Powering 12v router from a 12v battery bank, 12v connectors

freedj

I have a router that uses a 12v 1a wall wart and would like to power it directly from my 12v battery bank. In this application should I look for a 12v to 12v converter or would you simply connect it directly and expect that the normal range on the 12v bank would be acceptable?

I would like to skip the converter losses if I could but don't want to damage the router.

Also, what kind of connectors do people use for this kind of application? I am considering using banana plugs to make it easier to connected small 12v loads to the battery.

Blackcherry04

Re: Powering 12v router from a 12v battery bank, 12v connectors

freedj wrote: »

I have a router that uses a 12v 1a wall wart and would like to power it directly from my 12v battery bank. In this application should I look for a 12v to 12v converter or would you simply connect it directly and expect that the normal range on the 12v bank would be acceptable?

I would like to skip the converter losses if I could but don't want to damage the router.

Also, what kind of connectors do people use for this kind of application? I am considering using banana plugs to make it easier to connected small 12v loads to the battery.

It should work fine with a couple of caveats. Un-hook it if you Equalize, above 14.5 volts gets risky. I'd put in a inline fuse. Make sure the output is 12 V DC and not 12 V AC on the wall transformer. Then you need to check the Polarity of the plug. Some are " Center Ground " , most are not, but there is NO guarantee what yours will be. If you hook it up wrong , you'll smoke it ..... been there done that.

paulskirocks

Re: Powering 12v router from a 12v battery bank, 12v connectors

I went with a DC to DC regulated supply for all my sensitive 12 volt stuff, just to be safe...

BB.

Re: Powering 12v router from a 12v battery bank, 12v connectors

Remember that a DC to DC supply is a conversion step too... Pretty similar to 12 to 120 VAC. You probably have higher standby losses with an AC inverter--But I would check your DC to DC supply to make sure.

I have checked many of the power cord supplies of my laptop and USB AC adapters and they seem to draw less than 1 watt when the load is not drawing power--Pretty good results.

-Bill

Cariboocoot

Re: Powering 12v router from a 12v battery bank, 12v connectors

In some cases the equipment will actually operate on less than 12 VDC making it possible to put a diode (or more) in line and prevent the Voltage from rising above maximum when the batteries are charging. Takes a bit of finagling to figure it out though. May not be worth the effort.

freedj

Re: Powering 12v router from a 12v battery bank, 12v connectors

I think im going to put a 7812 voltage regulator in line to protect against overvoltage. They are less than $2 at the local radio shack. It's limited to 1A of current, but that's all my router needs so I should be in good shape.

freedj

Re: Powering 12v router from a 12v battery bank, 12v connectors

Hrm, that's not going to work as the 7812 requires 14v in. Back to the drawing board. Im trying to avoid a boost-buck converter but that might not be possible.

dhsola

Re: Powering 12v router from a 12v battery bank, 12v connectors

I've had a Zoom DSL modem running off a single 55A/h AGM battery through a 12V power strip for years. So far, no problem.
Have the cordless phone base (occasionally) running off it too but had to add 12V DC isolator (model #SH12-670) to get rid of the hum during calls. Used to have the hub switch running on it too, now that I recall.
The wall wart for the modem says 15V DC.
I run my laptop directly from a different 12V wet cell battery using this DC to DC adapter and a couple of alligator clips. Battery life is much better

RandomJoe

Re: Powering 12v router from a 12v battery bank, 12v connectors

I ran my Linksys WRT54G, cable modem (was an old Linksys, then the cable company upgraded me to a Scientific Atlanta), D-Link switch and a 7W ARM-based SBC for my firewall directly off my 12V bank for quite some time until I upgraded to 48V. I found the "12V" adapters actually were closer to 14V+ anyway (the Linksys ones were just transformer type, not switchers) so I didn't worry about it.

I will grant I don't equalize very often at all, can't say if I ever did it while they were attached.

I also had a pretty long wire back to where they are located, a 4-conductor 18-ga cable with the conductors paired (so 2 18-ga wires per + and -) probably 30-40 feet long. There was some voltage drop inherent in that too, as the four devices pulled about 1.5A combined.

I use Anderson Power Poles for my 12V DC connectors. I have a *LOT* of 12V stuff, being a ham radio operator... The price was a LOT better than I was paying for connectors at Radio Shack. I get mine here: http://www.powerwerx.com

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

dhsola wrote: »

I've had a Zoom DSL modem running off a single 55A/h AGM battery through a 12V power strip for years. So far, no problem.
Have the cordless phone base (occasionally) running off it too but had to add 12V DC isolator (model #SH12-670) to get rid of the hum during calls. Used to have the hub switch running on it too, now that I recall.
The wall wart for the modem says 15V DC.
I run my laptop directly from a different 12V wet cell battery using this DC to DC adapter and a couple of alligator clips. Battery life is much better

How did you attach the DC to DC adapter to the battery? I would like to be able to safely power a rather expensive computer (and a wifi router/modem) from a 12V battery during power outages and am looking for a way that costs as little as possible.

RandomJoe

Re: Powering 12v router from a 12v battery bank, 12v connectors

I'm not the person you quoted, but looking at the link provided if you get a model like that it has a cigarette lighter plug. Radio Shack sells (or used to!) "accessory outlets" that would work for that. The quickest temporary method would be one with alligator clips to attach to the battery, or simply attach the wire leads to the battery. Smaller batteries will have either quick-connect terminals or bolt holes you can bolt a ring terminal to.

For something larger with car-battery style posts you can either use an old battery cable (though those are rather thick) or get a "replacement" battery cable end. They have the post clamp on one end and some sort of wire terminal on the other. Intended for big battery cables, but the ones I've seen use a couple bolts to clamp the heavy wire down and you can put a ring terminal under the head of one of the bolts instead.

You should fuse whatever you hook up to a battery. Most of the "accessory outlets" I've had over the years came with a fuse in the wire, but if not you can also pick up an inline fuse at the auto store too.

Just looked on Radio Shack's website, this would be the quick & easy way:
http://www.radioshack.com/product/index.jsp?productId=3889591
Clamp the alligator clamps to the battery posts, plug in whatever you want to run.


That said, if this equipment normally runs off 120VAC and you only want a setup for power outages, I wouldn't bother with getting the DC-DC power supplies, which can be pricey. Instead just get a good quality true-sine inverter (I have a Samlex, there are a few others) and use that. Much simpler! For a smaller inverter like 300W you can (in a pinch, with low-power devices) use alligator-clips to attach it to the battery (think mine even came with them) though they tend to run better (and for higher power require) with good solid attachments to the battery terminals.

Edit:
Here's a link to the style inverter I use. You can see a variety of others on NAWS' site as well. I prefer to use true-sine (or pure-sine) inverters instead of mod-sine.
http://www.solar-electric.com/sa300wa12vos.html

Blackcherry04

Re: Powering 12v router from a 12v battery bank, 12v connectors

The only thing not mentioned is making sure you have the correct polarity. There is never a guarantee that one or the other is the + / - on the power supply or modem. Some will be marked and some not. Generally it's the center post, Positive, but not always.

The wrong connection will give you Magic Smoke real quick.
.

Cariboocoot

Re: Powering 12v router from a 12v battery bank, 12v connectors

Blackcherry04 wrote: »

The only thing not mentioned is making sure you have the correct polarity. There is never a guarantee that one or the other is the + / - on the power supply or modem. Some will be marked and some not. Generally it's the center post, Positive, but not always.

The wrong connection will give you Magic Smoke real quick.
.

If you're wiring up your own this problem can be alleviated by putting a diode on the positive lead from the battery. Any connections reversed downstream of it will result in a no-go. Of course you could accidentally put the diode in backwards .... nothing is perfect!

Another advantage to the diode is that it will drop up to 1 Volt from the battery; this can actually help on a solar charged system where the "12 VDC" can be as high as 15 when charging and some "12 Volt" devices will not take that much, but won't be harmed by having <12 available when the battery gets low.

Thom

Re: Powering 12v router from a 12v battery bank, 12v connectors

I just use a cigarette lighter cable . Never had any trouble . It's a netgear unit . Charge iPad phones MP3 players the same way .

Thom

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

Can I run a laptop directly from a battery (with an adapter similar to the one in your link) by snipping off the adapter's dc plug, splitting the wires of the cord, and attaching them to alligator clips?
Or would it be better to wire a DC outlet to the battery and plug the computer adapter into that?

May I ask how specifically you attached the router to your battery? Sorry to ask something so basic, but I haven't done these things before and I'm cautious.

Thank you.

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

Is there a way to reliably test the polarity of things? Can you explain a bit more about putting a diode on the positive lead? The diode concept is entirely new to me - looked it up and read briefly that it restricts current to one direction, but beyond that the elaboration and description of types got more complex than I can deal with at the moment. What kind would I use, how would it be attached? Would it be used in addition to a fuse, and if so, wired in before or after the fuse?

Thank you very much.

Cariboocoot

Re: Powering 12v router from a 12v battery bank, 12v connectors

You can test the output of each device's power supply with a DMM, note the polarity, and write down carefully which is positive and which is negative for the connector. If you have it reversed the reading will give negative Volts so make sure you watch for a little "-" showing up.

The trick with the diode is that you still have to get its output on what is the positive input to the device. If polarity is not observed there it can still be reversed. It can be protection for the device side, but not the power supply side. Nothing beats being careful. It's a pity manufacturers don't spend a few cents to build this in, but they don't expect their equipment to be used with other than their power supply and don't care what happens if it isn't.

If little Voltage drop is desired then you need to use a Schottky type diode, which does not reduce V much across it. Other diode types may drop 1 Volt or more, which can be useful if you are purposefully trying to keep Voltage below a certain maximum. The other key element is that it must be able to handle the current demands of the particular device. Not much of an issue with things normally powered by "wall warts" as they tend to draw <1 Amp on the DC side. Laptops are higher power users, but probably don't need the diode anyway.

BB.

Re: Powering 12v router from a 12v battery bank, 12v connectors

Another reason I sort of like AC even for smaller system... No polarity issues with DC devices.

If is something you will "hard wire"--It is something you only check once.

If is something you will be making on and off temporary connections--Then chances of mistakes is more likely.

For 12 VDC appliances/electronics, HAM (armature radio operators) us a lot of Anderson Connectors and can buy power distribution systems setup for exactly this application:


http://hamradionation.com/browse_vidfeeders.php?tag=Anderson+powerpole

-Bill

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

RandomJoe wrote: »

I'm not the person you quoted, but looking at the link provided if you get a model like that it has a cigarette lighter plug. Radio Shack sells (or used to!) "accessory outlets" that would work for that. The quickest temporary method would be one with alligator clips to attach to the battery, or simply attach the wire leads to the battery. Smaller batteries will have either quick-connect terminals or bolt holes you can bolt a ring terminal to.

For something larger with car-battery style posts you can either use an old battery cable (though those are rather thick) or get a "replacement" battery cable end. They have the post clamp on one end and some sort of wire terminal on the other. Intended for big battery cables, but the ones I've seen use a couple bolts to clamp the heavy wire down and you can put a ring terminal under the head of one of the bolts instead.

You should fuse whatever you hook up to a battery. Most of the "accessory outlets" I've had over the years came with a fuse in the wire, but if not you can also pick up an inline fuse at the auto store too.

Just looked on Radio Shack's website, this would be the quick & easy way:
http://www.radioshack.com/product/index.jsp?productId=3889591
Clamp the alligator clamps to the battery posts, plug in whatever you want to run.


That said, if this equipment normally runs off 120VAC and you only want a setup for power outages, I wouldn't bother with getting the DC-DC power supplies, which can be pricey. Instead just get a good quality true-sine inverter (I have a Samlex, there are a few others) and use that. Much simpler! For a smaller inverter like 300W you can (in a pinch, with low-power devices) use alligator-clips to attach it to the battery (think mine even came with them) though they tend to run better (and for higher power require) with good solid attachments to the battery terminals.

Edit:
Here's a link to the style inverter I use. You can see a variety of others on NAWS' site as well. I prefer to use true-sine (or pure-sine) inverters instead of mod-sine.
http://www.solar-electric.com/sa300wa12vos.html

Thanks very much for the reply and the links. I'd assumed I'd get an email if there were any replies, and I hadn't, so re-posted above, then noticed all the posted answers.

Your information is exactly what I was looking for. Do you think the Radio Shack adapter has heavy enough (it's 16 guage) wire? It's not fused and isn't supposed to exceed 10 amps current.

I was thinking about directly attaching these things to the battery because I can get a dc-dc adapter for the computer for under $20 on amazon, but you have me re-thinking the true sine inverter, especially as it has 2 ac outlets.

I haven't found an adapter to attach the router yet. It has a fairly skinny cord which plugs into the back of the router with a round jack and has a dc to ac adapter with ac plug on its other end. Do you know a way to attach that without a router-specific adapter??

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

Cariboocoot wrote: »

You can test the output of each device's power supply with a DMM, note the polarity, and write down carefully which is positive and which is negative for the connector. If you have it reversed the reading will give negative Volts so make sure you watch for a little "-" showing up.

The trick with the diode is that you still have to get its output on what is the positive input to the device. If polarity is not observed there it can still be reversed. It can be protection for the device side, but not the power supply side. Nothing beats being careful. It's a pity manufacturers don't spend a few cents to build this in, but they don't expect their equipment to be used with other than their power supply and don't care what happens if it isn't.

If little Voltage drop is desired then you need to use a Schottky type diode, which does not reduce V much across it. Other diode types may drop 1 Volt or more, which can be useful if you are purposefully trying to keep Voltage below a certain maximum. The other key element is that it must be able to handle the current demands of the particular device. Not much of an issue with things normally powered by "wall warts" as they tend to draw <1 Amp on the DC side. Laptops are higher power users, but probably don't need the diode anyway.

Thank you, that boils it down nicely.

jnh

Re: Powering 12v router from a 12v battery bank, 12v connectors

freedj wrote: »

Hrm, that's not going to work as the 7812 requires 14v in. Back to the drawing board. Im trying to avoid a boost-buck converter but that might not be possible.

Any modern router (or switch, Wifi AP, DSL modem, etc.) accepting 12VDC input already has a buck-type switching regulator onboard for converting the 12V down to 5V, 3.3V, 1.8V, or similarly low voltages, which means they have a relatively wide tolerance range. With the possible exception of cooling fans, if one is present, nothing inside these types of devices uses the +12V power directly. It's the ones that take +5V input that you have to be careful of.

I've tested a lot of devices from Netgear, Linksys, Cayman/Netopia, Ubiquiti, etc. over a 10V - 15V range, and operated them directly from a 12V battery bus for years without ever having any trouble, even when charging at 14.2V. Many marked for 9V are happy to run from 12-15V also, and since they are constant-power loads, the current draw goes down as voltage goes up (within reason). If you go too high, the buck circuit can end up switching at a much lower PWM duty cycle than intended, though, which can cause its inductor to emit annoying hissing or squealing sounds. Even that is usually harmless.

If you want to be extra cautious, open the cover and take a look at the electrolytic filter capacitor used on the DC input, which should be marked with a maximum voltage that should never be exceeded. 16V is common, but some are 25V or 35V. Another thing to check is the small DC-DC converter control chip being used -- e.g. MC34063 is one that was popular for a while. If you can find a datasheet online based on this part number, that will give a maximum input voltage. Usually the capacitor is the limiting factor, though, and in cases where that's marginal it can be replaced.

Occasionally there might be a power supervisor IC that prevents the device from operating if its input voltage is too high, requiring a dropping diode, etc. to satisfy, but these are rare on consumer-grade network gear.

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

BB. wrote: »

Another reason I sort of like AC even for smaller system... No polarity issues with DC devices.

If is something you will "hard wire"--It is something you only check once.

If is something you will be making on and off temporary connections--Then chances of mistakes is more likely.

For 12 VDC appliances/electronics, HAM (armature radio operators) us a lot of Anderson Connectors and can buy power distribution systems setup for exactly this application:


http://hamradionation.com/browse_vidfeeders.php?tag=Anderson+powerpole

-Bill

That's a useful thought about the lack of polarity issues with ac. The Anderson connection system is beautiful. I'm glad to know about it, and the videos are helpful. One more thing to consider, thanks.

RandomJoe

Re: Powering 12v router from a 12v battery bank, 12v connectors

elia wrote: »

Your information is exactly what I was looking for. Do you think the Radio Shack adapter has heavy enough (it's 16 guage) wire? It's not fused and isn't supposed to exceed 10 amps current.

It's fine as long as you won't be using more than 120W (12V x 10A). Running a laptop from that is fine, few are going to get anywhere near that unless they're the "desktop replacement" type. A couple lights would be okay, long as you're using LED or CFL. If you need more than that, just hook up two of the outlets (or whatever). However, you probably won't draw >10A from a single battery for very long. It may have the capacity to "last" for a few hours, but the voltage will sag pretty low which could cause some devices not to function properly.

I wouldn't run an inverter through the socket, as it's just as easy to hook the inverter directly to the battery (since you have to hook the socket to it) and that would be a far better connection for it.

There is also no reason you can't do both - wire an inverter AND 12V socket to the battery. Run some devices with 120V AC, and have some straight 12V stuff as well.

I was thinking about directly attaching these things to the battery because I can get a dc-dc adapter for the computer for under $20 on amazon, but you have me re-thinking the true sine inverter, especially as it has 2 ac outlets.

I'm a bit cynical, so tend to be overly suspicious of really cheap Ebay or Amazon items, so take this for what it's worth... :roll: I'd be very hesitant to trust my multi-hundred-dollar laptop to a sub-$20 power supply unless I had Really Good Proof it was actually a quality item! Indeed, that's another reason I went with AC inverters, rather than locating quality supplies for everything I just work on a single quality inverter then use the device's own power supply. It's one thing to experiment with a $40 router or cable modem, quite something else to risk my far more expensive laptop!

No problem adding outlets to an inverter either - just plug in a power strip. My small inverters only have a single outlet but I run multiple devices with a strip. Many plugs doesn't matter, just the total wattage.

I haven't found an adapter to attach the router yet. It has a fairly skinny cord which plugs into the back of the router with a round jack and has a dc to ac adapter with ac plug on its other end. Do you know a way to attach that without a router-specific adapter??

It isn't so much a router-specific adapter, as an adapter that supplies the correct voltage and can be fitted with the correct tip size. The problem is there is a bewildering array of tip sizes - many VERY close to each other. For lower-power items, Radio Shack does sell a multi-voltage adapter (switch on the unit lets you select the voltage you need) with a generic two-pin socket at the end. You then purchase an "adapt-a-plug" tip that fits your equipment. I think they have a catalog that cross-references a lot of devices, I usually just measure or take the device in and start trying out different sizes until I find one that fits well. The adapt-a-plug sockets into the end of the power supply's cable, then plugs into your device. You just have to ensure you get the polarity right, there are markings on the adapt-a-plug and cable end you line up to get the desired end result.

Many - but not all - wall-wart power supplies will list on the sticker how the polarity is wired. They'll show a little graphic of a circle with a dot in the center. A line from the center dot and a line on the other side from the circle are labeled with + and - indicating polarity. As was mentioned earlier, positive tip (+ connected to the center dot) is most common but not universal. If it isn't marked on the sticker, some devices will have it shown the same way beside the socket, though this seems less common lately.

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

You're right about the cheap adapter. That was probably wishful thinking. (None of your information -- or that from anyone else kind enough to have answered -- is falling on deaf ears. I'm finding it all useful, and many thanks to everyone.)

To wire an inverter and a 12v socket to a battery, would the connections for the inverter and the connections for the socket need to be insulated from each other at the battery terminals?

And if can get away with asking yet another question, can a trickle charger be connected to the battery also, or would the aforementioned connecters have to be removed first?

inetdog

Re: Powering 12v router from a 12v battery bank, 12v connectors

elia wrote: »

You're right about the cheap adapter. That was probably wishful thinking. (None of your information -- or that from anyone else kind enough to have answered -- is falling on deaf ears. I'm finding it all useful, and many thanks to everyone.)

To wire an inverter and a 12v socket to a battery, would the connections for the inverter and the connections for the socket need to be insulated from each other at the battery terminals?

And if can get away with asking yet another question, can a trickle charger be connected to the battery also, or would the aforementioned connecters have to be removed first?

The battery is a voltage source that can feed (or accept) to/from many connections in parallel. No need to separate them from each other. And if you have multiple batteries in parallel, you specifically want all of them to go to the same set of battery posts.

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

Sorry if this seems redundant, but I need redundancy here: Then if multiple connectors are attached to one terminal, they won't spark, cause interference with efficient current conduction, or somehow confuse transmission of current to the various wires/devices they're attaching even if metal parts of connectors touch each other? And even if one set of wires is bringing current in (trickle charger) and others are taking it out?

Cariboocoot

Re: Powering 12v router from a 12v battery bank, 12v connectors

elia wrote: »

Sorry if this seems redundant, but I need redundancy here: Then if multiple connectors are attached to one terminal, they won't spark, cause interference with efficient current conduction, or somehow confuse transmission of current to the various wires/devices they're attaching even if metal parts of connectors touch each other? And even if one set of wires is bringing current in (trickle charger) and others are taking it out?

Nope. Not a problem.

Think of it like a car: lots of accessories powered by the same battery, each with its own right size wiring and fuse. This is just the same thing.

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

OK, I'll trust it. I can accept the idea of energy being distributed from a central point on separate feeds; it's just a little hard to accept that the literal physical meeting of the various connections at the one point (instead of complete isolation from one another at the source) won't cause the occurrence of some kind of dramatic and regrettable event. That's quite surprising to me.

BB.

Re: Powering 12v router from a 12v battery bank, 12v connectors

Electricity in many ways (including lots analogies to simple and even higher level math) is very much like water.

Water "magically" appears at 60 PSI at the front of your house--Different size pipes carry it to different locations.

You can put a well in your back yard and (illegally) pump water back out to the street and turn your water meter backwards. etc.

There is reason we "isolate" electricity... But for common home/cabin type applications--You can have all electrical appliances share a common ground (or neutral)--Even AC and DC sides of your AC inverter can (with TSW inverters) can have the Battery negative grounded to the same earth rod as the AC neutral side.

The "rules" are fairly simple--The problem is that you have to "obey" all the rules at the same time or something can go badly wrong.

Try not to get too wrapped up in the what ifs---And just focus on your needs (i.e., DC power for a laptop and possibly a small inverter). That defines the battery size--Then that defines the charging sources (PV, generator, AC mains power)...

At that point, you have the "numbers" and it becomes looking up the various parts that fit into your paper puzzle. Put it all together (on paper), check the numbers--Then go out and buy the hardware.

Don't try to understand all the "theory" for everything--It is very confusing. Once you have a base knowledge, then you build on that base.

-Bill

Cariboocoot

Re: Powering 12v router from a 12v battery bank, 12v connectors

elia wrote: »

OK, I'll trust it. I can accept the idea of energy being distributed from a central point on separate feeds; it's just a little hard to accept that the literal physical meeting of the various connections at the one point (instead of complete isolation from one another at the source) won't cause the occurrence of some kind of dramatic and regrettable event. That's quite surprising to me.

Not really any different than what happens in your household breaker box: power comes from the mains, connects to the bus bars, and from there branches off to numerous sub-circuits. So long as the wiring is correct and the circuit protection in place the most dramatic occurrence that would happen would be rapid depletion of the battery.

elia

Re: Powering 12v router from a 12v battery bank, 12v connectors

Thanks to BB also -- I'll get a plan together at some point ( I have some considering to do) then run it by you all before finalizing. Does a simple: trickle charger (PV or electric) to battery to inverter (fused on battery side close to battery) setup need to be grounded, and how is that accomplished?