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Author Topic: LiFePO 4 batteries  (Read 2620 times)

K0UA

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RE: LiFePO 4 batteries
« Reply #15 on: September 23, 2019, 08:44:08 AM »

Purchased my LiFePo4 100ah deep cycle on Thursdy from Lithium Battery Store in FL.
So plunge in I did!

Well, that ought to do it!.  Let us know how many days you can run off of that one!.  Just kidding, I don't know what type of operation (duty cycle) you anticipate. But I do believe you are well armed for whatever you would want to do.
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73  James K0UA

KD8IIC

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RE: LiFePO 4 batteries
« Reply #16 on: September 24, 2019, 08:14:02 AM »

  Been running portable CW QRO (100w) a few times. I've been using a 33Ah AGM and charging
with 200w solar (15a) The battery has been sufficient. Needed only to charge at home to top it off
@ 14.2v it only took 2.7a at the start and a half hr later it was down to drawing just .1a.
 So yes, the 100Ah LiFePo4 deep cycle will do great.
I'm mounting it in my Toyota Mini Cruiser class C motor home to be the coach battery.
It only weighs 31LBS! The retiree weighs 65. So that's a savings right there in fuel and cargo.
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KI5GKD

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RE: LiFePO 4 batteries
« Reply #17 on: September 26, 2019, 12:11:03 PM »

About the only "shortcoming" with this chemistry is the inability to charge them when the temps are below freezing.  They have to be warmed up before charging.
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KD8IIC

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RE: LiFePO 4 batteries
« Reply #18 on: September 27, 2019, 05:22:20 AM »

Doubtful I'd be leaving it outdoors in the cold or in a cold vehicle.
Slight shortcoming that can be worked around...
Yes, specs for my 100ah are Charging Temp 32f to 114f.
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KD8SKM

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Re: LiFePO 4 batteries
« Reply #19 on: February 06, 2020, 01:39:15 PM »

Greetings:

I have been using LiFePO4 since 2012 when they were new on the market... can't say enough good things about them.

We use them at our off grid solar powered cabin and those 8 year old batteries are still performing like they did new!
in 2012 the longest I saw was 2000 cycles for 80% remaining capacity.... now I am seeing companies rate them as high as 7000 cycles at 80% depth of discharge with 80% capacity remaining!  Try to get that out of a lead acid battery and you will be disappointed.

Sure the initial cost is higher but given the cycle life and electrical performance they are far cheaper over their life than any deep cycle, AGM, marine ect.


In development of our charge controllers I tested several different deep cycle batteries and managed to kill one in 3 months!  Additionally they only return at most 70% of the energy used to charge them on discharge.... LiFePO4 returns a measured 99.8% of that charge energy.


I could go on and on but you can read about batteries on the solar components page of our website:
https://www.diysolarforu.com/solar-components.html

Cheers,

Rob
KD8SKM
DIY Solar for U
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AD0AR

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Re: LiFePO 4 batteries
« Reply #20 on: April 30, 2020, 06:19:29 AM »

I've been using a Bioenno 50AH LiPO battery for over 3 years now.  Not a ounce of lost capacity that I can measure. 
I use a coulomb counter meter that monitors battery capacity along with a relative running time left in the battery under the current load. 
On a full charge I can achieve about 55AH before the battery drops below 12v which exceeds the rated capacity of 50AH.
  Around 10.5vdc the BMS internally disconnects the battery from the load to prevent deep discharge that can damage the battery. 
  As I use this 50AH battery to power a portable 500W SGC SG-500 amplifier, I was able to get 100W+ more output using a battery boost regulator between the battery and the amp.  This boost regulator takes the 12-13vdc output from the battery and outputs 14.7vdc (it draws more current from the battery to make the conversion)
  The output from the amp is more linear, and on SSB I am able to achieve more than  100W more output than without and I am able to achieve around 575w PEP from the 500W amp while still maintaining linearity and still maintain a decent low IMD level.  (Using a Telepost LP-700 to monitor metrics)
Boost regulator-  https://www.hlabs.com/products/fluxpower/index_files/MobileApplicationofFluxCap.htm

To keep from deep discharging lead acid batteries, the boost regulator is bypassed when the battery voltage drops below 11vdc. 

Bioenno battery-
https://www.bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-50ah-lfp-battery-abs-sealed-ws

coulomb counter-
https://www.amazon.com/Huilier-Precision-Battery-Coulomb-Coulometer/dp/B07WHP174G/ref=sr_1_32?dchild=1&keywords=coulomb+counter&qid=1588252718&sr=8-32


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KD8SKM

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Re: LiFePO 4 batteries
« Reply #21 on: September 15, 2020, 12:45:30 PM »

To all fellow Ham's:

Another strong point of the Lithium Iron Phosphate battery is its low self discharge....

Manufacturers spec 2-3% per month in storage however my experience is far better than that.

On our 80 amp hour pack that we use at shows including Hamvention has been sitting over a year so I decided to top it off on a charger... This back has been in room temp cool storage about 65-70 degrees F the entire time and not on any sort of float charger.

To my amazement it only took 0.42 amp hours to top it off !
So it lost 0.52% of charge in just over a year.... far less than the 2-3% specified.
Try that with a deep cycle lead acid battery and it will damage it.

Another thing I want to comment on is charging below 32F - no manufacturer specifies it can be done however I also have experience with this.  They can be charged slower at less than 0.5 C rate because when cold the ESR climbs a lot.  Our cabin batteries have been charged in temps well below freezing many times and in fact the lowest was -21 degrees F after being without sunlight and heat for a week straight when the sun came out on a cold February morning and the solar power system awoke.

I would not try and charge above 0.5C in cold temps but it can be done - that pack is about 8 years old now and still delivering slightly above rated capacity.  Maximum possible charge rate is about 0.25C on that Solar System... so a 4 hour charge time from 0% state of charge in full sun.

Cheers,

Rob
KD8SKM
DIY Solar for U
https://www.diysolaforu.com
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AK5B

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Re: LiFePO 4 batteries
« Reply #22 on: September 15, 2020, 01:57:39 PM »

I have two Bioennos, one for my homebrewed bicycle lighting (3ah) and the other for 50-100 watt portable ops (30ah). Bought both Bioenno 2 and 6 amp chargers that they recommend as well as a Genasun  MPPT solar charge controller for use with my 83-watt solar panel.  If you ever need a solar charge controller that is completely RF quiet I recommend the Genasun---the company is run by hams, too!

I like my LiFePo batteries so much I may get another 30ah model (weighs only 9 pounds) for backup---not that I really need backup with one of these dependable and long-lasting little powerhouses!

73,

Jeff, AJ5J
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N4SRN

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Re: LiFePO 4 batteries
« Reply #23 on: September 21, 2020, 05:46:18 AM »

The instructions for my Bioenno 12V/30Ahr battery indicate to use a 6A charger designed for LFP batteries. I have one of the Bioenno 6A chargers, so not an issue.

It there much utility in storing that LFP with a Battery Maintainer? I have a 3A Battery Charger/Maintainer rated for lead acid and LFP batteries that I keep on my 35Ahr AGM VHF/UHF Go Box battery.

My HF Go Box holds that 12V/30AHr Bioenno battery and I have leads attached to allow me to plug in the 6A charger to a port on the Pelican case box.

Bret/N4SRN
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Bret/N4SRN
Bedford, NH  USA

W9IQ

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Re: LiFePO 4 batteries
« Reply #24 on: September 21, 2020, 06:08:25 AM »

The LiFePO4 battery has such a low self-discharge rate that I would question the need to keep in on charge and risk damage from lightning hits, etc. If you plug it once a month for an hour, it would be fully recharged.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

G4AON

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Re: LiFePO 4 batteries
« Reply #25 on: September 22, 2020, 12:18:05 AM »

The LiFePO4 battery has such a low self-discharge rate that I would question the need to keep in on charge and risk damage from lightning hits, etc. If you plug it once a month for an hour, it would be fully recharged.

- Glenn W9IQ
I have read elsewhere that lithium (including lithium iron phosphate) should not be fully charged for storage. This post from Power Sonic suggests a 50% state of charge:
https://www.power-sonic.com/blog/batteries/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/

My LiFePO4 battery charges relatively quickly, so unless you require “instant” power, it appears that trying to keep one fully charged may reduce the battery life.

73 Dave
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W9IQ

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Re: LiFePO 4 batteries
« Reply #26 on: September 22, 2020, 03:48:40 AM »

That is an interesting article, Dave but I would not rate a go-kit battery as one "in storage". By its nature it needs to be ready to go without warning or preparation unlike a simple portable kit, for example. Earlier in that same article they talk about using a lithium battery in a float charge application. I would judge the go-kit battery requirement as somewhere between these two scenarios.

Perhaps periodically pulling out the go-kit and operating off of the battery would satisfy the charge balance issue while ensuring that the kit is still in a ready status.

- Glenn W9IQ
« Last Edit: September 22, 2020, 04:06:32 AM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

G4AON

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Re: LiFePO 4 batteries
« Reply #27 on: September 22, 2020, 04:23:12 AM »

Glenn, as this forum is "Emergency Communications", I have to admit that keeping a battery near full charge is appropriate for near instant deployment. Mine is mainly used for hill top "semi QRO" contest operating, which is a bit different. I have several weeks notice, or at least a few days depending on the weather forecast.

Incidentally, the built-in charge control/protection circuit in my LiFePO4 battery auto disconnects it from charge when near 100%, making "float charging" a bit pointless. From memory, it won't take a charge when the SOC is near 100%, ie you probably cannot top it up from 95% SOC. BTW, the state of charge and Voltage, current, temperature, etc. is shown via a Bluetooth connection to a mobile phone app.

Having spent a considerable sum on a 68Ah LiFePO4 battery, I am keen to keep it in the best possible condition, for as long as possible. It is currently sitting at 64% SOC and is not likely to be needed until the weekend of 3rd/4th October for a UHF contest. It is typically used around once a month for hill top contest operating, sometimes more often for casual operating, depending on the weather and propagation.

Other than the weight, a high quality AGM at 1/3rd the cost of a LiFePO4, works fine for my /P purposes. My old AGM was working well at 6 years old.

73 Dave
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W9IQ

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Re: LiFePO 4 batteries
« Reply #28 on: September 22, 2020, 05:52:30 AM »

It sounds like you have your situation well thought out, Dave. Given the expense of these batteries, it sure makes sense to do your homework in order to maximize their life.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KF5LJW

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Re: LiFePO 4 batteries
« Reply #29 on: September 22, 2020, 01:09:18 PM »

Dave last thing you want to do is charge any Lithium battery to 100% SOC. If you do that you cut cycle life some 50 to 75%. You can most certainly FLOAT LiFeP04 batteries. Nearly every off Grid Solar and Telecom site using LFP all Float Charge the batteries at 95% SOC (13.6 volts). Requires no BMS, in fact even if you have a BMS will never be used if you float charge because it will never turn on.

All consumer grade BMS are Vampire Bleeders. One is installed across each cell. They turn on when the cell voltage reached 3.7 volts. When turned on is just a simple FET switch the places a Power Resistor across the cell to bypass some of the charge current usually 100 to 300 milli-amps. leaving the remaining current to over charge the cell. Once all cell Vampires turn on, charge is terminates and the Bleeders are turned off. This causes a lot of unnecessary stress on the cells.

No Lithium battery requires to go to 100%, doing so just stresses them. They work best in a Partial State of Charge less than 100%. No EV manufactured would allow owners to ever fully charge the traction battery. If they did would go bankrupt with warranty claims and lawsuits from vehicle fires. An EV battery would only have 300 to 500 cycles if they allowed users to fuly charge them. They run their batteries, depending on manufacture 90/10 or 20/80 SOC.

Once lithium cells are balanced do not need balanced again for quite some time. They do not suffer the parasitic losses other battery chemistries have. If you use a BMS, then you have a parasitic load drawing power from the cells unevenly causing them to become unbalanced.

I have another interesting hobby of building racing golf carts, and help others build DIY EV's. Most use no BMS at all, and Bottom Balance our LiFeP04 cells. That greatly extends the life and makes it impossible to ever over discharge any cell into reverse polarity. My current golf cart uses a 96-volt 132 AH LiFeP04. I charge @ 25 amps to 3.45 vpc (110.4 volts) until charge current tapers to 4 amps.

Try charging to 13.6, and then hold on Float.
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