Backup Power for Tablo

Tablo 4 Tuner DVR.
Seagate 1.5TB Backups USB Drive
Linksys WRT3200ACM Router.
3 Samsung monitors.
1 Linksys 3016 Cable Modem

What do all of these have in common? They are powered by 12volts. And I just figured out that when I lose power, even though the laptop switches to battery, the sudden loss of monitors really does piss off Windows 10 and it begins to misbehave worse than WinME.

So… Has anybody measured or have any data regarding the 12volt DC input on the back of the Tablo 4 Tuner? I have a 50AH Lithium Iron Phosphate 12volt battery (Medical Grade) sitting on the shelf in the closet. It is a Lead Acid drop in replacement. Output is actually closer to 14v when fully charged, dropping to 12.5 just before the disconnect solenoid opens up. Is 14 too high for the Tablo? Any ideas of what is considered to be the MAX / Magic Smoke Release voltage? I am already planning on knocking down voltage to the router using diodes (about .6v drop each diode) and will be taking it down to 12, with a max of 13.3-13.4 when fulling charged. I don’t have a high enough supply voltage that would allow me to use even a Low Dropout Regulator (usually 2volts higher than output). I do plan on using a 12v to USB charge hub to power the hard drive via a Y Cable. 1 of the type A connections is already prevented from sourcing power, that will be plugged into the tablo. The other connection will be plugged into the charge hub, and the drive will have power all the time.

If power fails again, the battery should be able to keep everything running for at least a few hours. 50AH will power 17amps of 12vdc current for at least 2 hours. And that is worst case scenario using ratings off of the various bricks and adapters.

I haven’t put my Tablo on batteries yet but I run many other devices using 12v DC. Most I purchase with batteries in mind. Those have circuitry to better handle the variance and the electronic noise. Keep in mind whatever you use to charge the battery will create that electronic noise. I suspect the voltage is not an issue however I stongly recommend you error on the side of caution. It won’t add much in cost to do it properly. For my router I purchased a DC to DC converter. This ensures my router gets the 12v that it likes wether my batteries are around 13.7V or all the way down to 10v where my DC shuts down for undervoltage. My router likes 19v which is also popular for many monitors. The DC to DC converter was also chosen to prevent electronic noise being introduced as well.

A 12v to 120v inverter is just wasteful when you have to convert it back to DC so I never really considered that as an option. I primarily charge my DC system via solar.

12vdc > 120vac > 12vdc via inverter is indeed wasteful. I used to rely heavily on APC UPS, but not same company anymore. Those haven’t been reliable for 15+ years now, especially failures in Smart Backups series.

I have usually opened up all of my toys and taken a look at the power supplies, looking for regulator info to be exact. Surprisingly, most use 5v electronics with similar power supplies. For these devices, I like to run input power down to around 9vdc. Sure does cut down the amount of heat that is created. Other devices, like my network equipment, are multivoltage. Logic is 5, but transmitter / receiver blocks are higher and often at 12v. If there is regulator in front of 12v, it is usually a buck that will knock down higher inputs but becomes passive when input is lower. I am not sure about my new router’s internals yet. Haven’t had opportunity to crack the case yet.

I suspect the Tablo is going to be 5v internals. No proof, just a feeling given its functions. But, until it is out of warranty, it likely will remain intact. I probably will insert a current meter on one side of the inputs. Then cut the wire between the probes. Start recording 4 shows, and I should have a good base current at full load. This might occur sometime today. Same with router. Have to see how far I get on honey do list.

I love using Dc-dc converters but I hate the price, complexity of additional equipment, and additional noise. You mention charger noise. The DC-DC converters common mode noise and output ripple are usually my biggest issues. Particularly for models that are isolated (no common mode though).

My favorite choice for chargers are the constant voltage converters that are used in RV and travel trailer industry. Auto Fan, thermal controls, voltage and current limiting, etc built in. Products of last decade show inferior design practices and component selection. Especially on the filter caps. 250v ratings on 120/240vac inputs. Seriously? Engineers place a lot of faith on input diodes in the doubled and rectified.

Anywho… 13.2 vs continuous at 40 amps with a regulation of between .5-1% tolerance and ripple max of 15-30mv from no-fill load is well within my comfort level. This is with an battery connected. I have found operation of these converters works better with a 10% minimum load, so task lighting is 12v, and laptop runs off an automotive adapter.

What are you using for converters, and why that particular model?

You can skip the middle man by using the power adapter that came with your Tablo, and wire the battery into the connection. That way you will never over-voltage the Tablo, and you will not need relays or any interrupt logic. Viola! Instant UPS for your Tablo. When the power drops, the battery will keep the Tablo running. When the power comes back on, the battery will recharge.

Simple. Cheap. Safe. Effective.

Thanks for suggestion, but there are several potential problems that you overlooked / ignored.

  1. a lead acid battery needs a charge voltage of
    13.2-13.5 for cyclic use and 13.5-14.1 for standby use.
  2. 12v lithium iron phosphate battery requires 14.4

So, usung oem adapter wont be sufficient to charge.

OEM adapter isnt designed to charge a battery.
3) Circuitry isnt designed for current required to charge a battery in a reasonable period even for a small sealed lead acid battery. Perhaps if it werent trying to power a tablo…
4) Circuitry for a power supply may not be capable of withstanding a voltage being applied to the output which would happen if power were to fail. 78xx series regulators are especially susceptible. Many switchmode drivers are as well.
5) inadequate current rating of adapter itself. Its intended to power a tablo, not to charge a battery, and certainly not to do both.
6) Wiring of adapter output too small, is only large enough to carry current of tablo demand with acceptable voltage drop.

Tablo protection.
7) if adapter fails, is warranty item. If modified, no warranty.
8) adapter is designed to operate a given load. Deviate from that, damage results. Output goes to zero, or output goes high potentially to 170volts which is the rms value of 120vac after it is rectified and filtered. In both cases, tablo doesnt work.

So…using a middle man of relays, converters, logic or whatever else is needed and expense is warranted.

A solution along your line of thinking does exist though. If a primary battery pack is attached using method you suggested but using a properly installed schottkey diode with a 3amp rating would work and would keep battery from being charged by and affecting adapter negatively. This would require that another diode also be properly placed between the adapter and connection point of battery. This prevents battery from affecting adapter, but also knocks down voltage by .4 to .7 volts. Tablo may not like this. The diodes are a minimum requirement for using a battery pack. The battery can be as simple as 8 alkaline batteries (lets say D cells) in series. This would run Tablo, under full load, for about 3 hours factoring current rating on adapter. Target voltage is 12, but battery will discharge and voltage will fall. Tablo quits when gets too low.

Using a dc-dc converter helps alleviate this by limiting and boosting supply voltage as needed and appropriate.

Using the diodes, a 12v rechargeable battery can also be used provided it has its own charger. Problem with declining voltage is still present. Corrected using dc-dc converters. Our original discussion revolves around this. And by using a common supply battery and corresponding charger, dc-dc converters are used to create the various voltages required by different devices from 5volts (usb) to 19volts (routers, monitors, laptops, etc) and including 12v for tablo and other networking equipment.

By the way… I have started using a powered usb hub to run my hard drive on. Hub is connected to a power bank that outputs 5v @ 3 amps via usb-a connection. If Tablo goes offline then the drive now has a better chance of resisting corruption due to it dying from lack of power during a data write. At least it will be able to save the internal cache.

You may be over-thinking this. What’s the peak output voltage of the Tablo power supply (measured)? You don’t need your battery fully charged. You just need enough to get you though a power blip. I have considered this just to deal with intermittent power interruptions to allow the Tablo to survive a few minutes when we get blips during thunderstorms so my recordings are not interrupted. Even without a fully charged battery, it will be superior to a bank of capacitors. If you are looking for hours of reserve, a UPS makes more sense.

I would not cut into the wires of the Tablo power supply. Rather, buy a matching male and female barrel connector and wire both to your battery. Connect the wall wart to the battery connector, and the battery to the Tablo using the new connector. Nothing about this can harm your Tablo, as the voltages will always remain in the range provided by the Tablo wall-wart.

Don’t get hung up on optimal charging voltages. You are not charging a phone…you are charging a very, very cheap UPS alternative for your Tablo.

Quick update on my “DC UPS”…

Battery pack is LFP, lithium iron phosphate manganese chemistry. Nominal voltage is 12.8ish give or take a few tenths. 15Ah @ rates 100dod. Charger is programmed to kick on when battery is 12.25v at terminals.

Charger is 13.5v output when battery is at beginning and end of charge cycle (constant voltage). I have a ‘stud mount’ rectifier diode that has a Vfd of .82v online with Tablo power cable. Across the diode are the normally closed contacts of typical 5 pin 20/30 automotive relay. One side of coil goes back to charger return, other side is isolated from battery using schottkey diodes in charger output going to battery.

Event sequence is:
Battery discharges to power Tablo through the normally closed contacts of relay, shorting rectifier. Tablo gets battery voltage.

Charger kicks in at 12.25 battery terminal volts, coil on relay is energized since is isolated via schottkey diode in charger output lead. Relay switches, rectifier diode is no longer shorted, battery begins to charge. Initially there is a .3 Vfd through schottkey diode, as 3A charge current tapers, it drops to .09 Vfd. Tablo sometimes sees a momentary spike of 13.2 but only last for a few tens of milliseconds, easily absorbed by power supply caps / inductors. When charger kicks off, battery voltage to tablo increases back to 13.5 and is usually drained off in a couple hours depending on Tablo activity.

This is by no means a final version, but more of proof of concept to justify. And for what its worth, Tablo ran just fine for 51 hours to a power supply voltage of 11.9v and from there I ran out of balls to let it go any further and risk drive corruption. Oh yeah, the usb drive is now powered via hub with its own wall wart. Did not notice any problems with floating grounds when charger was unplugged to let battery discharge.

I did notice however, some of my recordings, made during trial, do not have frame captures during the fast forward / reverse that you would expect to see featured when skipping commercials. I also have not been able to reproduce it.

…so much for quick update!

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Previously mentioned a UPS for Tablo, as well as other gear. I have changed directions, and so far, everything is working out very well.

I ordered a 9channel 5Amp 12v CCTV Power Distribution Panel in order to setup 4 security cameras. Looking at the terminal board, noticed that it was using 1.1Amp poly (resettable) fuses. Got a bright idea (!) and used a small alligator clip to jump across a few of them.

Sacrificing a spare power cord, I ran 12vdc from power distro panel to my tablo. Prior to putting in the inline fuse, I set the output voltage to 12.5vdc. Putting the fuse in, I feared the worse but was rewarded with a Tablo 4 Tuner OTA DVR that is working wonderfully! Wonderfully as in I haven’t had a glitch of any sort in over 4 weeks. Reduced voltage to 12.0 (and a few hundredths), temperature of my Tablo has dropped a few degrees, but only using relative measurement with my hands. PSA: Dont let kids use laser thermometer to entertain cats.

To clear up a lot of clutter, I ordered a 12volt 30Amp 18 Channel CCTV power panel monster off of Amazon. This one uses small glass fuses.
So, now I have a: (1) Linksys WRT3200ACM router (2) Two Western Digital Element external powered hard drives (1) Linksys 3016 Cable Modem (1) Generic tooless external hard drive case with 2TB drive (1) Powered P.O.S. wall ‘patch’ antenna (1) Security NVR (1) Tablo 4 Tuner and bringing up the last (1) 18650 battery charger. All are spec’d for 12v input. Each is fused (glass fuse model, remember?) with fuse equivalent to power supply rating. IE Tablo gets a 2A fuse. I did fudge and give the NVR a 3A as these darn things pop easily when NVR cold starts.

So, I have eliminated 9 wall warts, and centralized power distribution for my network “cabinet”. I no longer have 4 power strips daisy chained off each other. Wiring has been cleaned up tremendously. Lady of the House is happy. I am happy.

I would attach pic, but can’t figure out how, if it is possible. Upload button not working.

Next project is to run a high-amp circuit direct from power supply inside panel through fuses, over to laptop docking station, and use a DC travel charger to run laptop & docking station off of. 15Amps or so.

Project after that will be to add battery backup to the panel. 12v SLA or 12.8v LiFePO4 battery or 12v LTO (lithium tartanate, 5 cells) connected to +terminal on power supply through a 30amp 45v schottkey diode that has a Vfd of .315 to isolate them and allow independent charger to be used.

Oh yeah…
Western Digital drives use a 5.5mm x 2.5mm barrel connector
Tablo 4 Tuner uses a 5.5mm x 2.5mm barrel connector as well.
My 18650 battery charger uses a 2.5mm x 1.3mm barrel connector.
Everything else, so far, uses 5.5mm x 2.1mm barrel connector.

For those that only need backup for 1 device, Schneider / APC has (had?) a product called APC Connect that is able to supply up to 33 watts for up to 12 hours. Tablo power supply is rated at 24 watts…
$100 or so each. Intriguing, but I won’t pay that much just for 1 device.

For those that only need backup for 1 device, Schneider / APC has (had?) a product called APC Connect that is able to supply up to 33 watts for up to 12 hours.

Another option if you only need to backup the Tablo itself is to use a ‘Belkin Residential Gateway Battery Backup Rev B Model BU3DC001-12V’. These can be found quite inexpensively on eBay:

I doubt this will give the same 12 hours runtime that is stated for the APC Connect, but it should last several hours & is much less expensive.

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Good info! The APC was lithium powered and resulting in a much more stable output when mains fail. The Belkin gateway will likely be the selected option for most due to price, and possible to connect a larger battery (perhaps w/ ext charger) for the more ambitious and technical group.

FWIW, the APC solution has a 12hour life based on .5 (half) amp load. Peak load was around 3 hours id memoey serves. Belkin isnt listing run-times with various loads.

I have also discovered a design oversight in the CCTV panel I am using. Fan and vent arrangement lead to warm air being recirculated with cooling occurring by transfer of heat from air to metal box. Not that efficient either.

I have ordered the appropriate metal hole saw, grill / filter assy to correct. Basically will cut a 2.5" hole in front panel for power supply fan to exhaust through. Foam filter media will be attached to existing vents. Until I get the mod finished, I am just leaving the door cracked. Noisy, but much cooler.

Still cannot believe the design of cooling. The power supply had to have been changed / upgraded at some point in past. Current setup is plain idiocy.

Will post pics when I can get Android to behave properly with webpage.

FWIW, the APC solution has a 12hour life based on .5 (half) amp load. Peak load was around 3 hours id memoey serves. Belkin isnt listing run-times with various loads.

I have not tested runtime with Tablo. However, I have several of the already in-use. One of them powers my Internet modem and router. They both run on 12 volt. They both have a modest amperage requirements so I use a splitter & use both on one backup. Sometime back I had a power outage that lasted ~4 hours and they both stayed up during that time.

Finally figured out why I couldn’t upload pictures…something to do with permissions and external sdcard and Firefox.

First Pic is stock pic of a Let our 30A 18Ch CCTV Distributed Power Supply. Amazon. Edited out accessories.

Second Pic is same supply with highlights showing problem areas.
Blue - Vents at corners on side of cabinet. No filtration (yet).
Yellow - Intake vents of supply itself. I didn’t highlight for clarity, but supply sucks air in above terminal strip on (top) end.
Red - exhaust vent of power supply. Before mod, when door is closed exhaust air blows against door and recirculates around cabinet getting warmer and warmer.
Green - location to cut hole in door, direct inline with exhaust vent of power supply.

Used a Frankenstein circle cutter from Harbor freight to scrape a hole in door panel. Hole center was marked by using a small rubber ball cut in half. Flat side centered on supply, grease at top of round half. Close door, used center punch to mark middle of grease spot now transferred to door. Ball was a superball that cost me a quarter out of gumball machine.

Used a dremel to remove mushroom on bottom of each door hinge, popped pins, and took door panel to drill press to scrape out the hole. Ended up finishing cut with a body saw, but left jagged edge. I should have just bought the $20 3 inch stepped drill bit. Lesson learned.

Used hot melt glue to attach fan grill filter assy (sans filter) to front of door, centered over hole. Also used additional hot glue to cover sharp edges around hole. Didn’t use machine screws since they would have interfered with gasket.

Using fan grill as template, cut out center of 3inch square x 1/8inch thick double sided adhesive squares. 2 were stacked on power supply, 1 was applied to interior side of door. The Franken-gaskets work well to direct air from power supply through the door. Supply is approx 3/8inch set back from edge of cabinet interior. If gaskets were not used (I tried), some air blows out through door but some air recirculates.

Supply has been running just a degree or so above room temperature. Much better than the 130-140F temps I measured prior. I am no longer concerned with overheating.

Next mod will be adding an isolated battery to make a DC UPS. Actually, very next mod, still undone, is to add pieces of foam air filtration to each intake vent. Have to wait until I find suitable donor material or walmsrt sells foam “diy” foam filters again (seasonal).

Fan noise is about the same as when door was open. Adding the hole didn’t make it any quieter. And the damn fan runs 24/7 as its not on temp control.

I can post part numbers of materials if anyone is truly interested.






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