9V with 4Ah issue

[Security]

I am using the attached adapter. It should empower a circuitry with 4A for one hour (4Ah).

As a reference I have a 9V block battery, rechargeable, 200 mAh.

Using the 9V bb it works well for a very limited period of time due to it's low capacity. Using the adapter it seems as if not enough current can be delivered, as if there was a bottleneck.

So the pic does not start it's program using the adapter and a led(+5V -> led -> resistor -> ground) is flashing and shows a very dimmed light. This led is on like normal using a PSU or the 9V block.

What is wrong with the adapter, how to fix it?

[skimask]

I am using the attached adapter. It should empower a circuitry with 4A for one hour (4Ah).
As a reference I have a 9V block battery, rechargeable, 200 mAh.
Using the 9V bb it works well for a very limited period of time due to it's low capacity. Using the adapter it seems as if not enough current can be delivered, as if there was a bottleneck.
So the pic does not start it's program using the adapter and a led(+5V -> led -> resistor -> ground) is flashing and shows a very dimmed light. This led is on like normal using a PSU or the 9V block.
What is wrong with the adapter, how to fix it?

6 AA NiMN (or NiCad's) do NOT make a solid 9v...Only does about 1.2v per cell, 7.2v nominal...without a load.
Put a load on it, and it'll drop a bit more.
Try to run that low-ish voltage thru a 7805 type regulator and you'll be running up against the minimum voltage needed for a 7805 type regulator to regulate properly.

In other words, add 2 more cells and you should be ok.

[Security]

So you are talking about using three parallel 9V blocks instead of one adapter?

[skimask]

So you are talking about using three parallel 9V blocks instead of one adapter?

Ok, let's get smart here...I'm leading you somewhere...

Answer these questions...in order...

1) What is the NOMINAL voltage of a standard AA NiMH cell (not the peak voltage, not the depleted voltage, not the voltage you read from the meter right now, but the NOMINAL voltage according to any NiMH, or NiCAD datasheet)?

2) How many cells do you have in your pack?

3) Multiply the number of cells in your pack by the NOMINAL voltage of each NiMH cell in that pack. What is that value?

[Acetronics2]

Hi, Folks

So, replacing the 78xx series regulator by a LT 1083 ( 7.5 A )could be an idea ... instead of adding cells.


but ... I must raise AA cells (even the best : 2800 mah ) DO NOT reach the requested capacity ...

reminds me someone's projects ... but who's ???

Alain

[skimask]

reminds me someone's projects ... but who's ???
Alain

Are you thinking who I'm thinking?

[Acetronics2]

Hi, Ski

I'm glad to see your crystal ball went back from servicing ...

YOU WIN !!!

Alain

[mackrackit]

I am using the attached adapter. It should empower a circuitry with 4A for one hour (4Ah).

As a reference I have a 9V block battery, rechargeable, 200 mAh.

How are you figuring that?

Batteries in series, yes the volts are added. Amps are not. The amp output will be that of the weakest battery in the pack. If your batteries are 200mAh, then you can run a circuit drawing 200mA for one hour.

[Security]

Ok, let's get smart here...I'm leading you somewhere...

Answer these questions...in order...

1) What is the NOMINAL voltage of a standard AA NiMH cell (not the peak voltage, not the depleted voltage, not the voltage you read from the meter right now, but the NOMINAL voltage according to any NiMH, or NiCAD datasheet)?

2) How many cells do you have in your pack?

3) Multiply the number of cells in your pack by the NOMINAL voltage of each NiMH cell in that pack. What is that value?

You are asking the wrong questions. There is space for 6 batteries which amounts to 7.2Volts as you have already figured out. Adding two batteries is not possible here without creating a new adapter. And I am talking about creating in an injection molding sense.

If you got that opportunity you are lucky.

So, replacing the 78xx series regulator by a LT 1083 ( 7.5 A )could be an idea ... instead of adding cells.

Yes. As the one mentioned requires additional components to adjust the voltage a new circuitry is needed. This is what I desire to avoid.

[skimask]

You are asking the wrong questions.

I don't have to ask ANY questions. I'm just asking the questions so you can figure out what you're problem with the circuit is.

There is space for 6 batteries which amounts to 7.2Volts as you have already figured out. Adding two batteries is not possible here without creating a new adapter. And I am talking about creating in an injection molding sense.

If you've got a mold already, looks like you should've prototyped the circuit a bit better before creating a mold.
At any rate, whatever you decide to go with, if you look at the regulator's datasheet, you'll find a spec called the 'dropout' voltage or maybe (on the datasheet I'm looking at) 'Minimum Input voltage required to maintain line regulation'. In this case, it's 7.2v. You're battery pack is 6 cells, 7.2v NOMINAL. Put a decent load on those batteries, and you WON'T have 7.2v, could easily drop to ~6v even with a C/10 load (check the batteries spec sheet). And at 6v, you WON'T have 5v at the output, if you have an output at all.
If you change to a low dropout regulator (i.e. not a 7805 type, maybe an LT1129-5.0 type), you may get better performance from it (i.e. lower dropout voltage differential), thereby enabling your circuit to run at a lower input voltage.
Otherwise, looks like it's time for a redesign.

If you got that opportunity you are lucky.

Which opportunity is that?

[Acetronics2]

Hi, Selcurity

Adding two batteries is not possible here without creating a new adapter.

reaching one hour autonomy nor ...


For once, could you tell us what exists as a regulation ... you want to make work YOUR thing without changing anything ...

and it doesn't work yet !!! ... really funny.




Heuuuu, by the way ... LT 1083 EXISTS in fixed 5v output ...

Damned, ... its possible !

Alain

[skimask]

Heuuuu, by the way ... LT 1083 EXISTS in fixed 5v output ...

I wonder how far the battery voltage will drop under a 4A load...and if that battery voltage will be enough for even the LT1083 to still regulate properly...

[Acetronics2]

Hi, Ski

1.3v @ 7.5A ... that's Ok !

Note the MIC 2975x ... might only drop .3 to .5 v ( from my souvenirs )

But now ... 6 AA "hicap" NiMh cells should be around 0.45 Ohms internal resistance ... (0.223 - 0.3 measured for 4 CELL !!! )

a bit more for the wiring and awful connections ...

YOU WIN !!!

But 6 Sub C ... hé,hé ...

Alain

[skimask]

But now ... 6 AA "hicap" NiMh cells should be around 1.5 Ohms internal resistance ...
a bit more for the wiring and awful connections ...

You mean like this?
http://www.picbasic.co.uk/forum/show...2&postcount=32

YOU WIN !!!

What do I win?

But 6 Sub C ... hé,hé ...

Apparently that would require some sort of redesign...
Sub-C just might handle the load

[Acetronics2]

You mean Ted's work, I suppose ...

for sure !

Alain

[Security]

Acetronics, you are right: skimask, Ted's, mackrackit and Security are all the same person: me. Maybe "Get a life" is not such a bad advice I can give you here.

[skimask]

Acetronics, you are right: skimask, Ted's, mackrackit and Security are all the same person: me. Maybe "Get a life" is not such a bad advice I can give you here.

WOW!
Now THAT is a stretch!

[Acetronics2]

Hi,hi,hi "SelTedSec" you're really the best ...

too much "ApfelKorn" ??? ( Headache is really terrible ... )


Just look at Ski and Dave's photos ...

Not exactly the same "Boxing Category" ... between others. lol


Talking Electronics

I think your project is sunk ... now.

Alain

[skimask]

too much "ApfelKorn" ??? ( Headache is really terrible ... )

Oh hey! Thanks for reminding me of a particularly bad weekend back in Germany!
Wow that stuff tastes great, but the next day....holy crap!!!

[Acetronics2]

Wow that stuff tastes great, but the next day....holy crap!!!

I must agree ... twice at least.

Was not due to Berlin air quality, so ...

Thanks to God, I was just in the right position when I felt on my bed ...

Did you also tried the "Irish Mist" ... a great beverage too ...

Regards
Alain