I am working on a project that is requiring me to use a specific battery to power a specific pump. The pump I am using has a max current draw of 7A, with constant flow at 4A. They batter I need to use is 18V, so I am looking into using a linear voltage regulator to step down the voltage to 12V. I have very little experience with voltage regulators, however.

I found an L7812 voltage regulator, and am wondering if it would be sufficient.

These are the listed specifications:

Part Status:Active
Output Configuration: Positive
Output Type:Fixed
Number of Regulators:1
Voltage - Input (Max):35V
Voltage - Output (Min/Fixed):12V
Voltage Dropout (Max):2V @ 1A (Typ)
Current - Output:1.5A
Current - Quiescent (Iq):8mA
PSRR:55dB (120Hz)
Protection Features:Over Temperature, Short Circuit
Operating Temperature:0°C ~ 125°C
Mounting Type:Through Hole
Package / Case:TO-220-3

I am worried primarily about 2 things:
Does the dropout voltage increase if I draw more than 1A of current (since the pump draws 4A normally)
Is there a maximum current a voltage regulator is able to output, and if so, how do I tell what that maximum current is?

Any help is greatly appreciated, thanks.

 

Three-terminal linear regulators generally max out at 1A. Some are rated to 3A.

With 6V drop at 4A, the regulator would have to dissipate 24W.

LM7812 will not work. You need a buck converter that can handle 10A.

A pump is not fussy about voltage regulation. Power the 12V pump with a 12V battery.

 

If you must use a 18V battery than I second MrChips advice to use 10A, 12V buck regulator for best efficiency and minimum heat that you need to dissipate.

 

I am required to use the 18V battery, so switching to a 12V battery is out of the question. Would this buck regulator be sufficient for my needs?

The specifications are as follows:

Module Name: 12A DC Step Down Buck Converter
Module Type: Non-isolated step-down module
Module Size: 60*51*22mm
Input Voltage: 4.5V-30V
Output Voltage: 0.8V-30V ( continuously adjustable )
Output Current: 0A-12A 100W ( Can be up to 200W if enhance heat dissipation )
Work Temperature: -40 degree to + 80 degree
Switching Frequency: 300KHz
Transfer Efficiency: 95% (MAX)
Short-circuit Protection: Yes (Limited current 14A)
Over-temperature Protection: Yes (Automatically shut off the output once over temperature)
Reverse Voltage Protection: NO ( If need, please add large current tube.)
Connection Mode: Terminals or solder terminals. V-IN for input, V-OUT for output

The module has enhanced aluminum radiator and TVS tube, which make sure the work temperature be lower and safer. 50V/MLCC chip capacitor, combined with high frequency low resistance electrolytic condenser, make the output ripple lower.
Suitable for DIY of storage battery, power transformers, adjustable voltage regulator, 24V power supply, LED lights power supplies, industrial equipment step-down etc. and other work requirements. 12V to 3.3V, 12V to 5V, 24V to 5V, 24V to 12V and so on.

Transfer Efficiency test data:
Input 12V, Output 5V/10A, Efficiency 81%
Input 12V, Output 5V/6A, Efficiency 86%
Input 24V, Output 12V/8A, Efficiency 91%
Input 24V, Output 19V/6A, Efficiency 94%

Package Include:
1pcs 12A DC Step Down Buck Converter

 

yes

 

Be VERY cautious with those very cheap type converters from Amazon etc. Many use fake ICs or at the very least, are dramatically over-spec'd.
If you can afford to pay more, look for guaranteed manufacturers - from places like Digikey / Mouser / Element 14 etc - there's are literally 100s
of converters to chose from. Failing that, do a search for posts / threads from people who can vouch for an on-line listing.

 

Be VERY cautious with those very cheap type converters from Amazon etc. Many use fake ICs or at the very least, are dramatically over-spec'd.
If you can afford to pay more, look for guaranteed manufacturers - from places like Digikey / Mouser / Element 14 etc - there's are literally 100s
of converters to chose from. Failing that, do a search for posts / threads from people who can vouch for an on-line listing.

So I found this converter, but I am a little unsure about what I'll be getting and how to actually wire it. I do however trust this option a little more, and they have stock with both DigiKey and Element14

https://www.maximintegrated.com/en/products/power/switching-regulators/MAX17558.html/tb_tab0

Would this serve my needs? Also does anyone know what these look like? It seems like it might be some kind of IC

 

Would this serve my needs? Also does anyone know what these look like? It seems like it might be some kind of IC

Yes, that's just an IC controller.
It requires other components, including an inductor, a MOSFET, and likely a heatsink to make a complete circuit.
Building such a circuit is not for beginners.
You should look for a complete module that includes all those parts, such as the one you posted from Amazon.

 

MAX17558 ... Would this serve my needs? Also does anyone know what these look like? It seems like it might be some kind of IC

That's just an IC, way too much work. What country / state are you in? Do you have any electronics stores near you?
They will ALL have DC-DC converter DIN or enclosed types as well, off the shelf. Some vehicle spare parts stores should also have them.
You should be able to locally pick up 24V-12V converter, used in trucks etc. Check that they can go down to 18V (some start at 20V)
No need to take risks on www.
www.pbase.com/digsys/image/167965666 I've pulled apart dozens of those "shady" converters. Some people "upgrade" them, but it's not
worth the hassle.

 

Thanks for the help guys! If I have any more issues I'll post back on here.