who uses car batteries for power?

[troypiggo]

If you can't plug into the wall, say you're shooting at a remote site, and you use a car battery (not the one in your car so you can't get home :) ), how long a life do you get out of it?

I'd be running a laptop and HEQ5PRO Skyscan mount off it.

Do you recharge them? How? Do you swap it with your car one and let the car do the recharging?

[rmcpb]

Its possible UT you are better off getting a deep cycle marine battery that is made to handle major discharges. If a normal car battery gets discharged more than about 70-80% they are never any good after that. As for recharging you could get a secondary mount in your car so the battery is charged by the car when it is running and its a backup battery for your car as well.

[troypiggo]

Aah, yeah. Good idea. Thanks for that.

[Ian Robinson]

I've 2 x 6600mAH batteries and 3 x 4400mHA batteries for my lappy.
So I can easily go all night without needing to plug in the lappy. One 6600mAH will last me 3-3.5hrs.

Get a couple extra lappy batteries .... look for very high mAH values.

I've also the Pajero's 4x 12V sockets , got a whopper of a battery in the beast and if need be I can turn on the ignition every so often to keep the battery charged.Got the Projecta Jumpstarter (2x 12V sockets and one I can set to a range of voltages). Also got 2 spare 4x4 batteries in the garage that I can use if needed. Plenty of sources of 12VDC current.

[troypiggo]

Holy cow - I reckon you don't like running out of power? :)

[Ian Robinson]

No I don't.

Beauty is I am not limited in where I can go and my portable power supplies all have dual or multiple uses :
ie
the bike battery goes fishing with me to power the live bait pump
the jumpstarter was originally bought to power the car fridge when were not driving - ie stopping for a walk , or BBQ or a picnic when doing a 4x4 trip , this way , when we got back we simply swapped sockets on the fridge/freezer from the jumpstarter to one of the back sockets in the pajero and , and plugged the jumpstarter into the other , 2 in the back, to recharge it while driving.
the lappy batteries - originally bought the 4400mAHs when I bought the laptop - still good for a up to 3/4 hr each , teh 6600mAHs I bought a few months ago on the cheap through Ebay.

[AlexN]

A deep cycle marine battery might run your mount + DSLR over night, but I dont know about a laptop too...

You really want to look at a something around the 80~100AH mark if you want to run laptop, mount, dew heaters, camera/cameraS.... I've found these Astro toys of ours are bower hungry little buggers, and every I turn around, the power consumption of my setup multiplies... Ian's collection of batteries start to look tame when you've got 60~ cables hanging off your mount!

[AlexN]

Oh.. I forgot to mention.... Car/boat batteries, are not regulated. You might want to find a way to regulate the power from the battery. I've found unregulated power to my mount causes some pretty strange results with tracking/guiding some times... Sounds crazy, but its true...

[Omaroo]

I run an 80AH (amp/hour) deep cycle battery to run, for two nights, my guide/planetarium laptop (Asus eeePC), mount (G11) and six heaters (2x refractors plus two finder scopes - both ends). No problems. Idon't bother with charging off the car - I just plug in a 10A 12v charger I bought from SupaCheap when I get home and charge it overnight fro the next outing. I trickle it for a few days every month if it isn't being used.

The mount likes anything from 12-16vDC to run reliably - so a fully charged deep cycle seems OK in my case. I agree with Alex that some mounts really need the supply as specified in the literature.

One battery can do it all - it really depends on the draw of your thirstiest item - the laptop. My Toshiba drew 3.5A just guiding - even with the disk spun down. My little Asus eeePC draws just under an amp when running. Over two 8-hour imaging sessions that's 30-odd amp/hours worth of savings.

[Karls48]

I run my HEQ5 from old car battery that would not crank the engine bur runs the mount and GStar camera whole night.
By the way – there is no point in regulating battery output as it outputs pure DC current that no regulated DC power supply can match. As mater of fact, regulating battery output will introduce some AC noise to it. Only reason to regulate battery output would be if your equipment requires exact 12V DC input. And such a regulators are rare and expensive as they require at least 0.7V difference between input and output, your battery will not last long. At 12.7 V on battery the regulator will drop out of regulation.

[bmitchell82]

Like i have said before, its not how much or what you hook up to a battery, its all about Current Draw (I, A)(oomaroo said it all. the old lappy drew 3.5A and the new lappy draws under 1A) thats why a high mAH or AH rating is prefered... Amp hours is a engineers term that specifys how many amps can be drawn from a battery per hour it is not a standard SI unit. Though working it out is almost as simple as ohms law. V=IR add up your I's and AH's use a bit of devision and that will give you Hr's so you know approximately how long your battery will last for! thats the way i look at it. If anybody wants to see sample calcs on exactly how to do this just let me know and ill provide.