LiFePo4 Battery Use

KJ6YVT

Member #292
New member
Because Icom radios are rated at 13.8 V DC ±15% input (11.73 V DC to 15.87 V DC), I'm a bit concerned about the nominal 13.2 V four-cell LiFePo4 battery's terminal voltage being a bit low. That only provides a 1.47 volt reduction in battery output voltage before reaching the lower limit of Icom's specification. I'm wondering of a five-cell LiFePo4 battery with a terminal voltage of 16.5 volts would be high enough to cause damage to, say, and Icom IC-718? That's only 0.63 volts too high.

I'm thinking:

A 60Ah five-cell (3.2V Cells) LiFePO4 battery made of cells similar to these: <http://www.ebay.com/itm/171782395812> or these: <http://www.ebay.com/itm/171748308512>

A 100 Watt Renogy 12V Solar Panel Monocrystalline Foldable Charging Kit with 10A built in charge controller: <http://www.ebay.com/itm/281556876312>
Open-Circuit Voltage (Voc): 21.6V
Maximum Operating Voltage (Vmp): 18.0V
Maximum Operating Current (Imp): 2 X 2.78A
Short-Circuit Current (Isc): 6.17A

Either an IC-718 (3.8 Kg), IC-7100, or a Kenwood TS-480HX with 200 watts out, perhaps a solid-state amplifier

A suitably sized antenna tuner

Perhaps a 6-80 Meter Alpha EzMilitary antenna rated 500W in a 16" bag: <https://amateurradiostore.com/all-alpha-antennas-c-2/680-meter-alpha-ezmilitary-rated-500w-in-a-16-bag-p-286> Weight: 3 pounds

Or a Screwdriver

So, I'd end up with a moderately sized Pelican case, a 33.1 Lbs 19.9 X 27.2 X 2.8 In folding solar panel, a 3 lb 16" antenna bag, and perhaps a computer tablet. Such a station should be robust enough to provide reliable 24 hour communications despite occasional overcast and ~1.5 hours talk time through the night, and with bright sun, fully recharged in ~6 hours the next day.

What am I missing?
 

M0LMK

Member #2
Full Member
Staff member
I use a 13.2V LiFePo4 battery with my FT-857 and have no issues. The voltage drop curve is much shallower than other battery types so it works very well. Check the specs for the input voltage of the radio and check what the minimum is. Most are 13.8V +/-15% (so 11.7V to 15.9V) so will be happy with a 13.2V LiFePo4.

You should also note that you can not charge a LiFePo4 battery properly with the PV panel and charging kit that you linked to. You need a proper LiFePo4 charger with balancing inputs if you want to make sure you don't damage the battery so a simple 10A charge controller is bad news. You could use it with a big SLA battery like a 110AH marine battery but not with a LiFePo4 or LiPo battery.
 

G0DZB

Member #84
Award Moderator
What am I missing?

The kitchen sink ? :) You don't quite seem to understand the "portable operation" state of mind ! KISS is the way to start, not building a replica of your home station to put in a large vehicle.

"The inherent stability of this wide-band antenna makes constant retuning unnecessary" And use an antenna that isn't going to turn a large proprotion of your battery power in to heat !
 
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M0LMK

Member #2
Full Member
Staff member
Yes, that does look like a poor antenna choice for efficient operation. Get some real wire in the air... ;)
 

KJ6YVT

Member #292
New member
I use a 13.2V LiFePo4 battery with my FT-857 and have no issues. The voltage drop curve is much shallower than other battery types so it works very well. Check the specs for the input voltage of the radio and check what the minimum is. Most are 13.8V +/-15% (so 11.7V to 15.9V) so will be happy with a 13.2V LiFePo4.
Thank you for sharing your personal experience with LiFePo4 batteries powering your station. I'm still in the initial planning stage, and appreciate any data points offered.

I recall reading somewhere that LiFePo4 cells should not be discharged below 2.7 volts, or a battery terminal voltage of 11 volts. So, if the LiFePo4 battery is nearly exhausted at 11.7 volts due to its flat discharge profile, I can see that my fears are unfounded. Do you in fact find that the battery is nearly fully discharged when the voltage drops to 11.7 volts?

What sort of voltage drop/performance do you find when attempting to transmit at near that voltage?
Does the added (~22 amp) load drop the voltage well below the 11.7 volt minimum.
Does the PA continue to output rated power?

You should also note that you can not charge a LiFePo4 battery properly with the PV panel and charging kit that you linked to. You need a proper LiFePo4 charger with balancing inputs if you want to make sure you don't damage the battery so a simple 10A charge controller is bad news.

I presume you are referring to the charge controller included in the Renogy 12V Solar Panel Monocrystalline Foldable Charging Kit. Are you able to recommend a suitable solar charge controller replacement that is compatible with 4-cell LiFePo4 batteries? Can the output of the included Renogy charge controller be fed into a charger that is compatible with LiFePo4 technology?

From what I've read of LiFePo4 technology, it seems to be superior to all others for this application in the current marketplace. Do you agree? Is there something better on the horizon?

Thank you again for sharing your knowledge


Best regards,
Larry
 

G4CFS

Member #306
New member
What am I missing?[/QUOTE]

A reality check.

If it doesn't fit into a rucksack and can be carried on your back whilst walking to you operating location it should be left at home.

I use a FT-817 5 watts powered by a LiFePO4 4.2Ah battery into a 60/40/20M linked dipole on a 7 metre roach pole. Have worked all over the northern hemisphere in SSB and CW. I may stretch to a 35 watt linear if desperate. All this fits into a 35 litre rucksack with room for my flask of coffee and sandwiches plus water proofs and bothy bag.

73 Glyn
 

G4YVM

Member #58
Article Contributor
Ha ha. Good advice. Personally I can't fathom why anyone uses more than a few watts when portable either. Maybe 25 tops.

I use my self contained kx1 with just a few watts of cw and simple aerials. It just never fails. Why use more?

D
 

KJ6YVT

Member #292
New member
The kitchen sink ? :) You don't quite seem to understand the "portable operation" state of mind ! KISS is the way to start, not building a replica of your home station to put in a large vehicle.
Thank you for taking the time to enlighten me about the group's apparent philosophy. :) While the station I proposed may not be "man portable" due to the size/weight of the photovoltaic panels, it is reasonably compact and light enough to be carried some distance to a favorable operating location (under a tree?). I don't see how eliminating any of the components (XCVR, battery, photovoltaic system, tuner, antenna) can be eliminated and still retain functionality. Do you know something about that that I don't? :)

"The inherent stability of this wide-band antenna makes constant retuning unnecessary" And use an antenna that isn't going to turn a large proportion of your battery power in to heat !

I became aware of that particular antenna in this YouTube video: My New Solar Powered HF Ham Radio Portable System 3-5-2015. It would seem that the anonymous OM (Mike?) who recorded that video had some years of portable experience, and had done a commendable job of constructing a functional station. I found his choice of antennas to be reasonably light weight (~10 lbs), broad banded, and able to handle enough power to be reliably heard around the world in SSB mode during favorable propagation. Of course, the gain provided by a directional antenna would increase station functionality considerably. How do you feel about BuddiePoles? Another antenna contender is the 5-bandfolding hex-beam. Photographs

From your photographs on QRZ.com, I can see that you have a very portable station indeed. However, it was unclear what means you use to recharge your batteries. I'm contemplating my proposed portable station for emergency use, when mains power may be unavailable, and petrol conservation may be desirable, thus the photovoltaic system. That should be capable of powering the station indefinitely without necessity of any ancillary hardware, connections or consumables other than sunlight. :cool:

As you apparently find the suggested '6-80 Meter Alpha EzMilitary antenna' inappropriate, I would be interested in your recommendations for suitable antennas. And any other suggestions you may be able to offer.

The second contact I made after receiving my FCC license, while operating on a dipole strung on the carpet on the second floor, was with John Maguire, W1CDO. At the time, John was sitting in a tavern in Klamath Falls, Oregon, sipping a glass of Merlot while operating his radio station located in Roswell, New Mexico, via his iPhone. Now, that is a real portable station! :)

Thank you for taking the time Peter, to share your knowledge with this rather recently licensed (2012) Amateur.

Best regards,
Larry
 

G4YVM

Member #58
Article Contributor
No, that's not portable at all. It's a very fixed station with a long but invisible connection wire.

I'm sorry we're popping our philosophy at you, each to his own I guess.


73

D
 

KJ6YVT

Member #292
New member
Yes, that does look like a poor antenna choice for efficient operation. Get some real wire in the air... ;)

Hello Matt,

Thank you for your comment.

Are you able to provide some suitable antenna recommendations? Something 6-80 meters, light weight, and suitable for 500 watts?

I welcome your experienced input.

Best regards,
Larry
 

M0TCF

Member #142
New member
Just completed 'Life's a Beach' with an 817 and a home brewed antenna run up a 10m long fishing pole! I ran the station on and off, over three days, and managed it all using one properly charged internal battery pack. My radio and antenna plus a few odds and ends like spare patch leads, adapters etc. all went into one old laptop case, the fish pole doubled duty as a walking stick and my butties went in a should bag my son gave me as a gift on return from China (compete with a picture of Chairman Mao!!).

The best bit of advice I was given about going portable was to take into consideration how long you intend to transmit for - if it takes 3 hours to climb a mountain, how long are you actually going to hang around on the top? 30 mins is probably the max, esp taking weather into consideration so a battery that last no more than an hour will be quite satisfactory (an 1800milli amp usb charged item perhaps?). On the other hand a 24 hour stint on a field day weekend might in real terms require a 15 amp hour gel battery (I never use lead/acid, not suitable for safe portable work). Having said that the old PRC320 I was issued with in the Army only had 4 amp hr batteries, each of which lasted pretty well, however mil coms are all about speed and accuracy not about having a chin wag lol.

There comes a point, hopefully after only a few portable expeditions, that you realise just what and what isn't needed for success, and to be totally honest if you check the gear before you leave, its relatively a small amount - even running data modes these days can be done on a fairly reasonable mobile phone or a cheap tablet both of which weigh very little.
 

M0LMK

Member #2
Full Member
Staff member
Ok. Enough of the comments please chaps.

Everyone has their own view on what a /P station should consist of. Some of us like small, compact and low power whist others like large, extensive and QRO. We all use our /P equipment in different ways and one of the great things about the hobby is that we are able to.

For example, I have a homebrew man pack made from an FT-857 which contains everything I need for 6 hours operation in a back pack. Full HF/2M and 70cm with batteries, digital modes and several different antenna options.

20150501_194744.jpg

I also have a large "go box" style station that is far to big for back pack type operation but gets used for portable Special Event Stations, demonstration days and training activities. It's designed to be a full field station in a easy to use package. Just lift it out of the car, plug in power and antenna then away you go. Here is a picture of the beast...

20130328_095804.jpg

Both are portable stations built for very different jobs. Please bear that in mind when replying to posts.

Larry, here is a typical discharge curve graph from a LiFePo4 battery. This one is rated at 1200mAh.

2007101113592887292.jpg

You can see that in this case, the voltage tails off rapidly when there is only a small portion of the capacity left. I always shut my kit of at around 11.5V and have had no problems. I also have a battery monitor that beeps at me to let me know when it's time to swap batteries!

You need a proper LiFePo4 charge controller if you plan on using PV to top up depleted batteries. The Genasun range is well regarded so maybe something like this... https://genasun.com/all-products/so...ium/gvb-8a-li-lithium-solar-boost-controller/

It's important to remember that almost all PV charge controllers do not have a balance input so you will still need to use a proper LiFePo4 mains/12v charger to balanced the cells every few weeks. I have a 120W PV panel on the roof at home that charges a 200Ah SLA marine battery via a normal charge controller then I use the 12v output of that battery to power a LiFePo4 charger for charging my man pack batteries. Not the most efficient method and the 200Ah SLA is never going to go anywhere in a hurry but it does let me give the LiFePo4 a proper charge from a renewable source.

The Alpha antenna will work but please ignore all the "I worked 5000 miles using a wet piece of string" comments that you will hear. When the bands are open and good it is perfectly possible to work the world on 100mW using a wet branch for an antenna. Remember that the antenna is one of the most important parts of your station and if your going to the trouble of going /P then make the antenna as efficient as it can possibly be. A good starter choice would be to take a look at our very own Davids multiband antenna - http://www.arpoc.org/content/135-multiband-hf-antenna-easy.html. That will get you off to a good start. I personally use a linked dipole that is resonant on 80M, 60M, 40M, 30M, 20M and 10M. I can then also run this through the ATU to get onto other bands at the expense of efficiency.

Maybe you could give some content around how you intend to use the station, what bands and the locations types available to you (if you have lots of forest then you may not need a mast to get an antenna in the air!).
 

G0DZB

Member #84
Award Moderator
"'m contemplating my proposed portable station for emergency use, when mains power may be unavailable, and petrol conservation may be desirable, thus the photovoltaic system. That should be capable of powering the station indefinitely without necessity of any ancillary hardware, connections or consumables other than sunlight. "

I'm sorry but you are in the wrong place for advice on your proposed use. Here we are interested in operating from often remote places, where vehicular access may not be possible, (and here's the key part) for FUN. Battery charging is not an issue as after a few hours of fun we pack up our gear, and head back home for our dinner :)

You might me more "on topic" with the Rapid Deployment Amateur Radio (RaDAR) guys over at https://plus.google.com/communities/109283065808971118728

This might be of some help as well : https://en.wikipedia.org/wiki/Amateur_radio_emergency_communications#United_States_of_America
 
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KJ6YVT

Member #292
New member
Ha ha. Good advice. Personally I can't fathom why anyone uses more than a few watts when portable either. Maybe 25 tops.

I use my self contained kx1 with just a few watts of cw and simple aerials. It just never fails. Why use more?

D
Unfortunately I've never found the time to devote to learning Morse Code operation. I sincerely appreciate the functionality of CW mode, and I'm sure it's a fun mode, but probably not for me. I'm always surprised at how good a signal a few watts can provide during favorable propagation conditions, and have worked several continents with ~35 watts (exciter power), so I'm aware that power isn't always necessary for good communications. However, for reliable emergency SSB communications, I believe higher power may prove advantageous.

I've reached seniorhood, and probably not too keen in lugging a station too far off road. So why not contemplate adding a small, solid-state amplifier for SSB use, and enjoy the benefits in signal strength it provides?

W1CDO also constructed a KX1-based station albeit on an e-bike:.

W1CDO.JPG Now, that is interesting, and added power is considerably less of an issue. Range, on the other hand....

Being a new member of this group, I'm beginning to think I've tread on a "low power" ethos extant among members. No offense intended.

Thank you for sharing your knowledge with me, David.
 

G4YVM

Member #58
Article Contributor
I love the ebike mobile!!!

I keep meaning to fit a whip to my push bike but time..., ah time.

Anyway, I think you will find quite a QRP stance here but please don't let us intimidate you. We really don't mean to.

Welcome to ARPOC!!!

D

G4YVM
 

M0LMK

Member #2
Full Member
Staff member
Good call on the RaDAR group Peter.

Not all of us are low power Larry. I'm not usually less that 50W when I'm out portable and most of the time I'm up at 100W. ARPOC is not a specialty QRP group, just a group dedicated to all kinds of portable operation. Each to their own. As long as you enjoy doing it your way then that is all that counts.
 

G1YBB

Member #381
New member
Sounds like two types of portable operation being discussed here, backpacking where weight is a major consideration and essentially moving and base station by car, not too far from car.
Been on both sides of the coin, portable 60 foot masts, dual long yagis, generators and valve amps, but also full backpack portable, suitable for SOTA activations.

I use for that 4 cell LiFePo4 batteries to run my FT-857D. Voltage wise works great. I use an inline Ah meter so I can keep an eye on discharge usage.
I tend to use >50W,mostly because I choose to but also to make a bit more noise. I have worked a few stations giving me an S1 or S2 report so they wouldn't hear me on 5w most likely.
Antenna wise I prefer resonant antennas to save taking, connecting up and tuning a tuner. Multiband link dipoles are very light. Mine probably weighs a couple of pounds tops, and most of that is the RG58 feeder (which I prefer over lighter but lossier thinner coax).
Car supported portable we have taken everything bar the kitchen sink pretty much. And we never had the resources of the multi trailer tower gangs!
 
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