I have read a lot about lithium batteries on this site and the general internet and I think I have come up with a solution that might work. I just would like your knowledgable inputs first.
Would this setup work and is it a good solution?
My ts480 uses around 1-1.2A on RX and around 6.5A on 20m SSB AT 10W.
Im thinking a 4S lipo 14.8v 5000mAh battery like http://www.hobbyking.co.uk/mobile/viewproduct.asp?idproduct=15521&type=&idparentcat=
And then a voltage reducer like this
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Will it work? I think it will from all the stuff I read and will be cheaper than buying a tracer pack.
Thanks
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Why not this? you need no reducer with this one I think.
I think the UK price was 30 or 32. (EDIT: might be 22, I don’t remember. I saved the image on my desktop last week I looked for the same thing as you)
Tasos
I’ve been trying one of the new small lightweight Lithiom Iron/ Polymer (LiPo) batteries. FLOUREON® 11.1V 5500mAh 3S 5C Lipo RC Battery. This 3 cell LiPo battery gives just over 12volts when fully charged dropping to 11.3V when discharged.
I’m trying it with a FT570 transceiver but I think the voltage may be too low and causing audio distortion.
I wonder if the 4 cell type would be better although this will give 16volts when charged . Would this voltage be too high a voltage for most radios any advice welcomed.
The problem with most of these batteries is that they state the float voltage in various states.
That battery you describe Tasos probably has a nominal voltage of 11.1V, but this is slightly confusing as the description states 4S - 4 cell. A 3 cell has lower discharge rating of around 9V - which is often too low for most radio sets to operate correctly.
You have two options go with a 4 cell Lipo OR a 3 cell. One will give you 16.8V fully charged the other 13.2V.
16.8V is too high for most sets, Some people will claim it works - but I bet they have not checked the bias current on their final transistors … You may not want to carry on.
The compromise solution is to purchase a 4 cell and put two diodes in the positive supply line in FWD bias (0.7*2) = 1.4V. 16.8 - 1.4 = 15.4V. This is OK, but you are wasting power as heat, a 8000mAh battery suddenly becomes a 7200mAh battery hypothetically speaking.
Some others have found other cell technologies which give you the correct range.
IF you want a good project, you can always do it the proper way and design your own 95% eff Buck Boost regulator - Like I have done. I may publish this soon if people are interested.
Jonathan
Hi,
The best bang for buck is a 4s or even 6s LiPo and a switch mode regulator. A good 10A + unit costs about 10 USD. Combo is cheaper than a LiFePo for the same operating time. Of course you are limited by the regulator current whereas the LiFePo requires no regulator in the 4s format and provides all the current you need. Heavier and more expensive than the LiPo but a nice constant voltage well within 12 V rig ratings.
73
Ron
VK3AFW
Hi, running here a Zippy 8400 mAh 4S2P LiFePo Pack with the FT 857. Pack gives you fully charged 14,4V…so no reducing necessary. Works fine! Charger with balancing advisable.
Didn’t have any problems with security checks at airports up to now.
73 Franz ON9CBQ
Hi Anthony,
I’m like Tasos M6VAR you’ll not go wrong with the ZIPPY LiFePo4 4200 13.2v I have used then for the past tow years and they have never let me down.
Terry
G0VWP
Nearer 0.9 for power diodes.
Whilst 3S LiPo works fine for an 817, the fact the voltage starts low and drops down a lot makes the choice limiting if you ever want to tag on an additional PA. If you can guarantee you will only ever use an 817 or some trail radio (MTR etc.) that is happy to give full power on quite a bit less than 13.2V then buy LiPo. 4S LiPO with a diode dropper and switch is viable. When the voltage drops you can switch the diodes out to use more of the available capacity. Just make sure you make the system user-proof when you’re cold and tired and it’s wet and windy, you don’t want to apply 16.8V to the radio!
If you want to run anything which needs nearer 13.8V and are buying new then buy LiFEPo.
Yep !
No manual system would be in those conditions!
That’s why when I replace my LiPo cells it will be with LiFEPo 
Go with the LifePO4. No mucking around with a voltage reducer and when Mister Murphy is around the voltage reducer wont be in your back pack; then what?
Andrew VK1MBE
I go the other way. I use a 5000mAH 3S Lipo and then a battery booster ($3 on eBay). It’s rated up to 150w and I get no interference from its invertor that it uses to regulate the voltage to 13.8v output (it’s actually fully adjustable from 11-28v output if I remember correctly - input can go down to 9v and still get the set voltage out).
I haven’t tried a LifePO as they were somewaht more expensive however logically a 14v Lifepo should work fine without the need for any regulator other than the one that’s buit into the rig.
73 Ed.
The risk with introducing any kind of switching regulator is that it may generate local QRM. I once tried a commercial battery pack with built-in regulator that would have been perfect for SOTA were it not for the enormous racket it emitted at VHF. Ferrite helped but I never entirely eliminated the noise. I gave up and went back to “raw” batteries (not really a problem for the FT-817).
If you have a regulator design that is both efficient and “clean”, that would be very interesting.
OK i have found these two which will do without the regulator requirements etc. but can someone tell me if there is any difference or preference between the two? I know 4s1p and 4s2p means 4 in series and 1 parallel etc but they are both the same capacity(4200mah). Will choice merely depend on if I want twice the number of batteries and wiring in the battery or is there a technical reason to choose one of the other?
By my calculations I can get 5w or 10w for around an hours operating out of one of these batteries on my TS-480.
Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking this one is around 30p more expensive.
or
Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking
just to confuse matters
Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking also has 4s2p but has double the capacity.
Is it merely down to the size of cells the batteries are made of? Any advantage using more of lower capacity batteries?
Less is more! Fewer cells in the pack mean fewer connections between cells and fewer cells to fail. From my defence electronics days, connections were always the #1 failure issue (EMP excepted). The 4s1p is about 8% lighter.
I’d buy the 4s1p but YMMV.
I agree with Andy and I would like to say that personally I would get the 4Ah and not the 8 as you can later add a second one.
No extra weight is added if you get 2 x 4.3Ah VS the 8Ah and if you buy the second later it will have longer life (the pack of two I mean, as the second will have less cycles).
Its switching frequency is below 1 MHz, it features an elliptic low pass on the output with a -40 dB notch to eliminate the 2nd harmonic switching noise, which is the largest - its clean, simple and reliable.
Currently it develops 10A continuous load, it will boost from as low as 8V and buck from as high as 30V. Uses a H bridge configuration.
Its going to be a little contribution from me, its nearly finished but I will publish it on the reflector once I am happy with it. I am trying to solve a differential routing issue with the current sensing at the moment.
It would be the best solution by far. LiFePo4 is OK but it is larger and heavier then Lipo. With this converter you get the best of both. A stable efficient converter and low weight + reliability. Your radio stays happy with a constant voltage.
Jonathan
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I hadn’t really considered going for a better battery (lets face it when you go from a car battery to a 7AH SLAB thats already a big improvement) but as my interest in SOTA grows and the likelihood that I will be embarking on more serious SOTA walks increases I too am looking at ways of lightening my load.
I found this discussion interesting: KR7W's SOTA Adventure Blog: QRP Ops Battery Power... FYI
and this regulator which it promotes seems very economical: 3A Adjustable step down switching voltage regulator albeit not capable of the 10A of Jonathan’s.
Again not in the same league as Jonathan but for lower-current applications I’m using 18650 cells with a buck regulator to run my FT817. Switching ripple is 20mV p-p.