Hi,

Whats the best way to bump the 12v rail to 13.8?
I do need to keep the amps (20, 30 and 40)

Thanks for your time.
Eric

 

what is the power source at this moment???

 

The 12v source is a ac to dc converter switching power supply.

 

Then just adjust it to give 13.8V instead of 12V - why do you want 13.8V anyway?.

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You realize you are going to lose a bit of amps right? Power in always greater than power out, and you are turning some of it into higher voltage so that means a little less current.

Is there a reason you need it at 13.8V and not 12V though? I would imagine most things would run fine like that. I think 12V would be the nominal voltage for a 12V SLA battery and 13.8V is the peak voltage for the same battery pack.

 

hi,

As the amps are pulled (about 6 amps) the voltage tends to drop to around 11.4v

I am using it to power my chargers. They will error out at times complaining of loss of voltage due to this drop in to 11.4.

Is there a "POT" I can turn? Or do I need to add something?
How much amp drop would I be looking a you think?

 

If I understand you right, your power source can't provide enough power. YOu need another power source. YOu can't make extra voltage and current from nothing. A 12V supply that could actually supply 20A doesn't need to be bumped up to 13.8V.

Your local hobby store probably sells some power supplies.
http://www.fcsurplus.ca/shopping/sho...Power+Supplies

I use the PS26KX.

 

is it typical for a 12v power supply to drop to 11.4 volts at 6 amp pull?

Or is this a regulator problem?



I understand you cant get it form nothing but I have seen talk about putting a load on different voltage rails to increase the 12v rail or atleast make it stronger.

Like adding a sand bar to the 5v+ to increase the 12v.

 

you probably need make your own power booster for the big current you listed.

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F.N.

 

It's not typical for a 12V, 20A power supply. It probably is typical for a 12V, 7A power supply. Power supplies have a current rating and if you go beyond that, the power supply either overheats or the voltage droops down to zero as you pull more current.

Are you talking about placing a capacitor between the rails to supply the peak current demand? That might work if the peak currents are small enough for a short enough time and the converter is able to handle the average current over time, but not the peak currents.

 

Where this measurement was taken/if it is at the load point, obviously the lead drop would be there. the regulation components generally have to monitor the last point where from the load is to be connected. More expensive units have a 4 wire arrangement and the voltage feed back is taken right from the load itself. this type caters for correcting the voltage drop across leads to some extent.
then, if the output is taken after an isolating diode in series to the +ve lead, the voltage will drop on load , while on open measurememt with a DMM it might show 12V.

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Regards,
Sarma.

 

while underload I used my MM to check.

 

What is the amp rating on the power supply?


Torben

 

The difference 12-11.4, indicates a possible diode in series to load. If so, it is better to set it to the required voltage+diode drop.

__________________
Regards,
Sarma.

 

20A max on the 12v rail