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Questions tagged [lifepo4]

All related to lithium iron phosphate (or LFP) batteries

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56 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 ...
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13 views

Using SLA in place of LFP to test an LFP charging device

I'm testing a solar charge controller for LiFePO4 that uses absorption and float stages. By design, power-on initiates the absorption stage, and a timer terminates absorption and initiates the float ...
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1answer
54 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 ...
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1answer
46 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 ...
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35 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 ...
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2answers
48 views

charging 24v LiFePO4 with DC power supply intended for LED strip lights

I want to charge my 200Ah, 8 cell GBS LiFePO4 using my Honda 2000 watt generator. (I live on a boat). I have a BMS, active monitoring and all that. I just want to make sure the below power supply is ...
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1answer
20 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 ...
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50 views

Questions about using a step up/down voltage regulator in a solar charging application

In my portable 12V solar charging system, my MPPT charge controller and LiFePO4 battery pack don't play together well at end of charge. The battery disconnects at some low charge rate, and when this ...
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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 ...
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1answer
982 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 ...
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1answer
922 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 ...
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224 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 ...
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1answer
159 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 ...
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1answer
83 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 ...
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44 views

Dismantling 110v DC LiFePo4 Battery Pack

I've inherited a 110v battery pack that used to be used for a solar array made of 34 each 100 amp hour LiFePo4 3.2v for a nominal voltage of 108.8v all together. I'm getting about 90v total from the ...
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137 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 ...
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99 views

1S 3.2v LiFePO4 charging with built-in BMS

I have a project running with 2 AAA accu (=3v). I want to move to LiFePO4 3.2V battery. I choose this one because I can managed with this voltage but now my question is : how can I charge this battery ...
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178 views

Underpowering a DC/DC power supply and question about CC/CV (for battery charging using solar)

First off, here's the setup I have planned: 2x 100W 12V Solar Panels -> Solar Charge Controller Outputting 24V -> ...
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1answer
70 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 + ...
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1answer
454 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 ...
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1answer
982 views

LiFePo4 DC charging from alternator

From what I've read, replacing a lead-acid deep cycle battery with a LiFePo4 battery requires a different charge and float regieme than a standard 12v car alternator is providing. My question is, if ...
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358 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 ...
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1answer
317 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 ...
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2answers
68 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 ...
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2answers
52 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'. ...
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287 views

Battery Management System (BMS) Overcurrent Rating/Protection for LiFePO4 Battery

I plan on building an 8S LiFePO4 battery pack with these cells, capable of 120A maximum continuous discharge current: http://www.evassemble.com/index.php?main_page=product_info&cPath=2&...
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1answer
503 views

Calculate LifePo4 charging amps

How do I work out the optimum charging amps for a life 2p4s battery? I have 8 x 66ah sinopoly batteries. http://www.sinopolybattery.com/userfiles/files/SP-LFP66AHA.pdf Charge Specs * Standard ...
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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 ...
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1answer
419 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 ...
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1answer
202 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 ...
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108 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 (...
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1answer
283 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 ...
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297 views

MPPT Solar LiFePo4 charger with cell balancing and load managing

I'm building a robotic autonomous system with the solar battery as a power source. I will use 4 LiFePo4 batteries (A123, 26650) connected by two in parallel, and these two pairs in series, so voltage ...
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1answer
322 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 ...
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3answers
57 views

Massive Parallel Lithium Lead Wire Connection Point

I was wondering where the connection point should be on a "massive" parallel block of lithium batteries. Let's say there is a pack of 100 LiFePo4 18650 batteries all spot welded together with nickel ...
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1answer
341 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 ...
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1answer
135 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 ...
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1answer
264 views

Using switching to control load sharing of DC?

I'm not sure of the right terminology for what I am trying to ask about. Feel free to suggest a better question title. Lets say that I have a fully charged LiFePO4 battery, which I do not want to ...
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1answer
632 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 ...
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2answers
252 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 (...
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4answers
5k 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 ...
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3answers
401 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. ...
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1answer
830 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 ...
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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 ...
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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 ...
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2answers
2k 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 ...
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1answer
565 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/...
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5answers
8k 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 - ...
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3answers
275 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 ...
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3answers
234 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!