Portable power supplies

[mswhin63 (Malcolm)]

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

[beren]

I use a 105amp/hr AGM Blue apple thumper pack 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 (Steve)]

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/Austr...ct-4wd-Outdoor

Cheers, nix

[lesbehrens (Les)]

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]

Originally Posted by 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?

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 (Rob)]

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 (David)]

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 (Adam)]

Originally Posted by 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?

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]

Originally Posted by 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

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 (Rob)]

Originally Posted by 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

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

[mswhin63 (Malcolm)]

Originally Posted by lesbehrens

what should i look for when buying a generator?

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 (Simon)]

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 (Ron)]

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

[lesbehrens (Les)]

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