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### Topic: How to make a constant 12.5-11V battery (Read 408 times)previous topic - next topic

#### Tofer

##### Mar 24, 2019, 01:01 pmLast Edit: Mar 25, 2019, 04:07 pm by Tofer
Hello! I need a power supply working from a battery pack that provides 12.5V maximum when it is fully charged and not less than 11V when it is discharged. I'm thinking about 4S LiIon. But it is going to be 16.8V when it is fully charged and around 12V when it is discharged. It seems I need some kind of a reliable voltage regulator that changes the voltage according to the battery voltage level. Are there any bucks that can do it and supply 6A even when it is 12V on the input?

#### Paul_KD7HB

#1
##### Mar 24, 2019, 05:07 pm
Hello! I need a battery that provides 12.5V maximum when it is fully charged and not less than 11V when it is discharged. I'm thinking about 4S LiIon. But it is going to be 16.8V when it is fully charged and around 12V when it is discharged. It seems I need some kind of a reliable charge controller that changes the voltage according to the charge level. Are there any bucks that can do it and supply 6A even when it is 12V on input?

Batteries are charged with current, not voltage. A reliable charge controller will control the current based on battery voltage and TEMPERATURE. Those parameter are ALL based on the chemistry used in batteries.

Paul

#### Robin2

#2
##### Mar 24, 2019, 05:38 pm
Quote
How to make a constant 12.5-11V battery
Learn battery chemistry and equip yourself with an expensive laboratory.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

#### jremington

#3
##### Mar 24, 2019, 06:06 pmLast Edit: Mar 24, 2019, 06:07 pm by jremington
Quote
not less than 11V when it is discharged.
That would violate the laws of physics.

A better idea is to take a battery with suitable capacity and use a regulator of some sort to produce the required voltage and current.

#### Tofer

#4
##### Mar 24, 2019, 08:53 pm
That would violate the laws of physics.

A better idea is to take a battery with suitable capacity and use a regulator of some sort to produce the required voltage and current.
Exactly! This is what the question was about.))

#### Robin2

#5
##### Mar 24, 2019, 09:57 pm
Exactly! This is what the question was about.))
Well why didn't you say so in your Original Post ?

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

#### Tofer

#6
##### Mar 24, 2019, 10:35 pm
Well why didn't you say so in your Original Post ?

...R
Quote
It seems I need some kind of a reliable voltage controller that changes the voltage according to the charge level. Are there any bucks that can do it and supply 6A even when it is 12V on input?

#### MarkT

#7
##### Mar 24, 2019, 11:29 pmLast Edit: Mar 24, 2019, 11:31 pm by MarkT
Hello! I need a battery that provides 12.5V maximum when it is fully charged and not less than 11V when it is discharged.
Then you have big problems.  Reality doesn't make such batteries.

Perhaps you meant a 12V power supply, running from batteries?  I'd suggest
a LiPo cell and boost converter as one simple approach.

However its possible you need to monitor the state of charge too?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

#### Tofer

#8
##### Mar 25, 2019, 04:05 pm
Then you have big problems.  Reality doesn't make such batteries.

Perhaps you meant a 12V power supply, running from batteries?  I'd suggest
a LiPo cell and boost converter as one simple approach.

However its possible you need to monitor the state of charge too?
This is what I mean, sorry!

#### vinceherman

#9
##### Mar 25, 2019, 04:32 pm
Google says this should get you close to your requirements.

https://hobbyking.com/en_us/quanum-12v-5a-7-2-25-2v-dual-output-ubec.html

#### Tofer

#10
##### Mar 31, 2019, 11:15 pm
I can't find it in my country(

#### jremington

#11
##### Mar 31, 2019, 11:59 pm
Mail order works in most places.

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