Portable power supplies

[lesbehrens]

:gday:. i am wondering :question:what other people use to power the mounts,cameras etc when out on the field:shrug:. i do use a jump stater pack but i find is not enough to keep me going all night.:atom:
les

[Starkler]

What are you trying to power? If your jump starter pack is more than a few years old it might benefit from a fresh new battery as they seem to crap out after a few, especially if left idle for a long time.

I use 2x12ah gel cels to power my argo and dew straps and never look like draining the batteries.

[lesbehrens]

just my astro imaging gear. eq6, qhy8 and a laptop.

[madwayne]

Les

Up until SPSP, when my big battery died, I used a 90 amp hour for my laptop and a 40 amp hour battery for everything else, dew heater, mount and cameras. It would last me all night long in that configuration although the smaller battery would be fairly hungry for a recharge at the end of an all nighter particularly in Winter.

Now the 90 amp hour has passed on to a better place, I now use 2x 70 amp hour in it's place. One dedicated to the laptop and the other dedicated to dew heaters and cameras.

I haven't had the chance to test the new power setup since SPSP as I have not been out a single night due to Sydney's very inclement weather.

Hope that insight is of benefit.

Wayne

[adman]

You will need to fork out and get a deep cycle battery - something like an AGM (absorbed glass matting) battery. I picked up a 45 Ah one from 4x4 place last year for $155 - normally about $200. The car-starting type batteries are really just meant to deliver a shed-load of current in a very short time, then sit quietly being charged by an alternator until the next time you start your car. THey are not meant to be discharged to any great degree repeatedly as will happen with an all nighter at the scope.

Even 45Ah may be too small if you want your laptop to go all night.

Generally you really only want to discharge these to about 40-50%, and your laptop will draw a couple of amps, plus the rest of your gear, though the mount is fairly minimal.

Adam

[Starkler]

The laptop is the killer. A typical jump starter has no hope.

[RobF]

Les, how close to 240V are you at home? I've been surprised at how close power is generally at Astrofest, Ron's, Peter's. I like to be portable, but a good battery is so expensive you might be better off investing in a decent power supply set up first?
(probably completely off topic given the title of the thread, but hey, thought I'd throw it out there.... :D)

Failing that, you need to look up how many amps the QHY8 and laptop are pulling and figure out max time you would want to run and calculate some amp hour figures. Just quickly:

- Laptop - 1-3 amps?
- QHY8 - 1-3 amps?
- EQ6 - pretty negligible compared to above

If you say 3amps total, and want to run max 7hrs, and never take battery below 33% charge, that would be about a 33-40Ah deep cycle battery I'd suggest. I'd be surprised if the jumpstart pack is more than 17Ah total - and its debatable how well and how many times it would be able to do that anyway. It would be fine for just the EQ6, but pushing it to run just the camera OR laptop for any period.

[DavidTrap]

Agreed the laptop will kill your battery fastest - are you using an inverter to power the 240V power adaptor that comes with your laptop, or have you shelled out for a 12V power adaptor for the plugpack. The latter will probably improve your efficiency somewhat.

If I'm off 240V I have a 100amp/hr for the laptop and 30amp/hr for the mount, etc - fortunately this doesn't happen often.

DT

[mswhin63]

I use 4 X 28A/hr batteries from an old UPS (big one) and a 750W inverter which is a bit overkill.

[Barrykgerdes]

I gave up on batteries years ago far too expensive and unreliable. I now use a portable generator (2KVA) of the quiet type ($600), electric/remote start/stop. I use a sound proof box as well. On my normal load of caravan, five computers, telescope/mount and camera I get 12 hrs from 5 litres.

The residual noise should not worry anyone on a cold night If you have head cover. I can't hear the generator past 10 metres and set it up at the end of a 25 metre extension cord.

During the SPSP I ran the "house" and whole area from the generator using less than 1 litre of fuel/hr and supplied everyone with AC via a 12 way distribution box.

Barry

[DavidTrap]

What the? 5 computers?????

DT

[marki]

Batteries are a pain, expensive, large and too heavy. Like Barry I use a small genset (honda Eu10i) which has 1kv capacity clean power (excellent for laptops, garanteed better than mains) and will run for 8 hours on 2L of unleaded. Quiet as a mouse (52dB) and as light as a feather (~15kg wet). Best thing is it is about the size of a shoe box so takes up little space. It even has a special circuit to charge 12V batteries built in. A much better option then deep cycle batteries by a fair margin. Runs my mount, CCD's, laptop etc etc at idle. Details here.


http://www.hondagenerators.com.au/index.php?option=com_content&view=article&id=12&Itemid=2

Mark

[Barrykgerdes]

I'm well prepared.
My son and My grandson as well as me and I have one hooked up just for TV as well as two lap tops.

Mark has the right idea. Those little Hondas are great. I got a cheap generator off ebay 2.5 KVA but only half the price of the little Honda and I needed a bit more power. It is a little noisier 59db but the sound deadening fixes that.

We also have Bigpond next G internet

Barry

[lesbehrens]

its a little unpractical for me to run and extension lead to the nearest power source 500m away. i had thought of generators as my view on them would be too noisy so i wasn’t to sure on that
thanks for some ideas,:thumbsup:
les

[marki]

Les the Honda genies are so quiet you can have a normal conversation standing right next to it. There is no need to move it off into the distance or make a shield to cover it and no need to shout to be heard when near the machine. For AP they are ideal and rarely move above idle even when the mount is slewing at max rate with the peltier and dew heaters going flatout whilst the laptop is operating in flatten the batteries in 5 min mode. Love it as it is just so convienient. When I priced deep cycle batteries to do the same job it was huge and cost about $750.00 here. The generator just made a whole lot more sense.

Mark

[Steffen]

I find those generators attractive, too, but don't they cost twice as much? And a lot more to run as well (fuel, oil, maintenance)?

Cheers
Steffen.

[marki]

Steffen I got mine for $1300.00 so yes it was 2 x as much as the deep cycle battery but came with a 5 year warranty (not so with the batteries). The cost to run (fuel) is $2.00 for 8 hours. How much does it cost to charge a deep cycle battery 4X (would only get 2 Hr's by my power requirements). So for fuel the grand cost is 25c per hour. From the manual the engine oil gets changed every 100 hours of use (250mL), the spark plug, and air filter is replaced every 300 hrs. Valve clearances and fuel filter every 2 years. In short 2 halves of bugger all to run. Advantages over the battery setup are

1. It doesn't go flat.
2. Runs all night providing lots 240V power (boil the kettle, run the microwave, mount, camera's laptop etc).
3. Takes 10 seconds to refuel and you are away again.
4. Is very light and small so easy to handle.
5. Can be used for dozens of other applications (power tools etc).
6. Can be linked with another genset of same type to boost output to 2kV.
6. Can be used to charge flat 12V batteries of other astro folk :P.
7. Makes less noise then my LX200 in a slew (Okay so the battery is quieter) :D.
8. It's a honda so it is reliable and does exactly what it is supposed to do with no hassle.

For me points 1, 2, 3, 4, 5, 7 and especially 8 were the major selling points. I have used Honda gear in many hard industrial applications and they are virtually bullet proof (nb: I also drive honda cars but do ride Ducati's). Sure there are other cheaper options for genies but be careful about quality and make sure it is rated to power computers etc or you will end up in trouble. For me it was a no brainer in the end, the battery option was not even in the hunt as I would need 4 of them to do the job of 1 generator.

Mark

[Steffen]

Oh, I agree with all these advantages. I just think it is a very expensive luxury.

Regarding battery recharge costs, I'm paying about $0.18 per kWh, and 1kWh gives a hell of a lot of recharges. But running cost isn't nearly as much a concern as purchase price.

If I was more into camping a generator would probably make more sense. As it is I just need to help one laptop through the night, and for that I reckon a $100-200 AGM battery plus $50 charger are a better choice.

Cheers
Steffen.

[RobF]

Any recommendations on chargers for AGMs folks? I don't really want to spend over $100 for one if I can help it, but expect to get max battery life you get what you pay for?

[MrB]

Anything stated as computerised and multistage is fine.
C-tek is a well known brand, Powertech at Jaycar is the same thing(same factory)

[mswhin63]

I bought my from Jaycar as well. easy to use.

[beren]

I use a 105amp/hr AGM Blue apple thumper pack (http://www.blueapplethumper.com/2.html#) and a 70amp/hr AGM with a Ark battery box. The Thumper pack isn't cheap but its great for the dual role as a dual battery system for the fourbie/engel . Nearly came close to Marki's suggestion with a Honda genie, very nice. I use a 4 stage projecta charger to maintain the batteries.

[Phoenix]

Australian Direct - Just in case you don't know of this company who sell a range of deep cycle AGM batteries, including the thumper units (scroll down left column) at competitive prices, 24hr service, free delivery, with 100% customer feedback. I have no affiliation wit this crowd, I've just bought a few items from them in the past - including a 30Amp/hr thumper - good service and fast delivery.
http://stores.shop.ebay.com.au/Australian-Direct-4wd-Outdoor

Cheers, nix

[lesbehrens]

how do i know a good vs bad generator?
are all generators ok for sensitive equipment?
what should i look for when buying a generator?

[marki]

1. Buy a reputable brand. Quite a few people here use them, ask around. I chose Honda because it fitted the job perfectly and I know from previous experience that they are tough and reliable but it's a case of paying for what you get. There are cheaper options out there.

2. No all generators are not created equal. Those suitable for computers and lab type power packs have inbuilt circuits that ensure the power is both stable and free of spikes in current and voltage. This will be advertised with the product. Spikes in output can destroy delicate equipment and not all generators have these. Those that don't are usually much cheaper.

3. Carefully consider what you need and make sure it suits your requirements. You will need to calculate how much power you need to run your setup and choose appropriately. For me weight, size (I have a small 2 door convertable), fuel efficency, reliability, warranty, noise and clean power output were the major factors. The Honda did all this and more and has been well worth the money.

Mark

[RobF]

You may be very popular at the next star camp with limited 240V Les!

Will be able to charge for power.... ;)

I'm most thankful for the greater setup Barry had going at the SPSP.

[DavidTrap]

Les,

My basic understanding of generators (happy to be corrected by those with better knowledge of technical terms, etc):

The cheaper generators have a petrol motor connected directly to a generator that makes the AC power. That petrol motor must run at 3000rpm to produce 50Hz AC power. This is inefficient if you are using a large generator, eg >1kVA generator, but only drawing a small load (most astro setups would draw <0.5kVA (~500 watts). If you switch on a big load, the petrol motor takes a finite amount of time to ramp up it's output, so the voltage and frequency can vary - ie, the AC power is dirty. Because the motor is running at high speed all the time, they are usually noisy.

The expensive (eg Honda) generators use an inverter. The petrol motor turns a generator that produces DC power. This DC power is fed through an inverter to produce high quality, clean AC power. They are more efficient as the petrol motor can run slower and produce just enough power to meet your requirements. If you switch on a big load, the inverter can maintain a stable voltage and frequency of AC power (better than the cheaper generators) while the motor speeds up (not sure how ? capacitors??).

That's my understanding. I don't own a generator as I don't have need for one - fortunately all my observing sites have 240V. I'd definitely buy a Honda Inverter or equivalent if I needed one.

DT

[adman]

one of the cheaper c-tek ones goes for around $100. Good multistage charging and if you leave the battery connected to it, it will keep it topped up properly to maximize its lfespan...

Adam

[marki]

Sounds about right David. The Eu10i has an inverter to produce the 240V. As a consequence of producing DC power initially this allows a seperate circuit to charge batteries at 12V and 8 amps. With all my gear attached it revs at about 800 -1000RPM, virtually idle. It has an eco throttle setting which adjusts RPM to a given load. Honda have been very clever and the generator itself is part of the engine, not a seperate component and this is why they are so compact. Another clever innovation allows the gensets of the same type to be joined together in paralell to double the output. Mine is only a 1kV job but they also make 2kV and 3kV versions that are only slightly larger but of the same design.

Mark

[RobF]

Thanks Adam - they look good - will have to check some out

[mswhin63]

If you intend using for star parties, then probably look for batteries and inverter. Last year someone brought a gennie to a star party, quiet for me but not for a few others.

Didn't get used!

[MrB]

Good point Malcolm.
I used to take a Honda gennie camping, I thought it was nice and quiet... but then late into the night it would use the last few drops of the tank and splutter to an end.... dead quiet... bliss.
Doesn't matter how quiet a gennie is, the noise is still there and you realy notice it's gone when it goes.

Now I take two 80 Watt solar panels and batteries... zero noise.
Will never go back to a gennie.

[astroron]

Les,Where abouts would you be using a generator?
I would think that nearly all the places you go to have power, except maybe Barambah:question:

[lesbehrens]

hi. thanks for more info on the generators. i am looking at one because i have a very nice observing field in my back paddock which i would love to use but is a fair way from the house . i currently use my set up near the house at it best spot but the headlights for the high way spoil it to much a well as the power lines( so fussy), thats why i am looking.
les