Running DC devices off a battery instead of wall wort?

[lkruper]

I am working on a plan to run "essential" devices from solar/battery during a power outage. I may purchase a fridge/freezer with manufacturer support for battery input and also a TV that has a DC input options. However some things like DSL modem, Satellite TV, computers (laptop and desktop) have a AC-DC wall wort. Has anyone powered these sorts of things directly from the battery and thus eliminated the cost and inefficiency of an inverter?

When forum members suggested I look at constant DC chargers instead of 3-stage chargers for the UPS style application, I noticed that some of them listed UPS operation as a function. I presume this means AC -> DC Charger -> Battery -> devices where the devices would get power directly from the battery all the time, not just in case of a power outage? Does this work and does it take its toll on the life expectancy of the charger?

[SunEagle]

I am working on a plan to run "essential" devices from solar/battery during a power outage. I may purchase a fridge/freezer with manufacturer support for battery input and also a TV that has a DC input options. However some things like DSL modem, Satellite TV, computers (laptop and desktop) have a AC-DC wall wort. Has anyone powered these sorts of things directly from the battery and thus eliminated the cost and inefficiency of an inverter?

When forum members suggested I look at constant DC chargers instead of 3-stage chargers for the UPS style application, I noticed that some of them listed UPS operation as a function. I presume this means AC -> DC Charger -> Battery -> devices where the devices would get power directly from the battery all the time, not just in case of a power outage? Does this work and does it take its toll on the life expectancy of the charger?

The issue with using just DC voltage to run those items is that they may not conform to a standard battery voltage (6, 12, 24, 48). Those wall worts inverts the 120v AC and transforms the correct DC voltage and amperage for what it charges. That could be 18 volts, 9 volts or 5 volts where a 12 volt battery is too high or too low.

My best suggestion is to get a Pure sine wave inverter and use that as your AC source for those wall worts. Just make sure your battery is sized for your inverter usage.

Also most UPS are designed to provide enough power to keep their load on for a short period of time. But they can only be cycled a few times before the batteries start to fail to hold a full charge.

[lkruper]

The issue with using just DC voltage to run those items is that they may not conform to a standard battery voltage (6, 12, 24, 48). Those wall worts inverts the 120v AC and transforms the correct DC voltage and amperage for what it charges. That could be 18 volts, 9 volts or 5 volts where a 12 volt battery is too high or too low.

My best suggestion is to get a Pure sine wave inverter and use that as your AC source for those wall worts. Just make sure your battery is sized for your inverter usage.

Also most UPS are designed to provide enough power to keep their load on for a short period of time. But they can only be cycled a few times before the batteries start to fail to hold a full charge.

Thanks. I did just deploy an APC UPS for my DSL modem/Verizon Extender that looks like it should give me 3-4 hours for those two devices that total 20 watts on my kill-o-watt meter. I may take the extender off the UPS as it has the larger draw. Since I have POTS and can plug in an old dial phone I can live without cell coverage in an outage. I understand UPS systems don't have the same cycle capacity as deep cycle batteries, but my power has not gone out for a good long time. If I get a manual transfer switch in place and have my generator at the cabin with sufficient gas, the time will be enough to hook up the genny before the UPS fails.

I also may purchase another UPS and spare battery combo (about $300 total from Amazon - 1500) that will give me the same buffer for my Satellite receiver, dish and TV. Now that I see how much batteries, chargers, inverters and transfer switches cost, I am impressed I can get that much functionality from an APC UPS.

[SunEagle]

Thanks. I did just deploy an APC UPS for my DSL modem/Verizon Extender that looks like it should give me 3-4 hours for those two devices that total 20 watts on my kill-o-watt meter. I may take the extender off the UPS as it has the larger draw. Since I have POTS and can plug in an old dial phone I can live without cell coverage in an outage. I understand UPS systems don't have the same cycle capacity as deep cycle batteries, but my power has not gone out for a good long time. If I get a manual transfer switch in place and have my generator at the cabin with sufficient gas, the time will be enough to hook up the genny before the UPS fails.

I also may purchase another UPS and spare battery combo (about $300 total from Amazon - 1500) that will give me the same buffer for my Satellite receiver, dish and TV. Now that I see how much batteries, chargers, inverters and transfer switches cost, I am impressed I can get that much functionality from an APC UPS.

That is the right plan. UPS or battery just big enough to keep the loads on for a short duration followed by generators for longer outages.

[Sunking]

MacGyver aka James Bond aka Mickey Mouse UPS

Battery Charger > Battery > Inverter

As long as commercial power is on everything runs off the charger. Two design rules to make it work.

1. Battery must be AGM and loaded to no more than C/2

2. Charger must be large enough to run all connected loads, plus recharge battery in acceptabl etim elimit sof no faster than 4 hours and no longer than 24 hours.

Easy peazy.

Oh third rule. Doh! Inverter must be sized appropriately.

[lkruper]

MacGyver aka James Bond aka Mickey Mouse UPS

Battery Charger > Battery > Inverter

As long as commercial power is on everything runs off the charger. Two design rules to make it work.

1. Battery must be AGM and loaded to no more than C/2

2. Charger must be large enough to run all connected loads, plus recharge battery in acceptabl etim elimit sof no faster than 4 hours and no longer than 24 hours.

Easy peazy.

Oh third rule. Doh! Inverter must be sized appropriately.

Thanks, lots to think about.

One thing that bothers me is that most inverters seem to cut off at too low of a voltage to protect the battery. I searched and found "Blue Sea Systems m-LVD Low Voltage Disconnect" at http://www.amazon.com/Blue-Sea-Syste...TQ9YA89E8B5SHM

The video says it has an adjustable cut-off but gives no details.

Is there a better solution?

[Sunking]

Thanks, lots to think about.

One thing that bothers me is that most inverters seem to cut off at too low of a voltage to protect the battery. I searched and found "Blue Sea Systems m-LVD Low Voltage Disconnect" at http://www.amazon.com/Blue-Sea-Syste...TQ9YA89E8B5SHM

The video says it has an adjustable cut-off but gives no details.

Is there a better solution?

For emergency systems no, and good Inverters allow you to set LVD set point. You can make a good argument if using a daily cycle system that improperly designed discharging too deeply every day. But for an Emergency system rarely used you are not going to harm the batteries going to 1.8 volts on occasion under load. when rested they will snap right back to 2 volts.

[lkruper]

MacGyver aka James Bond aka Mickey Mouse UPS

Battery Charger > Battery > Inverter

As long as commercial power is on everything runs off the charger. Two design rules to make it work.

1. Battery must be AGM and loaded to no more than C/2

2. Charger must be large enough to run all connected loads, plus recharge battery in acceptable time limits of no faster than 4 hours and no longer than 24 hours.

Easy peazy.

Oh third rule. Doh! Inverter must be sized appropriately.

Here is a trial balloon.

Samlex Power supply - $18.61 - (SD-15A-12) to Samlex Battery Backup ($54.16)(BM-1225 ). Power with Sun-xtender PVX-340T 34AV AGM ($123) Instead of expensive inverter use Samlex/Meanwell (SD-15A-12) DC-DC ($12.60)

The Battery Backup powers from DC power supply until power goes out then switches to the battery. It is configurable for either 2 or 4 amp output. C/20 for the 34AH battery is 1.7... is +15% close enough? The power supply at 3 amps needs to be able to handle charging current + load + 20%. The load for my DSL modem, the only thing being powered by this is 0.5 Amps at 12v (6w at 110). The existing wall wort is +12V DC +-5% @ 600mA max. The charging current is 2, so the power supply at 3 is sufficient.

The power curves for the battery give me 0.51 amps for 72 hours. Total is $208.37 plus tax. I could add Samlex Battery guard for $129.98 to give me the ability to configure 10 settings for VLD to protect a $123 battery.

All of this is to keep my DSL modem up when the power goes out. I hope Verizon keeps DSL working along with the POTS telephone service. If it does not, then I would need to re-purpose these devices!

[inetdog]

I hope Verizon keeps DSL working along with the POTS telephone service. If I does not, then I would need to re-purpose these devices!

Last I heard Verizon did not provide POTS.
I was not aware that they even offered DSL as an ISP. Using Bell wires, I presume?

[lkruper]

Last I heard Verizon did not provide POTS.
I was not aware that they even offered DSL as an ISP. Using Bell wires, I presume?

I have POTS at my home and also at my cabin in the mountains both with Verizon. I have FIOS at home and had a really hard time getting internet and TV with them without converting my POTS to FIOS. In fact, they canceled the first order and I had to work with someone else who knew the ins and outs to get it done and keep POTS. I want POTS so that I do have a telephone in a natural disaster when power is out without maintaining a battery for their UPS.

At my cabin I cannot get FIOS and as far as I know Verizon has been there for years with POTS and DSL. Do not know the history behind it or if Bell was the originator.

[inetdog]

I have POTS at my home and also at my cabin in the mountains both with Verizon. I have FIOS at home and had a really hard time getting internet and TV with them without converting my POTS to FIOS. In fact, they canceled the first order and I had to work with someone else who knew the ins and outs to get it done and keep POTS. I want POTS so that I do have a telephone in a natural disaster when power is out without maintaining a battery for their UPS.

At my cabin I cannot get FIOS and as far as I know Verizon has been there for years with POTS and DSL. Do not know the history behind it or if Bell was the originator.

Makes sense.
BTW, you may find that by getting a totally unused VOIP line from Verizon to complete a promotional package you may lower your price to less than the price of Internet and TV alone. (At least for the first year or two.)

[lkruper]

Makes sense.
BTW, you may find that by getting a totally unused VOIP line from Verizon to complete a promotional package you may lower your price to less than the price of Internet and TV alone. (At least for the first year or two.)

Perhaps, but I don't really trust them not to disconnect POTS and remove the copper once they have access to my house

[inetdog]

Perhaps, but I don't really trust them not to disconnect POTS and remove the copper once they have access to my house

If they really are out to get you, you are not paranoid.

[Sunking]

Last I heard Verizon did not provide POTS.

Dave Verizon is 3 companies.

Verizon Wireless Cellular
Verizon Network, traditional land line and former GTE telephone company (POTS and DSL)). Example many cities in TX are Verizon Network including all of DFW.
Verizon Businesses which is a carrier and former MCIWorldcom.

Well there is a forth which is international VodaPhone who was the Parent Company Verizon. Verizon Wireless ate its Mother.