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how to convert 12v battery power to 9v? Answered

I need to convert 12v down to 9v(easy) but it must be a high amp output




Best Answer 3 years ago

Here is a power 12 volt to 9 volt down adjustable regulator for that Glow Plug...


Hi back to the drawing board melted the 7809 do they come in a bigger size?

the only T-220 size replacement is a LM-1084 Used the same pinout and the same calculations as the 317 Cept this one has a 5A rating :)

That ckt uses an LM317 a TO-220 ... ? ! ?

Not anymore, but You might find one as a TO-3 (only 3A) on eBay or other lost supplier of brick-brack.

Lastly use a switching power supply about 25A capable.

thanks to all for answers so far,other comments most grateful,thanks


3 years ago

It can not be more them1.3 times the rated current of your battery but you must use a down switcher.

What is the capacity (amp hours) of your battery ??

+1 We like numbers !

Can you also tell us what you concider High Amp?

I was hoping that the battery capacity would clue us in ... however chippy only joined today and may not know how to get alerts on his inquiry.

Of course he could have been a lurker for a time...

not lurker,just looking for help the battery is 100ah 12v,glow plugs are 9v,and i dont wont to fry them,no existing wiring,so am trying to get the volts down,there are 4 glow plugs,help

Hey,... there's a Lurker... and a fast Response ;)

In all Fairness, I lurked for a few years before I Joined :)

For a Glow plug, how much current do you need? a 9 Volt System seems odd...

Any more Details??

Pics of the parts are Nice :)

low plug has 9volt printed on it,so i asume it needs 9v but i dont know much about them,looked at others some are as low as0.09 of a volt some are 11volt but its this ones that fit my engine,i have blown a different set already and they are expensive! Help

pull up Google and search Voltage regulator a LM7809 will take 12V and bring it down to 9V

You may be able to use a simple resistor but it`s the most crude way to go about it.

Are they easy to do?or do i need more components?

If you can find that exact part, it doesn`t require Extra Components. You can add some Caps for voltage stability, but your application you should be ok without them :)

not sure about the high amp thing but the battery is 100ah

Start current is more then a 7809 1A current delivery.


3 years ago

Diesel engine glow plugs?

Those usually have a relay. My ancient VW has a little can relay that runs the plugs for a set period of time and then shuts them off. It is possible that your relay is bad if its burning out plugs. Since it is designed as a system I would think there is a voltage regulator built into it. I always bought a set of new plugs and the relay/controler as a kit.