Taperssection.com
Gear / Technical Help => Remote Power => Topic started by: boardmonkey on July 09, 2006, 11:44:42 PM
-
I am looking for a way to power an Alesis Multimix USB 8 and a Apple iBook G4 12". I know that it is a lot of power, but does anyone have any ideas for something smaller than a Car Jumper. I was thinking solid lead, but I don't know if I would get enough time out of that, and I am thinking of using it for Fests.
Love you hear your ideas.
Tim
-
Valence N-Charge
-
I have a very similar setup and battery issues at festivals have become a top concern. Recently I've "solved" them by bringing my whole setup in a cart with my RV's auxilary battery. That's what I would consider my worry free setup.
Now I'm currently trying to solve this problem so I don't have to drag that thing along.
And I've found the the best energy to cost ratio is just to get extra internal batteries for the iBook. I just got two extra and I get about 3~4 hours out of each of them.
I looked at the SLA batteries but once you do the math (or test it) you have to bring at least a 25 pound battery with you, to get you through a moderate festival day. I just tested a 7.5ahr SLA, without any interface attached, and it ran my ibook for about an hour and a half.
I looked at external lithium ion supplies also such as the valence n-charge mentioned....but these not only have a bad cost to energy ratio....when your using them as an external they are rather inefficient.... what I mean is your iBook uses the power from your internal batteries much more efficently than if you had the same rated battery, plugged in externally. Heres the math: the valence vn130 gives you 130w hours. your ibook external supply is 24volts. 130/24 = 5.4amp hours . The ibook supply is 1.875amps so 5.4/1.875 = 2.8 hours of run time. You get between 3 and 4 out of your internal, so this is actually rated for less power than the battery you already have. The Ncharge is around $200. I just got TWO internal batteries shipped to my house for $108.
So i think the solution is a combo.....
have enough internal batteries for your ibook to run on, and power the external device, and phantom power with whatever you want. You could get an expensive, lightweight lithium ion pack, or a cheap, heavy SLA.
I'm carrying a 7.5ahr SLA to power my MOTU traveler with phantom, and the ibook should be fine on the three internals that i have... if i come up short on a future outing, I'll just order another $54 dollar internal. It's the best option in my opinion. Also having the SLA with you is good in circumstances where you need to change the laptop battery halfway through a set....just plug it in for the few seconds it takes to change the battery, and then disconnect. Also it should be noted that if you put the ibook to sleep, it takes a charge rather efficiently from the SLA....this is good for toping off your internals during setbreaks and between bands at festy's
Future options I'm considering are solar panels for keeping the battery charged, and even a dynamo footpedal generator (about the size of the car booster packs) for those emergency situations.
BTW....you mentioned not wanting to get one of those car boosters.....I hate to break it to you, but unless you get one of the really big and heavy ones....that's still not going to give you the runtimes your looking for.....just remember this.....you get about 1and a half hours, from a 7.5ah SLA.....and your going to want to use a DC/AC inverter instead of running off of a DC12v > DC24v converter such as the iGo juice 70. This is because when the voltage gets low on the inverter, it just shuts off and your computer reverts to internal.....but with the iGo, your computer will go into a low power safe mode....cutting power to the screen backlight and the usb/firewire ports.....you won't be able to see anything on the screen unless you hold a light to it and look at an angle.....and your audio interface will stop "talking" to the computer. Just some words of warning.