$50 robot charger.

[Blood-man]

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?

[Soeren]

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.

[Blood-man]

Battery is NI-MH 6.0 V 1400 mAh

[Blood-man]

So, is there any way to make my battery work longer?

[SmAsH]

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...

[Blood-man]

My robot is $50 with 2 standard Hitec servos.
could it be the battery's fault?

[Soeren]

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.

[Blood-man]

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?

[SmAsH]

The 800mA charger would charge it quicker.
But really no charging circuit? Just a transformer?

[Blood-man]

But really no charging circuit? Just a transformer?

Yeah, just transformer. Do I need 1? And if I do, which one?

[Soeren]

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!(?)

[Blood-man]

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.

[Soeren]

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.

[Blood-man]

Many thanks!!!