When fully charged, my 4 AA rechargable batteries are at 5.7 volts. Is it safe to run a pic at this voltage, or should I try draining the battery a bit first?
Most rechargeable batteries will give you that higher voltage when freshly charged, especially if they are still warm. This is usually safe as it quickly drops as soon as it has a load on it. I use 4x AA for most of my Arduino and Picaxe projects with no problems.
So if I want to use my current batteries, then I should probably use them a bit before putting hooking them up to the robot?
You should be fine at 5.7V. Lots of people are running Picaxes on 6V here including me.
But that's not good, expect failure.
I've run off of 6v or 4AA/AAA batteries with no ill effects whatsover.
If it's a big enough issue, just add a diode or two to drop the v down to a safer level.
Again, no failures, no errors and I've run my procs for hours on end with no heat issues and never a hickup in data being recieved.
You should consult the data sheet: http://www.rev-ed.co.uk/docs/picaxe_manual1.pdf
It clearly states:
Power Supply:4.5V or 5V DC is recommended. Do not use 6V, 7.2V or 9V battery packs, thesecould permanently damage the chip. For trouble-shooting use 3xAA cells only.
Most rechargable AA batteries have a nominal voltage of 1.2V. So with 4 x 1.2 you should be getting about 4.8V. I'm not sure what kind of AA rechargables you are using to get 5.7 volts.
If you want to use 4xAA regular batteries, or anything above 5V, you should use some voltage regulation. Oddbot has a most excellent post on power regulation, which you may find informative.
I love LMR. A simple question that I thought I knew the answer to brings out multiple responses from experienced builders who know differently. It's nice to know that you can safely use a 6V battery pack with the Picaxe, despite their own documentation.
I feel a subject for the Video Show coming up here. Stay tuned...