Our French colleagues are now gearing up to “hit the hills”. Having created SOTA-France, they are now looking at the practicalities of light-weight operation from a summit. I have been asked about the types of power supply in use by experienced activators. Aha, I thought, there’s lots of useful information in the Reflector archives. However, due to the on-going transfer of functionality to SOTAwatch2 (or, perhaps, due to my incompetence?), I can’t seem to access the old stuff.
Can anybody help me with some websites to point the French guys towards? My own rechargeable pack, whilst excellent, is no longer available, having been purchased from the now-defunct source in Wales (817 shop, or some such name).
For higher power a lot of people use sealed lead acid batteries. I know that INKy and YSS do so and so do I. These are heavy but cheap. For short activations the FT817’s standard internal battery pack is fine unless you use power-inefficient modes such as FM. The battery pack that Roger referred to uses (I think) a LiPO battery. These have a very high energy density but the variable voltage packs have an internal voltage regulation system which reduces the overall capacity of the LiPO cell somewhat and limits the maximum current that can be drawn.
Incidentally the FT817 does not need a 13.5 Volt supply and thus the bare 11.1V LiPO packs are fine. LiPO cells are 3.7V so it is not possible to do packs with a voltage in the range 12-14V without a regulator.
I’m using a 12v 2.8Ah SLA cell which weighs about 1.2kgs. Certainly a Li-Ion/LiPoly cell would give me the same capacity for about a quarter of the weight. However, I already had the SLA in the shack and it was new. It has more than enough capacity for the activations I’ve been doing when used with my FT-817.
I’ve looked at using some Lithium packs from the RC model world but the best prices come from stores in the US and buy the time you’ve added on shipping they’re not so cheap. They do come with inbuilt overcharge, overdischarge circuits which are definitely a must with Lithium technology.
I’ve not long purchased a set of four Ultra Max 12V 3.3AH SLA batteries from Battery Masters - website:
I purchased four because I often do four summits in a day, Hi! The postage was the same for four as for one - min charge? They worked out at £8 apiece which makes the other fancy types expensive. Weight of each 1.3kg, about twice the weight of NiMH batteries.
I used to use a 12V 12AH SLA battery (Maplin), but at 4.2kg in a concentrated lump, the backpack was taking a bit of a pounding, so I have it in a bubble wrap cover. I’ve noticed the difference carrying 3kg less. Memories of that 29kg backpack day up Great Rhos in early December are in the distant past, thank goodness.
Last Saturday one of 3.3AH batteries ran my 817 + 25 watt output linear for 1 hour on SSB followed by another 30 mins on FM before the 817 switched off. I’ll still be taking the 12AH lump for those hidden West Wales summits… plus of course the 150 watt output linear!
In reply to G3VQO:
I use the battery packs that are used in Radio Control model aircraft and are available from model shops. They come in many voltages and capacities and are capable of high current flow and quick charging and are not too heavy. You can obtain nicads, nickel metal hydride or lithium packs. They come made up with plug. Just buy the correct plug and connect to your 817 etc.
Thanks for all of the useful comments. I have translated as best I can, and pointed the French guys in the general direction. Hopefully we’ll hear the results from 1st April…
This is a really interesting thread. On Sunday, my 2.3Ah OPP battery pack (fits inside the FT-817) last barely 10 minutes, running on 2.5 watts. I had been noticing that its lifespan seemed to be reducing sharply in the later 2006 activations. I think, therefore, it has probably had it.
All the options above seem like rather good ideas with their own merits. I just can’t quite decide at present.
Our French colleagues are now gearing up to “hit the hills”. Having
created SOTA-France, they are now looking at the practicalities of
light-weight operation from a summit. I have been asked about the
types of power supply in use by experienced activators. Aha, I
I use the standard pack that came with FT817ND and I carry also pack of alcaline cells for backup, but have never used them. There are many reasons why one hour on the summit is more than enough and the activation success depends more on antenna and mode used than the power. Of course the propagation conditions, availability of the chasers and other traffic on bands have some influence too. However the weather is probably the most tight constrain to the activation. So my view is that the battery pack is only a minor detail in the expedition, unless you plan a trip for several days.
That may be true, Jaakko, for the biggest mountains, and in the winter months, but please don’t forget that there are many smaller hills which are extremely inviting on a summer’s day. I have been known to spend several hours on some of the UK summits when the weather is kind. That is when you need a better power source than the internal FT-817 battery.
Thanks for that info Jaakko. As you say, a little expensive, but extremely useful in the right circumstances. Now, if only the sun shone everyday in England …