Robot Electrical Question

Alright. Looking at these, they say the cells are 2000mAh. Does anyone know if that is 2000mAh each, or total?

AKSoapy29:
Alright. Looking at these, they say the cells are 2000mAh. Does anyone know if that is 2000mAh each, or total?

The info says "•AA cells are 2000 mAh" which would indicate to me they are talking about a single cell. More than one cell is usually referred to as a battery. I've got the below charger and the recharge time is rated at 3-5 hrs. Bottom is a radio shack holder (not the best, but quick/easy to get.

http://www.rayovac.com/Products/Rechargeable-Batteries-and-Chargers/Everyday-Use-best-battery-charger/4-Position-AA-and-AAA-Charger-with-Batteries.aspx

The NiMH AA-cells bought at Walmart et al are typically 2000-2500 mAH is for the single
cell. Nicads are typically much lower energy.

Wire 10 in series, and you have 12V good for 2000+ mAH. The wallwart with my linksys
router is 12V @ 500 mA, so the AAs should be good.

oric_dan:
The NiMH AA-cells bought at Walmart et al are typically 2000-2500 mAH is for the single
cell.

Alright, I was just making sure.

oric_dan:
Wire 10 in series, and you have 12V good for 2000+ mAH.

1.5V * 10 is 15 volts. You would need 8 1.5V batteries (AA) to power the router.

I think I will buy some of these batteries and hook them up to the robot.

oric_dan:
Wire 10 in series, and you have 12V good for 2000+ mAH. The wallwart with my linksys
router is 12V @ 500 mA, so the AAs should be good.

Good point that these type cells output 1.2v instead of the typical ~1.5v alkaline cells.

As z-c said, 1.2V is the correct value for NiMH.

If the power supply for the router is unregulated and puts out 14.4v or greater at no load (I think mine put out ~16v with no load), then it might be easier to use 12 cells for an output of ~14.4v.

zoomkat:
If the power supply for the router is unregulated and puts out 14.4v or greater at no load (I think mine put out ~16v with no load), then it might be easier to use 12 cells for an output of ~14.4v.

My router wart is a switcher, featherweight job, and outputs 12.3V unloaded.

If the power supply for the router is unregulated and puts out 14.4v or greater at no load (I think mine put out ~16v with no load), then it might be easier to use 12 cells for an output of ~14.4v.

Unregulated wall warts typically put out 4-6V above their "rated"voltages
when unloaded. The output will drop to the rated voltage when you
draw the current indicated on the unit, eg 12V @ 0.5A.

The point of determining if the power supply is unregulated is to determine if the router has onboard voltage regulation, or if it no onboard voltage regulation and relies on external voltage regulation. If the router has onboard voltage regulation, then it might be tolerant of an external battery supply at 14.4v.

I just metered the power supply it came with, and it is outputting 12.28 volts, so I am preassuming the router is getting power from a pre-regulated power source. I could go with the 12 batteries to make things simple. A long time ago, I remember picking up some 12 volt regulators from Radioshack. I could probably go a couple batteries over and use that, but I would have to find a heatsink that wouldn't melt the plastic I am mounting everything to.

I've got a Netgear 614 router that has 12v @ 1a as it input power specification. Its power supply output (probably a switching unit) is rated at 12v @ 1a. The power supply measured unloaded output is 14.75v, so I figure the router is voltage tolerant for at least 14.75v supply voltage.

zoomkat:
I've got a Netgear 614 router that has 12v @ 1a as it input power specification. Its power supply output (probably a switching unit) is rated at 12v @ 1a. The power supply measured unloaded output is 14.75v, so I figure the router is voltage tolerant for at least 14.75v supply voltage.

Mine is a bit different. I think I might try opening it up somehow to see if I can find a regulator on the board. The model of the router I am using: Buffalo WHR-G300N V2.

Nice one Buffalo... I would have never thought there would be Torx screws under the bumpers. Unfortunately, I don't have a Torx that small, so I will see if I and use a Philips and a rubber band or something. Maybe flat.

These are my findings, and it doesn't look like there is any internal regulator. I think there might be a couple for the antennas, but then again, they could be transistors.


Well - I can see one voltage regulator - VR1 - but what it's for or such, who knows (well, you have the board, so you could find out). What's actually more interesting to me is U14 - that whole section around it appears to be the main power supply "nexus" if you will. Finding out what that IC is and what it supplies would be very useful/helpful. Also - measuring the voltage after those 0 ohm resistors/jumpers just southwest of U14 would also be interesting; it appears to be the main positive rail for the entire board. Likely, the positive "rail" is the plane on the top, and the negative/ground rail is the plane on the other side of the PCB (just guessing, though). Basically the fat light green areas are large "filled" traces meant to act as an RF reduction purpose. Likely, VR1 taps off of this. I would suspect that U14 outputs something lower than 12 volts, and VR1 takes that, and likely reduces it further. Maybe U14 outputs 5 volts, and VR1 takes it to 3.3 volts - or U14 outputs 3.3 volts and VR1 takes it to something even lower. Finding information on the other chips, datasheets and such - can help you figure this out more.

cr0sh:
Well - I can see one voltage regulator - VR1 - but what it's for or such, who knows (well, you have the board, so you could find out). What's actually more interesting to me is U14 - that whole section around it appears to be the main power supply "nexus" if you will. Finding out what that IC is and what it supplies would be very useful/helpful. Also - measuring the voltage after those 0 ohm resistors/jumpers just southwest of U14 would also be interesting; it appears to be the main positive rail for the entire board. Likely, the positive "rail" is the plane on the top, and the negative/ground rail is the plane on the other side of the PCB (just guessing, though). Basically the fat light green areas are large "filled" traces meant to act as an RF reduction purpose. Likely, VR1 taps off of this. I would suspect that U14 outputs something lower than 12 volts, and VR1 takes that, and likely reduces it further. Maybe U14 outputs 5 volts, and VR1 takes it to 3.3 volts - or U14 outputs 3.3 volts and VR1 takes it to something even lower. Finding information on the other chips, datasheets and such - can help you figure this out more.

Heh, took me a while to decipher your post, but I understand now. I am just guessing here, but those 'jumpers' you mentioned south-west of U14, I think those might be fuses. VR1 probably regulates power for the antennas, or the leds and other circuitry on the board. Looking at the photo, L19 and L62 (top left) could also be fuses; it looks like they are coming from the main power jack.

Unfortunately, I resealed the router, and it would take a heck of a lot of work and some new screwdriver bits to open it again.

The VR1 leads could be checked for continuity between the + and - inputs on the power in jack. If there is a connection with the power input jack, with the unit powered up, the output voltage of VR1 could be measured. A part number from VR1 might also determine the max allowed input voltage. Harbor Freight has inexpensive torx/security bits, which come in handy if you are a fix-it person.