacement which worked for ...
0
votes
1answer
723 views

LiFePO4 in parallel with solar charge controller?

I've decided to replace my lead acid battery bank with LiFePO4. I'm using the battery bank in a motorhome, where SoC can typically be at 30-50% for days, which is unacceptable for lead acid - just ...