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wireframewolf
12-27-2008, 04:11 PM
Hey all. I have a 12v Nihm battery for my robot... except it's not regulated, so at full charge I'm putting out between 14-15v. This is bad for all the components on my robot (and some of them may fry quickly), so I'm wondering if there's a cheap way to get it a consistent 12v. I suppose at an extreme I could possibly be using 11.5 amps (~2 amps for computer, ~6 amps for four motors, and if I have all seven 645s running at max at the same time, ~3.5 amps). This is terribly unlikely that I'm going to use anything close to that, but better safe than sorry. Preferably it'd be a small and light weight solution.

lnxfergy
12-27-2008, 04:35 PM
What exactly is your current setup? I ask because of this logic:

You probably don't need to regulate the motor voltage - just make sure your motor controller is rated for 15V or better.
Servos are gonna need something in the 5-7.2V range - so you are gonna need a switching regulator for that (I'm gonna leave that one for someone else to fill in)
Computer - I'm guessing you mean a Pico-ITX or mini-ITX since you are saying 2A. Your 12V niMH is comparable to a car battery so an automotive-style DC-DC converter, like a picoPSU, is probably what you want ($70, fairly small).

BUT - and this is a big one - 11.5A is a huge amount of power. If you are pulling this nearly continuously you're battery is gonna majorly heat up (not to mention the short run time) - have you looked at Sealed Lead Acid (SLA)? The weight will be higher, but the costs for a longer run time will be much lower. SLA is also better suited to this higher load.

Might be able to give better recommendations if you post a little more about specific components you are using (which PC, what motors, what motor controller, etc)

-Fergs