Nano Power Supply 12v bumped to 24v

[ssiewert]

It would be helpful if someone had some previous experience or recommendations in bumping up the typical 12v battery to Nano needs.  11.5-13.5 volts bumped to the 24v +/-5%.  

I don't want the added complexity and expense of two batteries, and the voltage of two in series would likely be outside the 24v +5% anyway, so some kind of voltage control is necessary.

I've found the Mean Well product-SD-15A-24 which will take 9-18vdc and give the 24vdc, but I don't need the 15 watt capability.  My preference would be to size for the 100ma the Nano calls for, and everything else run at battery voltage or less. (outputs 1&2 requiring diodes as per the manual).  

[support]

A boost type DC-DC converter should be able to output 24V from a range of input DC voltages. But DC-DC converter tend to be more expensive than batteries. Having two 12V batteries in series should be OK for the Nano-10 since these are DC output and will have little ripple in operation.

Nano-10 CPU alone draws approximately 120mA at 24V DC but this does not include current required to turn on output load or the relay coil. So you have to include in the load current as well when sizing your power supply.

[ssiewert]

A topping charge for two batteries could be 14.4 x 2 = almost 29 volts.  This wouldn't be an issue for the Nano?  I agree batteries have nice smooth power, but the Nano still has to be online when the batteries are getting recharged, so there will be voltage well over the 24+5%= 25.2v referenced in the spec.

The DC-DC power supply I mentioned is less than or equal to most the SLA batteries I'm looking at, and it would likely last longer than one battery.  There is no cost argument in favor of 24 volt that I can see.

On the Nano, 1&2 outputs sinking, 3&4 relays activated, 1-4 inputs sunk to ground, and the analogs pulling the maximum allowed, how many watts will the Nano use?  If someone doesn't recall immediately, there is design and testing notes for reference, no?

There is another reason to want everything but the Nano at 12 volts. The dc-dc power supply has a 30% loss.

[jbrandall]

For what it's worth:  For 2 years I have used step up converters to run 2 nano1's each.  Mine came from virtualvillage, but sure look like the ones I just found on ebay:

http://www.ebay.com/itm/12V-to-24V-Step-up-Power-Converter-Module-DC-to-DC-/180702970695?pt=LH_DefaultDomain_0&hash=item2a12bc8347

I don't know all the technical stuff but they worked outside in the hot sun and powered a few additional relays.  I am currently upgrading to FMD 16-16's that run on 12 volts and have 10 or 12 nano's and 6 or 7 converters to sell. jbr651@gmail.com

[ssiewert]

Good to hear the 12 to 24 volt conversion has worked for you.  Thanks for the post.

[support]

On the Nano, 1&2 outputs sinking, 3&4 relays activated, 1-4 inputs sunk to ground, and the analogs pulling the maximum allowed, how many watts will the Nano use?  If someone doesn't recall immediately, there is design and testing notes for reference, no?

The PLC draws around 0.15A when the two relays are turned ON and all inputs are turned ON. This does not include current for the load that are connected to the relay contacts. Also output 1&2 can sink as much as 2A current continously. How much current will your output draw depends on the load power requirement so you have to determine that.