Cold nights & batteries - a way to extend session?

[NickK]

Just thinking about the impact of cold nights on the battery life; the shortening of session could be a pain in the bum.

So why not get an old coolbox, run a set of cables through a drilled hole in the top (seal with silicon sealant). Before you leave the house, fill a hot water bottle and put into cool box (make sure it's not going to leak).

A hotwater bottle with a cover to prevent burns and keep the heat for longer works better as you don't need a massive amount of heat.

Then when you finish the session and the car is freezing - grab the hotwater bottle for the last remaining heat left in it!

[pleiades]

This looks like a nice idea! I will adopt it.

I am only wonder if battery needs air when working and give us energy. Is there a special reason for this need?

[JamesF]

If you're not sure about using a hot water bottle, then you can get a sort of bag filled with "stuff" (we had one filled with cherry stones, afair) that can be heated up in the microwave.

Can't imagine why batteries would need air to work, but I'd not want to keep lead-acid batteries in a confined space, just in case. Might be worth checking that whatever batteries you plan to keep inside aren't likely to emit explosive gases or

anything like that.

James

[pleiades]

Very clever solution this, with cherry stones . Do we know who much is going the temperature about?

I think most are lead-acid batteries but I don't also know for explosive gases on this type.

[beamish]

It's a great idea without the Hot water bottle- just needs to insulated from the cold brrr brrrr brrrr !

[JamesF]

AFAIR, normal lead-acid batteries can give off hydrogen which could easily mess up your night vision if something went wrong. I'm sure the risk is very small, but it's preferable to know it exists. Not sure about sealed batteries or gel ones. I imagine they'd be ok, but checking with the manufacturer couldn't do any harm...

James

[Steep]

Moors Mud in packs about 9"x7" , keep an eye on Lidl for the next time they have them, I think they were £4-5 each. You stick them in the microwave for 3 minutes and they stay hot/warm for 90 minutes or so.

[BenM]

have you tried lithium batteries

Energizer for one makes lithium batteries in all the standard sizes

[pleiades]

I like the idea of an old coolbox, but why don't keep the battery inside the car with a longer wire from car to telescope?

[Carbon Brush]

Although your post did not specifically say which battery type you are using, lead acid seems to have been assumed.

Lead acid battery performance does not degrade that much at low temperature.

This does suggest that either your battery is marginal, or there are other problems in the quipment.

Raising the temperature to say 40/50C will actually shorten battery life expectancy.

Hope this is useful.

David.

[brianb]

Raising the temperature to say 40/50C will actually shorten battery life expectancy.

Yes, and shouldn't be necessary. Just store the battery at room temperature and stick it in an insulated box / bag for use outside in cold temps. The box / bag doesn't need to be airtight, just reasonably draughtproof. As others have said, a hermetically sealed bag might just possibly be a Bad Thing.

The "cool bags" sold by supermarkets so you can get your ice cream home in a still frozen state are probably just the job.

[pleiades]

Although your post did not specifically say which battery type you are using, lead acid seems to have been assumed.

Lead acid battery performance does not degrade that much at low temperature.

This does suggest that either your battery is marginal, or there are other problems in the quipment.

Raising the temperature to say 40/50C will actually shorten battery life expectancy.

Hope this is useful.

David.

Yes, was useful. I search in Internet and found Lead Acid Batteries that lead acid batteries can work down to -15 C. I thought it was -3 C.

Also you have right, high temperatures is the problem.

I also found that discharging completely those batteries, can cut the life in half and more. That's why I changed batteries sometimes every 6 months (i.e. in my UPS). Because I left them to discharge completely. As I read the best is to discharge down to 75% of the total. " Lead acid batteries should never be run flat. The maximum recommended discharge is 75% of the total. This means that the battery should have a minimum of 25% of charge remaining when it is put on charge. "Lead Acid Batteries

[Bizibilder]

I don't think that there is any need for "hot water bottles" for batteries. If you keep your battery indoors to charge between observing sessions then it should remain roughly at ambient for the few hours that you will be outside. I must admit that my own one is in a plastic battery box and that I used some expanded polystyrene sheets to stop it sliding about which must have a slight insulating effect.

[Demon Barber]

Hi All here`s one i made last year,survived Kielder`s -11 deg`s last spring astro party,it`s a bit rough around the edges but works just fine 85amp batt, fused,and three power outlets,and a nice seat at the same time!

Regards

Mike

[brianb]

here`s one i made last year

Great idea, should work very well, only comment I'd have is that personally I'd replace the cigar lighter power outlets with something a bit less unreliable.

[Bizibilder]

What would you suggest? - most folk seem to use the cigar lighters.

[brianb]

What would you suggest? - most folk seem to use the cigar lighters.

Drifting off topic here but the issue with the cigar lighter sockets is that they're prone to intermittent contact and accidental pulling out. A great way to ruin a good session.

I use 13A mains sockets, wired with the 12V positive lead on the "earth" terminal and the negative lead on the "neutral" terminal. No connection on the "live" terminal.

[Demon Barber]

Hi Brian,i have got a supply of 24v plug and sockets,Hella type, have just rewired my heq5pro mount with them and have had no problems at all,just need to do a rewire on the cooler box,there is a gap in the market for a reliable mid size power connecter,but these seem to be working out fine,

Regards

Mike

[Carbon Brush]

The cool box is a very good way to house a battery and the connection gear. Such a simple and low cost solution.

Cigar plugs are a very low cost, usually low quality item. If you hunt around you can find better built ones. But buying without sight and trial is a gamble.

There is a good similar size alternative. Anyone heard of 'XLR' style audio connectors? These are very popular in the professional audio scene. Circular, a bit bigger than an old fashioned DIN audio plug. Cast metal robust case with locking latch. Chassis pin or socket available with (if you look around) 3 to 7 pins. Allows you to use the same connector style but not plug in the wrong place. Made by various manufacturers. This gives an idea of the range.

Rapid Electronics - Cables & Connectors

Hope this is useful.

David.

[dlp]

I've seen XLR used quite a bit for low voltage power, but I believe the connector of choice for power is one of the Amphenol series?

David

[pleiades]

As I said I like the idea (generally I like clever ideas) but the only thing that makes me wonder is, if batteries doesn't have problem at cold weather it's not useless a coolbox? Any answer?

[dmahon]

I was thinking of extending my 17Ah Maplins powerpack by using the "jump leads" to connect an additional battery on evenings where I am out long enough that it would be required. I presume that would work?

[brianb]

I was thinking of extending my 17Ah Maplins powerpack by using the "jump leads" to connect an additional battery on evenings where I am out long enough that it would be required. I presume that would work?

Yeah, I've done that, and also used the jump starter to "boost" my 70AH deep cycle battery in the last hour or two of a very long session.