Converting to 12v negative ground OT

[TodFitch]

As many of you know I have long claimed that a 6v electrical system in good shape is just fine in our old cars. And this post is not about that and I am keeping the original 6v positive ground system in the old Plymouth.

However the home phones are another matter altogether. A while back we switched to pure VoIP for the telephones in our house. Well, one 13 hour power outage recently made me decide that we needed more reliable phone service. Service that would stay up for a reasonably long power outage.

I noticed that most, but not all, of the network equipment associated with VoIP (DSL modem, Cable modem, one switch and the little Linux Asterisk box) we running on 12v DC with the outer barrels of their power plugs (the ground) being negative. They just happen to be run by "wall warts" that convert the AC house voltage to low voltage DC.

So I'm swapping out the remaining stuff for equipment (router and another switch) that runs on 12v DC. I'm going to run all that on a deep cycle battery far larger than the ones available in the UPS and I won't have the conversion losses (battery in UPS -> 115VAC -> wall wart 12VDC). I figure I can have the phone up for at least a day maybe even a couple of days before the battery is discharged too far. And will be able to sleep without the racket of the portable generator.

And if I want a quiet generator to charge the phone system battery, all I need is a modern car and jumper cable.

[Oldguy48]

You might want to consider the use of appropriately sized fuses in the power cords for those devices. A deep cycle battery would have enough energy to vaporize those cords in the event of a short in one of the devices you are going to connect. I know it's not likely to happen, but Murphy could come for a visit.:eek:

[Norm's Coupe]

Why not just pick up a Battery Backup like you use for the computer That way, you can just plug the phone directly into the backup during an outage with a 12 volt adapter. I can run the computer for at least 2 hours without AC power with the back up. I would think a phone would take much less power and the battery would last many more hours.

Edited November 17, 2009 by Norm's Coupe

[TodFitch]

You might want to consider the use of appropriately sized fuses in the power cords for those devices. A deep cycle battery would have enough energy to vaporize those cords in the event of a short in one of the devices you are going to connect. I know it's not likely to happen, but Murphy could come for a visit.:eek:

Those ham radio people have been down this route too. Nice little (but expensive) 12v distribution panels with individually fused outlets using "Anderson powerpole" plugs. Most of the devices claimed 0.75 to 1.5 amps so I am putting 2 amp fuses on everything.

Why not just pick up a Battery Backup like you use for the computer That way' date=' you can just plug the phone directly into the backup during an outage with a 12 volt adapter. I can run the computer for at least 2 hours without AC power with the back up. I would think a phone would take much less power and the battery would last many more hours.[/quote']

Been there, done that. And that is what I am replacing. Doesn't last 24 hours.