Replace Axon Voltage Regulator with a switching Regulator

[madsci1016]

I would like to keep my robot as efficient as possible without having two have two sets batteries with two voltages (as i have setup now)

My prime mover batteries are a pair of 14V 2.2Ah Li-Ion's I custom built (a friend gave me the cells for free )

I would like to use a switching regulator to bring that to 5V for the Axon, sensors and circuitry. This would require removing (or just shorting Vin - Vout ?) the resistive voltage regulator on the Axon and bridging the unregulated and regulated buses on the board.

Has anyone ever done this before? Problems with noise from switching regulator? How did you bridge the buses on the Axon?

[Admin]

If you want a higher efficiency, you'd be better off using a 6V battery. You can't run servos off 14V, anyway.

Maximum voltage regulation efficiency is always when the battery voltage and the regulated voltage difference is the smallest.

You'll have to cut off the Axon regulator and replace it with your switching regulator. You should get a switching reg that already has all the built in caps needed for low noise.

[madsci1016]

If you want a higher efficiency, you'd be better off using a 6V battery. You can't run servos off 14V, anyway.

Maximum voltage regulation efficiency is always when the battery voltage and the regulated voltage difference is the smallest.

I am running everything off a 6V Ni-MH right now, but i'm tired of the 6 V battery having to be recharged 3 times for every 1 time i charge the Li-Ion, and i would like the room used by the 6V back. My robot has no servos, and if it will in the future, it would only be a few. I was thinking about just using a external 3 Amp switching regulator and powering both the unregulated and regulated buses on the Axon off that. Has anyone run the regulated circuitry on the Axon with a switching power supply?

On a side note, Admin, I read in another post that you work for the Navy on UUV's, which coincidentally, I do to. I work on a base in Florida; NSWC PCD; are you anywhere near here?

[billhowl]

http://www.dealextreme.com/details.dx/sku.15149
http://www.dimensionengineering.com/BECFAQ.htm

I'm using this 5V/6V 3A Switch-Mode Ultimate BEC (Battery Eliminator Circuit) from dealextreme with 11V LiPo battery and set at 6V and connect directly to Axon power input, I did not disable the voltage regulator on the Axon and it work for both the servo and MCU.

[Admin]

am running everything off a 6V Ni-MH right now, but i'm tired of the 6 V battery having to be recharged 3 times for every 1 time i charge the Li-Ion

What mAh is your 6V at? I use a 4500mAh for my ERP giving me 30+ min of play time.

billhowl's suggestion looks good, too.

On a side note, Admin, I read in another post that you work for the Navy on UUV's, which coincidentally, I do to. I work on a base in Florida; NSWC PCD; are you anywhere near here?

Naval Research Laboratory, Washington, DC
This is what I'm working on:
http://www.societyofrobots.com/robot_fish.shtml

[madsci1016]

What mAh is your 6V at? I use a 4500mAh for my ERP giving me 30+ min of play time.

billhowl's suggestion looks good, too.

Naval Research Laboratory, Washington, DC
This is what I'm working on:
http://www.societyofrobots.com/robot_fish.shtml

My 6V is a cheapo 2000mAh, but i would still like to get rid of it just to clear up some space. I'm also a bit annoyed that my prime mover batteries are out-lasting my electronics battery by so much and that's why i wanted to tap into them. It also seems silly if i'm going to invest in a good switching supply and still have the Axon's on board regulator as well.

Billhowl's regulator is for 3 cell batteries when mine are 4, so i will have to see if they offer a different model for that.

The Robotics i work with are for the Navy's MCM ( Mine Counter-Measures ), UUV's that hunt down mines in various environments, and I would love to document what i do like you have, but since the program is mostly Secret Clearance or higher, they wouldn't like that very much. If you ever come to the Florida Pan-handle, i can show you around the base since you are a DoD employee.

[Admin]

Yea for maximum efficiency, you'd definitely want to just cut out the regulator in the Axon. You'd also do better with a 7.2V LiPo, and just put more cells parallel. Those additional cells to increase voltage also increases mass with no benefit - resulting in mechanical inefficiency since your robot has to lug it around.

The Robotics i work with are for the Navy's MCM ( Mine Counter-Measures ), UUV's that hunt down mines in various environments, and I would love to document what i do like you have, but since the program is mostly Secret Clearance or higher, they wouldn't like that very much. If you ever come to the Florida Pan-handle, i can show you around the base since you are a DoD employee.

Well I'm a contractor, not a Fed. I only have a secret clearance for industry, but I recently applied for a top secret clearance for government with a very good chance of getting it this year. If I'm down in Florida, I'll definitely take you up on that offer!

So is the Axon being used for a personal project, or being put into a UUV?

(I wonder if after I have the top secret clearance they'll let me see all those robots captured from those crashed alien spaceships . . . )

[madsci1016]

Well, changing the voltage is not practical. I would have to rebuild the battery packs with new Li-Ion regulator boards (since the ones i have are 4 cell boards). And i would have to replace the 4 drive motors since they are 12V. I have 6 packs and my robot uses two at a time, so i'd rather use what i have then try to change everything.

Really i can 'personally escort' any one person around the base, but can't tell you what you're looking at unless you have some sort of clearance. (Contractor counts).

The Axon is for a personal robot. The UUV's we have at work are commercial base platforms, and we add our own additional hardware and software. I am building my own UGV (powered by the Axon) in my spare time in an attempt to better understand how the commercial platforms function. First i'm tackling GPS navigation, then i'll buy some gyros and attempt inertial navigation. Then maybe my own UUV in the future.

I'll PM you my email. If you are ever in the Northern Florida area I'd be glad to show you around.