I think I bought the wrong battery pack !!

[Hasan999]

Hi... Im a beginner. I bought everything together, an Axon Microcontroller (from Society of robots) and Servos/sensors/batteries etc from Lynxmotion.

Everything is fine, except for the Batteries (my mistake, didn't realize while ordering) that it cannot be used in a Microcontroller !!

I bought 2 of these: 



First, please tell me that will a battery pack of 7.2V be ok for AxonMicrocontroller (on which I'll use 26 of HS-422 Standard Servos) ?

(if not, which battery pack should I have? - where can I buy that from?)

Second, (if the first answer is "yes"), is it somehow possible to use the battery pack (that I bought) for the Microcontroller? is there any converter cable? ...what do you suggest?

Third, should I do this: (i have no experience, let me know if it is a stupid idea) I was wondering, that the Switch (provided) which has 3 cables, 1 for the battery, the other for Microcontroller, the third for...(i dont know).... what if i cut the third cable, and replace THAT with the big pin Battery cable? 

Need help, urgently.

Thanks a lot.

[Trumpkin]

First, please tell me that will a battery pack  of 7.2V  be ok for AxonMicrocontroller

Yep, 7.2v is fine for the microcontroller, but some servos might fry at that voltage.

Second, (if the first answer is "yes"), is it somehow possible to use the battery pack

Sure it is, I would suggest snipping off the current connector and soldering on two breakaway female headers, like this http://www.sparkfun.com/commerce/product_info.php?products_id=115

Third, should I do this: (i have no experience, let me know if it is a stupid idea) I was wondering, that the Switch (provided) which has 3 cables, 1 for the battery, the other for Microcontroller, the third for...(i dont know).... what if i cut the third cable, and replace THAT with the big pin Battery cable?

I'm not sure what you mean by this, what would you do with the third cable once you replaced it with the big pin battery cable? The third cable is for charging the battery.

[Hasan999]

Thanks for the suggestion...

btw..

Yep, 7.2v is fine for the microcontroller, but some servos might fry at that voltage.

um... Not the HS422 Standard Servos  right??

[Trumpkin]

If you look here: http://www.trossenrobotics.com/images/productdownloads/hitec/hs422.pdf it says the operating voltage is from 4.8v to 6v.

[Hasan999]

Ok has anyone else got any opinions or suggestions?

Q1. Can a HS-422 Standard Servo support 7.2V ? ... (its not a lot higher than 6.0V)

Q2. Any converter cables available to replace the existing "BIG END" cable of the Battery-pack with the microcontroller sized pin socket?

Q3. If no, then should I cut-off my Battery-pack's end, and somehow improvise?  ---Suggestions?

Thanks

[Trumpkin]

Q1. Can a HS-422 Standard Servo support 7.2V ?

I personally wouldn't try it, because if it doesn't fry the servo, it will definitely shorten the life of your servo.

Q2. Any converter cables available to replace the existing "BIG END" cable of the Battery-pack with the microcontroller sized pin socket?

The "BIG END" cable I believe (not sure) is called a "Tamiya connector" the "microcontroller sized pin socket" is called a "Hitec connector", google it and see if you can find one.
EDIT: I just found this site http://www.cheapbatterypacks.com/?sid=2068989&pgid=adapter but at $5.95 per adapter + shipping it's kind of expensive.

[paulstreats]

Can a HS-422 Standard Servo support 7.2V ? ... (its not a lot higher than 6.0V)

 Just dont try it. It has a voltage rating for a reason. Your best solution is to diassemble the battery pack. Inside the film wrapper you will find 6 individual battery cells. These are rated at 1.2Volts each. Simply remove 1 of the cells to leave 5 and you have a 6Volt battery pack.

[Admin]

A 7.2V battery will work, but as mentioned earlier, it'll reduce the life of your servo.

I recommend buying a 6V battery with a Hitec connector. The 7.2V aren't entirely a waste, as you can use them for DC motors in the future.

this tutorial will show you how to make connectors:
http://www.societyofrobots.com/electronics_wire_connector.shtml

[Spoil9]

Can a HS-422 Standard Servo support 7.2V ? ... (its not a lot higher than 6.0V)

 Just dont try it. It has a voltage rating for a reason. Your best solution is to diassemble the battery pack. Inside the film wrapper you will find 6 individual battery cells. These are rated at 1.2Volts each. Simply remove 1 of the cells to leave 5 and you have a 6Volt battery pack.

No offense to the OP, but if he is having a hard time with simple connectors on battery packs i would not be suggesting to him to open a battery pack, remove a cell, and then resolder the connectors.

As Admin said, just buy a new battery pack. It sounds expensive, but you could also try building a simple voltage divider with 1W resisters?

[Hasan999]

Thanks everyone...

I personally think Paulstreats had the best solution... but again, as Spoil9 said, i shall not take the risk - I'll probably make it worse. [but if I know the system inside, i'd like to do that - I can't find any pic for the connections inside a Battery-pack]

I was wondering, if the (Axon) microcontroller itself could "limit" the voltage to the Servos? ...from your answers, it seems it doesnt !..hmm
[how about through programming? - can Voltage to servo's be controlled?]

By the way, I just made my own "connector"... Found a similar 2-pin connector for the microcontroller and the other end, I improvised for the battery-pack end connector.

Now, for the 7.2V problem, I think (after everytime I charge) I'll just put it on a "normal" motor to waste its battery voltage...to make it around 6.0V ...what do you think?

Thanks.

[Admin]

I was wondering, if the (Axon) microcontroller itself could "limit" the voltage to the Servos? ...from your answers, it seems it doesnt !..hmm
[how about through programming? - can Voltage to servo's be controlled?]

You can connect the servos to the regulated 5V line. The regulator can handle up to 1.5A, and you servos probably won't use more than 0.4A each. Worst that will happen is the regulator will overheat, and it'll go into thermal shutdown mode (an Axon safety feature). Nothing will get damaged. Its inefficient, and might cause your Axon to reset occasionally if you drain too much current at once, but it'll work.

building a simple voltage divider with 1W resisters?

Extremely inefficient, and will result in reduced life of the battery instead

I'll just put it on a "normal" motor to waste its battery voltage...to make it around 6.0V ...what do you think?

A 7.2V battery at 6V is a dead battery. Overdraining your battery will damage it.

[Hasan999]

Thanks Admin...

Finally i decided, that I'll cut-off that green thingy and remove a cell :p   ...to make it 6.0V

Naa.. i'll be carefull... I just have connect the Black-wire to the last remaining Cell, as it is now.

But are you sure it will solve the problem? ... e.g. Charging / usage / Current etc would be fine? right?

Thanks !!

[Admin]

If you plan to solder a wire to a battery . . .

Use a 40W iron or higher (cheap irons won't work). Put the heat at max. Do it as quick as possible, otherwise you'll boil the battery and damage it. Use a thick blunt tip.

Practice soldering onto metal first, if you aren't good at soldering . . .