TreadBot

[dragons_fire]

im in calgary alberta.. when you wrote CA, i thought maybe you thought i was in california..

its just starting to rain/snow right now. thats why i switched from big outdoor robots to making small indoor robots...

im not sure im happy with my battery choice for this bot. its a 730mAh 7.4V li-poly battery. my biggest issue is that its really not good to drain them past 2.5V/cell, so this pack can only go down to 5V. i may need to set up an ADC to measure battery voltage and have it shut down if it gets too low. and that gives me one more thing to worry about,.. i might remake the body so that its big enough to fit an alkaline 9V (its fibreglass and only took about 10 minutes to make). if i go to an alkaline, i cant charge it from a base station though, and nicads or nimh dont have much capacity.. alkalines are just ofver 500mAh at 9V, and the nicads are about 150-200 at 7.2V and nimh are about 300mAh at 7.2V....

[skimask]

i might remake the body so that its big enough to fit an alkaline 9V (its fibreglass and only took about 10 minutes to make). if i go to an alkaline, i cant charge it from a base station though, and nicads or nimh dont have much capacity.. alkalines are just ofver 500mAh at 9V, and the nicads are about 150-200 at 7.2V and nimh are about 300mAh at 7.2V....

You've got the base set up so you can stack PCB's on top of it. Make a board that'll hold a pack of AAA NiMH batteries laid flat and sits on top of your other PCB. They go up to about 700mAh in the AAA types. As far as shutting down at 2.5v/cell on the Li-Poly packs. Easy to set up an ADC pin to handle that for you. Kill the motor drive once you hit about 2.8-2.9v/cell, and that gives you plenty of time to put the thing on a charger. Have it beep or something to let you know.
I most definetly wouldn't go with alkaline batteries. It'll end up like a kids toy...run it for 5 minutes, then change batteries...

[dragons_fire]

i dont really have a problem with stacking it vertically, if i do, i can actually fit about 5 AA batteries (nimh are 1800-2500mAh) which would give me 6 volts for the motors and lots of capacity for it.. and they are rechargeable..
only problem with that is finding a 5-cell holder. or i can make a 5-cell pack, and mountit somehow, but it would be nice to use a holder, cause then i can change them out quickly while im testing...



PS. we have freezing rain mixed with snow now!!!

[skimask]

i dont really have a problem with stacking it vertically, if i do, i can actually fit about 5 AA batteries (nimh are 1800-2500mAh) which would give me 6 volts for the motors and lots of capacity for it.. and they are rechargeable..
only problem with that is finding a 5-cell holder. or i can make a 5-cell pack, and mountit somehow, but it would be nice to use a holder, cause then i can change them out quickly while im testing...

PS. we have freezing rain mixed with snow now!!!

And it's heading my way!

Swap the AA's for AAA's and you'll get a few more volts for the motors.
Less capacity, but maybe you can parallel them...

[dragons_fire]

thats what i did... i just picked up 2 x 3-cell AAA holders.
im going to change stuff around a bit, and add the switch and Vreg to the board with the battery holders..

[skimask]

thats what i did... i just picked up 2 x 3-cell AAA holders.
im going to change stuff around a bit, and add the switch and Vreg to the board with the battery holders..

And then...and then...and then...you could...ummm...ummm...put another PCB on top of that one...and then...and then...and then...put 9v worth of small solar cells on that...to..umm...ummm...umm...trickle charge the AAA's...

Are you planning on using a linear reg or switch mode?
Check out the LM2825-xx types. Self contained, DIP28/.6", a bit thicker than normal DIP28 types, but have the coil and everything inside the package. And it'll save you some power.

[dragons_fire]

to be honest, i dont really know much about voltage regulators (or anything). im using this reg: http://www.st.com/stonline/products/...035/LD1084.pdf

it may not be the best, but ive used them before, and i have some laying around...

and... and... thats why there is so many headers with pins going nowhere right now.. just so i can add more boards on top...

should mention i did look at solar panels.. one the size of this robot, would output around 20mA at 6v. just not worth it.. it would take forever for that to charge enough...

[dragons_fire]

double post!!!