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how much voltage will the vems take?

Started by Tony C, August 12, 2010, 11:47:52 AM

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Tony C

How much is the max limit the vems will take?
reason i ask i have been given a 240V/12v transformer,
and when powered up its giving a voltage reading of around 16.6 - 17.8 volts
this too high to power the vems up???

Vems Ecu, Twin Plenum efi and N2o
13.314 @ 104.39 mph (10/06/07 3.9 v8)
Sponsored by: www.caprisport.com & www.interpart.biz
Web site: http://www.capriracing.co.uk

Vems Firmware: V1.1.74

dnb

It's probably an unregulated power supply - as soon as you put load on it, the volts will drop to something more sensible.

I have seen 15v peak on my VEMS with no ill effects before now.

Sprocket

A 240v to 12v transformer is of no use as the 12v output will be AC. Unless of cource you are infact talking about an inverter which will give a '12v' DC output.

I personaly steer clear of unregulated power supplies as its a bit of an unknown in certain circumstances. In rush is a worry

dnb

Doesn't have to be AC.  Some have diode bridges in ;)

Tony C

this is defo 12V dc output,
says on the top.
240V AC / 12v DC

Vems Ecu, Twin Plenum efi and N2o
13.314 @ 104.39 mph (10/06/07 3.9 v8)
Sponsored by: www.caprisport.com & www.interpart.biz
Web site: http://www.capriracing.co.uk

Vems Firmware: V1.1.74

Sprocket

Quote from: dnb on August 12, 2010, 02:23:47 PM
Doesn't have to be AC.  Some have diode bridges in ;)

Its not exactly a transformer then, its a power supply :D

;);)

MWfire

ihmo vems has 18V zener diode for protection.

[email protected]

Theres a lot of over-voltage protection to handle the transient voltages caused by noise, cranking, alternator variation.
As said earlier if you're testing the voltage across the + and - terminals with no other load than the voltmeter then you're going to see a high value in an unregulated powersupply.
Try putting a 5K resistor across the terminals and measure the voltage across the resistor.

For a solid 12v supply I use a hard disk Power connector from Maplins and plug the VEMS into a spare PC PSU connection.

DI-Racing

  or, try an in line fuse,,works for me when dealing with unknown quantities ,,,;-)