Electronics > Projects, Designs, and Technical Stuff
How to convert 14.8V @ 10A Lipo battery output to 12V@10A ?
<< < (3/4) > >>
mariush:
Digikey has a category of products for this, dc-dc converters:

For example, this would work but it costs around 30$ : https://www.digikey.com/product-detail/en/tdk-lambda-americas-inc/I6A24014A033V-001-R/285-2434-ND/5481911

The datasheet only shows 14v in -> 12v out in graphs, but it will probably work with as little as 13v.

If you want super cheap and don't care about efficiency, you could just grab two or three  LM1084  (linear regulators) and parallel them using a 0.1 ohm resistor for each one as balancing resistors.  See page 15 in https://www.analog.com/media/en/technical-documentation/data-sheets/108345fh.pdf  but replace "2 feet of AWG18 wire" with a 0.05 ohm 1w resistor or something like that (AWG18 has around 0.021 ohm per meter/3ft of resistance)

Each 1084 has a peak current of 5A, so if you use 3, each regulator would have around 3.3A of current going through it.

The 1084 has a typical voltage drop of around 1.3A at 5A of current, but keep in mind they must be cooled... the total amount of heat they can dissipate is around 15 watts.

So LM1084/LT1084/*1084 could be used to output 12v with as little as 13.5v

Also, you should think about the maximum voltage the motor supports.
When the voltage drops below some threshold, it may be easier and cheaper for you to just use a mechanical relay to switch a dc-dc regulator and direct / through a bridge rectifier

Also... if you know the voltage is not gonna be above 14-15v and your motor isn't super picky about voltage then in theory you could use a bridge rectifier and a mechanical relay to drop some voltage

A bridge rectifier has 4 diodes inside, and depending on how you connect the wires, you could have two diodes in series to drop around 2v or you could have one diode and drop only 1v

For example see this 1.25$ 20A bridge rectifier : https://www.digikey.com/product-detail/en/smc-diode-solutions/GBJ2006TB/1655-1863-ND/7244891



Could have a voltage comparator or microcontroller or something enable the relay only when voltage goes above 13v... in default state relay is connected so that only 1v is dropped, if voltage is above 13v relay turns on and switching changes so you drop 2 x 1-1.1v
A 12v relay would work with 10v..15v, no worries.
 

james_s:
If you're just running a DC motor you don't need a regulator at all. Most DC motors will happily run at twice their rated supply voltage and usually down to 1/10th or less. If maintaining a specific RPM is critical then you should use a motor with a tachometer output and PWM control of the speed, otherwise just run it directly, it will be fine.
Simon:
12.8V is a fully charged lead acid battery at rest (more in fact), do you have a lead acid battery? if you cut off at 12.8V it may never work. If you are powering a "nominally" 12V motor 14.8V is fine.
IDEngineer:

--- Quote from: james_s on July 20, 2019, 06:38:10 pm ---If you're just running a DC motor you don't need a regulator at all. Most DC motors will happily run at twice their rated supply voltage and usually down to 1/10th or less. If maintaining a specific RPM is critical then you should use a motor with a tachometer output and PWM control of the speed, otherwise just run it directly, it will be fine.
--- End quote ---
I agree and was going to post something similar. If he doesn't need to control speed closely and just wants to protect the motor from "excessive" voltage, he could just do a raw PWM circuit and run it at high duty cycle. A MOSFET won't dissipate too much heat, no problems with gate drivers that suffer from high duty cycles, and he can ratchet the effective applied voltage down to whatever he likes.
ogden:

--- Quote from: Simon on July 20, 2019, 08:09:25 pm ---12.8V is a fully charged lead acid battery at rest (more in fact), do you have a lead acid battery?

--- End quote ---

I bet it is 4-cell 3.7V LiPo.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod