Running on Rechargeable Batteries

SpokePOV kit for bikes

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bikefreak
 
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Running on Rechargeable Batteries

Post by bikefreak »

If you plan to run the spoke pov's solely on rechargeable batteries, what adjustments needs to be made? I'm also trying to get the current as close to 20 amps as possible. Please keep in mind that this is the first time I've ever put together a PCB board. Thank you to anyone who can give some advice.

adafruit
 
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Joined: Thu Apr 06, 2006 4:21 pm

Post by adafruit »

spokepovs work with rechargable nimh type batteries just fine

however, no small battery will be able to supply 20 amps

you need a car battery for that much current

kayrock66
 
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Post by kayrock66 »

I think you mean 20mA :oops: , the current most LEDs seem to be spec'd at. For the blue LEDs I got, you're just about right with resistor packs shorted using rechargeables. Install the resistor packs provided, then short them to see if you like what you see. If you don't, remove short and run as normal.

akm
 
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Joined: Mon Dec 31, 2007 3:49 am

How to short resistor packs?

Post by akm »

Install the resistor packs provided, then short them to see if you like what you see.
How would one go about shorting the resistor packs, and would this be a permanent solution?

kayrock66
 
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Joined: Tue Oct 09, 2007 1:06 am

Post by kayrock66 »

The resistor packs have one pin that is the common. In this circuit it is connected to the positive supply. If you connect all the pins together on the solder side of the board then you have in effect connected the anode of the LEDs directly to the positive supply bypassing whatever current limiting effect the resistor packs previously have had.

Regarding the permanence, this doesn't harm the resistor packs, in fact in this condition they dissipate no power. When you take off the bridging of the pins, the resistor packs will operate in their original intended manner.

You should keep in mind, if you mistakenly load in regular 1.5V batteries in after you've done this mod to boost the current for rechargables, you might overdrive the LEDs.

bikefreak
 
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Joined: Wed Oct 03, 2007 7:17 pm

Post by bikefreak »

kayrock66 wrote:The resistor packs have one pin that is the common. In this circuit it is connected to the positive supply. If you connect all the pins together on the solder side of the board then you have in effect connected the anode of the LEDs directly to the positive supply bypassing whatever current limiting effect the resistor packs previously have had.

Regarding the permanence, this doesn't harm the resistor packs, in fact in this condition they dissipate no power. When you take off the bridging of the pins, the resistor packs will operate in their original intended manner.

You should keep in mind, if you mistakenly load in regular 1.5V batteries in after you've done this mod to boost the current for rechargables, you might overdrive the LEDs.
So in order to acheive around 20 mA using rechargeables would you have to buy anything that is not provided with the kit? Because you can get many different types of RN1-RN8 to achieve different ohm. There are two kinds of resistors. The R1 and the RN1-RN8. Do you have to short both types of resistors or just the (RN1-RN8)? Also, by shorting them do you mean that the pins are only touching/soldered onto the solder side without being connected to the reverse side. How much mAh should the rechargeables have? As much as possible?

adafruit
 
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Post by adafruit »

for any LED color, 22 ohm resistor packs will be as good as you can get. there's no way to get 20 ma per LED since its current limited at the 595's at something like 5-10mA


the SMALLER THE RESISTOR PACKS, the HIGHER THE CURRECT thus BRIGHTER LEDS
HOWEVER, DO NOT short out the resistor pack, its not good for the 595 latches.


i would use 22 ohm resistor packs, any lower and you could could damage the latches.

bikefreak
 
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Joined: Wed Oct 03, 2007 7:17 pm

Post by bikefreak »

ladyada wrote:for any LED color, 22 ohm resistor packs will be as good as you can get. there's no way to get 20 ma per LED since its current limited at the 595's at something like 5-10mA


the SMALLER THE RESISTOR PACKS, the HIGHER THE CURRECT thus BRIGHTER LEDS
HOWEVER, DO NOT short out the resistor pack, its not good for the 595 latches.


i would use 22 ohm resistor packs, any lower and you could could damage the latches.
Here is the spec sheet on the latches:

http://focus.ti.com/lit/ds/symlink/sn74hc595.pdf

Are you sure the mA has to be that low?

adafruit
 
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Post by adafruit »

bikefreak wrote:
ladyada wrote:for any LED color, 22 ohm resistor packs will be as good as you can get. there's no way to get 20 ma per LED since its current limited at the 595's at something like 5-10mA


the SMALLER THE RESISTOR PACKS, the HIGHER THE CURRECT thus BRIGHTER LEDS
HOWEVER, DO NOT short out the resistor pack, its not good for the 595 latches.


i would use 22 ohm resistor packs, any lower and you could could damage the latches.
Here is the spec sheet on the latches:

http://focus.ti.com/lit/ds/symlink/sn74hc595.pdf

Are you sure the mA has to be that low?
i post saying "the max current is 5-10mA"

you read the datasheet, it says 6mA.

why are you posting questions that have been answered twice?
do you just enjoy posting to this forum? :?

I mean. at this point im just getting frustrated. this forum is primarily here for me to offer tech support to people who have gone ahead and built the kit and need assistance getting it working.
personally, i can't take you step by step thru your project anymore, especially with all the posts and emails youve been sending. i have thousands of customers. i wish you luck, but i strongly suggest hiring someone who has the time to do this for you as i simply cant offer this level of hand-holding support! :(

bikefreak
 
Posts: 47
Joined: Wed Oct 03, 2007 7:17 pm

Post by bikefreak »

ladyada wrote:
bikefreak wrote:
ladyada wrote:for any LED color, 22 ohm resistor packs will be as good as you can get. there's no way to get 20 ma per LED since its current limited at the 595's at something like 5-10mA


the SMALLER THE RESISTOR PACKS, the HIGHER THE CURRECT thus BRIGHTER LEDS
HOWEVER, DO NOT short out the resistor pack, its not good for the 595 latches.


i would use 22 ohm resistor packs, any lower and you could could damage the latches.

Here is the spec sheet on the latches:

http://focus.ti.com/lit/ds/symlink/sn74hc595.pdf

Are you sure the mA has to be that low?
i post saying "the max current is 5-10mA"

you read the datasheet, it says 6mA.

why are you posting questions that have been answered twice?
do you just enjoy posting to this forum? :?

I mean. at this point im just getting frustrated. this forum is primarily here for me to offer tech support to people who have gone ahead and built the kit and need assistance getting it working.
personally, i can't take you step by step thru your project anymore, especially with all the posts and emails youve been sending. i have thousands of customers. i wish you luck, but i strongly suggest hiring someone who has the time to do this for you as i simply cant offer this level of hand-holding support! :(
I know what you posted. I just wanted to make sure because I'm not familar with this techno mumbo jumbo. I'll keep in mind what you said about this being for those who've already built it but I always thought this was a place where people can discuss the spokepov, not just a one on one chat. I've sent several e-mails in total but perhaps my posting on these forums has you thinking I'm everywhere. I was just trying to help myself and others to do some mods. Certainley I'm not the only one who is technically deficient and eager to do the same things as I.
Last edited by bikefreak on Sat Jan 05, 2008 5:35 pm, edited 1 time in total.

adafruit
 
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Joined: Thu Apr 06, 2006 4:21 pm

Post by adafruit »

you can post all you want... just saying that you're going to have to depend on other forum visitors to help you as i have to triage my attention. good luck!

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