Author Topic: battery pack help  (Read 2743 times)

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Offline aruna1Topic starter

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battery pack help
« on: February 12, 2009, 07:09:23 PM »
guys i bought a 12v 1500mAh Ni-MH battery pack for my first robot it has 3 wires ,black,red and white.i don't know what is the purposes of white wire(i guess red and black are for output).can someone tell me how to use theses three wires properly.i haven't use a battery pack before.

and also can some one give me a circuit diagram to make a charger for this battery pack please.
thanks.

P.S. I'll attach a photo of battery pack here.
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Offline MaltiK

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Re: battery pack help
« Reply #1 on: February 12, 2009, 07:28:56 PM »
guys i bought a 12v 1500mAh Ni-MH battery pack for my first robot it has 3 wires ,black,red and white.i don't know what is the purposes of white wire(i guess red and black are for output).can someone tell me how to use theses three wires properly.i haven't use a battery pack before.

and also can some one give me a circuit diagram to make a charger for this battery pack please.
thanks.

P.S. I'll attach a photo of battery pack here.


Do you have a multimeter? If not, don't do anything until you get one. Measure each wire, most likely the white wire is unused, but you can't be sure. Now you must make sure they are rechargeable, Ni-MH are, but are very enegery effecient. Here is what a quick google search yielded:



Looks like it runs on 5v, and a max of ~850mA, so sounds like a USB charger
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Offline aruna1Topic starter

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Re: battery pack help
« Reply #2 on: February 13, 2009, 08:28:25 AM »
well i have a multimeter. i found that it shows 10.92 volt when positive lead to red wire and negative lead to black wire.and also it shows 10.92 when positive lead connect to red wire and negative lead connect to white wire.but it does not give ay readings when leads of multimeter connects to white and black wires
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Offline Trumpkin

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Re: battery pack help
« Reply #3 on: February 13, 2009, 09:46:34 AM »
So, white and black must both be ground.
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Offline aruna1Topic starter

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Re: battery pack help
« Reply #4 on: February 13, 2009, 10:16:09 AM »
well isnt that odd :P
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Offline Jdog

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Re: battery pack help
« Reply #5 on: February 13, 2009, 10:45:09 AM »
Maybe one wire is used for battery monitoring.

Offline aruna1Topic starter

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Re: battery pack help
« Reply #6 on: February 13, 2009, 11:44:19 AM »
hmm
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Offline pomprocker

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Re: battery pack help
« Reply #7 on: February 13, 2009, 01:37:53 PM »
There is a pre-installed thermistor in the battery pack, power is usually cut off it it exceeds a certain temperature in this case. Read the datasheet if you can find one on temperature ranges of the cells

Offline pomprocker

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Offline MaltiK

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Re: battery pack help
« Reply #9 on: February 13, 2009, 09:16:13 PM »
I have the same battery, its similar to a computer fan, there is a white wire that is also grounded, however these are supposed to be grounded on a different rail, the computers ground them on the metal fram of the computer. If this isnt the case, then an extra wire for battery monitoring as someone suggested sounds feasible.
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Offline pomprocker

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Re: battery pack help
« Reply #10 on: February 13, 2009, 09:33:39 PM »
The 3 wires on computer fans are ground, power, and signal for monitoring RPMs

Offline Soeren

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Re: battery pack help
« Reply #11 on: February 14, 2009, 07:05:07 AM »
Hi,

well i have a multimeter. i found that it shows 10.92 volt when positive lead to red wire and negative lead to black wire.and also it shows 10.92 when positive lead connect to red wire and negative lead connect to white wire.but it does not give ay readings when leads of multimeter connects to white and black wires
It seems like the white wire may indeed be for monitoring.
To verify this, try to measure the resistance between black and white on your lowest Ohm setting - if the reading goes to less than ~1 Ohm (with the probes in really good contact with the leads), they are both connected to the same point (i.e. the 0V end).

Your photo is not sharp enough to read the label fully, but see if it says anything usefull.

It seems to read something about ½AA and that is probably the cell size, as they are packed in 2 rows of 5 cells.
A voltage 1.09V is pretty low, so you should not try to run anything off it before you get it charged.

Where did you buy it? Have you asked about the white wire there?

If you want to build the charger yourself, do you have an LM317 handy?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline aruna1Topic starter

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Re: battery pack help
« Reply #12 on: February 14, 2009, 12:15:02 PM »
it displays 10.92v not 1.09v :)
i dont have LM317 but i'll buy one if necessary
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Offline Soeren

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Re: battery pack help
« Reply #13 on: February 14, 2009, 03:56:39 PM »
Hi,

it displays 10.92v not 1.09v :)
i dont have LM317 but i'll buy one if necessary

10.92V for 10 cells equal a cell voltage of 1.09V
When dealing with batteries, it gets easier if you refer to cell voltage, as it will be the same no matter the number of cells you use.

I hate to repeat myself, but...
Did you measure the resistance between black and white wire?
Did the label say anything?
Where did you buy it?
Have you asked about the white wire there?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline aruna1Topic starter

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Re: battery pack help
« Reply #14 on: February 14, 2009, 08:00:54 PM »
Hi,

it displays 10.92v not 1.09v :)
i dont have LM317 but i'll buy one if necessary

10.92V for 10 cells equal a cell voltage of 1.09V
When dealing with batteries, it gets easier if you refer to cell voltage, as it will be the same no matter the number of cells you use.

I hate to repeat myself, but...
Did you measure the resistance between black and white wire?
Did the label say anything?
Where did you buy it?
Have you asked about the white wire there?


sorry here

infinite resistance between black and white wires
label says "NI-MH BATTERY 12V 1500mAh model:H-AA 1500B*10"
i buy it from local store.
they didnt know what is white wire.they just sell battery pack
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Offline Soeren

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Re: battery pack help
« Reply #15 on: February 14, 2009, 11:25:20 PM »
Hi,

Strange!
To sum up what you said:
Black to red potential = 10,92V
White to red potential = 10,92V
Black to white resistance = ¥ W   (or >20 MOhm I assume)

If that is indeed correct (sure about probing it right?), there seems to be diodes in both the black and the white leads with the cathodes directly at the 0V end of the battery and black and white leads on an anode each.
Can you see any bulges that might be diodes through the wrapping?

I looked at the pic once more, and it seems that the red lead is of a larger diameter than the other two - is that so or is it just an optical illusion?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline aruna1Topic starter

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Re: battery pack help
« Reply #16 on: February 15, 2009, 04:14:17 AM »
Hi,

Strange!
To sum up what you said:
Black to red potential = 10,92V
White to red potential = 10,92V
Black to white resistance = ¥ W   (or >20 MOhm I assume)

If that is indeed correct (sure about probing it right?), there seems to be diodes in both the black and the white leads with the cathodes directly at the 0V end of the battery and black and white leads on an anode each.
Can you see any bulges that might be diodes through the wrapping?

I looked at the pic once more, and it seems that the red lead is of a larger diameter than the other two - is that so or is it just an optical illusion?


nope no diodes

and wires are same diameter
guess it was made to be wierd :P
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Offline Trumpkin

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Re: battery pack help
« Reply #17 on: February 15, 2009, 03:01:43 PM »
You could just not worry about the white wire, as you probably won't need it.
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Offline Soeren

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Re: battery pack help
« Reply #18 on: February 15, 2009, 04:23:38 PM »
Hi,

nope no diodes

and wires are same diameter
guess it was made to be wierd :P

I think you didn't probe the leads correctly when measuring the resistance between black and white.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline Invent_or

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Re: battery pack help
« Reply #19 on: March 19, 2012, 06:34:48 PM »
I signed up to post in this thread.

The white lead can usually be safely ignored, as it is a temperature sensor, used to determine if the battery is too hot.

As yet I haven't worked out how it works, as the data sheet I have doesn't actually mention this feature!

(Note that this is for Lithium Ion batteries, and may not apply to other types.)

p.s. that's a lot of CAPTCHAS!

Offline Soeren

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Re: battery pack help
« Reply #20 on: March 21, 2012, 05:52:53 PM »
I signed up to post in this thread.
A lot of work, to wake up a thread that hasn't seen action in 3 years and isn't about lithiums.


The white lead can usually be safely ignored, as it is a temperature sensor, used to determine if the battery is too hot.

As yet I haven't worked out how it works, as the data sheet I have doesn't actually mention this feature!
You are sure it's a temperature monitor, you're sure it can be safely ignored, but you don't know how it works?
Sounds a bit indeterminate to me.

Posting actual knowledge is better than porting half baked theories. Actually, posting nothing at all, is better than porting half baked theories.


Some lithiums do indeed have a sensor - a simple NTC resistor with one end connected to the negative terminal - it can be checked in a few seconds with an ohm-meter.


(Note that this is for Lithium Ion batteries, and may not apply to other types.)

p.s. that's a lot of CAPTCHAS!
Exactly!
And all the Capthas are to keep old threads asleep ;)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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