What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 · November 2013

Ive edited this post. title is incorrect.

I am looking to deploy WiFi AP, wireless receiver, and a router. I want them powered 24/7 without using AC. They need to be self sufficient.
I need to power 3 devices at 24V using a total of 20Watts. I need the devices to be on 24/7. What would be the recommended cheap way of doing this. I was considering purchasing: solar panel/s?, batteries, voltage regulator, charging module. I was planning on powering the devices by the battery using a voltage regulator to try to normailze the voltage for the devices. I was planning on using the solar panels and a charging module to charge the batteries.
What would be the recommended type of battery and solar panel and charging module to accomplish such a task. These devices will be on roof tops. No trees. This is SouthEast WI. It gets cold.

jcheil · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

Don't try to do it without an AC inverter.

You will never get the perfectly regulated 12v needed to run the equipment from the batteries because the battery voltage can vary from 10.5-15.5 volts throughout the day and may damage the equipment or cause it to malfunction.

Better off just getting a very small pure sine wave inverter and using the AC power supplies that came with it.

If you absolutely cannot use an AC inverter, then you would have to get an expensive regulated 12v power supply that will accept that varied input voltage of 10.5-15.5 volts and produce a constant 12v out.

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

What you quote is 36W or 864Wh/day. This is a consumption of a small fridge and will require quite a big system.

However, your devices probably use much less, and if they don't, you may be better off buying newer, better devices. I would use Kill-a-Watt or other meter to measure what your devices are actually consuming. I bet it'll be less than 864Wh/day.

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

jcheil wrote: »

Don't try to do it without an AC inverter.
You will never get the perfectly regulated 12v needed to run the equipment from the batteries because the battery voltage can vary from 10.5-15.5 volts throughout the day and may damage the equipment or cause it to malfunction.

jcheil wrote: »

If you absolutely cannot use an AC inverter, then you would have to get an expensive regulated 12v power supply that will accept that varied input voltage of 10.5-15.5 volts and produce a constant 12v out.

At the cost of an inverter compared to a voltage regulator. Wouldnt a regulator be better to use and more cost effective?

jcheil wrote: »

Better off just getting a very small pure sine wave inverter and using the AC power supplies that came with it.

Is it truely better for me to go from 12v DC to an inverter and power the devices using there 120V transformers to 12V DC? That seems like it would waste more energy converting? I am not an electronics guru, so just asking.

NorthGuy wrote: »

What you quote is 36W or 864Wh/day. This is a consumption of a small fridge and will require quite a big system.

However, your devices probably use much less, and if they don't, you may be better off buying newer, better devices. I would use Kill-a-Watt or other meter to measure what your devices are actually consuming. I bet it'll be less than 864Wh/day.

I dont truly understand the power thing but I doubt seriously that the 3 devices need the same amount of power as a fridge. These devices are brand new 2013 released items. I just looked at datasheets on the devices. The Wifi AP its max consumption is 4W (Accepts 12 -24V Input). Router is Max 7W (Accepts 9 - 24 Input). Wireless Reciever is 8W (12 - 24V Input)

So to revise my OP question...
I need to power 3 devices at 24V using a total of 20Watts. I need the devices to be on 24/7. What would be the recommended cheap way of doing this. I was considering purchasing: solar panel/s?, batteries, voltage regulator, charging module. I was planning on powering the devices by the battery using a voltage regulator to try to normailze the voltage for the devices. I was planning on using the solar panels and a charging module to charge the batteries.

vtmaps · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

Welcome to the forum,

pctech101 wrote: »

The WiFi AP and Router are both requiring 12V DC 1A each. The wireless receiver requires 24V .5A

12 volts at 1 amp is 12 watts. 24 volts at 0.5 amp is also 12 watts.

pctech101 wrote: »

The Wifi AP its max consumption is 4W (Accepts 12 -24V Input). Router is Max 7W (Accepts 9 - 24 Input). Wireless Reciever is 8W (12 - 24V Input)

But now you indicate the power draw is much less than 12 watts.

Once you figure out your actual daily draw you can size your battery. After sizing your battery, you need to figure out how many watts of solar panels you need to charge them, and what charge controller to use. But first the battery size... How many days without sun do you want to plan for? Also, where are you located? What temperature will the batteries be in the winter (reduced capacity with lower temp)?

--vtMaps

westbranch · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

I just looked at datasheets on the devices. The Wifi AP its max consumption is 4W (Accepts 12 -24V Input). Router is Max 7W (Accepts 9 - 24 Input). Wireless Reciever is 8W (12 - 24V Input)

Not a facetious question as a battery can keep pumping out volts lower than 12 V...

What happens at 11.9 or lower volts for those listed as 12 - 24 V?

Can you post the brand/model for these units?

Strange this is an exact repeat of the same question a few days ago??

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

vtmaps wrote: »

Welcome to the forum,

Thanks

vtmaps wrote: »

But now you indicate the power draw is much less than 12 watts.

Once you figure out your actual daily draw you can size your battery. After sizing your battery, you need to figure out how many watts of solar panels you need to charge them, and what charge controller to use. But first the battery size... How many days without sun do you want to plan for? Also, where are you located? What temperature will the batteries be in the winter (reduced capacity with lower temp)?

--vtMaps

I am in SouthEast Wisconsin.

Reciever:
NSM5
http://dl.ubnt.com/datasheets/nanostationm/nsm_ds_web.pdf

Router:
Edge Lite
http://dl.ubnt.com/datasheets/edgemax/EdgeRouter_DS.pdf

AP:
Unifi AP
http://dl.ubnt.com/datasheets/unifi/UniFi-AP-DS.pdf

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

I need to power 3 devices at 24V using a total of 20Watts.

4 + 7 + 8 = 19W. If they were consuming this 24/7, they would consume 456Wh. But that's the peak. They don't consume at peak all the time. Actual consumption might be half of this or less. There's no substitute for measurement. Of course, you can size for 456Wh, but that would be a waste of money.

pctech101 wrote: »

What would be the recommended cheap way of doing this.

Connecting to grid would most likely be the cheapest.

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

vtmaps wrote: »

Welcome to the forum,

12 volts at 1 amp is 12 watts. 24 volts at 0.5 amp is also 12 watts.

But now you indicate the power draw is much less than 12 watts.

I think it is 19Watts MAX that is needed

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

If I use 2 twelve volt batteries in series, I roughly get 24 Volts. Right?

Anything below 12 volts and the signal decreases and the coverage will shrink.
I can power my devices with this probably until the voltage gets to 9 volts. Then the devices wont power on.

If the devices require MAX 19Watts. And I use 2 batteries in series to supply roughly 24 Volts. I will make or buy a voltage regulator so that no more than 24 Volts is applied to my devices. How many Ah's do the batteries need to be to supply voltage for 24 hours? 50Ah should provide 24 hours of usage (googling this stuff as I go)(2 12V 50Ah in series), right? Can a solar panel fully charge these batteries in daylight hours daily from what the devices draw? I have no idea what is needed to charge a 12V 50Ah battery running in series.

Staying off the grid, is this the best way to do it, using 2 batteries to get 24 volts and a solar panel/s to recharge the batteries.
Or is using the inverter method cheaper.
All the devices can be powered through 120V transformer which output 12V 1A, 12V 1A, and 24V .5A.
Or is using 1 battery with more Ah's better.

Im sure I can do this a number of methods. I am asking for help in determining what will be the best solution for reliability and cost.

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

I am asking for help in determining what will be the best solution for reliability and cost.

Yes, you would need batteries, solar panels, charge controller etc. The cost is, sort of, proportional to the size of these things. Cost for 500Wh/day (based on peak consumption) system will be neraly twice as much as the cost for 250Wh/day system (based on actual consumption). Therefore, it is important to know (measure) the actual consumption. If you don't do that, your only choice is to go with oversized (or undersized if the spec sheeds underestimate consumption) 500Wh/day system.

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

NorthGuy wrote: »

Yes, you would need batteries, solar panels, charge controller etc. The cost is, sort of, proportional to the size of these things. Cost for 500Wh/day (based on peak consumption) system will be neraly twice as much as the cost for 250Wh/day system (based on actual consumption). Therefore, it is important to know (measure) the actual consumption. If you don't do that, your only choice is to go with oversized (or undersized if the spec sheeds underestimate consumption) 500Wh/day system.

Okay. I will test the devices when I get the tools to measure. If my multimeter doesn't support amps/watt readin. Thanks

BB. · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

A DC Amp*Hour/Watt*Hour meter is nice for smaller loads/system.

A DC Current Clamp meter can help estimate current draw without having to do the typical insert DMM in wiring thing.

If you are ever going to do more monitoring on your system... A Battery Monitor (like the Trimetric) or Victron is really nice. But they are not "cheap" and can be hard to justify for smaller systems.

-Bill

jcheil · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

I'm just saying, I have personal experience with this stuff (especially computers), they will NOT like seeing voltages outside of their SPECIFIC designed voltage. I posted this before because a friend tried to do the SAME thing with his DVR CCD Camera security system at his camp and when the voltage dropped into the 11's, random devices would reboot (or freeze up), then one day when the system was in equalization (15.4v) the blue smoke came out of some of them

Sure they might "tolerate" a small fraction of a volt, but many of those devices (precision electronics) will act strange when seeing a voltage other than exactly 12v (or whatever they are asking for).

With an inverter, even if your batteries get down to 10.5 (which you should not let happen), you will always get that perfect 12v from the supplied transformers that came with the devices. Sure there is a loss converting DC to AC and then back to DC but with a small pure sine wave inverter I would consider that to be worth it.

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

jcheil wrote: »

Sure they might "tolerate" a small fraction of a volt, but many of those devices (precision electronics) will act strange when seeing a voltage other than exactly 12v (or whatever they are asking for).

Some devices are specially made to tolerate voltage swings. For example, I am now considering ALIX boards that stephendv suggested. They can tolerate voltages from 7 to 20V! The board I consider has 3 LAN ports, you can install Wi-Fi radio mini-PCI card and you get a full i86 computer, which, BTW, you can use as a router, switch, etc. Most people run Linux, but some even run Windows XP. And it only consumes 6W (some of the configurations even only consume 5W). Of course, Wi-Fi card will add 1W to it, but still.

So, by choosing solar-friendly devices, it is possible to avoid these problems and also cut the consumption.

jcheil · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

NorthGuy wrote: »

Some devices are specially made to tolerate voltage swings. For example, I am now considering ALIX boards that stephendv suggested. They can tolerate voltages from 7 to 20V! The board I consider has 3 LAN ports, you can install Wi-Fi radio mini-PCI card and you get a full i86 computer, which, BTW, you can use as a router, switch, etc. Most people run Linux, but some even run Windows XP. And it only consumes 6W (some of the configurations even only consume 5W). Of course, Wi-Fi card will add 1W to it, but still.

So, by choosing solar-friendly devices, it is possible to avoid these problems and also cut the consumption.

Yeah, but YOU are way smarter than the average bear when it comes to those kind of electronics

99% of the world just buys "off the shelf" devices and some of them don't like the variations.

zoneblue · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

I disagree. If thats all its doing, and all the gear is nearby, use a 24v battery, and whatever dc converters you require for your gear.

If you have gear already, chances are it will be a rainbow spectrum of plug packs. 5v, 7.5V, 9v, 12v, 19v etc. These voltages are all doable with 3 dollar dc converters such as the ones i use:

http://dx.com/p/mini-dc-dc-voltage-stabilizer-regulator-module-red-126106

If you are wanting to run small computers that require an atx compatible power supply, i have used these before and foudn them reliable:

http://www.ebay.com/itm/130W-mini-ITX-ATX-Power-DC-DC-converter-Pico-PSU-Y2-/181252102012?pt=PCA_UPS&hash=item2a3377977c

They have a wide input range and will power even up to small sandy/ivy bridge systems. Alix tends to be expensive, hence ive steered away from them, and use intel atom dual nic boards such as D2500CC. There performance is 10x better, for about twice the power use, and a quarter the cost.

There are/will be ARM based gigE solutions appearing soon, such as cubietruck.

Pico and similar for smaller PSUs. However many of the newer low power mini-itx boards now have a 12v socket.

Theres also the hacked wifi router route, which is also suitable for your task maybe.

http://en.wikipedia.org/wiki/List_of_wireless_router_firmware_projects

Hopefully that gives you some ideas.

ZB

jcheil wrote: »

Don't try to do it without an AC inverter.

You will never get the perfectly regulated 12v needed to run the equipment from the batteries because the battery voltage can vary from 10.5-15.5 volts throughout the day and may damage the equipment or cause it to malfunction.

Better off just getting a very small pure sine wave inverter and using the AC power supplies that came with it.

If you absolutely cannot use an AC inverter, then you would have to get an expensive regulated 12v power supply that will accept that varied input voltage of 10.5-15.5 volts and produce a constant 12v out.

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

zoneblue wrote: »

Alix tends to be expensive, hence ive steered away from them, and use intel atom dual nic boards such as D2500CC. There performance is 10x better, for about twice the power use, and a quarter the cost.

It is interesting how prices are stacked in different parts of the world. In Canada, D2500CC based computer consts about 50% more than ALIX. D2500CC certainly is more powerful, but looks like it consumes around 25W - 4-5 times more than ALIX. That's almost the same 40W as my current server based on last-millenium desktop computer.

jcheil · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

zoneblue wrote: »

I disagree. If thats all its doing, and all the gear is nearby, use a 24v battery, and whatever dc converters you require for your gear.

If you have gear already, chances are it will be a rainbow spectrum of plug packs. 5v, 7.5V, 9v, 12v, 19v etc. These voltages are all doable with 3 dollar dc converters such as the ones i use:

http://dx.com/p/mini-dc-dc-voltage-stabilizer-regulator-module-red-126106

If you are wanting to run small computers that require an atx compatible power supply, i have used these before and foudn them reliable:

http://www.ebay.com/itm/130W-mini-ITX-ATX-Power-DC-DC-converter-Pico-PSU-Y2-/181252102012?pt=PCA_UPS&hash=item2a3377977c

They have a wide input range and will power even up to small sandy/ivy bridge systems. Alix tends to be expensive, hence ive steered away from them, and use intel atom dual nic boards such as D2500CC. There performance is 10x better, for about twice the power use, and a quarter the cost.

There are/will be ARM based gigE solutions appearing soon, such as cubietruck.

Pico and similar for smaller PSUs. However many of the newer low power mini-itx boards now have a 12v socket.

Theres also the hacked wifi router route, which is also suitable for your task maybe.

http://en.wikipedia.org/wiki/List_of_wireless_router_firmware_projects

Hopefully that gives you some ideas.

ZB

Sure that would work IF he wanted to go UP to a 24v battery system to run 12v devices.

But then all those little DC-DC converters just more things to break and wire up properly IMO. And yes I know you are essentially replacing the AC transformer with the DC converter, but lets face it, those AC transformers are pretty much solid now-a-days.

But if I recall from previous posts (could be mistaken), ZoneBlue, you are a big fan of DC everything so I completely understand where you are coming from (and please no offense intended at all).

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

I am willing to go to 24V. I thought it was a better alternative. One of the devices I want to use is powered over ethernet and it requires 24V for nominal performance. I thought going to 24V would save a lot of problems since my devices will work between 12 - 24V. I don't know how much a battery will drop when not being charged by a solar panel while powering my devices, yet.

jcheil · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

I am willing to go to 24V. I thought it was a better alternative. One of the devices I want to use is powered over ethernet and it requires 24V for nominal performance. I thought going to 24V would save a lot of problems since my devices will work between 12 - 24V. I don't know how much a battery will drop when not being charged by a solar panel while powering my devices, yet.

But again, now you are saying you have something that NEEDS 24v. If that is the case then you would have to further increase your battery bank voltage above 24v to be able to use a DC-DC converter to assure you always have at LEAST 24v because a 24v bank can go as low as 21v and as high as 30v. When you were talking about all 12v(ish) devices, going up to 24v battery bank assured that your 24v-12v DC-DC converters would always have at LEAST 12v as the source voltage.

I know everyone has their opinions, but seriously, look how complicated this is getting? Just get a small PSW inverter and be done with it. Everything works right out of the box on 110v, no hassle. You are gonna have a MESS of little converters and wires with different DC voltages on them hanging all over the place. Again, just my opinion.

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

If I need 20w and I have an 75w inverter (i believe its input voltage is 12-24) and use it to pwer said devices. What size, amount of batteries, solar panel wattage should I use.

I haven't ran any of the devices via battery to test the performance at 12 v. I am sorry I asked before getting all information before hand. I didn't know what to ask. Once I do more testing I will determine if stuff will run at 12 and keep connections.

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

I don't know how much a battery will drop when not being charged by a solar panel while powering my devices, yet.

You should expect 11-16V in 12V system, or 22-32V in 24V system.

It'll be somewhat smaller variation for AGM batteries because you do not equalize them. Your devices should tolerate 11-15V in 12V system, or 22-30V in 24V system.

If that's Ok with your devices, DC is your best bet. If not, replacing some of the non-compliant devices may be a cheaper alternative.

Rybren · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

If I need 20w and I have an 75w inverter (i believe its input voltage is 12-24) and use it to pwer said devices. What size, amount of batteries, solar panel wattage should I use.

I haven't ran any of the devices via battery to test the performance at 12 v. I am sorry I asked before getting all information before hand. I didn't know what to ask. Once I do more testing I will determine if stuff will run at 12 and keep connections.

Get a Kill-a-Watt meter and run your devices through it using the supplied AC-DC adapter. Let the items run (while using them) for at least a 24hr period. You'll then have a pretty good idea of what they will consume and you can size your battery bank accordingly.

zoneblue · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

NorthGuy wrote: »

It is interesting how prices are stacked in different parts of the world. In Canada, D2500CC based computer consts about 50% more than ALIX. D2500CC certainly is more powerful, but looks like it consumes around 25W - 4-5 times more than ALIX. That's almost the same 40W as my current server based on last-millenium desktop computer.

Thats interesting, alix more or less requires your first born child here. Stuff that originates from the pacific tends to land here cheaper than anything atlantic originated. The US is the absolute worst frieght wise, probably some kind of indirect export tarif. As a rule if theres a choice we buy stuff anywhere ahead of the US.

Re 2500CC, about 10W for the board minus drives. But i agree 10W is a bit, I only use my server during the day, and the drives certainly use as much as the board! Watch out for the silvermont atoms NG, they are due out at christmas, they promise 3 times better efficiency. Its called intel trying to catch up to the ARM market.

zoneblue · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

Complicated, hmm, complicated you say?

If the system concerned has no ac loads at all, why use a dual conversion through ac? How can a system with two layers of converters be more complicated than a system with one? How can a system that has to dance a delicate balance of having an inverter sized just big enough to run the loads, but not have a large idle draw, be less complicated?

And thats without taking into account cost. In a tiny system like this the idle and dual conversion losses of using an inverter, potentially double the size of the array and battery. How is that any less expensive? How does adding an inverter make it less expensive? You certainly dont want some nasty thing that will go pop the third time you plug it in. So you need to lay the bucks for a name brand. That puts you into a bigger inverter, at least 300W. Worrying about the inverter... now thats complicated.

I never said that dc is right for everything, we use ac for power toolds, kitchen tools, laundry the same as anyone.
And as for a mess of wires, thats life. Take a look behind your pc or tv.

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

zoneblue wrote: »

Watch out for the silvermont atoms NG, they are due out at christmas, they promise 3 times better efficiency. Its called intel trying to catch up to the ARM market.

May be something with a power footprint of ARM comes out of Intel, requiring only 2W of power. Sort of, Intel based Raspberry-PI. Intel needs to hurry with that before everything gets ported to ARM. My ARM-based phone is very powerful and has extremely low power consumption, definitely less than 1W. If I could go to ARM without big hassles, I definitely would.

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

I have some 12v batteries laying around at work. I am going to try powering my one device with higher wattage demand and see if it will run safely on a battery. I will also test it using 2 12v batteries. Once I determine if it will function stabley at whichever voltage I will post more info as to my needs. I think devices will probably run perfect on 2 12v batteries for a 24v supply but instead of guessing, I will attempt. Most of the hardware has temp sensors and I can monitor performance during usage. Once I know if 24 vs 12. I will get help finding best batteries and solar panel. Thanks for thoughts so far

NorthGuy · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

I have some 12v batteries laying around at work. I am going to try powering my one device with higher wattage demand and see if it will run safely on a battery. I will also test it using 2 12v batteries. Once I determine if it will function stabley at whichever voltage I will post more info as to my needs. I think devices will probably run perfect on 2 12v batteries for a 24v supply but instead of guessing, I will attempt. Most of the hardware has temp sensors and I can monitor performance during usage. Once I know if 24 vs 12. I will get help finding best batteries and solar panel. Thanks for thoughts so far

They probably will run fine on the batteries if you simply connect them, because the voltage of a charged battery at rest is close to nominal and very stable.

However, when a charge controller starts charging the batteries, the voltage will rise. Also, for battery maintenance, you may need to do a procedure called equalization, where the voltage rises even further. When batteries get discharged, the voltage falls. You need to test all these situations.

pctech101 · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

That sounds like regulation stuff. Once I find my supply voltage I will regulatemy voltage. At this point there is no need to worry about it. Thanks for the. Heads up though.

jcheil · November 2013

Re: What do I need to power my project? 12V DC 2A draw + 24V .5A draw

pctech101 wrote: »

That sounds like regulation stuff. Once I find my supply voltage I will regulatemy voltage. At this point there is no need to worry about it.

I have a feeling you are going to let the magic blue smoke out of your equipment...

What do I need to power my project? 12V DC 2A draw + 24V .5A draw

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