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Author Topic: L-Ion?  (Read 3829 times)

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Offline nanob0tTopic starter

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L-Ion?
« on: May 01, 2007, 11:17:35 AM »
Hello,

I am currently constructing robot, and I am in need of power.  I have checked a few battery websites and did some reading to find out that I don't like Nickle based batteries.  I would like having a battery that would last me, not only this robot, but other projects I may begin that may require similar voltages or such.

I was wondering if anyone knew a manufacturer of Lithium-Ion batteries.  I went through many sites without much luck.  I am looking for 4.8-6.0 volt batteries.

Any help would be appreciated.


______________ EDIT_________________

I guess I'll get another question out of the way.

This robot is going to be very small.  I want to mount IR on it, because it doesn't need to detect incredibly large distances, and I have found a large number of products available.  Usually I'm handed a product and told to figure it out and get it to work with the robot.

I see IR Rangefinding and Sharp IR.  Any prefrences?   I have a feeling they are the same thing though O_o
« Last Edit: May 01, 2007, 11:20:46 AM by nanob0t »

Offline hgordon

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Re: L-Ion?
« Reply #1 on: May 01, 2007, 12:48:08 PM »
Li-ion chemistry produces 3.6- 3.8V cells, so you'll need to go with 2-cell packs and then use a voltage regulator to hit your target voltage.  Make certain that the battery packs have "charge protection circuits".  http://www.batteryspace.com and http://www.all-battery.com have okay prices and reasonable selection.

I've only blown up one Li-ion battery pack - the explosion was loud and it produced a LOT of smoke.  My fault - I tried to recharge a non-rechargeable "primary" battery pack.

============

With IR, there are 2 basic types of sensors - proximity and range-finding.  The range-finders have a linear sensor array, while proximity sensors generally just have an emitter and detector.  The proximity sensors are a lot easier to interface and cost a lot less, but they don't provide range.
« Last Edit: May 01, 2007, 12:51:48 PM by hgordon »
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Offline nanob0tTopic starter

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Re: L-Ion?
« Reply #2 on: May 01, 2007, 02:50:13 PM »
Thanks, that answers my battery questions.  I found lithium-ion batteries, but only in 3ish volts, so I assumed they only did it in that big of cells.  I guess I'll buy two.

Thanks hgordon.

I understand the two types of IR, I just thought there may be a difference between the two titles.  I picked out one, I think it will work for my application.  I need it for very basic obstacle avoidance, so it will have to be more linear.

http://www.acroname.com/robotics/parts/R48-IR12.html

It's made to report distances back to me in analog.  I have already calibrated something like this, so I don't think it will be difficult.  It's going to be a small robot, so the distance isn't too durastic.  It's minimum is 4'', but I will equip my robot with a simple tactile sensor to detect if it hits anything, just in case  ;D

Opinions?

Offline nanob0tTopic starter

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Re: L-Ion?
« Reply #3 on: May 01, 2007, 03:40:05 PM »
Make certain that the battery packs have "charge protection circuits". 

I found L-Ion batteries with a built in 'Protection IC'.  Is this what you were referring to?

Offline hgordon

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Re: L-Ion?
« Reply #4 on: May 01, 2007, 07:26:53 PM »
Quote
I found L-Ion batteries with a built in 'Protection IC'.  Is this what you were referring to?

Exactly.


I haven't worked with the range-finding IR devices.  Instead, I've been using TV remote receivers and discrete IR LED emitters.  Add a transistor and a  couple of resistors, and the total cost is about $1.  We have 4 sets of these emitter/detector combos on our robot.
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Offline nanob0tTopic starter

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Re: L-Ion?
« Reply #5 on: May 03, 2007, 09:15:35 AM »
I'm thinking of getting these:

http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=507   =  Battery
http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=478   =  Charger

This is for a smaller robot.  Any thoughts?

I don't believe it has a protection IC though.  Can I get a schematic or something in order to incorporate this in? 


Thanks

Offline JonHylands

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Re: L-Ion?
« Reply #6 on: May 03, 2007, 09:17:57 AM »
It looks like it has one... From the specs:

- Made of 2 2200mAh cylindrical 18650 cells with PCB and poly switch for full protection
- Built-in IC chip will prevent battery pack from over charge and over discharge and prolongs battery life

- Jon

Offline nanob0tTopic starter

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Re: L-Ion?
« Reply #7 on: May 03, 2007, 09:20:08 AM »
It looks like it has one... From the specs:

- Made of 2 2200mAh cylindrical 18650 cells with PCB and poly switch for full protection
- Built-in IC chip will prevent battery pack from over charge and over discharge and prolongs battery life

- Jon


I feel stupid.  Thanks for noticing my mistakes.   :-X

Offline hgordon

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Re: L-Ion?
« Reply #8 on: May 03, 2007, 09:44:58 AM »
That's basically what we use.  Be careful not to short the leads, as this can fry the circuit board, and then you just have a paperweight.  I haven't found out whether these circuit boards can be repaired, but currently have 8 battery packs that have suffered from accidental shorts during assembly.
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Re: L-Ion?
« Reply #9 on: May 03, 2007, 10:30:51 AM »

Offline nanob0tTopic starter

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Re: L-Ion?
« Reply #10 on: May 03, 2007, 11:24:12 AM »
That's basically what we use.  Be careful not to short the leads, as this can fry the circuit board, and then you just have a paperweight.  I haven't found out whether these circuit boards can be repaired, but currently have 8 battery packs that have suffered from accidental shorts during assembly.



Eek, I don't want to spend that much money :-X  Stupid capitalism.  I usually make sure that everything looks good before I plug in a battery.  I take extra caution making sure batteries don't heat up.  That's not fun O_o   I had a huge project I was working on and wrapped batteries in electrical tape, because I couldn't find a holder.  I figured out that I was shorting the batteries were overheating when the tape was melting off of them   

=_=



potentially useful for you:
http://www.dimensionengineering.com/CellShield.htm



I'd like to purchase one, but again I'm confined by capitalism.  Then again, the investment might be worth saving me money.  I'll figure it out when I kill my first L-Ion.   ::)


I guess while we're on powering topics.  How do you determine support electronics for a microcontroller?  I have one that runs on 5v.  Voltage Regulator, what else? 

Offline JonHylands

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Re: L-Ion?
« Reply #11 on: May 03, 2007, 11:31:47 AM »
I understand the two types of IR, I just thought there may be a difference between the two titles.  I picked out one, I think it will work for my application.  I need it for very basic obstacle avoidance, so it will have to be more linear.

http://www.acroname.com/robotics/parts/R48-IR12.html

It's made to report distances back to me in analog.  I have already calibrated something like this, so I don't think it will be difficult.  It's going to be a small robot, so the distance isn't too durastic.  It's minimum is 4'', but I will equip my robot with a simple tactile sensor to detect if it hits anything, just in case  ;D

Opinions?


I use those exact modules on my mini-sumo robots - they work great for that.

http://www.huv.com/miniSumo

You need an A/D converter on your micro-controller, and you need to realize the distance is not linear with voltage - I ended up building a 128 byte lookup table that I use to convert input voltage (0-1023) to distance in cm.

- Jon

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Re: L-Ion?
« Reply #12 on: May 03, 2007, 12:06:22 PM »
Quote
You need an A/D converter on your micro-controller, and you need to realize the distance is not linear with voltage - I ended up building a 128 byte lookup table that I use to convert input voltage (0-1023) to distance in cm.
if you dont care about processing speed, you could also use excel to write an equation for you that uses exponents . . .

Offline nanob0tTopic starter

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Re: L-Ion?
« Reply #13 on: May 03, 2007, 12:54:46 PM »
No no no.  I know how to get parts running and get my IR calibrated and stuff.  I did that with an IRPD for my robotics project I did for a competition.  I actually used excel to come up with an equation and rounded some numbers, it worked very well.  I ran it through an A/D converted, then changed it to an understandable distance.

I mean, what electronics do I need to regulate the power going to the Microcontroller.  I need to power the controller to run, and I'm not exactly sure what I need to use, as I have never done it before.  I would run a google search, but I'm not sure what to look for.  If you can point me in the right direction, that would be wonderful.

Also, if I power the microcontroller with 5 volts.  Will the controller pull enough current in order to run the electronics, or do I need to separately power everything? 

Batelle has me working on programming and mechanics.  Not so much the electronics, so I'm sort of confused due to my lesser experience.   This is the whole reason I'm doing this project.

Offline JonHylands

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Re: L-Ion?
« Reply #14 on: May 03, 2007, 01:03:49 PM »
You need a regulator for the micro-controller. Depending on the battery pack minumum power, you can probably get away with using an LDO (low drop-out) regulator like a National LM2940. You can order that from Digikey, along with the 22uF and 0.47 uF capacitors you will need.

If your battery voltage is always going to be above around 6.3 volts, you can use this, which is more expensive, but also more efficient and requires no external parts:

http://www.dimensionengineering.com/DE-SW050.htm

You can power at least a couple of the GP2D12 IR rangefinders off either of those regulators, in addition to your micro-controller.

- Jon

Offline hgordon

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Re: L-Ion?
« Reply #15 on: May 03, 2007, 01:22:40 PM »
We're using Recom R-785.0-1.0 (5V) and R-783.3-1.0 (3.3V) 1 amp switching regulators with good results.  Like the Dimension Engineering parts, they have the same pinout as standard LM78xx regulators, and efficiency is 90%+.  I think single-piece pricing is in the vicinity of $8 - $9.
« Last Edit: May 03, 2007, 01:23:55 PM by hgordon »
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