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Author Topic: $50 robot charger.  (Read 1456 times)

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Offline Blood-manTopic starter

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$50 robot charger.
« on: October 27, 2009, 07:15:10 PM »
I bought 300 ma 6 vdc transformer for my robot. After I charge it for 1 hour my robot loses all energy in less than 1 minute. Would it be batter for me to buy 800 ma 6 vdc transformer?

Offline Soeren

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Re: $50 robot charger.
« Reply #1 on: October 27, 2009, 07:24:40 PM »
Hi,

What kind of batteries do you use and what mAh rating do they have?

Btw. no transformer gives DC, so the corrrect term would be "power supply", rather than transformer.
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 Blood-manTopic starter

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Re: $50 robot charger.
« Reply #2 on: October 27, 2009, 07:27:44 PM »
Battery is NI-MH 6.0 V 1400 mAh

Offline Blood-manTopic starter

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Re: $50 robot charger.
« Reply #3 on: October 28, 2009, 02:57:49 PM »
So, is there any way to make my battery work longer?

Offline SmAsH

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Re: $50 robot charger.
« Reply #4 on: October 28, 2009, 03:02:00 PM »
Well, it depends. If there is a fault, yes. If not, no.
Does you robot have big motors on it that draw lots of current?
In my opinion, a small robot shouldn't kill a battery like that in a minute...
Howdy

Offline Blood-manTopic starter

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Re: $50 robot charger.
« Reply #5 on: October 28, 2009, 03:03:36 PM »
My robot is $50 with 2 standard Hitec servos.
could it be the battery's fault?

Offline Soeren

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Re: $50 robot charger.
« Reply #6 on: October 28, 2009, 05:09:54 PM »
Hi,

Battery is NI-MH 6.0 V 1400 mAh
Charging for 1 hour with a 300mA charger will put around 300/1.4 = 214mAh on the battery (max.) - not much.
This is IF you are using a proper charge circuit - I'm not sure you are, since you just called it a "300 ma 6 vdc transformer".
What exactly are you using to charge the battery (full circuit please)?

Let's start with that, since if you use something wrong, you can ruin your battery pretty quickly.

NiMH cells are nominal 1.2V and has a charge termination voltage (V_ct) of 1.40V to 1.45V.
6V means that it must be a 5-cell battery, which then needs a V_ct of 7.0V to 7.25V - can your charger reach that voltage (plus any voltage drops in your circuit and contact points?

If not, it won't even get the 214mAh aboard.
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 Blood-manTopic starter

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Re: $50 robot charger.
« Reply #7 on: October 28, 2009, 05:28:47 PM »
6V means that it must be a 5-cell battery
You right.
What exactly are you using to charge the battery (full circuit please)?
Actually there is no circuit... I just plug battery to the transformer and wait.
Charging for 1 hour with a 300mA charger will put around 300/1.4 = 214mAh on the battery (max.) - not much.
Would 6 VDC 800 MA WALL TRANSFORMER  be fine?
« Last Edit: October 28, 2009, 05:39:00 PM by Blood-man »

Offline SmAsH

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Re: $50 robot charger.
« Reply #8 on: October 28, 2009, 11:48:13 PM »
The 800mA charger would charge it quicker.
But really no charging circuit? Just a transformer?
Howdy

Offline Blood-manTopic starter

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Re: $50 robot charger.
« Reply #9 on: October 29, 2009, 05:49:04 PM »
But really no charging circuit? Just a transformer?
Yeah, just transformer. Do I need 1? And if I do, which one?

Offline Soeren

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Re: $50 robot charger.
« Reply #10 on: October 29, 2009, 06:00:19 PM »
Hi,

Actually there is no circuit... I just plug battery to the transformer and wait.
Oh Gee... That explains a lot.
Why do you think there's something called chargers if a transformer would do?
Well, at least we now know why you only get 1 minute.


Would 6 VDC 800 MA WALL TRANSFORMER  be fine?
If you need to charge, a suitable charger will be fine!
I just told you, that you need at least 7V, so why do you ask if another 6V transformer will work?  I'm sure you are aware that 6 is less than 7!(?)
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 Blood-manTopic starter

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Re: $50 robot charger.
« Reply #11 on: October 29, 2009, 06:31:48 PM »
Why do you think there's something called chargers if a transformer would do?
you right... so can you give me link that will explain everything to me, because I don't know which one I need.

Offline Soeren

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Re: $50 robot charger.
« Reply #12 on: October 31, 2009, 12:40:53 AM »
Hi,

you right... so can you give me link that will explain everything to me, because I don't know which one I need.
Batteryuniversity is a good place to start. It will not tell you everything, but you will be able to lay a good foundation.
For a commercial product, I guess you should start looking at sites which sells R/C equipment - they usually have universal chargers that can charge several types and setups.
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 Blood-manTopic starter

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Re: $50 robot charger.
« Reply #13 on: October 31, 2009, 08:15:28 AM »
Many thanks!!! :)

 


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