View Full Version : Article: Portable Power - An Operator's Options

22nd May 2015, 17:26
You can view the page at http://www.arpoc.org/content/142-portable-power-operators-options.html

23rd May 2015, 09:09
I'm building a LiPo Automatic battery reducer for the 4s series which can also support a charger.

23rd May 2015, 09:35
I ditched the 4s LiPo (3s voltage is to low for the FT-857) and now only use LiFePo4. Stable 13.2v output without the need for a voltage dropper (inefficient), a shallower discharge curve so you get more usage out of the battery and less likely to blow up when being charged!

23rd May 2015, 23:12
Yep, I'll be replacing my LiPo with LiFe batteries too, the price is pretty much like for like now on Hobbyking!

26th May 2015, 11:51
Thanks for the information. I use a Werker WKA12-7.5F2 12V 7.5Ah AGM Sealed Non-Spillable battery. Saturday my KX3 arrived which is replacing the HB1A. I use end-fed or mobile whips for antennas.
Will send some photos of my portable operations if you want them.

72's Dan, Ni9Y
ARRL Technical Specialist since 2009
KN9EUV 1955
K9EUV 1956
USN Radioman 1958
First Class Radio Telephone 1961
Ni9Y 1986

26th May 2015, 14:55
Hi Dan,

Thanks for the comment. With KX3, you should be able to have a look at LiFePO battery packs as well for lower weight.

Why not post a thread in the "Show off your station" forum with some pics of your setup?

Stefan 2I0SEH

7th Jun 2015, 15:26
Thanks for the article Stephan!
I'm mainly QRO when I go /P since my QTHs are not usually too far away so I can carry the 35Ah slab. However, I would prefer something much lighter like a LiFePo.

I live 1/2 the year off grid so batteries are important to me and I wanted to point out that when looking at battery capacities, not all batteries are the same.

A typical leisure slab has a useful capacity of about 1/2 of its rating. That's when the voltage starts to fall, either too low to be useful or so low that the life of the battery would be affected.

When looking at LiFePo batteries, the story is different. A LiFePo maintains its voltage far better than lead acid batteries. They are, however, sensitive to being over-discharged and the voltage must be monitored to ensure that you do not go below the voltage for your particular cells. Another advantage is that they will give out almost all of their rated capacity before reaching that voltage. So when calculating what size LiFePo you need, it could be a much smaller capacity than your slab was. Alternatively, you could operate for longer, or at higher power from the LiFePo.

As you rightly say, LiFePo batteries should have the right kind of charger. This is not only for safety but also because they have a far higher charge acceptance rate and purchasing a correctly sized charger would allow you to recharge the battery very quickly indeed.

17th Jul 2015, 10:15
Ive yet to finish project,but at the last Ham rally i went to, i picked up a 12 watt solar panel for £2. This has a nice deep frame to mount some batteries. A quick look on aliexpress and i found some 2900ma AA cells for just over 40p each so i ordered 50 of them.

The plan is to mount the cells inside the panel frame, add a leg and handle and this should make me a self contained, self charging power source.

11th Aug 2015, 05:57
Sorry if I seem dense but could some kind soul please explain to me why extreme care should be taken soldering the leads on a LiPo battery? I am waiting for delivery of a ZIPPY Flightmax 8400mAh 4S2P 30C LiFePo4 Pack which has 5.5mm bullet connectors. I was planning to install Powerpoles by crimping and soldering!

Thanks, David

11th Aug 2015, 16:05
If you short out the battery it is capable of delivering 30C x 8.4A = 252A !!! Thats enough to arc weld the wires together !! And shortly after that the whole thing will probably go critical ! Thats why :-)

12th Aug 2015, 20:01
Like Peter said. You can solder them fine but take extra precautions to ensure that you don's short out the battery otherwise things will go very bad, very fast.

You will also find it difficult to get the solder to take well on the Zippy wires and they are far too big for a 15/30A PowerPole terminal so make sure you have the 45A versions. I just made a 5.5mm bullet to PowerPole adaptor for my packs. Much easier and less chance of a KABOOM!

13th Aug 2015, 19:40
Thanks for your responses. I'm making a short bullet to powerpole lead and I will shrink wrap the bullets and do everything with powerpole!

73 de David

14th Aug 2015, 07:46
Sorry ... another question ... should I solder, crimp or solder and crimp the powerpoles? I am using 30A ones for everything (and nothing runs more that 10W so I should be fine).


8th Sep 2015, 15:37
Sorry it's taken me a while to get back here, but I tend to crimp and solder, nothing beats a belt and braces approach.

9th Sep 2015, 12:17
Thanks ... I will do that on the higher power connectors but probably not bother now that they're all assembled on the low amperage ones!