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Why paralle battery is more save power?
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Boki
electronics forum Guru


Joined: 05 May 2005
Posts: 350

PostPosted: Fri Jun 02, 2006 10:00 am    Post subject: Why paralle battery is more save power? Reply with quote

Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Best regards,
Boki.
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Pooh Bear
electronics forum Guru


Joined: 24 Mar 2005
Posts: 3507

PostPosted: Fri Jun 02, 2006 10:21 am    Post subject: Re: Why paralle battery is more save power? Reply with quote

Boki wrote:

Quote:
Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Very likely.

Graham
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Fred Bartoli
electronics forum Guru


Joined: 02 May 2005
Posts: 457

PostPosted: Fri Jun 02, 2006 10:27 am    Post subject: Re: Why paralle battery is more save power? Reply with quote

"Boki" <bokiteam@ms21.hinet.net> a écrit dans le message de
news:1149242416.285444.25040@u72g2000cwu.googlegroups.com...
Quote:
Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?


Boky's style answer:

SMPS


--
Thanks,
Fred.
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Boki
electronics forum Guru


Joined: 05 May 2005
Posts: 350

PostPosted: Fri Jun 02, 2006 3:47 pm    Post subject: Re: Why paralle battery is more save power? Reply with quote

Pooh Bear wrote:
Quote:
Boki wrote:

Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Very likely.

Graham

why ?
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Pooh Bear
electronics forum Guru


Joined: 24 Mar 2005
Posts: 3507

PostPosted: Fri Jun 02, 2006 4:02 pm    Post subject: Re: Why paralle battery is more save power? Reply with quote

Boki wrote:

Quote:
Pooh Bear wrote:
Boki wrote:

Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Very likely.

Graham

why ?

Simple really. The batteries will produce only ~ 2.5V at end of life so a LDO
regulator can't make 2.8V from that ! There is no choice but to use a step-up
configuration.

Graham
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Don Lancaster
electronics forum Guru


Joined: 30 Apr 2005
Posts: 416

PostPosted: Fri Jun 02, 2006 4:52 pm    Post subject: Re: Why paralle battery is more save power? Reply with quote

Pooh Bear wrote:
Quote:
Boki wrote:


Pooh Bear wrote:

Boki wrote:


Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Very likely.

Graham

why ?


Simple really. The batteries will produce only ~ 2.5V at end of life so a LDO
regulator can't make 2.8V from that ! There is no choice but to use a step-up
configuration.

Graham



In general with a decent regulator, SERIES batteries will provide a much
longer lifetime than parallel ones.

Because the drawdown can be much deeper.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: don@tinaja.com

Please visit my GURU's LAIR web site at http://www.tinaja.com
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Roger Hamlett
electronics forum Guru


Joined: 28 Apr 2005
Posts: 302

PostPosted: Fri Jun 02, 2006 8:58 pm    Post subject: Re: Why paralle battery is more save power? Reply with quote

"Boki" <bokiteam@ms21.hinet.net> wrote in message
news:1149242416.285444.25040@u72g2000cwu.googlegroups.com...
Quote:
Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Best regards,
Boki.
The reason is because of the voltages involved, and how deeply the

batteries may be discharged. Some batteries can give useable power down to
very small fractions of their starting voltage. If the LDO, drops 0.1,
with two 1.5v batteries, the cell voltage can only drop to 1.45v, before
the rail starts to drop. A classic 'alkaline' battery, has a fairly linear
discharge curve, and at 50% of it's starting capacity, will already be
down to about 1.2v. They are useable down to about .9v, before being
considered fully discharged. The step up system, allows the whole of this
area to be used, but at the 'cost' of perhaps 5%, for the switcher losses.
Conversely, the series system, only allows perhaps the first 10% of the
batteries capacity to be used before the rail starts to drop. The
difference between perhaps 10% 'useable', and perhaps 85%...

Best Wishes
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Boki
electronics forum Guru


Joined: 05 May 2005
Posts: 350

PostPosted: Sat Jun 03, 2006 6:37 pm    Post subject: Re: Why paralle battery is more save power? Reply with quote

Roger Hamlett wrote:
Quote:
"Boki" <bokiteam@ms21.hinet.net> wrote in message
news:1149242416.285444.25040@u72g2000cwu.googlegroups.com...
Hi All,

A circuit needs 2.8V.

But designer didn't put it by two serial battery(1.5V+1.5V) with LDO to
2.8V.

It uses parallel battery and a voltage pull up IC.

Originally, I guess it is pull by capacitor, but he said that is pull
by inductor.

Is that true?

Best regards,
Boki.
The reason is because of the voltages involved, and how deeply the
batteries may be discharged. Some batteries can give useable power down to
very small fractions of their starting voltage. If the LDO, drops 0.1,
with two 1.5v batteries, the cell voltage can only drop to 1.45v, before
the rail starts to drop. A classic 'alkaline' battery, has a fairly linear
discharge curve, and at 50% of it's starting capacity, will already be
down to about 1.2v. They are useable down to about .9v, before being
considered fully discharged. The step up system, allows the whole of this
area to be used, but at the 'cost' of perhaps 5%, for the switcher losses.
Conversely, the series system, only allows perhaps the first 10% of the
batteries capacity to be used before the rail starts to drop. The
difference between perhaps 10% 'useable', and perhaps 85%...

Best Wishes

Professional!

Thank you very much!

Best regards,
Boki.
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