Activations at sub zero C

Hi all,
Yesterday I activated G/SB-006 Shillhope Law. Nothing particularly exciting about that, the hill is easily accessed via a quad bike trail, but being a 2 pointer it attracts the 3 winter bonus points. Nice.

So off I went, driving to the access point just as dawn broke on an icy landscape. Because of the forecast low temperature I had taken the precaution of carrying 2 10Ah Lipo packs. The air temperature as I left the car was -9C, I guess it did not warm up as I ascended to 500m asl at the summit.

As is my norm I first tried to activate on 7MHz but was beaten back by the wall of “contesters”, apologies to those who listened for me before I QSY’d to 60m cw.

Yes I remember: Weekends = Warc and 60m bands.

So back to the batteries:

Using the first pack I made about 40 QSO’s at which time the battery voltage had fallen to 10V, perhaps only 60% usable capacity had been available. During this time I kept the second battery pack warm by keeping it in my clothing. When I started using it it’s temperature would have been about 20C. It maintained the voltage better, but soon cooled and the terminal voltage declined. Moral of the story, I am going to make a 1.5m extension power lead so I can snuggle the battery during use and preserve the terminal voltage and capacity (or stay in doors).
Another lesson learnt.

David (Nanook from the North)


I’ve activated many times in sub-zero temperatures but I guess I never hung around long enough to notice any LiPO battery degradation :grin:

73, Barry N1EU

An advantage of external battery packs is that you can keep them warm in your clothing.

How about putting them in a Tupperware box with a handwarmer?

The obvious place is in your underpants. Why? Well you can unzip your flies, extract the cable from the pack that you coiled up when dressing then rezip to keep the cold out. Reverse the process when you have finished. I suggest this action is best performed when other people are on the hill as the look on their face (before they inform the police) will be priceless.



Fortunately my coffee was too hot so remained unsipped at the time of reading your post.

Sticking a LiPO in your underpants is an act worthy of Darwin Award consideration IMHO. :scream:


Only if you are wearing some shiny metallic finish underwear Barry like these.

Stick to cotton or Merino Wool and you’ll be as safe as houses.

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Yes, and to be serious, I have noticed my 4Ah LiPOs “go off” when cold. But it does have to be quite cold. So around 0C, a few degrees either way doesn’t make a significant difference. But certainly when it’s -5C and below, they do have obviously less capacity. My 2 packs are 7.5 years old now and seem to take longer to charge than I remember when they are well discharged. If they are showing reduced capacity at typical GM hill temperatures, I’ve not really noticed it.

Rescue teams carry(*) thermal pads to keep Nitrous Oxide warm as apparently below about 10C it separates into Nitrogen and Oxygen, and breathing the nitrogen bit on its own could be a problem… The Medics also used to have a sterile saline bag - which in winter conditions was kept under a shirt near an armpit! ( This is if you are ever unfortunate enough to get severe hypohermia one of the issues is shock and fluid loss, so slow rewarming and a warm saline drip i/v improves your chances…). … so although the prospect of slipping a battery into your pants may seem extreme ( I presume in a fireproof bag, possibly wired to a solar panel in your headgear? ) it turns out that slipping i/v fluid up your armpit is not that unususal.
(") There were UK protocols approx 15 years ago and may now be well out of date.


I never thought I would see the day when you would appear on Sotawatch wearing nothing but your underwear, Andy!

A sight for sore eyes indeed …


Goodness gracious great balls of fire

Some balls are held for charity
And some in fancy dress
But the balls that are held for pleasure
Are the balls that I like best

Courtesy of AC/DC

It seemed appropriate to the direction this topic has gone :innocent: (whilst retaining clear links to power supplies)

As one of the qualifications for being a moderator is a dirty mind, I think we had better leave it at that!

One thing we used to do while climbing - in cold Wx - was to urinate on our hands. If you need to warm your lipo up you could give it a go… (Tongue in cheek comment - please don’t actually try this).

On a more serious note, there’s always insulation. A cool bag works both ways hint hint.

And on the guy lower down the rope then, presumably :smile:

Was that because you had been stung by crag jellyfish?

I never did that on rock or ice, it strikes me as a recipe for yellow icicles!

Just to close off this tread:

The author wearing his Erve Duvet plus 2 base layers, one intermediate layer, one Buffalo and neck gaiter.

And the view with the trig and Cheviot in the background



OK, this got the better of me. Just what is a:
Erve Duvet and one Buffalo? :wink:

73, Todd KH2TJ - who once operated an PRC-104 and PRC-77 up above the frozen tundra in Lapland near the Finnish border back in the early 80’s while on deployment in Norway…